WN 100 FBOTt 1W4 UNIVERSITY OF CALIFORNIA SAN OIEGO B 3 1822 01207 5479 LIBRARY university op california SAN DIE&O BIOMEDICAL LIBRARY UNIVERSITY OF CALIFORNIA, SAN DlEfiO DATE DUE ««»i«k O H SEES TtB * D nww UDV $ 1 * £K a .4 n »% • • • ■■* M/IR c; RFC? J 19 FEB 2 3 RECO OCT 9 1984 nrrr 1 : i nnro GAY LORD PRINTED IN US A UNIVERSITY OF CALIFORNIA SAN DIEGO B 3 1822 01207 5479 (k> Plate. Photographs of Electric Discharges. ELEMENTS OF GENERAL RADIO-THERAPY FOR PRACTITION ERS BY Dr. LEOPOLD FREUND, Vienna. TRANSLATED BY G. H. LANCASHIRE, M.D. Brtjx., M.R.C.S. Eng., L.R.C.P. Lond. Assistant Physician to the Manchester and Salford Hospital for Skin Diseases. With One hundred and seven Illustrations in the J^ext and one Frontispiece. NEW YORK REBMAN COMPANY, 10 West 23D Street, Cor. 5th Avenue. LONDON AGENTS : REBMAN, LIMITED 129 Shaftesbury Ave., London, W. C. 1904 Entered according to Act of Congress, in the year 1904 BY REBMAN COMPANY in the Office of the Librarian of Congress, at Washington All Rights Reserved Entered at Stationers' Hall By REBMAN LIMITED, LONDON BUKR PRINTING HOUSE NEW YORK TRANSLATOR'S PREFACE. The translator has pleasure in introducing Dr. Freund's work to a larger circle of the English-speaking profession. For the undertaking itself he feels that no apology is needed; Dr. Freund's position in this department of medicine more than justifies the enterprise. The author is known — though the fact appears in many quarters to have been insufficiently recog- nised — as the man to whom, perhaps, more than any other we owe the foundation of Roentgen-therapy. The following pages, indeed, speak for his arduous labours in the whole subject of radio-therapy. Apologies are rather needed for this English setting; these are freely extended, both to the author, whose meaning may possibly have been in places misconstrued, and to the reader. Here and there a somewhat free translation has been rendered necessary by the exigencies of the language — a necessity which all readers of German will be the first to acknowledge. In cer- tain places omissions have been made with the author's permis- sion. In conclusion, the translator's grateful thanks are recorded for the kindly help afforded him by many friends. G. H. Lancashire." Manchester, January, 1904. AUTHOR'S PREFACE. In this work I have attempted to bring the essential features of a recent form of treatment before the notice of a larger circle of medical men. I had before me the task not only of describing in a comprehensible manner the technique, the indica- tions for and results to be expected from the various radio- therapeutic methods, but also of tabulating and arranging the fundamental physical laws these nature-forces obey, thereby more fully explaining their physiological effects. Six years' arduous theoretical and practical work in all the branches of radio-therapy treated of in this volume form my excuse for a partial survey of this department of medicine, and may fairly entitle me to undertake a work of this nature. I have not limited myself to the description merely of my own investigations and conclusions, but have quoted every au- thor who has written on this subject, controlling wherever pos- sible his deductions by my own experiment. Where it seemed advisable for the further comprehension and investigation of a subject, the older physical and photochemical works have been quoted. I have purposely presupposed but little knowledge on the part of the reader, as will be seen in the introductory chapters on physics. I have tried as far as possible to include the most recent ideas, drawing from the knowledge obtained in practice up to the present time, while referring the reader to the various sources which afford fuller information on the separate subjects. Above all, the present work makes no claim to have thoroughly exhausted its subject, nor must the conclusions ar- rived at be considered infallible. It is a truism that, however complete an observer's knowledge may seem to be, in course of time fresh facts partly contradict his earlier conclusions. It requires but a brief glance to show the enormous amount of work which a large number of investigators have already vi AUTHOR'S PREFACE accomplished, and the great progress which has been made in a few years with the question of radio-therapy. Such zeal, such intense interest as the most talented and able chemists, physicists and medical men of every country have shown in attacking these most difficult problems, remain almost without parallel. Al- though this branch of science can hardly be said to be more than in its infancy, gaps in our knowledge having everywhere to be filled and rubbish to be removed, we have already achieved bril- liant theoretical and practical results, leading one to hope that radio-therapy will obtain an acknowledged place among our methods of treatment. One need onlyrefer to the undeniable and astonishing results achieved in the department of skin disease, which has so markedly attracted the attention of dermatologists. Nevertheless, the claims of radio-therapy as a treatment for dis- ease are still disputed; from time to time medical men, among whom are some of repute, although none can claim personal experience, feel called upon to refer to Roentgen-therapy, d'Ar- sonvalisation, etc., as exploded and soon-to-be-forgotten meth- ods. True, such croakings may deter the scientific ardour of others, but cannot really impede the progress of radio-therapy. "Science is progressive. Its development is as necessary and irresistible as the tide. It is also a stage of development of the natural forces, and as such is sure in due time to compel recog- nition, should not those who now try to belittle its influence and hinder its progress prefer to ally themselves with it." These words of John Tyndall, which were addressed to the opponents of natural science, might also be taken to heart by the opponents of radio-therapy. If any of my colleagues whose work lies out- side this field should feel induced by my modest efforts to pay in the future more attention to this subject, or even if they merely admit the raison d'etre of the methods laid down and scientifically justified in this book, my aim is accomplished. I trust that the fact of my drawing largely upon my own personal experience and investigation will not tend to prejudice the reader against my work. My heartiest and sincerest thanks are due to Hofrath Director Prof. Dr. J. M. Eder, Hofrath Prof. Dr. Anton Weichselbaum, Prof. Dr. Eduard Valenta, Prof. Dr. Anton Lampa and Docent Dr. Anton Ghon, who have light- AUTHOR'S PREFACE vii ened my otherwise enormously difficult investigations and both in word and deed most kindly helped me. Special thanks are owing to my highly esteemed teacher Hofrath Prof. Dr. J. Neumann, who has always followed my work with friendly interest, and has of late given me the opportunity of furthering my scientific investigations by placing the radio-therapeutic laboratory of his clinic at my disposal. L. Freund. INTRODUCTION By radio-therapy we mean the employment of any form of radiation for therapeutic purposes. The name "radiation" comprises usually a series of physical manifestations which, ac- cording to the present state of our knowledge, can be divided into two groups {Lamp a) . In the first group fall electro- magnetic radiations (radiations of electrical energy), heat rays, light and ultra-violet rays; in the second group cathode rays, Roentgen rays, the rays emitted by glow-worms (Muravka) , Becquerel rays, radium and polonium rays. All these radiations possess active powers by reason of cer- tain inherent physical characteristics. These are known as radiant energy. Physicists have formulated various hypotheses as to the character of this radiant energy. According to one authority, radiant energy is a form of activity produced by the enormously rapid and regular vibration of an imponderable sub- stance, ether, which permeates space and matter. Acording to the number of vibrations which the ether-par- ticles produce in a given second, one classifies different kinds of rays, and the effect upon our sense organs varies with the peri- odicity of these vibrations. We appreciate vibrations of 160 to 400 billions per second as "dark heat-rays. 1 ' If, however, the rate of vibration exceeds 400 billions per second, we are con- scious ol them not merely as "heat-rays," but on account of their effect upon our eyes, we call them "light-rays." In this case the particular rate of vibration determines colour impression. All ether vibrations which are under 160 and over 790 bill- ions per second we are quite unable to appreciate. There are, however, ways and means by which these rays can be brought within our visual capacity. Thus, for instance, heat-waves of great-wave length can be demonstrated by Langley's bolome- x INTRODUCTION ter, while short-waved ultra-violet rays can be indicated by pho- tography or by the fluorescence of a platino-barium-cyanide screen. Next in order to the well-known ether-vibrations of the heat- rays comes a space as yet uninvestigated, which is succeeded in turn by the much slower vibrations of the more lengthy electric waves. In these latter, according to Hertz, we have only 1,000 million vibrations to the second. The difference between light- waves, heat-waves and electric waves is not qualitative, but merely a question of gradation. Rubens and Aschkinass showed the most lengthy heat-waves to be one six-hundredth of a milli- meter in measurement, vibrating at the rate of five millions per second. On the other hand, Lam-pa has shown the short- est electro-magnetic waves to be four millimeters in length, vi- brating at the rate of seventy-five thousand millions per second. Proceeding now along the ray-scale from the large electric waves (with wave-lengths from several meters down to a few millimeters, and vibration rates from a few millions to many milliards per second) to the smaller heat and light-waves (with wave-lengths of 0.02 millimeter to 410 millionth millimeter) we come to the still quicker, shorter-waved hyper-ultra-violet rays discovered by Hertz. These latter accomplish 800 billion oscilliations per second, and are distinguished by the peculiar properties they possess. Electric waves Un- known Infra- red T3 0) Pi bo C u O O U O <3J 3 M "o Ultra- violet Hyper- ultra- violet Roent- gen rays We might, perhaps, also include in this first group of radia- tions the Roentgen rays, which many physicists are inclined to regard as a species of very short-waved light-rays. The first kind of radiations belonging to the second group, the cathode rays, may be considered as consisting of small material particles ("corpuscles") which, like the ions (see p. 26), are charged with negative electricity. According to Thomson's measure- ments, the material amount of the corpuscles is, however, much smaller than that of the electric ions, indeed, only about one- INTRODUCTION xi thousandth of the latter, whereas, the electrical state is identical in each instance. According to /. /. Thomson, the corpuscle is com- posed of a particle of solid matter bound up with a qualitatively different electric charge. A broader view, which is shared by a large number of investigators, is comprised by the conclusions Helmholtz arrived at in 1 88 i. Helmholtz observes that in the case of electroly- sis (see p. 25) the ions (charged chemical atoms) are arranged in the neighbourhood of the electrodes as neu- tral bodies, so that a discharge or a partial exchange of charges of opposed nature takes place there. This oc- currence cannot take place instantaneously; the charges must at least for a very brief time lead independent existences; one may, therefore, consider that equal charges of 1 "value" represent the elementary quan- tity of electricity; or, in other words, the electric atom. Stoney has proposed the name "electron" for these elec- trical atoms, a name now universally adopted. The corpuscle with its charge is identical with the elec- tron. According to Kaufmann, 1 ) the electrical atoms are electrical particles which have the power of moving with a velocity of 1-5 — 1-3 the velocity of light in space, but which are also able to assume independent vibrations of their own, and to transfer these to others of their kind. They can unite themselves with material particles, becoming free again, however, thereby allowing the manifestations of electrolysis. At the same time the chemical atoms which, charged with mutually neutral- ising electrons, appeared non-electric, discharge or ex- change their positive and negative electrons, and in doing so they must have the capacity for leading a sepa- rate existence, if only for a short period, being likewise able to freely wander in the conducting metal. Granted ') See W . Kauffmann, "Die Entwicklung des Elektroncnbegriffes." Allg. Naturforscherzeitung, Jalirg. 1. Nr. 1. — A. Lampa, Ueber Strahlung. VVien 1902. Braumiillcr. xii INTRODUCTION now that you have positive and negative electrons, there is yet a remarkable difference between the two; the vi- brating electron is always negatively charged, whereas the positive electron remains motionless. Hence it might happen that up to the present only negative elec- trons have been observed, and it is quite possible that they alone exist. On this point, however, no absolute verdict can be given. The electrons have been also com- pared with material atoms, and it has been found that the former amount to about the 2-1000 part of an atom of hydrogen. Thanks to the electron theory, an ex- planation is now possible of the hitherto obscurest por* tion of recent physics, including cathode rays, Roentgen rays and Becquerel rays. Hitherto physicists have en- deavoured to explain electrical phenomena by mechan- ical laws; these attempts have not proved entirely suc- cessful. Perhaps better results would ensue from the endeavour to explain mechanical phenomena by means of electrical theories, and to assume that the supposed inertia of certain matter is only imaginary. In that case, electrons would be considered as original atoms, the various grouping of which would produce chemical ele- ments, and it would appear reasonable to look for the known chemical elements amongst these groups which happen to be sufficiently stable, and to discover a con- nection between the relative distribution of the elements and their atomic weights. Finally, we may hope for a solution of the obscure problem of gravity by the aid of the electron theory. The rays proceeding from the so-called radio-active sub- stances (radium rays, Becquerel rays) may be classed with cath- odal rays. This is evident from properties all these rays possess in common, viz.: the power of diverting the magnetic field, of causing phosphorescent effects, and of giving conductive capacity to gases. We have in the radium salts a class of bodies capable of spontaneously emitting corpuscles or electrons. A cathodal-ray electron moving with enormous velocity must, on striking a solid body, necessarily discharge an electric INTRODUCTION xiii wave in an explosive manner into space, just as a projectile pro- duces sound-waves at the moment of impact. There are many grounds for supposing that Roentgen rays are caused in this way. 1 ) This would form a second explanation of the phenomena of these mysterious rays, whose remarkable properties, as we shall see, many other theories endeavour to explain. All these rays have this property in common, viz., the power of exciting phe- nomena in bodies at a great distance from the source of energy, without visible effects upon the intervening space. (In reality this is, however, an effect which is transmitted from particle to particle into space.) The following properties may be defined as common to all the varieties of radiation at present employed in radio-thera- peutics: They cause chemical changes, fluorescing bodies to glow, and alter the electrical state of bodies with which they come into contact. The phenomena above mentioned, discovered for the most part within the last few years, have now also acquired some im- portance in medicine, more especially by reason of the distinct and peculiar influence they exert upon living organisms, an in- fluence which, up to the present, we have not been able to obtain by other means. The result has been that we have been able to employ these various radiative methods as curative factors in certain diseases with absolute success, and that this branch of treatment undoubtedly signifies in many cases a distinct progress in therapeutics. It is only of late that medicine has turned her attention to this matter, consequently, as yet, her conclusions are by no means exhaustive and the knowledge acquired by no means complete. However, it is already evident that besides the "distance-effect" 2 ) ') W. Kauffmann, "Die Entwicklung des Electronenbcgriffes." — A. Lampa, "Ueber Strahlung." 2 ) By the expression "distance-effect" we mean in a physiological sense the effects which a stimulation produces, not at the site of irritation, hut on another part of the organism by means of the circulatory or nervous system. Reflex action may be taken as an example. For our present purposes, how- ever, we shall consider "distance-effects" in a physical sense ; that is to say, those effects which the radiations produce on the part they strike. xiv INTRODUCTION common to all these radiations, each of them produces appear- ances and changes which, despite certain differences of degree rather than of kind, can all be brought into one category. At this juncture we must refer to the chapter on the physio- logical effects of radiations. We may regard these radiations as physical irritations, which, like other (e. g. f chemical) irritations, in small amounts are stimulating to granulation tissue, whereas, in stronger doses, they cause destructive effects. So, as is the case with all kinds of excessive stimulation, an over-dose of radiations brings about destructive changes and cell-death. It has long been a well- known fact that electricity employed in certain forms promotes tissue-nutrition. 1 ) It is also known that Roentgen and light- rays used with lower intensity stimulate the growth of certain tissues and organisms, as well as the proliferation of hairs, col- ouring matter, and pigment. Moreover, it is well known that all three agencies bring about diseased conditions when employed with greater intensity, ranging from simple inflammation to actual necrosis. The earlier investigations of S. Exner, Kistiakowsky , Schan- dinn, Joseph, Provdzek, and others, have proved that light, heat radiations, electricity, and Roentgen rays influence the molecular movements of living cells, certain other elementary phenomena of life being similarly affected. Again, according to experiment, the character of the tis- sue-damage and the finer molecular changes in the protoplasm appear to be in all cases similar, whatever be the particular agency employed: vacuolisation degenerations resulting from the action of light (Glebofsky) , Roentgen rays (Gassman) , high-frequency electricity {Freund) . With regard to the visi- ble clinical effects which may be ascribed to radiations, we may, arguing from experiment, make the following definitions : i. The physiological effect of a radiation stands in direct relation to its intensity, in inverse proportion, however, to its wave-length ; i. e. t other things being equal, the short-waved rays l ) The reader is referred to the Preface, and also to page 112, etc., for the relations existing between d'Arsonvalisation and radio-therapy. INTRODUCTION xv cause more powerful and enduring effects than the longer- waved. 1 ) 2. The signs of reaction only become visible after a latent period, the length of which stands likewise in inverse proportion to the wave-length and intensity of the radiation employed. 3. The physiological effect of the radiations is enduring. As regards the penetration-effect of the radiation we can lay down no absolute rule; it would appear, how- ever, that this also bears direct relation to the wave- length; that is to say, long-waved rays penetrate more deeply than shorter-waved (compare, for instance, blue and ultra-violet) . 4. Those rays which have the property of exciting fluores- cence (Roentgen rays, ultra-violet rays, blue and Becquerel rays) appear to exert more physiological effect. Very likely fur- ther experience and extension of our knowledge may tend to somewhat modify these definitions. The assumption that all the above-mentioned physical phenomena and their physiolog- ical effects may be ascribed to the same or similar elementary causes, may claim some justification. This is proved by the various change-effects which have been observed in recent years to follow from different physical phenomena (electricity, light, etc.). It is known that the latter are not independent of one another; that one manifestation may call forth another. Thus electricity may produce light phenomena, Roentgen rays, ultra- violet, light, and vice versa. One cannot, of course, here attempt a demonstration of all those interesting matters which a number of emi- nent physicists have so ably argued in favour of the fore- going theories. The reader is referred to the lucid expositions of Kayser 2 ), Jaumann*), and Lecher*), a careful study of ') E. Aschkinass and IV. Caspari suppose that the common source of the effects produced by ultra-violet, Becquerel and Roentgen rays is to he looked for in the dissociating power ("ionisation") possessed by all three. Goldstein holds the ultra-violet light alone responsible. The author, however, is inclined to ascribe an important role to fluorescence. 2 ) Lehrbuch der Physik. Stuttgart bei Enke rgoo, pp. 563. , a ) Vorlcsungen ueber Elektricitaet und Licht. Leipzig. J. A. Barth, 1901. *) Ueber die Entdeckung der elektrischen Wellen, etc. Ibid. iyoi. xvi INTRODUCTION which will amply repay the worker in radio-therapy. In the present work reference will also be made in the appropriate sec- tions to those circumstances which justify one in explaining the different physiological changes after radiation by a reference to analogous physical occurrences. CONTENTS PAGE Translator's Preface iii Preface ............ v Introduction ............ ix Contents xvii i 2 3 4 5 6 7 8 9 io ii 12 13 14 15 16 17 18 19 20 I. ELEMENTS OF ELECTRICITY Positive and Negative Electricity . Conductors and Non-Conductors Transmission of Electricity .... Manifestations of Electrical Energy Electrical Distribution, Influence and Induction Electrical Condensers ..... Electric Machines ...... Contact Electricity, Galvanism, Galvanic Batteries Accumulators ....... Ohm's Law ....... Technical Measure-Units .... Battery Connections ..... Ramification of Current ..... Measurements of Electrical Currents Heat and Light Effects of the Galvanic Current Thermo-Electricity ...... Magnetic Effects of Electric Currents Induction ....... Spark Induction Apparatus .... Interrupters ....... 2 2 5 6 12 12 17 19 27 29 32 34 36 33 4i 44 45 47 56 64 21. 22. 23- 24. 25. II. TREATMENT WITH HIGH-FREQUENCY CURRENTS High-Frequency Currents . . . . Instruments for High-Frequency Currents Technique ......... Physiological Effects ....... (a) Effects on the Body Surface of the Spark Discharge (b) Effects on Bacteria ...... (c) Histological Experiments ..... The Therapeutic Uses of High-Frequency Currents Indications for the Method : 1. The Induction of Analgesia .... 2. Diseases Associated with Defective Metabolism 3. Tuberculosis ....... 4. Nervous Diseases ...... 5. Diseases of the Skin and Mucous Membrane . Resum6 ........ 85 94 100 104 121 126 152 if>5 166 167 170 172 J 74 180 xviii CONTENTS. APPENDIX "Permeating Electricity" ........ 182 III. TREATMENT WITH X-RAYS X-RAY METHODS 26. Cathode and Roentgen Rays ........ 187 27. Vacuum Tubes .......... 201 28. Some Practical Hints on the Installation and Employment of X-Ray Apparatus ........... 215 29. The Development of the Therapeutic Employment of Roentgen Rays 229 30. Method of Treatment with X-Rays ...... 243 31. Indications ........... 261 1. Diseases of the Hairs and Hairy Regions . . . 262 Favus .......... 262 Sycosis Vulgaris and Folliculitis Barbae .... 266 Tricophytosis ......... 271 Blepharitis ......... 271 Trichorrhexis Nodosa ....... 274 Alopecia Areata ........ 274 Hypertrichosis ......... 276 2. Ulcerations and Skin Diseases resulting in Ulcerations . 281 Lupus Vulgaris ........ 281 Epithelioma, Ulcus Rodens, Mycosis Fungoides, Lepra, 291 and Sarcoma of the Skin ...... 294 Various Chronic Ulcerations ..... 295 3. Acute and Chronic Exudative Dermatoses and Granula- tion-formations ........ 295 Chronic and Acute Eczema ...... 295 Psoriasis ......... 296 Prurigo .......... 298 Lupus Erythematosus ....... 298 Acne Vulgaris, Rosacea, Furunculosis .... 300 4. Naevus .......... 301 The Treatment of Internal Disorders with X-Rays . . 302 32. Physiological Effects of the X-Rays ...... 305 33. The Active Agent of this Method 322 34. X-Ray Dermatitis .......... 337 IV. BECOUEREL-RAYS 35. Becquerel-Rays .......... 351 36. Their Physiological Effects ........ 355 37. Some Therapeutic Experiments ....... 363 V. TREATMENT WITH HEAT AND LIGHT RAYS ELEMENTS OF LIGHT-PHYSICS 38. Light Theories 3 6 9 39. Light Sources ......••••• 37° 40. Diffusion of Light 37 2 41. Intensity of Light 372 CONTENTS. xix 42. Photometry 43. Katoptrics 44. Dioptrics . 45. Aberration 46. Absorption 47. Dispersion 48. Ultra-Red Rays 49. Ultra-Violet Rays 50. Light Interference 51. Refraction of Light 52. Effects of Light 53. Physiological Effects 54. 1. The Effect of Light on Plants 55. 2. The Effect of Light on Bacteria 56. 3. The Effect of Light on Higher Organisms 57. The Therapeutic Employment of Light . 58. (a) Treatment with Sunlight Sunlight 59. Sun Baths 60. Open-Air Light Baths 61. Chromotherapy 62. Concentrated Sunlight 63. (6) Treatment with Artificial Light . 64. Treatment with Incandescent Light 65. Treatment with Arc-Lights 66. Therapeutic Employment of Non-Concentrated Arc- 67. Employment of Concentrated Arc-Lights ♦Lupus Vulgaris . Alopecia Areata Lupus Erythematosus Epithelioma Naevus Vascularis Other Skin Diseases Venereal Diseases 68. ( 104 Apparatus by Lortet and Gcnoud 497 105 Giant-cell of Lupus .... 503 106 Lupus Nodule 505 107 Strebel Instrument 515 I. ELEMENTS OF ELECTRICITY. RADIO-THERAPY ELEMENTS OF ELECTRICITY. 1 § I. Positive and Negative Electricity. As is well known, there are two electric states, which are complementary to each other. In this respect they may be com- pared to positive and negative quantities, or to heat and cold. The electricity of a glass rubbed with a piece of felt or leather smeared with amalgam is not identical with that of resin rubbed with an animal skin, for one of these attracts and the other repels the electric pendulum. Both electricities have been universally termed "fric- tional electricity," the one being "glass-electricity" and the other "resin-electricity ." The former is known as positive and the latter as negative electricity. Experi- ments have shown further that the same body may be- come alternately positive and negative, according to the nature of the body with which it is rubbed. For instance, if rubbed with amalgam, glass becomes posi- tive; if rubbed with wool or fur, negative. § 2. Conductors and Non-Conductors. There are substances which transmit electricity with ex- traordinary facility, and which conduct it to any distance, part- ing with it equally well; there are others again which conduct ') Text-books: Mueller-Pouillet, Lehrb. d. Physik, Bd. 3. — H. % Kayser, Lehrbuch d. Physik. Stuttgarl igoo. — F. K'drner, Lehrb. d. Physik. Wien und Leipzig 1897. — ^. Pschcidl, Grundriss der Naturlehre. Wien und Leip- zig [897.- /.. Graetz, Die Electrici'taet, 7. A.uflage, Stuttgart. — L. Grum- nach, die Physik. Erscheinungen und Krafte. Leipzig [899. — /. G. Wallen- tin, Die Generatoren hochgespannter Electricitaet. Wien, Pest, Leipzig 1884. — Calm, has elektromagnetische Feld. Leipzig 1900. — Wiedemann, Lehre von der Elektricitael eti \rticles and Lectures by B. Walter, A. Lampa, E, Lecher, etc., quoted in the text. RADIO-THERAPY it with difficulty, and only part with it at places which happen to be touched. The first are called conductors, the second, non- conductors. This may be otherwise expressed : All bodies offer some re- sistance to the transmission of electricity. In non-conductors this resistance is very marked, while in conductors it is insig- nificant. If a conductor is meant to retain its electricity, it is necessary that none but non-conductors be allowed to touch it. Hence it follows that non-conductors are also insulators. A conductor can only remain electrified so long as it is insulated, that is to say, surrounded only by non-conductors. Air is also an insulator: were it otherwise, the electricity contained in charged bodies would be rapidly dissipated. There are no absolute non-conductors of electricity, hence we should only speak of good and bad conductors. Those bodies which stand midway between these con- ditions are known as "half -conductors." Pfaundler gives the following table of the known conductors, half-con- ductors, and non-conductors, in which the various sub- stances are arranged in their order of conductivity. Conductors Half-Conductors Non-Conductors Metals Alcohol Dry oxides Coal Ether Fat Graphite Powdered glass Ashes Acids Flowers of sulphur Ice at 25 Solutions of salt Dry wood Phosphorus Sea water Marble Chalk Riverand springwater Straw India-rubber Rain water Ice at o° Etheric oils Snow (wet) Porcelain Living vegetable mat- Well-dried vegetable ter matter Living animal matter Leather, parchment Soluble salts Feathers, hairs, wool, Linen silk Cotton Jewels, mica Glass Wax, paraffin Sulphur Resin ELEMENTS OF ELECTRICITY 5 The conductivity of a body may be modified accord- ing as the latter is soaked or covered with moisture, as well as by alterations in its temperature, or the consti- tution of its surface. Bodies having a rough surface conduct better than smooth. Heat operates in the first instance indirectly by its drying effect, through which bodies lose their conductivity either wholly or in part. On the other hand, other bodies become conductive by means of heat, because they soften or melt. For instance, glass, resin, and wax become more conductive when heated so as to soften. Ice also, which is a non-con- ductor at — 25 , becomes a half-conductor when heated to o°. Gases and vapours are insulators so long as they remain dry and free from dust. § 3. Transmission of Electricity. Experiment proves that electricity which is produced by friction, or by induction (see § 5) has a tendency to lie only on the surface of a charged body. This phenomenon is ex- plained by the fact that similar kinds of electricity repel one another ( § 4) ; consequently all the electrical particles added to the body take up a position as remote as possible from those which it already contains of a like kind. The surface-elec- tricity is called a charge. By bringing an electrified body into contact with a neutral body, electricity of the same kind may be transmitted to the lat- ter. If an insulated conductor is allowed to touch an electrified body, the electricity passing into the former does not remain at the point of contact only, but is distributed over the whole surface. By repeated contact with an electrified body an insu- lated conductor can be more and more charged with electricity. If the conductor be not insulated, but, for instance, held in the hand, any electricity communicated to it at once extends to the whole body and thence to the earth generally, thus becoming dissipated; the discharge has become "earthed." 6 RADIO-THERAPY Sunlight has the property of dissipating negative electricity, also burning magnesium and electric arc- light. Polished wires, or plates of aluminium, mag- nesium, or zinc cannot be made to long retain negative electricity once they are exposed to sunlight. § 4. Manifestation of Electrical Energy. With the aid of the electric pendulum, or the gold-leaf electroscope, one may demonstrate the fact that similar kinds of electricity repel, and dissimilar kinds attract one another. The electrical forces which produce these results are forces capable of operating at a distance. These obey the universal law : P — -^- ; that is to say, they are directly proportional to the product of the electrical quantities acting upon one an- other, and inversely proportional to the square of their dis- tance. (Coulomb's law.) The quantity of surface-lying electricity in a body is known as the electrical density. If a body has a surface S and a quantity O of electricity, its electric density D = ^. This electricity, owing to the mutually re- pelling property of similar electrical particles, has a tendency to spread over a body or to leave it; that is to say, it has a certain tension (potential), the amount of which depends upon the quantity or density of the accumulated electricity, or the size of the electrified body. Electricity in a given conductor can only, therefore, be considered in a state of equilibrium when the repellent effect of particles and the potential is every- where the same. In any conductor the tension is everywhere the same ; not so, however, the density. On asymmetrical bod- ies the density of electricity is unequally distributed, being greater where the curves of the former are small. The smaller the surface on which a given quantity of electricity is collected, the greater the electrical density in this region. The loss of electricity (point-discharge), however, increases in ratio with the thickness of the electrical density. Electricity is constantly passing into the dust and water particles contained in the air surrounding the site of this point-discharge. ELEMENTS OF ELECTRICITY 7 Since like electricities repel each other, these elec- trically charged dust and water particles become also repellent, and so give rise to the "electric wind." Just as a charged body can unload itself at the discharge- point, so also, if connected with the earth and placed opposite another charged body, it can exhaust the latter. This property depends upon "influence." (See below.) The proportion which the amount of electricity contained in a conductor bears to its tension depends only upon the shape and size of the conductor. This proportion is called the capac- ity of the conductor. . Quantity of electricity Capacity = — - — Tension From this formula results: . Quantity of electricity Tension = — — -^— Capacity By the electrostatic unit one signifies that quantity of elec- tricity which exercises a force of 1 dyne at a distance of 1 cm. upon an equal quantity of electricity. The unit of energy (dyne) is that force which can move a mass of 1 gramme 1 cm. in one second. In practice, however, one uses another unit, which is con- siderably larger and which rests upon other foundations. This is called the "coulomb," and is equal to 3,000,000,000 electro- static units. By the electro-static unit of tension is denoted that which produces an absolute electro-static unit of electrical quantity in a sphere of 1 cm. radius. The cause of tension is called electro-motive force. Elec- tricity contained in a body can, by reason of its tension, do work or overcome resistance when leaving that body. The amount of this capacity for work, "electric energy," depends upon the amount of accumulated electricity, and upon its tension and quantity of electricity, and is expressed in kilogramme-metres (divided by 9.81, see below.) The neighbourhood ol an electrified body is known as the "electric field;" within this zone the body is especially active in 8 RADIO-THERAPY an electrical sense. The force brought to bear on an electrical quantity i is known as the electrical field- force (H) in that locality. On a point containing the electric-quantity e a force H e will be exercised. The unit has a field in which an energy of i dyne is brought-to bear on an electric quantity (E Q) i. In the same way a space in which magnetic forces are acting is called the "magnetic field," and the amount of the magnetic force, acting at a given point of this field on a unit of magnetism, is called the field-energy. In order to symbolise the influence which an electrified and magnetised body has on the surrounding space, the scientist as- sumes the existence of lines of force proceeding from the poles into space. These in a manner represent the energy of the poles. For instance, the expression is often used "An iron core emits lines of force," which conveys the idea that the iron is magnetised, and possesses magnetic poles. The lines of force are distributed in more or less regular curves, according to the shape of the electrified bodies brought near each other. These lines of force diverge more and more as the distance from the emitting body increases. The field-force of a given locality is indicated by the quantity of these lines of force con- tained therein; that is to say, their number in a sheaf whose sectional area is one square centimetre. Two conductors in the same field have, as a rule, different tensions. If we join the two conductors by a wire, they form practically one conductor; the difference in their respective ten- sions becomes equalised, the electric particles move along the wire from one to the other (from the body of higher poten- tial to the lower) until a uniform tension obtains. An "elec- tric current" is established. In a similar manner water, which is standing at dif- ferent levels in two different vessels connected by a tube, in consequence of the law of gravity endeavours to at- tain one uniform level. This endeavour is called ten- sion; it represents a force the amount of which varies with the respective altitudes of the two levels. 'Ten- sion'' is synonymous with the following expressions used frequently in electricity: Potential, electric pressure, fall ELEMENTS OF ELECTRICITY 9 of potential, tension and pressure-difference, etc. A term which comprises all the foregoing is "electro-mo- tive force." Employing our water simile again, this E. M. F. varies with the level difference. On the other hand, the effect of the water does not alone depend upon this difference of level, but also upon its quantity. In one case an infinitesimally small quantity of water may be acting at high pressure, in the other a very large quan- tity may flow from a slight altitude only. Static elec- tricity may be compared to the former instance, where a strong, though brief, effect is produced, whereas the second instance finds a parallel in voltaic, dynamic, or galvanic electricity, where a considerable and constant energy is manifested. Putting the matter otherwise: If an electric particle moves in an electric field from one conductor to another, the tension in these conductors is not identical; they have a "potential-dif- ference." The work done by the motion of an electrical quantity from one conductor to another is equal to the product of the electrical quantity and the tension-difference of the two conductors (anal- ogous to the amount of work accomplished by a body falling from one level to another under the influence of gravity.) If this electrical quantity equals 1 coulomb, the work done by the forces in this motion is exactly equal to the tension-difference of the two conductors. It follows that the tension-difference between two points A and B of an electric field is equal to the work required to bring 1 coulomb from A to B. The unit of tension-difference at two points is found by measuring the work in kilogrammeters required to move 1 coulomb from one point to the other. In practice, however, one never employs this unit, but another in which kilogramme of energy only is required to move 1 coulomb from one place to another. This unit of tension-difference is called 1 volt. 1 volt x 1 coulomb = - kgrm. 9.81 io RADIO-THERAPY The tension-difference of a place A, B, or C, as compared with that of the earth, is indicated briefly as the tension) or po- tential) of that place. m r A B i | 1 1 Fig. i. Let m be the acting mass representing a point containing the electrical quantity + m, this point giving off energy to the surrounding space. According to Coulomb's law, a repellent force -j-„ is ex- ercised in the direction d upon a point A of this space contain- ing a positive unit of electrical quantity. The formula -j signifies the potential of the point A subjected to the energy of m, or more briefly, the potential of A. If this point moves in the direction of electric force toward B, this force accomplishes work (force X distance). The point A charged with electricity represents, therefore, a certain potential energy in the electric force-field, which may be likened to that employed in raising a weight; this energy will be exhausted in the process of removal to an infinite distance from m. The electric potential of a body signifies the capacity for work of its electrical tension. The po- tential A is, therefore, the work required to bring the electrical unit under the action of the mass m from A to infin- ity; or, again, the work which must operate against the electrical field-force in order to bring the unit of positive electricity from infinity to A. The potential of the earth is called O; one can, therefore, use the phrase "from the earth" instead of "from infinity." We can only observe and measure differences of po- tential, or determine the potential down to a "constant" (the value of which may be disregarded), consequently, the poten- tial of the earth may be valued as O. The earth's condition is taken as a standard for all meas- urements, and differences of potential are compared with it. We therefore obtain the same potential-differences for different bodies, no matter what potential we assign to the earth. ELEMENTS OF ELECTRICFD' n Tension, like tension-difference, has i volt as its unit. If, therefore, one speaks of a tension of 6 volts as obtaining in a conductor, one means : The electric forces acting in the field must perform a work 6 X — — kgrm. in order to bring i cou- r 9.81 6 & lomb from the conductor to the earth. By "surface-tension" of a charge is understood the force with which electricity is discharged from a surface. Since each "quantity" here acts both as repelled and repeller, it is clear that this force must be proportional to the square of the elec- trical density. With regard to this "surface tension," it must be noted that its identity with "tension" merely is not implied. It is true the word tension is frequently employed to denote "po- tential." It would, however, be more correct to strictly confine the expression to that force which drives off electricity from the surface of a charged conductor. In the case of a sphere the relation between "tension" of electricity on the surface and "potential" is easily indicated. Let G stand for the density of electricity on the sphere; then the tension T = 2 - o -2 . On the other hand, the potential being V, E the whole charge of the sphere and R its radius, then R Since the charge is equally distributed over the sphere, the E surface-unit receives the charge a = -~, S being the surface of E the sphere; further G = j^- Moreover, T = 2 - g 2 = 2- 4 ; on the other hand, E = R V, hence R"-V 2 T — ■ ——— or T = - • V 2 = — - V 16--" R* ' 8 7rA rJ ' 26 The points of an electrical field whose potentials have a con- stant value constitute a plane surface. No work is needful for moving an electrical quantity alojig a plane surface. At every point of the latter the force emanating therefrom acts at right angles to that surface. 12 RADIO-THERAPY Electrical equilibrium can only obtain in a conductor if all points have the same potential. The unit of capacity is pos- sessed by that conductor which receives exactly a tension of i volt from an electrical quantity of i coulomb. The unit of capacity is called i farad. In practice one often uses the millionth part of a farad as the unit of capacity. This is termed a microfarad. § 5. Electrical Distribution : Influence, Electrostatic In- ductor. If an electrified body be brought near a non-electric insu- lated body, the latter becomes also electrified. A separation of its electricities has taken place, assuming that in every non- electric body positive and negative electricities are already present in equal quantities at any given point. The body acted upon has become electrified by "influence," and the side turned toward the influencing body becomes the site of an opposite kind of electricity (by reason of the mutual attraction of dis- similar electric particles). This is known as "bound" elec- tricity, being dissimilar to that of the influencing body; the similar, or "free," electricity escapes to the side farthest from the influencing body- Experiment shows: 1. That electrical quantities separated by influence are inversely proportional to the square of the distance. 2. That they are directly proportional to the influ- encing electrical quantity. §6. Condensers. It is only possible to accumulate electricity in a conductor up to a certain stage, viz. : where its potential equals that of the source of electricity. If, however, the charged conductor has sharp edges or points, its potential cannot be raised quite to this standard, since through these a certain amount of elec- tricity is lost into the air. (See p. 5.) A "condenser" is an apparatus assisting in the storage of electricity to a higher de- gree. It consists of two metal plates separated by a thin insu- lating layer of varnish or air; one is called the collecting-plate, ELEMENTS OF ELECTRICITY 13 the other is the condensing-plate. If the collecting-plate be charged to its utmost capacity, it is found that on touching the condensing-plate with the linger still more electricity can be received by the collector. The explanation of this is as fol- lows: When an "earthed" conductor is brought in the neigh- bourhood of a charged conductor, the tension of the latter falls considerably, in consequence of which it is enabled to retain a still further supply of electricity. The capacity of the collect- ing-plate (the "earthed" condenser being adjacent) is denoted usually as the capacity of the condenser. The capacity of a condenser C is the proportion between an electrical quantity E lying on the collecting-plate and the tension of the latter V , the p condenser being "earthed." We now have the formula C = -p.; E from his V = -p and E = V C. The capacity of a condenser depends upon the shape and size of the plates, upon their near- ness to one another (the shorter the distance between the plates, the greater the capacity), and, again, upon the molecular and material constitution of the insulating medium (the "di- electric"). The condensing capacity is greater in the case of solid or liquid dielectrics than if air only is employed. The "dielectric-constant" signifies the proportion which the capacity of a condenser fitted with a solid or liquid dielectric bears to that of one which only has air as its insulating medium. Par- affin has a dielectric constant of 2.3, india-rubber 2.9, oil 2 to 5, ebonite 2.6, vulcanite 3.15, sulphur 3.84, glass 6 to 10, mica 8. If an electrified body be brought near a good conductor, the electricity of the former and the "bound" electricity of the latter accumulate on adjacent surfaces by reason of their mu- tual attraction. If the electrical density is in each case sufficient and the bodies are not too far apart, the two electricities com- bine, the effect being to produce both light and sound. In this way an "electric spark" results. Here the light is caused by glowing particles passing from one body to the other, the sound by air-condensation in the vicinity of the spark. As before mentioned, we are able to accumulate large quantities of elec- tricity by means of "influence" or "binding." A convenient ap- i 4 RADIO-THERAPY paratus for this purpose is to be found in Franklin's "plate." This consists of a level glass plate fitted with tin-foil on both sides, the layers of metal not being allowed to come close to the edge. If we connect one of the tin-foils with a positively charged body, positive electricity (+ e) will flow from the latter until the potential becomes identical with that of the tin-foil. In the second tin-foil electricity becomes separated by "influence;" negative electricity becomes attracted, positive repelled. If this second layer of foil be "earthed," then its negative electricity becomes "bound," its positive electricity flowing away to the earth. These quantities of electricity are relatively pro- portional to e, and nearly inversely proportional to the distance separating the respective layers of tin. They may, therefore, be expressed by Ke, K representing a fraction of which the denominator is proportional to the thickness of the glass plate. Accordingly, if the sec- ond tin-foil be on the left, the "binding" takes place through + e on the right, giving — Ke on the left. The latter quantity, however, again binds on the right a quantity + Ke. One can, therefore, add K 2 e to + e on the right without any loss of electricity. This new quan- tity + K-e again binds on the left — K 3 e, + K 3 e going to earth. This new quantity again binds + K 4 e on the right, and so on. One sees, therefore, that electricity on the right-hand plate may be augmented by While, therefore, originally the tin-foil on the right could only receive + e, it is now in a position to take up x — - e. — J -^tf = »i is called the augmenting index. i — A„ i — A 2 It is greater when the distance between the tin-plates is decreased. The plate on the right, which is connected with the supply, always holds more electricity than that on the ELEMENTS OF ELECTRICITY 15 left, since in addition to its "bound" electricity it con- tains that which Bows to it after the binding. If, there- fore, the two plates be joined by a wire, an escape of electricity occurs from right to left, accompanied by sparking at the moment of juncture. A convenient form of accumulating apparatus is found in the Ley den jar. This consists of a glass jar with the tin-foil pasted inside and out to 2-3 of its height. The lid is formed by an insulating cover, which is pierced by a metal rod. One end of this rod is in contact with the inner layer of tin-foil. The other end terminates in a knob. This rod transmits electricity to the inner layer. The outer layer is connected with the earth. The capacity of a Leyden jar depends upon its size; or, more correctly, upon the area of its tin-foils. A considerable number of Leyden jars may be joined to- gether, forming a battery. They may be joined by connecting all the inner and all the outer layers respectively. This gives one a connection in parallel, or /'// quantity; the number of jars then act like one jar of n-fold size. Or again, the outer foil of one jar may be joined to the inner foil of another, and so on. This gives one connection in series, or tension-connection, one then obtains between the terminal layers the n-fold poten- tial difference of a jar, but in the discharge the electrical quan- tity of a single jar only. This particular combination is called also a cascade-battery. If a Leyden jar be discharged by a brief connection only of the layers, after a little time a second connection will produce another, though feebler, spark. In the same way, after re- peated pauses, a third, fourth, or more sparks may be obtained, each progressively feebler. This is called the jar-residue. In explanation of this phenomenon, it may be assumed that under the influence of surface-tension electricity permeates the glass from both sides; the surface-tension once removed by the discharge electricity slowly returns again to the surface. We have seen that, dealing with a sufficient density and po- tential difference, an equalising of dissimilar electricities accu- mulated in two neighbouring conductors separated by a dielec- tricum can be effected in the form of a spark. The amount of 1 6 RADIO-THERAPY density required increases with the thickness of the insulating medium. In the air, the length of the. spark discharge is about proportional to the density of the electricity accumulated. If, however, the air be rarefied, the spark-length capacity in- creases, and in tubes filled with gases whose pressure only amounts to a few millimetres, the spark length may advance to many metres. These spark discharges produce many effects. These may be mechanical, instanced by the perforation of solid insulators, transport of solid particles from one conductor to the other, etc. ; chemical, causing decompositions or combina- tions; thermic, igniting powder, melting iron wire, etc.; and light-effects, as shown by the visible spark, the illumination of Geissler's tubes, etc. Finally, feeble magnetic effects of the discharge can be experimentally demonstrated. In these re- spects the discharge simulates dynamic electricity. In the case of powerful discharges, where simultaneously large bundles of sparks are emitted, the positive pole behaves somewhat dif- ferently to the negative. From the former, trains of sparks stream off from different portions of the pole, uniting before reaching the negative pole to strike it in one focus only. An- other kind of discharge takes place when there is but little re- sistance. If a powerfully charged Leyden jar have its two layers of foil connected by a good conductor, more positive elec- tricity flows to the negative layer than is required to neutralise it. This excess flows back to the positive layer, but again too freely, so that a return again takes place. In this way the current is several times reversed before equilibrium is attained. This phenomenon may be compared with the swinging to and fro of a liquid column in connection with two vessels, and is called an oscillating discharge. The number and duration of these oscillations depend upon the spark length and the capacity of the battery. Feddersen made searching experiments upon the duration of the electric spark. He made his obser- vations upon a spark-reflection in a rotating mirror, and saw in the first place instead of a spark-line a band of light, showing that the spark possessed a definite dura- tion. He noticed in this band alternate light and dark ELEMENTS OE ELECTRICITY 17 places, a proof that the discharge stops and recom- mences periodically. Feddersen also calculated the period of these oscillations to be about one-millionth of a second. §7. Electrical Machines. Electricity may be continually formed by friction and ac- cumulated in an insulated conductor by means of Carre's ap- paratus (Fig. 2). This consists in the main of two discs revolving in opposite directions. The layer of these discs (B) Fig. 2. Fig. 3. Fig. 2. — Carres machine (from "Die Generatoren hochgespannter Electricitat" von Dr. J. G. Wallentin, Wien, Pest, Leipzig, Hartleben's Verlag 1884. p. 89). Fig. 3. — Wimsh'urst machine (from L. Gractz "'Die Electricitat." Stuttgart, Engelhorn, 1898, p. 34). is made of ebonite, the smaller (A) of glass. During its ro- tation the latter rubs between the two friction-pads D and acts as an inductor. While this disc (the glass) revolves compara- tively slowly, the disc B revolves very quickly. As seen from the figure, these discs partly cover each other. Opposite the 1 8 RADIO-THERAPY ebonite disc B stand the combs E and F, the second of which is connected with a cylindrical metallic conductor C, the other with a rod T, terminating in a knob. This machine acts as follows : The positive electricity of the rubbed glass disc influences, with the aid of disc B, the comb E and draws from it negative electricity, which collects on the disc B; the knob of the conductor C consequently becomes posi- tive. The negative electricity of the dielectric disc draws from the comb F its positive electricity, and is thereby neu- tralised. The conductor C itself becomes negatively electric (W allentin) . This apparatus gives good results. With but few rota- tions, provided the discs be large enough, one can obtain sparks up to i ^ centimetres. Another influence machine, which is often used for medical purposes, is the JVimshurst (Fig. 3). This consists of two glass or vulcanite plates placed close to one another, each re- volving round a common centre, but in opposite directions. Each plate bears on its outer face a number of metal sectors, and runs between a metal fork provided with spikes pointing to the plate. To each metal fork a brass rod is connected, ending in a knob, which in its turn communicates with a Leyden jar. Finally, the machine has an "equaliser" on each side. This consists of a metal arm, one end of which supports a wire brush whose bristles rub against the revolving metal sectors. On actuating this machine electricity immediately develops, which sparks or "brushes" from knob to knob. The "equal- isers" are not placed exactly opposite to each other, but at an angle of 6o° with themselves and the horizon. The electrical output of this machine is not due directly to friction, but to the small, though constant, normal charges in the insulated sectors. These act by "influence," and as this is the case not with one sector alone, but with all of them, the terminal pole becomes more and more powerfully charged. One cannot enter here into a more detailed explanation of the action of this apparatus. ELEMENTS OF ELECTRICITY 19 §8. Contact Electricity, Galvanism, Galvanic Batteries. If two different metals be brought into contact, one becomes positively and the other negatively electrical. This electricity in nowise differs, except in its mode of origin, from that pro- duced by friction. It is assumed, in explanation of the above phenome- non, that on the contact of different conductors an elec- tro-motive force appears which develops positive electric- ity of a certain potential on one, and negative electricity of an equally definite potential on the other. Each conductor, therefore, possesses its own peculiar tension, a different value for each. The potential-difference of the two is constant, being dependent only upon the na- ture of the metals and quite independent of their size, the size of their plane of contact, or of the absolute potential value of each metal. If electricity be transmitted to both metals or to one of them, or if one of them be "earthed," the potential-difference remains the same. Many theories have been advanced as to the origin of this separating or electro-motive force. Volta thought that the mere contact of the metals produced their po- tential-difference. Others have looked for an explana- tion in chemical changes as a cause of voltaic electricity (F. Exner) . Volta's experiments with various metals led him to deter- mine a tension-series. This he arranged in tabular form, the first of the couple in contact taken in the order read being posi- tive and the second negative. This tension-series, also called conductors of the first order, reads as follows : Zinc, lead, tin, iron, copper, silver, gold, coal, platinum, manganese. If the figure 5 be taken as representing the potential-difference of zinc and lead (expressed symbolically by Zn/Pb = 5), ac- cording to Volta's results, we get the following values for dif- ferent combinations : ZnfPb = 5 CujAg = 1 PbfSn = 1 ZnjAg= 12 SnjFe = 3 Sn/Cu = 5 FejCu = 2 ZnfFe = 9 2o RADIO-THERAPY The law relating to tensions is as follows: If a chain be formed of several metals in contact with one another, the dif- ference in potential between the final links is equal to the sum of the potential-differences of all the links, or is equal to the potential-difference which would result from direct contact of the final links. From this it follows that the greater the dis- tance between the individual members of the chain, the greater the electro-motive force. The electro-motive force cannot be increased by a repetition of the same combination. It can be shown by calculation that in a closed circuit of conductors of the first group the electric dissociating power equals o, that is to say, the tension is everywhere alike; the electricity is in equilibrium. Again, a potential-difference results when met- als and liquids are brought into contact. If the potential-dif- ference between zinc and copper be .considered as ioo, ac- cording to Kohlrausch, the following figures are obtained in different combinations : Zinc Copper Silver Gold Platinum water = —61.6 water = —330 water = — 17.0 water = -33.7 water = —44.7 Liquids do not obey the law of tensions. In contact with metals they become partly positive and partly negative. They are called conductors of the second class. Thus, for example, every metal in contact with water becomes negative, and that in a different degree for dif- ferent metals, while the water becomes positive. Water, therefore, cannot be included in the tension series. Let us immerse a zinc and copper plate in a vessel of water. Both metals become in the first place negative, the water positive. Expressed in numbers, the tension of the zinc is the half of — 61.6, that is, — 30.8. This positive tension of the water (+ 30.8) goes over to the copperplate. Now, however, the copper receives through the electric separating power acting on the water, the half of — 33-Q, that is, — 16.5. But the positive ELEMENTS OF ELECTRICITY 21 tension from the water prevails over the negative of the copper ( — 16.5) with the result that the copper plate receives a positive tension, 4- 30.8 — 16.5 = + 14-3- On the other hand, the positive tension of the water, -f- 16.5 (which it received by contact with the copper), is added to the negative tension ( — 30.8) of the zinc plate. The tension of the zinc plate is, therefore, — 30.8 + 16.5 = — 14-3- The same rule applies to all other metals. It follows that when two metals are immersed in a liquid, one of them becomes negative and the other positive. The metal which by its own separating-power becomes more power- fully negative remains always negative. Such a combination is termed a galvanic element. The ends of the two metal plates are called the poles. The copper plate contains the positive, and the zinc the negative pole. A gal- vanic element, the poles of which are not connected, is called an "open" one. The law that the two metals have a definite potential-differ- ence, which depends only upon the nature of the two metals and the liquid, and not upon their size and shape or the quantity of the liquid, applies also to the galvanic element. This defi- nite tension-difference is called the electro-motive force of the element. If the poles of an element charged with a potential-differ- ence are connected by means of a conductor, a current must result; electricity always flows from a place with higher poten- tial to one with lower. Since, however, the source of the charge (the contacts) remains within the element, demanding the same potential-difference in the poles, fresh electricity flows at once to the latter and equalises itself through the connecting wire. One sees, therefore, that this current-flow and equalising process must be constantly going on ; the electricity never arrives at a state of equilibrium, but a continuous current results. This is called a galvanic current. The source of the current is to be found in the chemical energy which is spent when employing conductors of the second class; these hitter, as is well known, are required for a current-producing element. 22 RADIO-THERAPY The positive electricity flows uninterruptedly from the higher tension along the wire connecting the two poles, thence through the metal and liquid. In the case of the above-men- tioned element positive electricity is found at the copper pole. This positive electricity flows, therefore, from the copper pole along the connecting wire to the zinc pole, thence from the zinc plate into the water, and so to the copper plate again. We have thus a closed circuit. Or the negative electricity may be described as flowing through the wire to the copper, thence to the water and zinc. Thus the current may be followed for pur- poses of description in one of two ways, but the general method is to consider it as flowing from the higher potential to the lower, that is, in the direction of the positive current. We speak of a stream of water flowing from a higher to a lower level, and in the same way an electric current is under- stood as passing along a conductor from a point of higher to one of lower tension. As has already been mentioned, the tension-difference between these two points constitutes the elec- tro-motive force. The amount of water which passes in one second a given point in the course of a stream is governed by the force of the current, and may be expressed in litres or kilogrammes. In the same way the quantity of electricity, that is, the number of coulombs passing a given sectional area of the wire in one second, is called the intensity or strength of the electric cur- rent, and is measured in units of amperes. The motive force of a stream of water, or of water falling from a height, cor- responds to the tension-difference between two points in an electric current, or its electro-motive force. As regards work- capacity a comparison may also be drawn between a current of electricity and one of water. We have seen that a current of water results from its movement along an inclined plane by reason of gravity; if there were no hindrance to its progress, the velocity of the water would become greater and greater in its course, being as great at any given point, as though it had fallen directly there from its original level. This, however, is not the case with water-streams, the current ELEMENTS OF ELECTRICITY 23 being found to move comparatively slowly in certain places. This results from obstruction to its progress by fric- tion with the bed of the stream. The work accom- plished by gravity in the movement of the water over this obstruction is, of course, not lost: work, indeed, can never be lost. The energy expended receives its equiv- alent in a certain amount of heat, which, though hardly measurable, raises the temperature of the water and its bed. By the aid of water-wheels, turbines, and the like, one can transform the energy of the falling water into me- chanical power. The maximum of work which one can extract from a waterfall per second, is estimated by mul- tiplying the height of the fall by the weight of water falling in that second. Just as the effect of flowing water is measured in meter-kilogrammes, the product of volt and ampere (the watt) indicates the power of an electric current between two points in its course. If be- tween these two points there is an uninterrupted con- ductor, the heating of the latter constitutes the only work-effect of the electric current, and the amount of heat thus developed must be equivalent to the product of volt and ampere. One can with the aid of liquids, since they do not obey the law of the tension-series, at will increase potential-difference of electro-motive force by repetitions of the same combination. If we take a galvanic element in which the tensions of the two metals differ to the extent of 1 volt, and earth the zinc plate, the tension of the latter will become o; that of the copper will be 1 volt. Any conductor joined with this copper plate also participates in this tension; this will apply, moreover, to the zinc plate of a second element if it likewise be attached. The copper plate, however, of this second element must already possess a tension, of 1 volt higher than its zinc fellow, conse- quently it now possesses a tension of 2 volts. Similarly, the copper plate of a third element connected in a 24 RADIO-THERAPY like manner will possess a tension of 3 volts, and so on. If one, therefore, in this way connects a certain num- ber (;/) of galvanic elements, the tension-difference (the electro-motive force) will be greater than in any single element. A series of galvanic elements arranged in the above manner by coupling them together, is called a chain, or battery, and this particular mode of connection is termed serial. The terminals are called battery-poles. In addition to the galvanic elements described above, which contain only one kind of liquid, there are others in which the metals are immersed in different liquids. In this case the liquids are separated by a porous clay diaphragm. Of the two plates (of the first class of conductors) , one is invariably made of zinc. In strong batteries this is always amalgamated in order to pre- vent corrosion while the element is at rest. The commonest forms of galvanic elements are given as follows, together with indications of their electro- motive force : 1. Daniell's cells: Amalgamated zinc in 25% sul- phuric acid, copper in concentrated copper sulphate solu- tion. Electro-motive force in volts : 1.068. 2. Meidinger's element: Zinc in solution of mag- nesium sulphate, copper in concentrated copper sul- phate. Electro-motive force: 0.952 volt. 3. Hansen's element: Amalgamated zinc in 8% sulphuric acid. Carbon in fuming nitric acid. Electro- motive force: 1.88 volts. 4. Chromic acid element (Bunsen) : Amal- gamated zinc and carbon in a solution of 12 parts bi- chromate of potash, 25 parts concentrated sulphuric acid, 100 parts water. Electro-motive force: 2.03 volts. 5. Grove: Amalgamated zinc in 25% sulphuric acid, platinum in fuming nitric acid. Electro-motive force: 1.93 volts. 6. Leclanche : Amalgamated zinc in solution of ELEMENTS OF ELECTRICITY 25 sal amoniac, carbon with a mixture of manganese. Elec- tro-motive force: 1.48 volts. The galvanic current, in addition to mechanical, magnetic, electro-dynamic, inductive-light and heat effects, causes chem- ical action. It if passes through a liquid, chemical decomposi- tion always results, the process obeying well-defined laws (elec- trolysis) . The immersed plate connected with the negative pole of the battery, is called the cathode; the other, con- nected with the positive pole, is the anode. The sub- stance underlying decomposition is known as the electrolyte; its particles separated about the plate are the ions. If the galvanic current be conveyed through dilute sulphuric acid, hydrogen is evolved at the cathode and oxygen at the anode. Electrolysis obeys the following laws (Faraday) : 1. The amount of decomposition-products formed in a given unit of time is proportional to the intensity of the current; that is to say, to the electrical quantity passing through in that period. 2. Each unit of current at the electrodes evolves chemically equivalent quantities (that is, such quantities as are capable of chemical re-combination) . If a certain electric quantity be required to traverse an electrolyte, according to Faraday's law this can only be accomplished by the removal of a definite quantity of hydrogen from anode to cathode, thence escaping. This relation between the transmission of electricity and the ions leads one to assume that the latter are direct car- riers of electricity. We see that under all conditions, whatever be the chemical combination with which we are dealing, positive electricity always accompanies the hy- drogen ; we may suppose, therefore, that H in the com- bination HS0 4 has a greater affinity for positive elec- tricity than SO4, which fulfills the role of carrier of nega- tive electricity. One may, therefore, conceive each atom of a combination as being charged with a definite elec- 26 RADIO-THERAPY trical quantity, base and acid, indeed, being charged with dissimilar electricity. Every hydrogen ion bears a certain electric quantity. According to Faraday's second law of electrolysis, each current-unit produces chemically equivalent quantities at the electrodes. Therefore, the chemical value of each ion moving in the electrolyte appears joined with a defi- nite and unchangeable quantity of positive or negative electricity. Therefore, every single-value ion conveys just as much electricity as an H-ion, while the two- and three-value ions convey double or triple electrical quan- tities. If one measures the current passing through, and the amount of hydrogen evolved, one can estimate ex- actly how much electricity falls to I grm. of hydrogen or to i ion. This quantity is known as the electron (see Introduction) ; it amounts to about 6 X io~ 10 = ( t^t. — ;-) electrostatic units. \io milliards/ Water is decomposed by the current in the galvanic ele- ment; hydrogen and oxygen are formed, H at the copper and O at the zinc. Experiments show that such plates covered with gas produce an electro-motive force and a current which pro- ceeds in an opposite direction to the original current. This secondary current endures till the decomposition products are dissipated. Plates which are covered with decomposition-gases are described as polarised; the cur- rent which they produce is the polarisation-current. In a galvanic element the water is decomposed, hydrogen going to the copper plate and forming a film there which breaks the current. Galvanic polarisation (electro-motive opposing- force) explains the early weakening of the original electro-mo- tive force of the element, and its final reduction to a minimum. Herein lies the unreliability of galvanic elements. Primary elements, of whatever system, all have the disadvantage of being very dear to work compared with their capacity, either requiring very frequent and by no means easy renovation, or possessing very little current-power. ELEMENTS OF ELECTRICITY 27 § 9. Accumulators. Accumulators, or "secondary elements," obtain their effect by reason of the polarising action of oxygen and hydrogen ar- ranged as ions. In Plante's accumulator two lead plates are immersed in dilute sulphuric acid. If a current be passed through, oxygen is "separated" at one plate (the positive) , lead- ing to the formation of peroxide of lead, which is seen as a red- dish-brown deposit on the plate. Meanwhile, the other plate (the negative) becomes coated with sulphate of lead by the ac- tion of sulphuric acid. The accumulator is fully charged only when this latter process is complete. It has, through the influ- ence of the electric current, received chemical energy, a chem- ical power of work. The saturation-point of charging is marked by the evolution of hydrogen and oxygen at cathode and an- ode, respectively, the electricity being no longer able to induce chemical action on the plates themselves. During the charg- ing the sulphuric acid solution becomes more and more con- centrated. If the accumulator-circuit be closed a reversed polarisation current results, reducing the peroxide to oxide on one plate, the sulphate on the other plate being likewise altered to oxide. When both plates have become chemically identical, the current ceases. By repeated charging and unloading the plates become more capable of the peroxide charge. Plante's elements had to be worked for a long time in this way before they could be made to retain any considerable charge. Faure tried to remedy this defect by pressing a layer of lead oxide onto the plates in the first instance. This layer, however, had a tendency to fall from the plate, a failing which was obviated to some extent later by grooving the plate. By constant use the chemically active portion of the plate tends to become porous and spongy, and is easily destroyed, especially when quickly charged. Moreover, the plate is then liable to get easily bent, and both plates may come into contact, thereby effecting a "short-circuit." Even without such a contingency the capacity of the accumulator is prone to become impaired through the falling of masses of the porous material to the floor of the bat- tery, whereby the plates may become bridged across and a short circuit established. The chemical process does not penetrate 2 8 RADIO- THERAP Y very deeply into the lead plates; the accumulator's capacity, therefore, depends upon the size and number of these plates and their general formation. An accumulator may, however, be charged afresh any number of times, and will be capable of evolving each time a discharge current which is distinguished from that of the primary battery by its height and constant elec- tro-motive force. The discharge current, however, never quite equals the primary current in actual quantity. In the Tudor accumulator the positive lead plates are pro- vided with deep horizontal grooves. The negative plates are cross-barred and contain lead-masses in the grooves, which, during the charge, become completely changed to spongy lead. The plates are cast into shapes with projections on either side fitting into the vessel holding them. A series of positive plates soldered together and a similar series of negative plates are now placed into a wooden or glass receptacle containing dilute sul- phuric acid. Contact between adjacent positive and negative plates is prevented by the insertion of glass rods between them. The vessel is made deep, so that a considerable space is left be- tween its bottom and the lower ends of the plates; here any fall- ing substance has room to accumulate. The leaden ledges of the positive plates of one cell have grooves in which the negative plates of another cell fit, for just as one can couple up several galvanic elements, the same can be done with several accumu- lator-cells to form a battery. These compound-celled accumu- lators are arranged in wooden cases lined with lead. The sepa- rate cells are connected in series, so that at either end a positive and negative pole is left free with which to control the battery. Accumulators much used are those of Gottfried Hagen, Guelcher, Boese, Pollak, and others. While accumulators are of the greatest practical im- portance, it cannot be denied that as yet their construc- tion is by no means perfect. Amongst the many draw- backs to their use may be mentioned their sensitiveness to shocks and over-exertion, the difficulty of transporting them, their rapid loss of power, frequent failures on ac- count of internal derangement in the shape of bending of the plates, etc., cracking of glass cells, leakage of acid, ELEMENTS OF ELECTRICITY 29 their high initial cost and expensive up-keep. Many of these disadvantages are, it is claimed, obviated in the Behrend-Dessauer apparatus. This is formed of cells packed with glass powder and a hygroscopic fibre, the whole mass soaked with dilute sulphuric acid and press- ing the active spongy portion of the plates in position. Thus any bending of plates, with consequent short cir- cuit, is avoided, likewise falling down of the spongy lead. Each accumulator-cell has an average tension of 2 volts. The cells should never be exhausted beyond a certain point, or the plates will be impaired. Their limit for each size of accu- mulator is indicated by the maker. The electrical quantity given out during the period of discharge (expressed by multiply- ing the highest possible amount of discharge by the number of hours in which the current is evolved) is termed the accumu- lator-power or capacity in ampere-hours. Thus a battery which gives a maximum current of 6 amperes in 10 hours' discharge has a capacity of 60 ampere-hours. An accumulator of this capacity can also supply a 1 ampere current for 60 hours, a 3 ampere current for 20 hours, and so on. One cannot, how- ever, obtain a current exceeding 6 amperes. If the ampere- hour capacity of the accumulator be divided by the product of the corresponding time of charging and the strength of the pri- mary current, one obtains its relative value in ampere-hours. This usually amounts to 90% or 95%. § 10. Ohm's Law. The force or intensity of an electric current was defined on page 24. Static electricity of the kind found in a Leyden jar is high in pressure but low in quantity, nnd we know that, though its discharge is violent and characterised by striking phenomena (physiological, light, etc.), these are but momentary. On the other hand, a galvanic current, though of lower tension and less electro-motive force, is comparatively rich as regards quantity. It can consequently be employed tor lighting purposes, or for mechanical or chemical purposes. (Compare the work capacity 3 o RADIO-THERAPY of a large quantity of air or water under low pressure with a small quantity under high pressure.) Other things being equal, the greater the electro-motive force, the greater the quantity of electricity flowing through a given sectional area of a conductor. The working value of a quantity of water depends, as we have seen, upon ( i ) its pressure, (2) the strength of its current. An electric current is similarly situated, but a third important factor must be added, the resistance of the conductor. A stream-current meets with obstruction from friction with its bed; moreover, caeteris pari- bus, a current flowing in a wide channel will be much more pow- erful than a narrower one. In order to obtain the same current- force in the narrow that we have in the wider channel, it will be necessary to increase the rapidity of flow or the water-pressure. With an increasing resistance the current-force decreases. Ohm's law is as follows: The intensity of an electric current (I) is directly propor- tional to tJie electro-motive force (£), but inversely pro- portional to the resistance (R) . R One may add that the force of the current is the same in all parts of the current-circuit when the current is con- tinuous. A conductor's resistance depends largely upon its composi- tion, that is, upon its specific conducting resistance (K) . Again, the resistance varies directly with the conductor's length (/) and its sectional area (/). We may, therefore, add the following equation : R = K j. Heating increases the resisting power of metals, but decreases that of carbon. In order to reduce a current of electricity to a required in- tensity it is often necessary to interpose various resistances in its path. These are known as "rheostats." Rheostats may be constructed on the decade-resisting principle, which measures re- ELEMENTS OF ELECTRICITY 3i sistances of 1-100 times the unit and more. When, however, the object is to quickly interpose resistances into a current-cir- cuit, determination of this exact capacity being unnecessary, the so-called ballast-resistances are useful. The form of those usu- ally employed for strong currents is known as a crank or lever- rheostat (Figs. 4 and 5), where a series of German silver, "nickelin" or "manganin" spirals, which offer great resistance to the current, are fixed and insulated in a frame. By means Fig. 4. Fig. 6. Fig. 4.— Lever-Rheostat (from Graetz L. Electricity, Stuttgart, Engelhorn, p. 91). Fig. 5.— Lever-Rheostat of Reiniger (Gebbert and Schall, Erlangcn). of the lever a greater or less amount of these metallic spirals can be interposed in the path of the current. With the lever- knob to the extreme left the current is interrupted; as it moves to the right a gradually increasing resistance is established. Fig. 6 depicts another variety of resistance, in which a single spiral of uniform thickness, composed of German silver or nick- elin, forms the resisting medium. By sliding a "contact" over 32 RADIO-THERAPY this in either direction, the length of the resisting path can be varied. § II. Technical Measure-units. The following technical measurement-units have been agreed upon since 1 88 1 as indicating current-strength, conductor-resist- ance and electro-motive force or potential difference : i. The current-strength unit is I ampere: This cor- responds to a current-intensity capable of precipitating o.ooi 1 1 8 gramme of silver in one second from an aqueous solution of sil- ver-nitrate. Measured electro-magnetically, the unit of current- strength is that which, traversing an arc of I cm. length and i cm. radius, acts with a force of i dyne on a mag- net pole (one) situated in the middle of the circle com- pleting the arc. The "practical" unit of the current- strength, i ampere, is the tenth part of the above (C. G. S.) unit. The quantity transmitted by the current, one on a time-unit through a given sectional area of conductor, is accepted theoret- ically as the unit of current-quantity or electrical quantity. The "practical" unit is, therefore, that electrical quantity which, with a current strength of i ampere, flows through a sectional area ol conductor in one second. It is called an ampere-second, or i coulomb. (See p. 12) for the electro-static unit of electrical quantity.) 1 coulomb = 1 ampere X 1 second. From this we derive the working-unit of an "ampere-hour." The ampere-hour is that electrical quantity which traverses a conductor in one hour or 3,600 seconds with a current-intensity of 1 ampere, An ampere-hour, therefore, corresponds to 3,600 coulombs. The capacity or holding-power of an accumulator is usually expressed in ampere-hours. By this one un- derstands that electrical quantity which is evolved dur- ing the average discharge-period, and which is expressed by the product of the greatest force of current-discharge ELEMENTS OE ELECTRICITY 33 and the time in hours during which the current can be utilised. 2. The unit of resistance is possessed by that conductor in which the electro-motive force 1 produces the current 1. This unit is called 1 ohm. The ohm is defined as the resistance of a column of mer- cury of 14.4521 grammes, 1 square millimetre cross-section and 1.062 m. length, measured at 0°C. 3. By the unit of electro-motive force is meant that elec- tro-motive force which produces a current of 1 ampere intensity in a conductor possessing 1 ohm resistance. This unit was termed "volt" at the electrical congress held in Paris. The unit of electro-motive force may be deduced from the phenomena of an induced current, or from the current's working capacity. 1 volt is, we may mention, the electro-motive force of a zinc-copper element {Latimer Clark's normal ele- ment). It is about 10% less than the electro-motive force of Daniell's element. The unit of current capacity (work or heat) is indicated when the work is accomplished by a current in 1 second, as, for example, when the heat equivalent to a unit of work is produced in a wire. (See p. 42.) The unit is given by a current 1 and a resistance 1, or also by the electro-motive force 1 producing the current. The practical unit is, therefore, the volt ampere, that is to say, the capacity for the electro-motive force 1 volt when producing the current 1 ampere in 1 second. The unit of effect in one second is called 1 watt. This, multiplied by the total working period, gives the total energy involved (or accumulated). One usually ex- presses this in watt-hours. The consumption of electrical en- ergv is reckoned in watt-hours. The eftect of one watt = — 5- b ' 9.81 kilogrammeter per second. The effect of one horsepower amounts to 75 kilogrammeters or 736 watts. The effect of one watt is, therefore, equal to —7 horse- power. 34 RADIO-THERAPY § 12. Battery-Connections. If we close the current circuit of one or more elements, two kinds of resistances are to be distinguished ; the internal, or more- important resistance of the element, and the external, or less-im- portant resistance. The latter (Ra) depends upon the cross- sectional area, the length and the specific conducting-capacity of the wire joining the two dissimilar electrodes (including, of course, the apparatus to be worked). The internal resistance is offered by the liquid of the element. By connecting a fresh element, therefore, fresh resistance is unavoidably added. As we know, Ohm's law reads : E l= R- Since the total resistance is made up from the external and internal resistances this formula now becomes E i = Ra + RV or, substituting for the letters the measurement determinations, A - v a {Ra + Ri) Experiments with two vessels of water provided with escape- tubes show that when these are at the same altitude and the escape-tubes are in connection with one another, the escaping water is under the same pressure as if it flowed from a single vessel; it has, however, only half the resistance to overcome, since both escape-tubes are joined to form a single tube of double the sectional area. Hence, an increase in the intensity of the A\ A\ As A\ As As ! 23 z + z + z -»- z + z + z - /* Van 3 + 3+3+3+3+ 3 = y '8 Amp TZ >T T- Tl Tl V- 3 + 3+3+3+3 + 3 = 48 Amp Fig. 7. Fig. 8. Fig. 7. — Parallel connection (from Donath B. Die Einrichtung zur Erzeu- gung der Roentgenstrahlen, Berlin 1890, p. 9). Fig. 8. — Serial connection (from Donath B. Die Einrichtung zur Erzeugung der Roentgenstrahlen, Berlin 1899, p. 8). ELEMENTS OF ELECTRICITY 35 stream results. If, however, the vessels are arranged one over the other the resistance will be doubled, as also the pressure. The same thing applies in the coupling of galvanic elements. Their connection in parallel Fig. j results, therefore, in an increase of current and quantity. Connection in series, or tension-connec- tion (Fig. S), augments the electro-motive force. From the above the following formulas may be given for serial and parallel connections of n elements: I ) J — ~ /> ,-5— and 2) 1 = - w -. ; 11 Ri + R a ' R 1 - + Ra n that is to say, in the case of serial connection the electro- motive force, also the internal battery-resistance, equals the electro-motive force and the internal resistance of a single ele- ment multiplied by the number of elements joined together. On the other hand, in the case of parallel connection one obtains a battery whose total electro-motive force equals that of any one of the joined elements. The internal resistance of the latter, however, is correspondingly smaller, as the number of elements joined is increased. Let us examine serial connection more closely. If, for instance, the resistance of the connecting-wire be very small compared to the internal resistance of a single element, so that it may be disregarded, it practically follows 1. E I = Ri One therefore gains nothing in the way of current-intensity by serial connection. The total current is approximately as strong as though one were dealing with one element only. If, on the other hand, the wire-resistance be very great, far greater than the total resistance of the series, one obtains practically R a Consequently the current-strength is about n times as large as if , one were using one element only. 3 6 RADIO-THERAPY Let us now examine conditions in the second case. If the wire-resistance be small compared with the internal resistance of the battery, so that it may be disregarded, then E of an element — i/u Ri of an element The current-strength is, therefore, about n times greater than that of one element. If, on the other hand, the wire-resistance be very great, it follows that E of an element / = Ra the current strength in this case is practically the same as that of one element. One, therefore, gains nothing in the shape of current- strength. We have, therefore, these two rules: // we wish to obtain the greatest possible current-strength when dealing with considerable external resistance connection in series is advisable; on the other hand, parallel connection should be employed when the external resistance is very weak. § 13. Ramification of Current. The strength of current is not everywhere alike, when deal- ing with conductors of a branched form; various strengths ob- tain along the different branches, being inversely proportional to the resistance they offer. The two following laws given by G. Kirchhof bear on the questions of current-intensity and the individual branch-resistances : 1. At any part of the ramification system the force of the current flowing toward that part equals the sum of the forces of current flowing away from it. 2. In the case of a ramification system forming a closed figure the sum of the current forces obtaining in each branch of the system multiplied by the resistances of the same equals the sum of the electro-motive forces existing in the current circuit. In Wheatstone's Bridge (Fig. 9) the current ramifies ELEMENTS OF ELECTRICITY 37 through two conductors between which a cross-communication is established, so that four branches, a, b, c, d, result. A current generally Hows through bridge O, whose force and direction depend upon the relations between the four branch resistances. The bridge-resistance only disappears when the following proportion exists: a : b = c : d. From Ohm's equation it is seen that if one examines the distribution of tension on the conducting wire alone, E = 1 R. Now, since the electro-motive force corresponds to the tension- difference at the conductor's termi- nals, one may also say: The differ- ence between the tensions obtaining at either end of a conductor equals the product of its resistance and the current-force. The tension, there- fore, at the end of a current-con- ducting wire is smaller than that at the beginning, the tension-loss cor- responding to the current-force mul- Fig. 9.— Wheatstone's Bridge, tiplied by the resistance of the wire. The greater the resistance of the wire, the greater is the loss of tension. Hence it follows that the tension-difference at the poles of a closed galvanic element is smaller than the element's electro-moti\ e force. The tension-loss is here caused by the overcoming of the internal resistance of the element; it cor- responds to the current-force multiplied by that internal resist- ance. The tension-difference at the poles of a current-producing apparatus (battery or dynamo) is called the tension of the terminals. (This is a variable figure, being thereby distin- guished from the electro-motive force of the apparatus, which remains constant.) In the case of a branch-system in which the commencements and terminations of all the branches are severally connected {"parallel-connection" of conductors), the resistance of an indi- vidual branch is not equal to the sum of the resistances in all the branches, but is equal to the resistance which would be offered 3 8 RADIO-THERAPY by one conductor whose sectional area corresponded to the sum of sectional areas of the individual branches. In case of a conductor-system where the commencement of one branch is connected with the end of another the total resist- ance is, however, clearly increased. If the resistances of indi- vidual branches be indicated by r 1} r 2 . . . . r n their total re- sistances in parallel-connection R p is shown by the equation 1 = .* + • • ■ + ' R t r their total resistance in serial connection RH by the equation Rh = r x -f r 3 + . . . . + r n . § 14. Measurement of an Electric Current. If an electric current be flowing parallel to a magnetic needle, or spirally around it, the needle becomes deflected from its usual north and south direction, the amount of deflection varying with the intensity of the current. If one imagines a person swimming in the direction of the positive current, turning his face mean- while toward the needle, the north pole of the latter becomes de- flected toward his left hand. {Ampere's rule.) This property of a magnetic needle may be employed, not only to determine the existence of an electric current, but also its direction and force. On this principle galvanometers have been constructed. In these the current passes along a few spiral turns of thick wire offering but little resistance, so that the instrument influences the current-intensity of the circuit. The amount of deflection then indicates the amount of this current-intensity. An ampere- meter is merely a galvanometer with the dial registered in Ampere's manner. These instruments are only suitable for feeble currents. In measuring currents of greater intensity, the amperemeter re- quires adaptation in the shape of "shunt-circuits." These are connected to the terminals of the amperemeter, and the re- sistance of each "shunt" corresponds to the resistance of the meter itself. Consequently, only a certain portion of the current ELEMENTS OF ELECTRICITY 39 actually flows through the instrument, the amount varying in- versely with the number of shunts. The indicated number on the dial, therefore, multiplied by the number of shunts, gives the intensity of the main current. By its inclusion with a branch or shunt-circuit, a galvanome- ter may also be used to indicate tension difference. An instrument for this purpose, however, differs from the amperemeter in that a great resistance is offered to the current, the conducting-wire being thin, and arranged in a great number of spirals. The amount of deflection caused by a current Fig. io. Fig. [i. (coming from a source with small internal resistance) is propor- tional to its electro-motive force, or to the tension-difference of the two points in the circuit which are connected through the meter. The dial being suitably registered, one can read off the amount of this electro-motive force or tension-difference, expressed in volts. The apparatus is called a voltmeter y Apparatus for measuring electric currents are also con- structed by the aid of other magnetic properties which they pos- sess. For example, in the amperemeter and voltmeter of the "Allgemcinc Klectricitatsgesellschaft" (Figs, io and 11), the attraction of a wire spool, through which a current is flowing on 40 RADIO-THERAPY an iron core, is utilised. A metal rod, hanging from a spiral spring, is drawn more deeply into the spool as the current in- creases. The force with which the metal rod is attracted varies with the square of the current-strength and the square of the number of spiral windings. By means of a lever the movement of the metal rod is transmitted to an indicator furnished with Fig. 12. Fig. 13. (From L. Graetz 1. c. p. 336.) a dial. The instrument is registered in amperes of volts, accord- ing to its situation in the main-current or branch-current. Figs. 12-13. W. Weber's electro dynamometer is also used for measuring continuous and alternating currents. The principle of this apparatus is founded on the electrody- namic effect which two conductors have upon one an- other, whereby they are constantly striving to become parallel, and the current in them to move in the same direction. The amount of this electro-dynamic force depends upon the relative situation and distance of the two current-circuits, also upon the strength of the cur- rents. (The sine of the angle between the conductors is then proportional to the square of the current-force.) With a different arrangement in the winding of the spool the instrument can also be used for measuring tension- differences. ELEMENTS OF ELECTRICITY 41 Hummers amperemeter and voltmeter are often employed tor alternating currents. In these instruments a piece of light iron foil is arranged so as to be capable of rotating inside a wire spool, and in such a manner that the axis of the rotation does not coincide with the axis of the spool, but is placed eccentrically. When a current passes through the spool the iron foil revolves on its axis until it reaches a plane where its weight is balanced by the electro-magnetic force. An indicator joined to the foil shows the current-force on a dial (or the tension in the case of a shunt-circuit). It may be here noted that so-called "hot-wire instru- ments" are employed sometimes for the purpose of measuring the intensity and tension of alternating cur- rents. Their principle lies in the fact that a platino-sil- ver wire traversed by a current becomes heated, and thereby lengthened. The wire is connected with an axis which re- volves as the former alters in length, thereby actuating an indicator. The stronger the current, the greater the heating and lengthening of the wire, with corresponding greater movement of the indicator. § 15. Heat and Light Effects of the Galvanic Current. A current flowing through a conductor has to overcome re- sistance, and, therefore, do work. This active energy is partly transformed into heat. The law relating to this heat-forma- tion is as follows: The amount of heat developed in a given portion of a conductor in a given time increases with the square of the current-strength, and directly with the resistance of the conductor. {Joule's law.) A = RP To insure the safety of electric installations, short pieces of leaden wire (fuses) are introduced along the conductors. Their thickness is so gauged that the wire melts before the current can reach a dangerous limit, which might otherwise happen in case of short-circuiting. 42 RADIO-THERAPY This accident of short-circuiting happens when the cur- rent finds a shorter path through contact between indi- vidual portions of the circuit, whereby any existing re- sistances (lamps, motors, inductors, etc.) are eliminated. A short-circuit current has naturally far greater energy, and may, therefore, be very dangerous. This heat-effect finds an important application in electric in- candescent lamps, in which carbon filaments made from cellulose are brought into a state of incandescence within vacuum glass globes. The lighting power of an incandescent lamp depends upon the current-strength and the resistance of the filament. As a rule, not merely the current-strength required for normal burn- ing of a lamp is indicated, but also the amount of tension-dif- ference at its terminals. Since the resistance of the lamp is known, the normal current-strength required follows directly from this tension. The resistance of an incandescent lamp is generally very high; it requires, therefore, high tension, but a comparatively weak current. Numbers are usually placed on the lamp indicating the necessary volts and amperes. Parallel- connection of lamps is the most effective. Joule's law, as quoted above, has the same bearing upon the arc-light as upon the incandescent lamp. Whereas, how- ever, with the latter we have an uninterrupted conductor brought into incandescence by the current; in the case of the arc-lamp two carbon points and an intervening layer of air form the conducting medium, whereby the carbons and the air laden with carbon particles are made to incandesce. If one interrupts a powerful galvanic current, a spark is produced at the site of interruption. This phe- nomenon is due to change of resistance at this point, whereby high electro-motive force is induced in the cir- cuit, and a spark flies across the air-space separating the two poles of the conductor where its continuity is broken. (For Induction, see below.) If we send a powerful current through two pointed rods of carbons in contact with one another, the latter become incan- descent at the point of contact in consequence of the high re- sistance offered there. If, after incandescence has been ELEMENTS OF ELECTRICITY 43 established in the points, the rods are slowly removed a short distance, a light violet arc-light results ("Folia's arc-light 1 '), which is due to burning carbon particles torn off by and carried with the current from the positive to the negative pole. It is essential, however, that the elec- trodes (the carbons) be first in contact and afterward separated. The air then conveys the current, for if its electro-motive force and tension are sufficient, electricity can overcome the resistance of a warmed layer of air; this is accompanied by the develop- ment of such intense heat that the carbon points and the particle- laden air intervening become white-hot. A crater-shaped depression (Fig. 14) is found at the posi- tive carbon, giving forth a dazzling radi- ance. The negative carbon becomes gradu- ally pointed, and is consumed at only half the rate of the positive (their diameters be- ing equal). In order to help in the forma- tion of the crater, the positive carbon ismade with a core of softer and better conducting material. (When employing rapidly alter- nating currents the condition and rate of FlG - *4- combustion of the carbons are identical.) ,„ „ „.. ' (From F. Korner, The arc-light is produced only when the Lehrbuch der Pby- carbon points are from 2-8 mm. apart; sik, Wien und Leip- therefore, there must be some contrivance , zlg ' ; Deutlc e , 1 • . • i- 97. P- 389) tor regulating this distance. As already mentioned, considerable electro-motive force is requisite for a Volta's arc-light; this results more especially from the fact that in the arc-light itself an electro-motive opposing force exists of about 40 volts (perhaps resulting from destruction of the electrodes or from electrolytic decomposition of the air), which must be overcome by the current. Hence the terminal tension at the carbon points must always be greater than 40 volts. Moreover, the cur- rent-intensity must be very high, because, according to Joule' 7 law, the heating of a conductor is proportional to the resistance and the square of the current-intensity. 44 RADIO-THERAPY Naturally, the brightness of an electric arc-lamp depends not only upon the length of the arc itself, but upon the strength of the current traversing the carbons. It is cus- tomary to indicate the lighting-power of an arc-lamp by the intensity of the current required to work it. Arc-lamps may be joined either serially (this is seldom done), in parallel, or in groups. In the latter event groups of serially arranged lamps are joined in parallel to the main current. In the case of parallel connection of arc-lamps, resistances are placed in front of the lamp circuit. § 16. Thermo-Electricity. We have seen (p. 23) from the laws relating to tension- series that a current cannot be obtained from a series of metals alone. This statement, however, only holds good if the tem- perature of the whole series be constant. If at some part of the metal-chain the temperature be raised or lowered, a current results, which is known as a thermo-electric current. This cur- rent always flows from the higher-temperature locality to the lower. Thus, if at some point in the series (say, where two ad- jacent metals are soldered together) the temperature be low- ered, the current flows towards that point. The electrical ten- sion invoked is greater (given equal temperature differences) the farther the respective elements of the series are situated from one another. Becquerel arranged the following series for the production of a thermo-electric current: Bismuth, nickel, platinum, cobalt, silver, lead, copper, zinc, iron, antimony. The electro-motive force of a thermo-electric series also depends largely upon the temperature difference of the soldering places. Frequent attempts have been made to produce stronger thermo-electric currents by uniting several elements in the man- ner of galvanic elements, to form the so-called thermo-pile. Inasmuch as the electro-motive force of even the most effectual single combination is very feeble, many separate elements re- quire connection in series for this purpose. Guelcher's thermo- ELEMENTS OF ELECTRICITY 45 pile can be used for practical purposes, such as charging accu- mulators. In this apparatus hollow positive electrodes are cast, as in small tubes of chemically-pure nickel; the negative electrodes, likewise tube-shaped, are cast from an antimony- alloy. The tubular positive electrodes convey gas, by which, through a small Bunsen-flame, each element receives a certain amount of heat. The small flames heat a piece of iron connect- ing the positive and negative electrodes. The larger-sized pile constructed thus, and consisting of 66 distinct elements, gives at average gas-pressure an absolutely constant electro- motive force of 4 volts, with an internal resistance of about 0.6552. (The internal resistance of a thermo-pile is small, the elements consisting of metals only.) The mechanical effects of electrical currents upon one another, as shown in induction effects, effects of a current upon a magnet and vice versa, were dealt with when speaking of electro-dynamometers. § 17. The Magnetic Effects of Electric Currents. Iron or steel brought near a conductor transmitting an elec- tric current become magnetised. This magnetic effect can be intensified by arranging the conductor in the form of a spiral with the several windings on the same level; or as a solenoid, which consists of rings arranged in parallel, one behind the other. A solenoid itself'behaves like a magnet. If hung up so as to be freely movable, it comes to rest in the magnetic meridian, and shows other phenomena pertaining to the magnet. An electric current passing through an insulated wire which is arranged spirally round an iron rod, brings the latter into the magnetic state. Its poles may be determined by Ampere's law, above quoted. The magnetising force of such an electro-magnet is propor- tional to the current-intensity and number of spiral windings. With cessation of the current soft iron at once loses its mag- netism, whereas steel, under the same circumstances, remains magnetic. A current growing stronger produces less magnetism 46 RADIO-THERAPY than a weaker-growing current. This is known as hysteresis of iron. The "pulling effect" of a solenoid upon an iron core has been already mentioned (pp. 39, etc.) . The magnetic action of electrical currents is turned to ac- count in the regulators of arc-lamps, in various current-inter- rupters, and in electric meters. An electric meter measures the quantity of electric energy consumed. An electric current does work every second which is equal to its tension (in volts) mul- tiplied by its quantity (in amperes). The number of watts (volt-amperes), therefore, stands for the chemical energy pro- duced each second by the current. The period of consumption is reckoned in hours. If, there- fore, we multiply the number of watts by the number of hours, we get the total consumption of energy expressed in watt-hours. Since the tension is always constant, one need but measure the number of ampere-hours (current strength multiplied by time) . This number multiplied by the constant tension V , therefore, gives the number of watt-hours. Avon's electrical meters, mostly used with continuous-cur- rent installations of constant tension, consists mainly of two clock-work pendulums exactly synchronised. A metal rod hangs from the lower end of one of the pendulums, and swings with it over a solenoid traversed by the current about to be measured. The magnetic influence of the solenoid accelerates the speed of its pendulum. This acceleration can be compared with the speed of the other pendulum, which swings free. An indicator is connected with the clock-work of both pendulums in such a way that only the difference in velocities is registered. While no current is passing through the solenoid the indicator is motionless; the moment a current passes it shows the acceleration of the mag- netised pendulum. The amount of movement of the indicator is thus proportional to the current-strength, and affords exact measurement of the electrical quantity passing through the sole- noid. Where the tension is not constant the amount of energy consumed can be measured by the watt-hour-meter. This is ELEMENTS OF ELECTRICITY 47 similar to the preceding apparatus, but the pendulum swinging over the solenoid is not provided with a bar-magnet. In place of the latter there is a roll of fine wire, which lies in a "shunt- circuit" to the main current. The force with which the cur- rents in both circuits act upon each other depends upon the product of their current-strengths. Since, however, the strength of the current in the shunt-circuit depends upon the tension at the terminals of this circuit (its resistance being invariable), the force depends upon the product of tension and current-strength, consequently upon the watts. The movement of the indica- tor by the pendulum accordingly bears direct relation to the product of the watts and the duration of the current. A dial is arranged to indicate the energy in hecto-watt-hours. This instrument can also be employed for alternating currents. In Thompson's meter an electro-motor turns an armature- core wound in the form of a drum. This actuates a copper disc set between magnet poles, and also a numerating apparatus. The turning of the copper disc is hindered and regulated by the magnet poles (see Foitcault's currents, below). The velocity of revolution of the disc, which is affected by the current to be tested, consequently affords an indication of the watts con- sumed. § 18. Induction. We have already seen that an electric current produces mag- netic forces. Now the reverse holds good to a certain extent, viz. : magnetism itself can, under certain conditions, produce electricity. {Faraday.) If a magnet be brought near a conductor fitted with a gal- vanometer, or withdrawn from the same, the galvanometer in- dex moves, thereby showing that the conductor is traversed by a current. This phenomenon occurs every time the magnet is ap- proached to, or withdrawn from, a point directly opposite the conductor. If a steel magnet be brought near the iron core of an electro- magnet, the core itself becomes a temporary magnet. At the same moment an electric current appears in the closed circuit of the spool. This current is only temporary, whereas the steel- 48 RADIO-THERAPY magnet keeps the iron core in a state of magnetism. The cur- rent is only manifested while the steel magnet is approaching the core. The electric wave 1 ) thus produced in a wire circuit while magnetism is originating is called an induced-current, being transmitted from the magnet to the distant wire-circuit (in- duced) . After this induced current wave is over, a fresh wave pass- ing in the converse direction may be produced by removing the steel-magnet from the iron core and thereby dissipating the magnetism of the latter. This current is also very brief, being, like the first, merely an electric wave. By alternately originating and dispersing magnetism an electric current may be produced in a closed wire-circuit, which continually changes its direction — an alternating current. Fara- day's discovery may also be expressed as follows: If a conduc- tor interferes with lines of force, induction takes place in it. Electrical energy is manifested therein. The electro-motive force of this induced current is greater, the greater the strength of the inducing magnet and the number of spiral windings,, and again, the quicker the inducing magnet is approached to and withdrawn from the spiral. If the external resistance through which the induced current is meant to flow be increased, the elec- tro-motive force of that current must also be increased, and therefore, other things being equal, there must be a greater num- ber of windings. By thus augmenting the number of wind- ings very considerable external resistance can be overcome. For this reason a secondary spiral is attached to "spark-inductors" (see below) , consisting of very long and fine copper wire. The internal resistance of the spiral should probably approach as nearly as possible to that of the external resistance of the cur- rent-circuit. The induction caused by a magnet is termed "magnetic-in- duction." Just as an electric current is produced in a closed circuit by the above-mentioned method, so an induced current can be invoked in wire-spools which are made to rotate before ') The expression "current wave" signifies the very brief duration of each induced current. ELEMENTS OF ELECTRICITY 49 the poles of a magnet. The same principle underlies all mag- neto-electro machines. Here also it follows that the induced current must constantly be changing its direction, according as a spool approaches or withdraws from a pole, l^hese machines are, therefore, alternating-current machines, which produce elec- tricity manifesting itself in individual electric waves, rapidly succeeding one another, and continually changing their direc- tion. Alternating currents can only be transformed into con- tinuous currents by means of certain complicated apparatus {commutators) . But a continuous current may also be produced directly by one machine; the principles of this machine (which has an importance for us by reason of its use in radio-therapy) may be here briefly ex- plained. The earlier magneto-electric machines were IG ' IS ' very imperfect, their magnetic field being weak ( From Corner, and not fully utilised. Siemens' double-T -mag- net apparatus (Fig. 15) constituted a marked improvement. A cylinder (armature-core) rotates between two hol- lowed-out poles of a horseshoe magnet. Spiral wires are wound lengthwise round this cylinder, so that the windings on the axis-core lie parallel. When the arma- ture rotates alternately north and south poles are in- duced in it, while alternating currents are produced in its spiral winding, which become transformed into con- tinuous currents by a commutator. The dynamo-electric machine of Siemens (1867) remedied the defect of rapid loss of power by the steel magnet (see Lenz's law below). In place of permament magnets, Siemens em- ployed electro-magnets, produced by causing the induced current itself to flow round the iron core. Even the softest iron core possesses traces of residual magnetism; hence, during the first revolution of the armature a current, however feeble, will result. This feeble current is first conducted round the electro-magnet, which it strengthens. Thereby still stronger induced currents are produced, which strengthen the magnet anew, and so on 5Q RADIO-THERAPY until the magnet reaches its saturation-point. In this way pow- erful currents may be obtained in a short time from very small quantities of magnetism through the reciprocating action of magnet and spiral-winding. By a peculiar shaping and winding-arrangement of the spool — known as the armature — a constant and continuous current can be produced in place of the wave-like currents of earlier machines. Here we shall briefly consider the principle of the gramme-v'mg, a type on which many dynamos are founded. An iron ring rotates between the poles N and S of an electro-mag- net (Fig. 1 6) . The ring carries a large number of wire spools, two neighbouring spools being joined with one another and a metal plate belonging to the current-collector, the whole being insulated from the axis of rotation. The collector possesses as many plates as there are spools. When the iron ring rotates, poles are formed in it in the neighbourhood of N and S. These Fig. 16. (From Lotheisen, Lehrbuch der Physik, p. 605.) poles are apparently constantly changing their position in the ring because of its rotation, and hence moving through the spools. Consequently currents are produced in the latter, which in the case of spools above the neutral zone B D are moving in one direction, while in the lower part they move contrariwise. Two wire bristles (the brushes) are in contact with those col- lectors which happen to be in the neutral line. One brush re- ceives positive and the other negative electricity, both being at- tached to conducting wires which convey this electricity to the apparatus requiring it. The armature has not the shape of a gramme-ring in all dynamos; other contrivances are employed ELEMENTS OF ELECTRICITY 5i ^4 ^4* u4 9 w \° 10 \o \o a d\ c\ 81 J, Fig. 17. instead, so that one therefore distinguishes ring-machines from drum-machines, and so on. Alternating currents which, as we have seen, are produced by magneto-electric machines are not quite so useful for radio- therapeutic purposes as continuous currents. The electro-mo- tive force of an alternating current reaches zero at a certain time a (see Fig. 17), increasing afterwards to the highest value A, and then decreasing again to zero b. Next the direction of the current is altered, so that electro-motive force and cur- rent-strength become nega- tive. The electro-motive force falls to the highest negative value B, afterwards reaching zero again. By the "period" of the alternating current we understand that time in which a wave-move- ment is completed, with its concomitant position and negative electricity (the period a c) . This period has a positive and a negative phase; that is to say, it corresponds to a single alternation of the current. The greatest current-strength is known as the amplitude of the alternating current. By phase of the alternating current we understand the current-strength at a given time (reckoning from the point where this current-strength is at zero) divided by the amplitude. Two alternating currents may be distin- guished from one another ( 1 ) by their average current strength, (2) by their periods (one may have a period of rks second, the other a period of yfo second), (3) where their periods are equal, by the fact that they do not attain their maxi- mum value at the same time; or, in other words, do not pass zero and change their current-direction simultaneously. A sys- tem of alternating currents possessing equal periods, but whose phases are different, has important properties dependent upon these very phase-differences. Such alternating currents acting together are called multiple-phase currents. The rotary cur- rent is a special kind of multiple-phase current. 52 RADIO-THERAPY In every magneto-electric and dynamo-electric machine the electro-motive force depends upon the strength of the magnetic field, the proximity of the iron-core to the magnet poles, the velocity of rotation of the anchor, and, finally, upon the number of spiral windings on the latter. If a continuous current be sent into a dynamo, the latter begins to rotate. It is then called an electro-motor. In order to understand the principles of an electro-motor one needs but to call to mind the simple laws of electro-mag- netism ; by the flowing of the current through the anchor-wind- ings and the ring-spools magnet poles are produced in the iron, and it is easily seen that adjacent poles in ring and anchor are of the same kind. Magnetic poles of the same kind must repel each other; the electro-motor begins to work, turning in the opposite direction to that it would have were it a generating ma- chine. The rotation of the motor may be transmitted and utilised in various ways by lengthening its axis, employing eccentrics, con- necting-rods, etc. Alternating and rotary current motors are of a very complex nature, which cannot be described here. (The author here describes common forms of con- tact apparatus. — TRANSLATOR.) Electrical currents have also an inducing effect, known as electro- or volta-induction. If an electric current be opened or closed in the inducing or primary coil of an induction-apparatus, a brief current (the in- duced current) is produced in the secondary coil. When the pri- mary current is closed, the secondary current flows in an opposite direction; when, however, the primary current is opened, both flow in the same direction. The same result is attained if one quickly strengthens or weakens the intensity of the primary current by means of a rheo- stat, or if one rapidly introduces the primary coil .within the secondary coil (corresponding with the closing of the main cur- rent) and withdraws it equally rapidly (corresponding with the opening of the main current) . Since the free electricities which appear at the terminals of the secondary coil on opening and closing the primary current are directly opposed, the induction ELEMENTS OF ELECTRICITY 53 apparatus may be regarded as an alternating-current machine which, from one moment to another, is alternately producing currents of opposite direction. With regard to the strength of the induced current, that is to say, the electro-motive force induced, the following laws apply: The electro-motive force of the induced current is greater: 1. The greater the inducing strength, that is to say, the greater the strength of the exciting current in the primary cir- cuit and the greater the number of windings in the primary coil; or, in the case of magneto-induction, the greater the strength of the inducing magnet. 1 ) 2. The greater the number of windings in the secondary coil. 3. The greater the rapidity of the interruptions, that is to say, of the changes in the main current. 4. The less the distance between the secondary coil and the inducing body (the primary coil or magnet) . The tension of the induced current depends upon the pro- portion obtaining between the number of windings in the two coils; the greater the number of windings possessed by the sec- ondary coil compared with those of the primary coil, the higher is the tension of the induced current. At the same time, how- ever, the strength becomes so much less, by reason of the great resistance offered by the many windings of thin wire in the sec- ondary coil, whereby the current is weakened. One obtains in- duced currents of remarkable strength by introducing bundles of soft iron-wire within the primary coil; this results from the magnetisation of the iron core. We have then voltaic and mag- neto-induction acting in co-operation. We may also explain the mode of action of this apparatus by assuming that the cur- rent traversing the primary coil produces a magnetic field around the common axis (see p. 12), and that this magnetic field, when formed or dispersed, induces a tension in the secondary coil, the amount of which depends (apart from other factors) upon the size of the magnetic field. From this point of view the action ') Sir also the principle of I >rssaun's apparatus, described later on. 54 RADIO-THERAPY of the iron core may be readily understood. 1 ) The dis- charge-current of a Leyden jar likewise produces, as Masson has shown, an induced current in a neighbouring wire. This can best be demonstrated by an apparatus constructed by Ries. Just as a current at the moment of its make and break has an induction effect upon an adjacent conductor, it has a like effect upon its own conductor when the latter is composed of a number of spiral-windings. This is known as self-induction, and the current thereby produced is called the extra-current. When the main current is "closed," a so-called extra current of the interruption appears in the spirals of the conductor; its direc- tion is opposed to that of the main current, and thereby the in- tensity of the latter is not allowed to at once attain its maximum. With "opening" of the main-current an "opening-current" is produced in the spirals, having the same direction as that of the primary current, which latter it intensifies, causing considerable augmentation of the spark at the site of interruption (see above) . On account of the high tension, the insulation of the wires may be destroyed, for which reason powerful cur- rents must not be suddenly interrupted. A shorter time is required for the disappearance of a current in a coil on "opening" the circuit than for its production on "closing." We know, however (see above) , that a tension' pro- duced by induction is greater the quicker the successive induc- tions follow one another. Consequently, the induction-tension in the secondary coil is greater on "opening" than on "closing." (On closing the circuit only a small spark is formed, or even none at all, whereas it may be very considerable on "opening.") With the help of special apparatus, which only permit either the "opening" or the "closing" waves of the induced coil to pass through a body, it can be shown that the induced current pro- duced by the opening of the primary current possesses a greater electro-motive force than that which is produced by closing. W T hen we come; however, to examine the chemical effects of the opening and closing currents respectively, we find that the elec- trical quantity traversing the induced circuit is in both cases iden- 1 ) B. Walter, Fortsch. auf d. Geb. d. Roentgenstrahlen. Vol. I, p. 29. ELEMENTS OF ELECTRICITY 55 tical. Since, however, the opening current is much briefer than the closing, it is evident that the intensity of the former must considerably exceed that of the latter. In cases where high tensions are required only the opening tension in the secondary coil need be considered, so that the cur- rent-waves produced by the apparatus in use may be regarded as waves of one direction. The foregoing explains, moreover, why electro-induction apparatus shows a certain polarity at the terminals of the secondary coil, in spite of the production of alternating currents, which polarity manifests itself in a striking manner w T hen the discharge is effected in a rarefied atmosphere. The self-induction of a conductor and the electro-motive force of its extra-current are mainly dependent (the alterations of the current-strength being equal) unon the shape of the conductor. It follows, therefore, that the relation which the electro-mo- tive force of the extra-current bears to the speed with which the current-strength is varied in the coil is merely dependent upon the shape of the coil. This relation is known as the co-efficient of self-induction, or the self-potential of the coil. Straight wires have but little self-potential. If one bends a wire in the middle, for example, so as to make it appear double, the current in each half has an opposite direction, and the self-potential in the wire is very small. If one bends it, however, in the form of a roll, its self-potential becomes more considerable, and greater still, if an iron core be placed within the spool. Each conductor, therefore, possesses a definite self-induction co-efficient or self-potential, the amount of which depends upon the shape, dimensions (length, sectional area) and winding of the conducting-wire. Whereas the tension of the primary current may practically be regarded as a factor forcing the current into the primary coil, on the other hand, the self-induction co-efficient represents the magnetic inertia-moment of this coil, which endeavors to check the rapid development of the current. B. Walter proved experimentally that the tension of the secondary closing current grows in direct proportion with the amount of the primary tension, and in almost inverse proportion with the amount of self-induction in the primary coil. By increasing the amount of self-induction in the primary 56 RADIO-THERAPY coil the closing tension in the secondary coil becomes therefore di- minished, whereby, as we shall see, the "life" and scope of reg- ulation of a "soft" Roentgen tube are considerably augmented. If one diminish the self-induction, for instance, by sending the primary current through fewer windings of the wire, a greater current-strength must be employed if the magnetic and inductive effects are not to be impaired. Lenz lays down the following law relating to the direction of induced currents: In all cases of electro-magnetic induction the induced currents have such a direction that their counter-effect strives to hinder the process of their development. Induced currents are met with not only in linear conductors but in massive metallic bodies; these are called Foncaidt's or whirl-currents. According to Lenz's law, the direction of these induced-currents is such that they counteract the activity of the conductor-mass. The opposing currents produced in this way in the massive core of an electro-magnet on closing the current thereby hinder the development of the magnetism ; in like man- ner, on opening the current, induced currents are produced in the iron mass of the core, which have the same direction as the vanishing current, and delay the disappearance of the magnetism. Foucault's currents, consequently, account for a considerable and useless consumption of energy; they are, moreover, troublesome by being transformed into injurious heat-effects (see Joule's law) . One tries to remedy this defect as far as possible by suit- able distribution and arrangement of the metal-masses. Thus the iron-cores of electro-magnets are not arranged as one solid mass, but in bundles of thin insulated iron-wires or plates. In these no very pronounced induced-currents can arise, since they are confined to interrupted conductors. For the same reasons the coverings of the iron-wires are not made of metal, but of an insulating material, such as ebonite. § 19. Spark Induction Apparatus. For present purposes, perhaps the most interesting applica- tion of electro-magnetic induction is to be found in spark-induc- ing apparatus. By their means we may produce all those phe- nomena for which high-tension electricity is required. The main ELEMENTS OF ELECTRICITY 57 object of the apparatus is, therefore, to transform currents of low tension to others of high tension. Ruhmkorfs coil (Fig. 1 8) consists of a primary thick-wire coil P, the core of which is filled with a bundle of thin iron wires M insulated from one another, and of a secondary coil of thin wire S arranged outside the primary coil, and having a very great number of windings. 9s U) Fig. 18. In order to produce rapidly-succeeding induced currents in the secondary coil the primary coil current has to be opened and closed with corresponding rapidity; this is done by means of an interrupter ("rheotome") . Interrupters are of various types, and will be referred to later. The efficacy of the whole apparatus is greatly increased by means of the condenser K (Fizeau's con- denser), which is connected with the primary coil. This con- 5 8 RADIO-THERAPY sists of a series of superimposed sheets of tin-foil, insulated from each other by sheets of paper which are larger than the tin-foils and are impregnated with resin. Sheets of oiled silk are often used instead of paper. The tin-foils are so arranged that the first, third and fifth sheets, and so on, are in connection with one another and overlap the paper sheets on one side, the sec- ond, fourth, sixth, etc., overlapping on the other, and being like- wise in connection. In the case of large induction coils the layers of the condenser sometimes reach the size of 20 qm. These layers are in connection with those parts of the interrupter where the make-and-break occurs. The effect of this is to make the spark at the site of interruption (created by the extra cur- rent in the primary coil) smaller. "Extra-current" electricity passes into the condenser, positive towards one layer and negative towards another. These opposite electricities immediately re- unite through the medium of the primary coil, the battery, and the current-circuit which connects the two layers. Hence a current arises which is in opposition to that of the battery, whereby a momentary "demagnetising" of the iron core results and the induced current is made of shorter duration. Thus the condenser allows the interruptions to take place with greater rapidity, with the effect of increasing the tension in the secondary circuit and the spark-length. Whereas without a condenser the sparking is very pronounced at the interrupter, by introducing this appliance into the primary circuit the interruption-spark is made very much weaker. A condenser's value does not alone depend upon its size: it requires to be "tuned," as it were, to the primary coil, to which it must bear a definite proportion. Experiments by T. Mizuno 1 ) (Tokio) have shown that the capacity of the condenser has a great influence on the spark-length, and that by exceeding a certain ca- pacity the spark becomes shorter again. Mizuno men- tions a series of experiments showing that the spark- length increases with the strength of the primary current, and that a definite condenser-capacity goes best with a given current-strength. *) Phil. Magazine. ELEMENTS OF ELECTRICITY 59 It is, therefore, advisable to have an apparatus whose capacity can be regulated by means of certain contriv- ances. Such an apparatus has been constructed by Radi- guet. According to Weriheim Salamonsen (Fortschr., Vol. IV., No. 3), the introduction of a small resistance in the condenser's circuit has a powerful effect in diminishing the "vibrations" which arise at the moment of interrup- tion, by leaving the so-called lime-constant 1 ) of the in- ducing current. These vibrations cause a considerable potential-difference at the two ends of the current-circuit at the interrupter, which is equalised by the spark. By using Salamonsen's apparatus one is consequently able to avoid those disturbing explosions which are apt to occur when using mercury interrupters. Coils fitted with electrolytic interrupters (ITehnelt's inter- rupter, see below) are not worked with a condenser. The self- induction of the primary coil (which is negatived by a con- denser) is an important adjunct in interrupters of this type. A Ruhmkorfs coil possesses yet another contrivance (Fig. iS, S JV) by means of which it is not only possible to rapidly interrupt the current passing through the primary coil, but also to change its direction at any time and, therefore, alter the poles of the induced circuit. The apparatus consists of a cylinder of ivory, vulcanite, or wood (Fig. 19) resting on a couple of pivots insulated from each other. The cylinder can be turned by means of a handle between two copper beds. To the latter screws are connected, which receive the ends of the primary (a) coil-wire (b). A couple of small metal-plates are screwed fast to the cylinder — one screw joins the right-hand plate with the upper pivot, another the left-hand plate with the lower pivot. Springs slide over both plates, and each spring is in connection with a pole of the electrical source. The drawing ') Time-constant — (L = self-induction coefficient ; R = resistance). R 8 It determine the amplitude of the vibrations: (i = Ac — — - sin /? +) in single periods. 6o RADIO-THERAPY shows the course of the current for one position of the commu- tator. On rotating the cylinder through 180 the current is reversed; at 90 the springs no longer slide on the metal plates of the cylinder, but on its wooden non-conducting portion, whereby the current is interrupted. Another frequently used form of dis- connector consists of a flat piece of metal fastened to a wing-shaped horizontally ro- tating handle. As the handle turns the wings come into connection with two flat springs which are in connection with the conductors. Thus the circuit can be made or broken. The primary coil consists, as before mentioned, of thick wire of shorter length than that of the secondary coil. This wire is wound on a hollow cylinder of wood or papier-mache. The cylinder is filled with a bundle of thin soft-iron wires, each wire being separately varnished. The cores of modern coils (those, for instance, of the Allgemeine Elektricitats-Gesell- schaft, Berlin) are made of layers of iron plates. Besides great magnetic conducting capacity an almost perfect freedom of "whirl-current" is thereby obtained, so that losses of energy in the iron are practically obviated. We have already seen (p. 58) that self-induction plays an important part in the working of a coil with Wehnelt's inter- rupter, and that this applies more especially when working the apparatus in conjunction with a Roentgen-ray tube. It follows that in order to be able to properly regulate and in- crease the life of a vacuum tube we require some method for increasing the self-induction of the primary coil. For these cases in which it is required to weaken the effect of an inductor worked with Wehnelf s interrupter B. Walter recommends the following proceeding 1 ) : On a thick roll of cardboard 3 cm. in diameter about 150 turns of copper wire f mm. thick, and *) Fortschr. a. d. G. d. Roentgenstr., Vol. II, p. 225. ELEMENTS OF ELECTRICITY 61 duly insulated, are wound. This "inductive" resistance is in- troduced behind the ordinary regulating resistance into the primary current-circuit. If the former resistance be not suffi- cient of itself to weaken the eftect of the coil on the tube, some of the latter resistance (the main resistance) may be used with the same object. If, however, the interruptions in the Wehnelt vessel are even then irregular, we may increase the self-induc- tion by putting a suitable number of iron wires about i mm. thick and f£ cm. long into the cardboard roll. This per- mits a considerable augmentation of the ordinary regulating resistance. With an ordinary resistance placed in front of the in- ductors used with Wehnelt s interrupter one cannot obtain a weakening of their eftect. The explanation of this lies in the fact that self-induction (dependent on the number of windings in the primary coil and the size of its iron core) is now much smaller than in the former apparatus, so that by simple weaken- ing of the current with an ordinary resistance the "primary opening tension" originating on interrupting the current is no Fig. 20. — Spark-inductor with primary coil for variable self-induction, by Max Kohl, Chemnitz. longer strong enough to produce a sufficient quantity of gas, or a strong enough explosion of the latter at the anode of a 62 RADIO-THERAPY Wehnelt's interrupter — two conditions upon which the inter- rupter of the primary current largely depends. In order to weaken the induction-effect, we may, however, augment the self- induction in the current-circuit. This is accomplished by the simple method of Walter already mentioned. Walter constructed for the same purpose primary coils with Fig. 21. variable self-induction, which adapt the capacity of the inductor to the vacuum of the Roentgen tube. This he effected by ar- ranging the windings of the primary coil in several divisions, allowing the current to flow through one, two, or more of these divisions by means of a suitable switch (Fig. 20). The indi- vidual coil-windings can be connected serially, in two groups, or in parallel. The ends of the wire windings terminate in "contacts" at one side of the primary coil (Fig. 21). At these "contacts" pins are arranged on which plugs fit, according to the connection desired between the terminals of the several Fig. 22. coil-windings (Fig. 22). By connecting the windings serially (for soft tubes) the self-induction of the primary coil is con- siderably increased; by connection in two groups (for tubes of medium density), or in parallel (for hard tubes), the self- induction becomes, dn the other hand, diminished. The primary coil is covered with an insulating layer of ELEMENTS OF ELECTRICITY 63 glass, ebonite, gutta-percha or paraffin. Many makers con- struct the primary coil in such a manner that it forms a separate and independent part of the apparatus, so that it is introduced when required within the secondary coil, and may be exchanged for another at any time. In other kinds of apparatus the secondary coil is wound directly on the primary. The former consists of a very thin and long copper wire, which is every- where uniformly insulated. The diameter of the wire varies in different apparatus from \ to ^ mm. Its length is considerable, reaching many kilometers in the larger models. By increasing the length of wire one gets a greater potential- difference; by increasing its diameter one gains in electrical quantity. One of the greatest difficulties met with in the construction of coils lies in the proper insulation of the secondary circuit, the least defect in this respect leading to discharges within the apparatus which in a short time fuse the wire and render the apparatus worthless. The several layers of wire, which is al- ready of itself well insulated, are, therefore, insulated from one another. This is done by embedding them in paraffin, or each layer may be varnished or covered with wax or silk; or again, a sheet of waxed paper or gutta-percha may be arranged between the layers. Even with these precautions it may be very difficult to induce a current with safety through so long a wire, so that with the larger-sized coils the plan recommended by Poggendorfi is adopted. In this method the secondary coil is built up of several short coils, separated from one another by insulating plates, but with their wire-ends in contact (see Fig. 18). The insulation is thereby much improved, and in case of short-circuiting repairs are much more readily executed. M. Levy has constructed coils in which the gutta-percha in- sulation can be readily removed and replaced when showing signs of deterioration, which this kind of material is apt after a time to do. F. Dessauer's apparatus gives a secondary current which is very strong, but of relatively low tension. This is arrived at by diminishing the resistance in the secondary circuit. Ac- cording to Dessauer, the large coils used for Roentgen-ray work 64 RADIO-THERAPY (whose secondary coils are made up of an enormous number of windings of exceedingly thin wire) supply a current of very high tension; but this on the other hand has to overcome a tremendous resistance in the coil. 1 his is not an ordinary re- sistance, but a so-called "impeding-resistance," for the current traversing the secondary coil is not a regular but rather a rapidly pulsating current, whose intensity increases to a maxi- mum and then decreases with each pulsation. The resistance increases with the length of the wire in far greater ratio than the tension with the number of windings. By shortening the wire in the secondary coil, therefore, Dessauer obtains a lessen- ing of the resistance, and consequently an increase in the cur- rent-intensity of the secondary circuit. The ends of the wire in the secondary coil are in connection with two perforated terminal screws. One of the latter bears a rod with a metal point, the other a rod with a metal disc. The tension-difference of the terminals determines the dis- tance which the disc shall be I. placed from the point in order 1 — — I 03 that a spark may jump from t, * one to the other. The spark- Fig. 23. ing-distance of a coil is the greatest distance which a spark will jump from one terminal to another. The sparking-distance is often, though not quite correctly, taken as a measure of the capacity of the coil. If one examines the course of a spark in«the spark-gap be- tween the terminals (see Fig. 23), one sees that with the cur- rent flowing in one direction the spark jumps between the point and the edge of the disc a; with the current reversed the jump- ing is from the point to the centre of the disc. In the first instance the point is known as the cathode, the disc as the an- ode; in the second vice versa. § 20. Current Interrupters. The capacity of an induction-apparatus depends very large- ly upon the manner in which the interruptions occur in the pri- — I -SB ELEMENTS OF ELECTRICITY 65 mary current. The interrupter must be capable of giving a great number of interruptions, and the latter must take place suddenly, completely and equally. Interruptions can be effected in a primitive manner by hand with a tile, or a toothed wheel the points of which are made to close the current. Generally, however, automatic interrupters are used, by which the process can be more effectively carried on. The simplest appliance of this kind is to be found in Neefs ham- mer, which can be readily understood from Fig. 18. It con- sists of a spring provided with an iron piece E (the hammer) placed opposite the iron core of the coil. This spring is con- nected with one of the battery poles through the wire of the primary coil. The wire from the other battery pole is con- nected with the platinum screw Sch, which can come into con- tact with the spring supporting E. When the current circulates through the primary coil it makes the iron core magnetic, so that the hammer E becomes attracted. As a result of this the current becomes broken, the iron core is demagnetised, the ham- mer springs back into contact with the platinum screw, and a fresh current is established. The whole process is then re- peated, and in this way makings and breakings of the current rapidly succeed each other. The number of interruptions in a time-unit depends upon the length and tension of the spring and the size of the armature-core. The same principle under- lies Deprez's, Ernecke's, the Allgemeine Elektricitats-Gesell- schaft's, Max Levy's and other interrupters. F. Dessauer 1 ) arranges contact plates (Fig. 24) on both sides of the middle of the spring, and opposite these two contact screws K 1 K z are placed. With A' 1 touching P 3 the current is closed; the magnetised core then attracts the spring, A' 1 is released and the current broken. By swinging forward the contact-plate P- strikes the screw K 2 and the current is again established. Now the magnetised core endeavours to keep the spring in this position, but this force is met by the inherent elasticity of the spring. Since the magnetism can only act upon the length of the spring (from p to the armature core), ') Fortschr. a. d. G. d. Roentgenstrahlen, Vol. II. 1 1 |. p. 155. 66 RADIO-THERAPY whereas elasticity obtains throughout its whole length, the lat- ter prevails, and the spring moves away from the core. By this arrangement Dessauer's break gives double the number of in- terruptions compared with Neefs apparatus. It gives, moreover, a much longer period of contact, and, conse- quently, more power- ful induction effects (Fig. 25). Fig. 24. Fig. 25. Fig. 24. — F. Dessauer's platinum-interrupter. Fig. 25.— F. Dessauer's platinum-break, Aschaffenburg. All platinum-interrupters have one defect in common : they are liable to be soon destroyed, the surfaces in contact being burned away. Moreover, the spring often "sticks." The ra- pidity of interruptions again is small in proportion to what is attained with more modern apparatus. This rapidity, never- theless, must not be too great, otherwise the extra current formed at each closing of the inducing current cannot properly escape, and the core of the coil cannot be fully magnetised, in consequence of which the induced current does not reach its maximum of intensity. Spring-interrupters have the advan- tage of cheapness and simplicity, and may be useful in dealing with less powerful primary currents and smaller coils. Foucault invented a mercury-interrupter for working large coils. The main principle of this apparatus consists in closing ELEMENTS OF ELECTRICITY 67 the current by means of a metal rod dipping into a vessel of mercury. In order to effect a sudden interruption, avoiding at the same time the formation ot an extra-current spark in the air and the production of mercury-fumes, the mercury is cov- ered with a layer of water, or a mixture of water and alcohol. By allowing the interruption to occur in liquids of low con- ducting power, instead of in the air, we are able to obtain a more rapid series of interruptions in the primary current, also a more rapid escape of the "opening" induced current, whereby the latter gains in intensity. Again, with the air-spark at the site of interruption we have connection maintained for several mo- ments between the separated portions of the interrupter; this favours the strengthening ot the opening-spark by the extra- current. When employing a badly conducting liquid as the medium the formation of the opening-spark is prevented, whereby the circuit is more rapidly broken. Fig. 26 shows on the right the simplest form of mercury- hammer-interrupter (on the left is a Neef's hammer). The illustration clearly shows its mode of action. In smaller coils Fig. 26. — Spark-coil with Neef's hammer and mercury-interrupter, by Max Kohl, Chemnitz. the contact-pin is attracted directly by the iron core. In the case of larger apparatus, however, the interrupter acts inde- pendently, having its own electro-magnet and special electrical 68 RADIO-THERAPY supply. In order to be able to regulate the rapidity of inter- ruption, the lever, which carries on one hand the contact-pin, and on the other the anchor for the magnet, is provided with a vertical rod along which a movable weight glides. By rais- ing or lowering this weight the movement of the lever can be varied. Interrupters of this kind have two mercury vessels with ascending and descending contact-pins. At one of these the t&& Fig. 27. — Foucanlt's interrupter. (From /. J 7 'alien tin , Die Generationen der Spannungselektricitat, Wien, Leipzig, Budapest bei Hartleben, p. 223.) interruption occurs of the special current intended for the elec- tro-magnet of the interrupter. At the other, at the same time, the current traversing the primary coil is alternately opened and closed (Fig. 27). Foucanlt's interrupter cannot work above a certain speed. It is, however, desirable for many purposes to have a greater range of current-alterations within the time-unit at one's dis- posal. This requirement is met by the recently-constructed mercury-motor, turbine and electrolytic interrupters. ELEMENTS OF ELECTRICITY 69 In the first, small rapidly-moving motors are employed, worked by a special current. A vertical movement is obtained from the rotation of the motor (by means of a small eccentric Fig. 28. — Ludwig Schulmeister's interrupter, Vienna. or a crank-pivot and connecting-rod) and transmitted to a sil- vered rod dipping into a vessel of mercury which can be raised or lowered. With the rod immersed in the mercury the cur- rent through the primary coil is closed; with the rod raised from the vessel the current is opened. By means of a regu- lating resistance the rapidity of the interruptions may be varied Fir,. 29.— Turbine-mercury-break by Boas (Allg. Elek. Gesell., Berlin). through a wide range. The mercury is covered with a layer of alcohol, petroleum, or pure water. Fig. 28 shows the de- sign of an interrupter made by /,. Schulmeister, of Vienna. 70 RADIO-THERAPY Like the coil to which it belongs, this is worked by a branch from the main (street-current, when this is continuous), con- suming but little electricity, is comparatively noiseless, and is of very simple construction. Consequently it can readily be taken to pieces and put together again, and the mercury vessel can be easily cleansed. The resistance-dial indicates approx- imately the number of interrupters per time-unit. An inter- rupter of another kind, which gives a still higher rate of inter- ruptions, is the turbine-mercury interrupter of the Allge- meine Elektricitats-Gesellschaft, Berlin (Fig. 29). A metal tube, bent at right angles, has one arm vertically im- mersed in mercury. By rapid rotation of the tube, with this vertical arm as axis, mercury is sucked up and emitted from the horizontal arm in the form of a jet, owing to centrifugal action. The jet strikes a metal ring perforated at intervals with aper- tures. With the jet striking the metal ring the current is Fig. 30. — Max Levy's interrupter, Berlin. closed; each time, however, it coincides with an aperture the current is opened. Consequently the number of interruptions in a given time can be increased by employing rings with a ELEMENTS OF ELECTRICITY 7i greater number of apertures. The rate of interruption, of course, also depends upon the speed of revolution of the tube (which is actuated by an electro-motor whose speed can be va- ried by resistances). The mercury is covered with a layer of Fig. 31. — Mercury-break by Reiniger, Gcbbcrt and Schall. alcohol. About 150 c.cm. mercury and 1400 c.cm. absolute alcohol are required to fill the interrupter. Max Levy, of Berlin, has devised a modification of the apparatus (Fig. 30). The chief difference lies in the fact that the mercury jet rotates, and not the "contact-ring." By means of a suitable pump, which has an axis in common with the ring, mercury is driven up the rectangular tube and squirted in the form of a jet against the contact ring and its apertures alternately. The contact-pieces being triangular, with the apices below, by adjusting the height of the mercury tube it is possible to vary the duration of the individual current-periods. The pump works even when the motor is going very slowly, so that this type of interrupter can be used when a very slow rate of interruption is required. In the original apparatus a glass covering encloses all the working-parts; the condition of the mercury, etc., can thus be kept under observation ami con- trol, fn Reiniger, Gebbert and Schall's apparatus the mercury (Fig. 31) is squirted from a fixed tube I) against a fixed contact plate C, the interruption being effected by rotating wing-shaped 72 RADIO-THERAPY insulating pieces F, which cut the jet at intervals and prevent it from striking C. 1 he mercury is pumped from D by a cen- trifugal-pump placed in the case C, whose axis also carries the interrupting wings. The length of the mercury jet can be varied by means of a screw placed on the cover of the appara- tus which raises or lowers the contact plate. The rapidity of the interruptions depends upon the rate of rotation of the main axis, the number of wings and their size, and upon the dis- tance of the contact plate from C. The turbine-mercury-interrupters for alternating currents of the Allgemeine Elektricitats-Gesellschaft, Berlin, are con- structed on the same principle as those for continuous currents. Their rate of interruption, however, cannot be changed at will; it depends always upon the number of periods of the alternating current which is used, and this in most cases amounts to 50 per second. The apparatus is constructed exactly on the same lines as the turbine-continuous-current interrupter. The motor, however, is not fitted at the side, and is not joined to the turbine axle by an endless cord, but lies over the interrupter and is di- rectly coupled with the axle. The speed of the motor exactly conforms with the alternation-rate of the current, so that the current-closings and interruptions always occur at the same periods of the alternating current-phase. The arrangement is of such a kind that the current is only closed in the same half of the current-phase, so that only current waves of one direc- tion enter, their effect being, therefore, identical with that of an interrupted continuous current. In order that the motor may run with a certain velocity, corresponding with the rate of alter- nations of current, it requires some regulating. This is effected by means of a hand-wheel which is pressed against the axle of the interrupter by an eccentric. A Roentgen-ray tube intro- duced within the secondary circuit of the coil shows by its reg- ular end even fluorescence when synchronism has been attained in the interrupter (Fig. 32). A. Londe and L. Leroy, also IV . A. Hirschmann, con- structed rotary interrupters with sliding contacts working with- out mercury jets. In these the interruption is brought about by a ELEMENTS OF ELECTRICITY 73 contact brush sliding over a round metal disc provided with insulating sectors. I hese appliances give a considerable rate of interruption (up to 2,000 per minute). Quite recently an interrupter has been brought out which works on an entirely- different principle and is a simple and effective apparatus. This is A. II clinch' V) electrolytic interrupter, in which all the parts are fixed, and whose effect depends entirely on electrolytic ac- tion. It can give an enormous rate of interruption (from sev- eral hundreds to 2,000 per second), and this with regularity. Fig. 32. — Turbine-mercury-interrupter for alternating-currents. (Allg. Elek. Gesellsch., Berlin.) Many physicists have studied the peculiar light- and heat-effects which are produced by passing powerful currents from small electrodes through a conducting liquid. While experimenting on the question of electrolysis II 'clinch was struck by the hum- ming sound elicited when the smaller of the two electrodes (using thin platinum wire and a large lead plate in dilute sul- phuric acid solution) was connected with the negative pole of a powerful battery. Richarz ( 1 890-1 S92) had already shown that this humming sound corresponded with irregularities in the current traversing the fluid. ') Elektrotechnische Zeitschrift, Berlin, [899, p. 76. Wiedemann, An- nak-n. [899. Bd. LXVIII, )» 233. 74 RADIO-THERAPY Wehnelt now examined this inconstancy of the current more closely and found that it consisted of a series of total interrup- tions. It is calculated from the position of the humming sound in the scale that there are some 1,700 interruptions per second. ,. ■ ■ .'■ =1 m Ml &8&e I , & : y' ■•- I ■ *M| 1 , ;f. ",V '..■:, r*% 1 K-'i -. *,Ti Fig. 33. — Spark effects with an instrument (electrolytic-interrupter) by Max Levy, Berlin. Acting on these observations, the idea occurred to Wehnelt of placing an electrolytic apparatus in the primary circuit of a coil; he thus obtained a most effective interrupter. With higher tensions (1 10 volts) the smaller (negative) electrode soon be- came red-hot and melted away, the spark-stream of the sec- ondary circuit becoming feeble and irregular. Much better results were obtained when the smaller (the "active") electrode was made positive (anodal) and the larger one negative (cath- odal). 'The result was surprising. On passing the currents (about 100 volts) a powerful arc-light was produced between point and plate of the secondary coil terminals. When point and plate were separated for about 25 cm. this arc-light was broken up into a sheaf about the thickness of a lead pencil, composed of innumerable sparks interwoven one with another." Fig. 33 gives an illustration of this phenomenon. ELEMENTS OF ELECTRICITY 75 If the Ruhmkorff's coil be excluded from the current-circuit no interruption occurs, but the active electrode immediately be- gins to glow; on introducing the coil this glowing ceases and a distinct sound is heard, the note of which corresponds with the interruption-rate. A reddish-yellow veil of light now sur- rounds the active electrode, but when the latter is also negative this light becomes of a bluish-white tint. Spectrum analysis shows in the former instance the spectrum of hydrogen, in the latter that of platinum. The foregoing observations show that the active electrode must be connected with the positive and the other electrode with the negative pole of the main current in order to obtain good and constant action of the electrolytic interrupter. The most common form of this interrupter consists of a large square glass vessel covered by a perforated vulcanite lid. On the lat- Fig. 34. — Max Kohl's electrolytic interrupter, Chemnitz. ter lies a terminal in connection with the negative lead plate. A metal rod pierces the lid, bearing at its lower end a platinum pin, while a porcelain tube encloses the rod itself. Some acid always rises between the anode-pin and the porcelain tube; this, 76 RADIO-THERAPY if allowed to rise as far as the vessel lid, would penetrate the fittings of the tube and rod, and so reach the surface, thereby causing a side-circuit. It is, therefore, necessary to allow a vent for this unavoidable rising of the acid (which is partly an effect of the explosion), and this is done by fixing a small glass tube on one side of the upper part of the porcelain tube. The upper end of the metal rod (anode) is connected with the positive pole of the main supply by means of a terminal screw. Here, also, is a regulating screw by which the platinum pin may be made to emerge more and more from the porcelain tube; thus the active surface of the anode (i. e., that part of it through which the current enters the fluid) may be increased or diminished at will. Other things being equal, the rate of interruptions depends upon the area of this active surface; the greater the surface, the lower the interruption-rate. Thus by increasing the active sur- face of the platinum pin, by pushing it further out of its insu- lating cover, the rate of interruptions is lowered; on the other hand, the current-strength is increased. If one increases ten- sion by switching off resistances at the current-regulator, with- out at the same time increasing the platinum anode-surface, the rate of interruption and the current-strength are both aug- mented. This is at once made evident by the louder humming sound, the pitch of which is raised. Other factors on which the interruption-rate depends are the resistance and the self-induction of the. circuit made and broken by the interrupter. Now the part both these factors play bears relation to the fact that the interruption takes place at a certain current-strength, penetrating through the surface- unit of the active surface. This current-strength must be at- tained before an interruption can possibly occur. The time required for this purpose depends to a great extent upon the resistance and the self-induction of the current-circuit, as we have learned from the theories relating to current-closing. The smaller the self-induction, the greater the number of interrup- tions per second. In the case of a circuit without self-in- duction the apparatus does not work, but gives one interruption only. Without self-induction in the closing-circuit the tension ELEMENTS OF ELECTRICITY 77 required for the production of the above phenomena is gen- erally a higher one. The current-interruptions of an electro- lytic interrupter are of such a kind that no condenser is required for the coil. Self-induction, which in other cases is most care- fully avoided, or at least minimised as far as possible, is not only absolutely harmless when using interrupters of the Wehnell type, but actually favours the production of the Roent- gen-tube phenomena and exact interruptions. Toiler and IT a Iter explain this peculiarity by the fact that the primary opening tension (which with other interrupters produces disturbing secondary effects with the opening-spark- ing, having, therefore, to be diverted into the condenser) is actually a favourable factor with electrolytic interrupters by reason of its decomposition-effect on the water-gases, whereby the continuity of the current can be restored. In some recent Roentgen-ray apparatus the electrolytic in- terrupter is so arranged that in order to work tubes of varying degrees of hardness several (3 to 6) different sizes of active electrodes are employed. These may be switched on at the connecting-board without having the troublesome arrangement of the platinum-pin to go through. (Walter and Albers- Seho nb erg's compound Wehnelt.) W . A. Hirschmann's electric interrupter with surface con- tacts (Figs. 3$ and 36) consists of a platinum plate lying be- 0. R. P. angem. Fig. 35. tween two porcelain surfaces, and in connection with the posi- tive wire, and also a rod-shaped leaden electrode, the size of which is varied according to the current-strength. The plat- inum electrode may be converted at any time into another of different thickness. By this arrangement not only is a smaller current consumption secured, but another practical advantage is gained. For any defect in the porcelain tube arising from 78 RADIO-THERAPY wear and tear can be repaired by simply grinding off the end of the tube. With other electrolytic interrupters the porce- lain tube after a time becomes hollowed out by the flame pro- ceeding from the platinum pin, whereby it is rendered useless Fig. 36. and must be replaced. Interrupters of this type are also con- structed with several pairs of electrodes. In order to gain a proper conception of the events taking place in an electrolytic interrupter, it is necessary, as V oiler and Walter have shown, to examine the gases appearing at the electrodes, both in regard to quantity and kind. We find the gas evolved at the active electrode consists of not only oxygen, which must appear at the anode, but also of hydrogen, which with normal electrolysis appears at the cathode. This apparent abnormality might be explained by assuming that the great heat attained in the locality of the active elec- trode (resulting from the narrow sectional area of the conductor here) causes an evaporation and decomposition of the water, so that in addition to the oxygen which is electrolytically sep- arated, both hydrogen and oxygen appear from the steam. The cause of the interruption may, therefore, be found in the gas- eous envelopment of the active electrode. As soon, however, as the current (and with it the heat-supply) is cut off, condensa- tion of the steam occurs by the surrounding cold liquid, where- ELEMENTS OF ELECTRICITY 79 by the current circuit is restored. It may be mentioned in proof of this theory that as soon as the water has reached a tempera- ture of 90 C, whereby condensation can no longer take place, the apparatus ceases to work. The action of the apparatus is helped by the opening-spark, which Hies through the zone of steam and gas round the anode (hence the luminosity in this region), thereby favouring the union of hydrogen and oxygen in case these have not already escaped. I he foregoing gives an outline of the theories which Wehnelt formed on the mode of action of his interrupter. Moreover Simon 1 ) considers that the heat developed so ener- getically in certain parts of the current-circuit, as described above, may be regarded as the essential cause of the interrup- tion. On this hypothesis he has formulated a theory of IT clinch's interrupter which is certainly in harmony with experiment, so far as the interruption-rate is concerned. A double cell (Fig. 37, A A) with two large lead plates F F as electrodes, divided by a porcelain partition D, which is fur- nished with one or more small apertures, should act as an interrupter (Caldwell- Simon interrupter). This is found to be the case. The interruption takes place at the small aperture through which the cur- rent is made to pass. Here watery vapour is periodically evolved, followed each time by condensation, and thus the current is alternately broken and made. According to Simon, this interrupter differs from IT clinch's in being inde- pendent of the current direction, working equally well with continuous or alternating currents. The apparatus, more- over, does not stop working when the acid has become heated after long working. IT clinch's apparatus, as has been men- tioned, is useless when once a temperature oi 90 C. has been attained. D'Arsonval found that W clinch's interrupter works well with an alternating current of no volts, and is as Fig. 37. — Platinum- interrupter. (After Ruhmer, by Max Levy, Berlin.) '; Elektrotechn. Zeitschr., 1899, p. 440. 8o RADIO-THERAPY good for Roentgen work under these conditions as a continuous current. This proves that the current interruption only takes place during one phase. The effect on the interrupter during that phase when the active electrode is negative is quite insig- nificant, and may be disregarded. When using an alternating Fig. 38. — Max Levy's platinum-interrupter, Berlin. current the wear and tear of the platinum pin is considerable; it requires, therefore, to be made of corresponding strength and size. Simon's interrupter acts, however, with each phase of an alternating current, being independent of the current-direction, and is consequently not suitable for X-ray work in its original form. By utilising a property of aluminium discovered by ELEMENTS OF ELECTRICITY 81 Pollak 1 ) and Graetz 2 ), however, this interrupter may be so modified that by its use an alternating current may be made continuous. These observers found that by employing this metal as anode a great resistance is offered to the current's passage in certain electrolytic liquids (especially potash and soda), and that if the tension does not exceed a certain limit the current-flow is completely barred. If, then, one of the lead electrodes E (Fig. 37) be replaced by an aluminium plate, the current only flows through to the primary coil when the alumin- ium is acting as cathode. The plate-interrupter is a modification of Simon's appara- tus. In order to alter the size of the plate-apertures, and thereby the rate of interruption, the apparatus is provided with porcelain plates D having holes of different sizes. The plates are interchangeable. Over-heating from high current-strengths or prolonged use is prevented by means of a system of cold-water circulation through a porcelain tube E attached to the lid of the apparatus: The use of electro-magnetic induction apparatus in radio- therapy will be discussed in later chapters. ') Elektrotechn. Zeitschr.. 1897, p. .359. ') Sitzungsber. d. k. bayr. Akad. d. Wissensch, 1 Mai, 1897. II. TREATMENT WITH HIGH-FREQUENCY CURRENTS. TREATMENT WITH HIGH-FREQUENCY CURRENTS. 1 § 21. High-Frequency Currents. In the year 1 88 i Morton 2 ) described a method of using elec- tricity for the local treatment of muscle and nerve disorders. He brought the terminals of the discharger of an electrical machine so near together that sparks passed between them. He then put his patient in the circuit connecting the tin-foils of the condensers. Morton was the first to produce by means of this arrangement and to therapeutically apply high-fre- quency currents, for he had used the oscillating character of the condenser-discharge to increase the frequency of an alternating current. The condensers were charged in this case through an induction apparatus. Morton's high-tension oscillating cur- rents have been used by Leduc 3 ) and F. Winkler*) in similar affections, and, of course, with results similar to those produced by other forms of high-frequency apparatus. In the year 1893 Tesla described an arrangement by which he produced currents of rapid alternations and high-tension. He passed them through glass tubes containing a partial vacuum, thereby obtaining brilliant effects of illumination. These currents of Tesla are of great medical interest, since they produce powerful physiological effects, and may be applied ') Literature referred to: Doumer, Annales d'electrobiologie, electrodi- acrnostique et electrotherapk'. Vol. I-IV. — Dr. H. Kurella, Zeitschrift fur Elektrotherapie und arztl. FJektrotechnik, V<>1. I-IV. — Fouveau de Cour- mcllcs, L'annee electrique, iqoo, 1901. — F. Winkler, Festschrift fur Hofrath Prof. Neumann, 1900. — L. Bouchacourt and /. Rimond, Annales d'electro- biologie. 1900. Vol. III. p. .334. — Rcinigcr (Gebbert & Schall's Catalogue, 1902). *) Quoted by Downer & Oudin, Aim. d'electrobiologie, 1000, p. 507- ') Compt. rend, du XII Cong. int. de Medicines. Vol. II, Sec. IVa, p. 70. *) Wiener med. Presse, 1900, No. 41. 86 RADIO-THERAPY successfully in the treatment of various diseases. In order to understand Tesla's discovery, one must have some knowledge both of the laws of electrical induction and of the phenomena accompanying the discharge of a Ley den jar. We know that electricity at the moment of its appearance and disappearance induces electricity in a neighbouring conductor, and we know that one can produce alternating currents of high tension by means of induction apparatus. We have already learned (p. 1 8) that when a Leyden jar is discharged the whole posi- tive and negative quantities of electricity are not dissipated, but that many discharges of gradually decreasing intensity occur at very short intervals afterwards. These facts have been known for many years. They were first theoretically deduced by Kirchhof and Thomson, who ap- plied to electricity the laws already known dealing with the motion of liquids. Under like conditions the behaviour of electricity may be compared with that of water which is accu- mulated in two vessels in communication with each other at the bottom by means of a wide pipe. If the water level be low- ered in one vessel so that it rises in the other, on leaving the liquid to itself repeated alterations in the level will occur where- by the water repeatedly flows to and fro within the pipe; the two columns of water will oscillate until equilibrium is finally established. Now the same thing occurs when the positively and negatively charged tin-foils of a Leyden jar are brought into contact. The electricities counterbalance themselves in the same way as do the differences of water level in the commu- nicating vessels. The process of discharging is not completed in one transition of electricity from the inner to the outer tin- foil, but a repeated passage of electricity to and fro occurs. It would seem as though electricity possessed inertia, though this is not the case. Self-induction takes the place of "vis in- ertiae." When the excess of electricity begins to flow from the interior of the Leyden jar (which we will suppose to be charged at the beginning with positive electricity) an excessive amount goes to the outer tin-foil, leaving the interior of the jar lacking in positive electricity; the inner foil is thereby negatively charged. The superfluous positive electricity collected on the HIGH-FREQUENCY CURRENTS 87 outside flows back again to the inside, but again in excess, so that a new current of electricity is produced in the opposite direction. When the conducting wires of the two tin-foils are brought near together a spark results. The electricities in this spark are in reality flashing to and fro until equilibrium becomes established. This phenomenon is called electrical oscillation. Clark Maxwell showed that a kind of magnetic transverse undulation occurs in the space surrounding a conductor where this electrical oscillation is going on. This undulation he be- lieved to possess all the qualities of waves of light, and that while it may be transmitted with any wave length it must always have the velocity of light, i. e., 300,000 km. per second (the electro-magnetic theory of light). Hertz proved experimentally that an electro-magnetic dis- turbance is as an effect of induction transmitted with the veloc- ity of light through space, and that these electric waves possess the same qualities as light. It is indisputable that electro-mag- netic induction, electric and magnetic manifestations are trans- mitted through the air not instantaneously, but with the ve- locity of light. An electrical wave of this kind would, therefore, be identical with a light wave. As far as we know, the source of electrical oscillation is to be found in the discharg- ing of larger or smaller quantities of electricity. Kirch ho ff has proved that electrical discharges are trans- mitted not only in the air but also along wires with the velocity of light. Lecher showed that the transverse ether waves are transmitted between parallel wires in a direction parallel to the latter, whereas the direction of the waves of the main current, of the electrical force, is perpendicular to the surface of the wire. Hertz proved that from such electric vibration ether waves proceed which are transmitted through space and non-conducting bodies (dielectrics) with a velocity which in the air is almost equal to. that of light. These waves of electric power are subject to the same lawsof reflection, refraction and polarisation as ordinary light. Hertz reflected the waxes from a perpendicular screen of metal ; 88 RADIO-THERAPY "fixed waves" were formed by interference between di- rect and reflected waves, between the primary conductor and the screen. In other words, at certain points there was no ether vibration. Hertz's electric waves pene- trate insulating bodies, such as glass, paraffin, sulphur, wood, but never metals. The current flowing through the wires in this experiment is repeatedly changing its direction ; it is an alternating current. The current-reversals produced by discharging Leyden jars are extraordinarily rapid (alternating high-frequency currents); it has been proved that they may take place 100,000 times, even 1,000,000 times per second. (Alternating currents as supplied for ordinary purposes do not usually change their direction more than 80 times per second.) This alternating current soon loses intensity. But when an immediate re-charging of the Leyden jar is provided for by suitable apparatus a perma- nent alternating current can be supplied. Tesla produced a series of remarkable phenomena by means of the electric oscillations caused by the discharging of Leyden jars. When the current of an ordinary alternating-current ma- chine is conveyed through the inner winding of an induction coil the latter shows very powerful induction effects; the alter- nating-currents produced by the secondary coil are strong enough to light an incandescent lamp placed in their circuit. The inducing power becomes greater when the rate of alterna- tion is increased. Tesla alternatively charged and discharged Leyden jars by means of alternating-currents, by rapidly succeeding currents from a Ruhmkorjf's coil, thereby intensifying the frequency of the currents. He converted these comparatively strong high- frequency currents into currents of extraordinarily high tension by conveying them through a primary coil of slight resistance (and self-potential) ; over this primary coil he placed a sec- • ondary one, formed by numerous windings of thin wire. He thus obtained induction-currents of remarkably high-tension and high-frequency. Primary and secondary coils together are called Tesla s transformers. In Fig. 39 we have a sketch of Tesla s apparatus. The HIGH-FREQVENCY CURRENTS 89 inner tin-foils of the Leyden jars C\ and C 2 are positively and negatively charged from the secondary terminals of the Ruhmkorff's coil A. The outer tin-foils are in connection through the primary winding P P of Tesla's transformer and through the spark-gap B. Alternating-currents are produced in the primary coil of the transformer; they are synchronous with the oscillations of the discharge in the spark-gap. These high-frequency alternating currents induce alternating currents in the secondary coil 5 S; these currents combine high-fre- quency with high-tension. On account of the enormous ten- Fig. 39. sion obtaining in the windings of the secondary coil of the transformer, the latter requires to be immersed in oil, which forms the only satisfactory insulating medium; otherwise sparks would inevitably pass between the separate windings of the wire and soon destroy the apparatus. These high-frequency currents ( Tesla's currents) possess some extraordinary physical properties. They do not require a closed conductor for their transmission; they are transmitted as electric waxes through the air. They illuminate Geissler's tubes even from a considerable distance. 1 hey also possess a 9 o RADIO-THERAPY quality which is of a special medical interest : they are devoid of danger despite their enormous tension. When we consider that ordinary alternating currents of about 2,000 volts' tension are very dangerous to life, it is an extraordinary fact that these alternating currents, though possessing a tension of a hundred times greater, are absolutely harmless. An electrode of a Tesla transformer may be touched with a metallic rod held in the hand, without danger. An incandescent lamp, the poles of which are held by the experimenter and an assistant, will be illu- minated the moment the current of sparks passes into the metal- lic rod. The experimenter's body forms part of the conductor for the current which is illuminating the lamp; the current must, therefore, be of considerable intensity; nevertheless it does no harm and causes no disagreeable sensation. This fact was known to the French physiologist A . d' Arson- val, even before Tesla. D' Arsonval proved that a solenoid traversed by high-tension-currents induces powerful currents in an organism which it encloses. A man's body placed within a large solenoid forms an electric conductor in which currents are induced of the same high-frequency as those in the solenoid. When the man within the solenoid forms a circle with his arms which is closed by a small incandescent lamp, the latter becomes lighted by the induced currents circulating through his arms. According to d' Arsonval, this experiment is more successful if the subject of the experiment first moistens his hands with a sat- urated solution of sal ammoniac. By so doing the resistance between the two hands is lessened by about 600 ohms. The ex- periment can also be performed with other animals, e. g., eels. Although this procedure acts very vigorously on the organism, no sensation is produced. D' Arsonval published the results of his experiments in 1891, 1 ) but he employed a rather different apparatus to that of Tesla. There are two Franklin plates (condensers) C (Fig. 40) ; the tin-foils of one side of these plates are in circuit with the poles of the secondary coil of the induction apparatus A and spark-gap B. The tin-foils of the other sides are connected by l ) Societe de Biologic, Feb. 24 and April 24, 1891. HIGH-FREQUENCY CURRENTS 9i a thick copper wire D, which forms a little solenoid having from 15 to 20 windings. Besides this smaller solenoid a larger one E can be placed in the circuit of the discharge-current at H; the patient is placed within the larger solenoid. Syn- chronously with every dis- charge through the spark- gap a corresponding dis- charge takes place on the tin-foils of the condensers in connection with the sole- noid. These discharges pass through the solenoid, where in consequence high - fre- quency currents arise which are synchronous with the oscillations of the discharge- spark at the condenser, and possess about the same high- tension as currents from an electro - static machine (about 20,000 volts). D' Arsonval originally ar- ranged the experiment so that the terminals of a "shunt" were in connection with two windings of the solenoid D. This formed a conductor of weak resistance and helped in the production of self induction 1 . The effect of the high-frequency currents in the shunt was more intense when its points of contact were far apart. The maximum effect was gained when the contact was connected with the first and last winding. The high-frequencv currents passing through the solenoids create an electric field in (heir vicinity. This can be demon- strated by the fact that an incandescent lamp placed in a metallic Fig. 40., ') \ movable core "f oft iron within the solenoid also helps in this way. 92 RADIO-THERAPY circle which is suspended within the solenoid E without contact with the same is illuminated as soon as the solenoid is traversed by the high-frequency currents. If the bulb of a thermometer be wound round with several turns of thick copper wire, through which high-frequency currents are passing, the mercury in the bulb becomes heated and may even be brought to boiling point. The electric field existing in the vicinity of high-frequency cur- rents has a marked effect in the cure of several diseases. D'Ar- sonval utilised this physiological effect on the human body by exposing the whole body of the patient to the influence of the electric field ("general treatment") . Faraday, Maxwell and Hertz found that conductors had the effect of localising the electric oscillations on their surface, so preventing them from becoming diffused; acting on this idea Ou din arranged an apparatus by means of which high-frequency currents could be localised and made to act on circumscribed parts of the body. He constructed an apparatus like a tuning fork, having a certain rate of vibrations; through this the high- frequency currents were passed, while a second tuning fork was brought near the first (both forks being in tune with each other). When the first fork vibrated the second also vibrated in sympathy with it, producing the same note. Hertz proved by means of this instrument, which he called a resonator, that within the compass of the waves of a primary electric conductor vibrations are induced in another (secondary) conductor; these are strongest near the elevations of the waves and weakest near the nodal points. The intensity of electrical resonance depends upon the shape and size of the secondary conductor. Hertz found that a resonator of a definite capacity is necessary for a given primary apparatus in order to obtain the best effect. The resonator must be tuned to the primary conductor. On dm proved that the electrical vibration in the resonator depends directly upon the capacity and self-induction of the cir- cuit formed by the resonator. The vibrations which occur in a d'Arsonval's solenoid may be used as "primary" oscillations; differences of electrostatic tension will arise in every conducting body of a certain capacity placed near the solenoid, and these differences will produce cur- HIGH-FREQUENCY CURRENTS 93 rents in the body itself. When the conductor is formed of sev- eral windings of copper wire, currents will be formed by self-in- duction in the separate windings strong enough to enable sparks to be drawn from the end of the conductor; here, too, the maxi- mum of efficiency will be obtained with bodies of a definite electric capacity. This capacity must be variable according to the construction of the high-frequency apparatus which is being used. Metallic bodies placed in the neighbourhood of the sole- noid emit a very long spark or none at all, according as the rate of vibration produced in them is increased or decreased ; in other words, the capacity of the body has to be tuned to that of the solenoid. These differences become still more marked when the body is connected to the solenoid through a metal wire; but they are only then shown when the body possesses a certain self-induction. Thus such effective vibrations can be produced in proportion to the self-induction and capacity of the body as to give very long sparks. If one of these factors, either the self-induction or capacity, be altered, the oscillations rapidly diminish, and may even disappear entirely when only a slight difference obtains between the two factors. Oudin's resonator considerably increases the tension of the high-frequency current; it is easily adjustable, so that it can be adapted to all phases of d' ' Arsonval's apparatus, /'. e., it can be tuned to another electrical pitch. In effect the resonator consists simply of a solenoid of copper wire having a low re- sistance, which is wound round an insulating cylinder. When one end of d' Arsonval's solenoid D is connected by wire with a certain point of this resonator a powerful and continuous aigrette of sparks becomes visible at the end of the resonator. In this attached resonator the electrical oscillation takes place synchronously with that in the connecting wire (solenoid). By a suitable arrangement an aigrette of sparks 9 to 10 cm. in length may be emitted from the resonator, while that from the primary solenoid is only 15 to 20 mm. in length. When the point of contact of the wire is moved some centimetres in one direction or the other, the length of the sparks becomes rapidly diminished. The secondary solenoid must, therefore, be tuned to the primary in order that its vibrations ma) be synchronous. 94 RADIO- THERAPY When the capacity of this resonator is increased by connect- ing its free end with a wire terminating in an electrode, the rate of oscillation is modified; in this case the point where the current enters the resonator must be altered in order to obtain at the electrode the same aigrette and the same spark as were emitted by the resonator without the electrode. It is only the last spiral of the resonator or a conductor joined to it which emits sparks. The effect of the remaining windings upon each other prevents them from giving discharges into the air. When a larger ca- pacity is added to the resonator, e. g., larger Leyden jars, the sparks grow more vigorous and may cause a painful sensation. {Ou din consequently only used small condensers.) A res- onator which is made of thin wire emits a thin, long, sinuous and comparatively painless spark, and the aigrettes (or quiet dis- charges) are less vigorous. By using the thicker wire both discharge and spark grow more powerful. § 22. Apparatus. Direct currents from the main, accumulators, or bi-chromate batteries of about 6 ampere intensity are usually employed as generators of high-frequency currents for medical purposes. These currents are first transformed from low to high tension by means of a Ruhmkorjf's coil, the sparking capacity of which need not exceed 25 cm. The primary current is interrupted by means of a motor-mercury break, a turbine interrupter, a JJ'ehnelt's apparatus, which latter is especially suitable. The alternating current which is produced by the coil, and which can- not be used directly, is transformed by the condenser into a high- frequency current. The condenser consists of two Franklin's plates, arranged as in Fig. 40 and placed within a flat box (Fig. 41 ) , outside which may be seen the small solenoid and the spark- gap with the connecting screws. Or the apparatus may be con- structed as shown in Fig. 60 e. Here two Leyden jars are placed behind the spark-gap (which is put under a bell-jar to deaden the sound of the discharge; within the bell-jar a small vessel containing soda-lime is placed to absorb the nitrous fumes. From the outer tin-foils of the jars two conductors issue which end in two terminals, between which a third is placed. Where HIGIl-FREOl'E.XCY CURRENTS 95 general d'arsonvalisation is required the small and the large solenoid are joined to this terminal. The author made his large solenoid as follows : A basket wound round with twelve turnings of thick copper wire is placed on a long table. The windings of copper wire are continued through two terminals on either side of the table into other windings below the table top; the two terminals of these wind- ings are in connection with the terminals of the condenser Oudin's earlier resonators consisted of 40 to 50 m. of cop- per wire one-half to 3 mm. in thickness, wound round an insu- lating cylinder 40 to 50 cm. in height and 30 cm. in diameter, B'MSMVH GAIFFE Bi : i d.g. Fig. 41. — D'Arsonval's apparatus. the distance between the several spiral windings being 1 cm. By means of a terminal the conducting wire from one end of a d'Arsonval's solenoid was fixed to a suitable part of the res- onator. The other end of the solenoid remained free or was earthed. (Later on Oudin connected this with the lower end of the resonator.) The modern type of resonator, e. g., that by Radiguet, Ducretet, Bonetti, has the following construction (Fig. 42) : the inner tin-foils of the Leyden jars are connected with two spherical terminals, which can be approached to or re- moved from each other. The resonator proper consists of a vertical cylinder covered with paraffin wax and having a spiral groove in which the wire is laid. The wire is i\ mm. in thick- 9 6 RADIO-THERAPY ness and has 50 turnings, with a distance of 8 mm. between each turning; the whole length of the wire amounts to 45 m. The electrode is attached to the upper end of the wire; the lower end is connected with the outer tin-foil of one of the Ley- den jars, while the outer tin-foil of the other jar is in connection with one of the lowest windings of the resonator, its wire being attached to a metallic ending which can be moved up and down the resonator along a groove. Thus the resonator is divided into two solenoids. We have now to produce electrical oscillations in both sys- tems. The rate of oscillation depends on the product of the capacities and self-inductions of these systems, and the arrange- ment is most effective if both sys- tems have an equal rate of oscilla- tion. The first system consists of the Ley den jars N M (of constant capacity), the outer tin-foil of which is discharged through the spiral winding E F (of variable self-induction). The second sys- ' '-n tern includes a conductor of vari- ^ able capacity, the body which is to be electrified, and a wire coil of constant self-induction. The sec- ond system must allow of being "tuned" in order to make the prod- uct of its capacity and self-induc- tion harmonious with that of the first (resonance). This is accom- plished by altering the number of windings, i. e., adding or taking away whole windings or por- tions of them (Oudin). Kurdla 1 ) "earths" the end of the re- mainder of the resonance coil which is not included in the circuit so that this portion may not disturb the resonance. O. Rochefort devised a bi-polar resonator (Fig. 43). He Fig. 42. 1 ) VII Congr. d. deutsch. dermatolog. Gesellsch. Breslau, 1901. Sitzungs- ber., p. 488. HIGH-FREQUENCY CURRENTS 97 divided each of the outer tin-foils of his two condensers into two parts by connecting two of the inner tin-foils of 4 Leyden jars with each other, and attaching to each of these two con- necting parts a metal rod ending in a knob {A B) . These knobs placed opposite each other formed the discharger; the 4 outer tin-foils are placed in the circuit at four points F H M L of two resonators, as shown in Fig. 43. Under these conditions the two resonators, although acting upon each other, are, elec- trically speaking, separate and act like two resonators. They are worked by the same interrupter and each gets an equal cur- Fig. 43. — Rochcfort's Bi-polar Resonator. rent, though these run in contrary directions through the pri- mary spiral. According to Oudin, the capacity of the primary spiral F H must correspond with that of the secondary one, in order that the maximum of effluvium may be obtained. The secondary capacity consists of the capacity of the secondary spiral H K, and that of the whole conductor in connection with the point K. In order to make these capacities agree the point H must be moved elsewhere; both resonators require to be regu- lated in this way. The direction of both effluvia is toward one another, not be- cause they are of contrary electricities, but because the capacity of one resonator attracts the effluvium of the other. When equal effluvia are produced in both resonators by connecting the 9 8 RADIO-THERAPY wire which leads to H with F, and that which leads to F with H, the mutual repulsion of both effluvia can be easily seen in a dark room; this is shown still more clearly in a photograph. By ar- ranging the apparatus in the way just mentioned, Rochefort ob- tained bi-polar effluvia 50 cm. in length. Rcchefort made a bi-polar resonator with two simple con- densers by connecting the lowest spirals of both resonators with each other (Fig. 44, M F) and also the external armatures with two points near the middle H L. This arrangement, however, makes each resonator too dependent on the other; moreover, it is difficult to regulate them when the capacities of their secondary coils are very different. The electrodes are the same as those employed in galvanisa- tion and faradisation, i. e., plate-electrodes, knob-electrodes, brush-electrodes, etc. Oudin's electrode is often used for local treatment. This consists of a long ebonite handle at the end of which a thick metal rod is fixed, covered by a small glass dome. The conducting wire is conveyed through a side hole in the handle to the metal rod. Oudin used a very pliable material woven from metal wire, such as is used for theatrical dresses, as electrodes, covering the material with moistened chamois leather. By this means he was able to spread the current over a fairly large and well-con- HIGH-FREQUENCY CURRENTS 99 ducting surface, thereby preventing the patient from receiving disturbing sparking effects. M. Kohl constructed internal electrodes for use in the body cavities. A conducting wire is passed through small ebonite sticks of various length, thickness and shape, according to the cavity to which they are to be introduced. The part of the body which is to be treated does not come into direct contact with the conducting wire, but serves in a manner as a condenser's foil. When the bi-polar condenser is used the patient holds in his hand a brass cylinder connected with one of the resonators, whilst the end of the other resonator is joined to the other elec- trode. In every case the length of the resonator must be adapted to the capacity of the electrode and that of the patient's body if perfect resonance is to be obtained. The author has obtained considerable augmentation of power by connecting the condenser in the following way : The conductors from the poles of the secondary coil of the induction apparatus are led to the inner tin-foils of the two Leyden jars; the outer tin-foils of the jars are connected with each other as well as with one knob of the spark-gap ; the other knob being connected with one of the two rods which lead to the inner tin- foils of the jars. In this way the spark is made much brighter in the spark-gap; it is a fatter and noisier spark than that pro- duced by the ordinary mode of connecting the two jars; more- over the discharges from the resonator, if this be suitably ar- ranged, are more vigorous. Nevertheless, by the ordinary arrangement a longer spark-gap can be traversed. When both jars are connected in parallel the spark- ing becomes still more vivid. The two jars now act like a single jar of double the size; hence the quantity of the dis- charge is increased, whilst with the ordinary arrangement one obtains double the difference of potential but only the electrical quantity of a single jar; but the discharge from the resonator, other things being equal, is weaker in the case of parallel con- nection of the jars. Parallel connection is, therefore, not suit- able for medical purposes. The effluvium from the resonator can be modified, firstly, by ioo RADIO-THERAPY regulating the primary current of the induction-coil (by taking resistances out of the circuit of the rheostat or adding more cells to the accumulator; when Wehnelf s interrupter is used the same object is attained by altering the length of the anode-pin) ; secondly, by altering the distance between the knobs of the spark- gap, the farther these knobs are apart the stronger the effect; thirdly, by regulating the resonator; fourthly, by the use of dif- ferent electrodes. Oudin has experimentally proved that the resonator pro- duces greater electrical energy than electrostatic apparatus. The intensity of high-frequency currents was accurately measured by d'Arsonval. § 23. Technique of the Application of High-Frequency Currents. D'Arsonval distinguishes between an indirect and a direct ap- plication of the currents. In the former (general d'arsonvalisation) either the method of auto-conduction or of condensation may be employed. In the auto-conduction method a large spiral, *running round the patient's couch, is placed in the circuit from the outer tin- foils of the condenser ; the patient, fully dressed, sits within the spiral without being in actual contact with the conduc- tor 1 ) ; the patient is thus placed within the electrical field and totally charged with electricity, so that sparks can be drawn from any part of his body. In the condensation method, the pa- tient is laid on a couch made of some badly-conducting material; the bottom of the couch is made of metal and is connected by a wire with one end of the solenoid D (Fig. 40) , while the patient takes hold of the second part of the condenser (represented by the couch), i. e., an electrode leading to the other end of the solenoid. 1 ) A solenoid of this description can easily be arranged in a corner of the operating-room hy making a door so as to shut off a triangular space here, two sides of which are made by the walls of the room and the third by the door. In this space the solenoid is placed. The conducting wire runs round the three sides of the enclosure, suitable contacts being made so that the circuit is closed when the door is shut, HIGH-FREQUENCY CURRENTS 101 Direct application of high-frequency currents is performed as follows: The patient is connected with one end of the sole- noid D by two metal plates on which he places his feet, or by a foot-bath, while the current is closed by an electrode which is connected with the other end of the solenoid and placed in the patient's hand — bi-polar application. Local bi-polar application of the currents is arranged by placing in the patient's hand a metallic electrode which is in connection with one of the terminal spirals of the small solenoid, the other terminal spiral being connected with a second electrode which is brought near the por- tion of skin to be treated; or Oudin's resonator may be at- tached to one end of the solenoid and a Oudin's electrode con- nected with the other end, and applied to the skin as desired. When the bi-polar resonator is used its discharges are ap- plied by connecting the end of one coil with a metallic electrode placed in the patient's hand, the effluvium from the end of the other coil being directed toward the part of the body under treat- ment. The above directions are quite sufficient for auto-conduc- tion and for condensation ; the sittings may take place twice or three times a week or daily for ten to thirty-five minutes. The pa- tient must be warned of the noise made in the spark-gap, lest he be alarmed; he must also be very careful not to touch any part of the apparatus which is not given into his hands by the opera- tor; otherwise he runs the risk of receiving shocks. One proceeds differently with the application of high-fre- quency currents according to the condition of the disease under treatment. When, for example, the electrolytic effect of the current is especially called for, the proper electrode should be rapidly approached to the skin and pressed tightly upon it so as to spare the patient any disagreeable sensation (see Fig. 60) . Then according to requirements the electrode is left for a longer time in situ (e. g., at the tender spots in the case of sciatica) till a lively sensation of warmth is felt; or the electrode may be slowly and with some pressure passed along the course of the nerve trunks; the latter may be accomplished either with the point of the electrode or with the latter so held that it covers a greater surface. When, how e\ er, the mechanical effect of the discharges is required the electrode is kept at some slight dis- 102 RADIO-THERAPY tance from the skin; a bright brush of sparks then plays upon the skin from the electrode followed by a distinct sensation of warmth and pricking. The explanation of this phenomenon is as follows : When the electrode is in close contact with the skin, the resistance to the passage of the current is very weak; with the electrode at some distance from the skin, however, the re- sistance is much increased, for the current has to traverse the air, which is a bad conductor. 1 ) According to the formula J 2 R (p. 41), the degree of heating depends upon the resistance. Much of the effect depends upon the kind of electrode employed. (The reader is referred to the different ways in which the dis- charge can be increased by altering the modes of connection, p. 98.) When using Oudin's electrode there is an appearance of violet light radiating toward the skin from the most adjacent point of the electrode. This luminous aigrette is seen on care- ful inspection to be composed of an infinity of fine, shining sparks; part of these would seem to penetrate the glass wall, part are absorbed by it. Small sparks issue in much smaller number from the outside of the glass covering of the electrode when the latter is kept at not too great a distance from the skin ; the effect caused by these sparks is quite insignificant. The fact that the sparks actually penetrate the glass covering, especially if the latter be thin, is proved by the presence of minute fissures in the glass after some considerable wear. These fissures are found to lie in the line of passage of the sparks. To some extent a condensing power exists in the glass case which may be conceived as acting like that of a Leyden jar. The spark discharge from the metallic terminal of the electrode to its glass covering becomes more power- *) According to Lord Kelvin — A spark-gap of 0.5 mm. corresponds to a tension-difference of 2.910 volts. .1 •3 .6 •15 .20 4.8.30 11.460 20.470 29.340 31-350 The above figures indicate the high resistance of the air, which can only be overcome by high tensions. HIGH-FREQUENCY CURRENTS 103 ful the nearer the apparatus is placed to the skin and the moister the state of the latter. Since the treatment usually causes a slight perspiration at the parts treated, the apparatus works more effectively toward the end of the sitting. With the glass covering removed there is no diminution in the intensity of the discharges; the sparks now strike the skin with undiminished vigour. Used in this way, the apparatus is more powerful and decidedly more effective, and it may be rec- ommended in this form for the treatment of skin disease. Still more vigorous effects will be obtained by arming the ends of the wire from the resonator with a faradic brush. This gives one an apparatus which is very useful for local stimulating purposes. When the electrodes are kept at some distance from the skin, a spark-brushing is produced which may be compared to that obtained from monopolar discharges from induction coils (see below), though the effect is weaker. The patient's body may be charged with high-tension elec- tricity by placing a metallic electrode in his hand; the operator then massages the diseased part with his bare hand, drawing sparks from the patient's skin in the process; but the electric cur- rent is much more effective when locally applied than when used in this manner because of the strong resistance offered by the body. Another variation consists in the operator holding the electrode in one hand while he passes the other hand over the affected region of the patient. Local d'arsonvalisation is best applied daily from 10 to 15 minutes; the appearance of a red-brown colour on the skin is an indication for stopping the treatment until the part resumes its normal appearance. For the local treatment of the head or face the patient is best seated in a revolving chair having an adjustable head-rest. Care must be taken that the wire leading from the apparatus to the electrode does not come in contact with the patient; care must also be taken that sparks are not too long applied to a small area of skin, otherwise blisters and sores may develop. 1 04 RADIO- THERAPY § 24. Physiological Effects of High-Frequency Currents. High-frequency currents are not injurious to the human organism; they traverse it with an intensity and tension sufficient to light an incandescent lamp, without causing the least sensa- tion. D' Arsonval 1 ) showed that neither muscles nor the periph- eral ends of sensory nerves are impressed by these extraordinarily rapid oscillations; on the contrary tissues, especially epidermis and denuded nerve endings through which high-frequency cur- rents have passed, are said to become less sensitive to normal stimuli. Thus an anaesthesia lasting from 5 to 20 minutes may result, though it does not penetrate very deeply. In the au- thor's experience the anaesthesia produced by high-frequency cur- rents is very insignificant, though he would by no means call into question d' Arsonval' s opinion on this point. Probably, as be- fore suggested, the different results obtained by these most able French physiologists are to be explained by differences in the arrangement of their apparatus. Doumer and Oudin believed that the anaesthesia described by d' Arsonval and recommended by him for surgical operations is the first stage toward cell- death, which is quite analogous to the anaesthesia caused by freezing. 2 ) Baedaeker, on the other hand, states that hyperaesthesia is induced by high-frequency currents. D' Arsonval propounds two theories with the view of ex- plaining the remarkable phenomenon that sensory nerves are not affected by high-frequency currents. 1st. The currents do not act on the organism, because they only spread throughout its surface, or, 2nd. The peripheral nerves are only sensitive to electric vibrations of low-frequency; just as the terminals of the acoustic and optic nerves will remain unaffected by ether vibrations which are above or below certain limits. Against the first theory we may urge the fact that sinusoidal currents'""), without causing any marked sensation, have some in- *) Ann. d'electrobiologie, Vol. I, No. 1. 2 ) Ibid. 1900, Vol. Ill, p. 513. 3 ) These are alternating currents, consisting of gradually increasing and decreasing waves. They are produced by means of suitable transformers HIGH-FREQUENCY CURRENTS 105 fluence on tissue-nutrition; they must, therefore, be penetrative to some degree. Vittorio MaragUano ') states that the heat effects which are produced by high-frequency currents, after they have traversed a considerable depth of living or dead tissue, prove that d'Ar- sonval's currents take not only a superficial course, but also pene- trate more deeply. L. Hoorweg ~) is also of opinion that d'Arsonval's high-fre- quency currents do not remain on the surface of the hu- man body, but penetrate it completely; this is also shown by the results of Einthofen's and Ley den s experiments. In the author's opinion even d'Arsonval's second theory is unnecessary. When a primary current in a Faraday's induc- tion-apparatus is very rapidly interrupted by means of a motor- break violent muscular contraction can be evoked without the least sensation of electricity on the part of the patient (d'Arson- val). In this case a current of definite intensity and tension induces a certain number of alternating currents of likewise defi- nite qualities. When we diminish the rate of interruption with- out interfering with the primary current, the tension at the poles of the secondary coil becomes raised, i. e., the induced current has (the resistance not having been interfered with) a greater intensity than before. The author's bacteriological experiments have proved (see later) that with a higher current-intensity more powerful effects are obtained. We are, therefore, enti- tled to expect that a reduction in the rate of interruption of the primary current is followed by an increased intensity of the secondary current, and in consequence of that more marked phys- iological effects, e. g. } sensation. This, indeed, is the case. We may reasonably suppose the same to obtain in the case of high-frequency currents; by reason of the rapid alternations the intensity of any single shock may conceivably be very insignifi- cant. On the other hand, we may expect that by raising the in- tensity of high-frequency currents (by suitable windings of the which regulate and reduce the intensity and tension of currents from the main (alternating or rotary). *) Clinica medica, igoi. No. 7. ») PMger's Archiv., Vol. LXXXIII, 8. 106 RADIO-THERAPY coils and construction of the condensers) the physiological effects will become much more marked. In the low intensity of these currents may lie, therefore, the explanation of the remarkable fact that they produce so trifling a sensation. We must, however, distinguish between the effects of the electric current and that of the electric discharges on the sensory nerves. The latter produce the same sensations in the case of high-frequency currents as do the discharges of any other kind of static electricity. Again, we must not associate the two facts that on the one hand high-frequency currents cause no sensation, while on the other hand they are said to produce analgesia. H. Kitrella 1 ) noted that when the resonator to which the electrode is attached is only connected in a uni-polar manner with the solenoid D, d'Arsouval's current evokes a marked sensation of formication and a tetanising effect in the muscles; the latter does not take place in the case of bi-polar connection. D'Arsonval infers from his experiments that high-frequency currents have a great influence on metabolism and cell-produc- tion. By their action respiratory combustion is intensified, the quantity of oxygen consumed in the unit of time as well as that of carbonic acid eliminated is heightened. In one instance an increase took place in the latter of from 17 to 37 litres. This augmentation of the process of combustion is also indicated by the increase in the amount of urea excreted, while that of uric acid is diminished (Lazat and Gautier) . At the same time the body parts with more heat; nevertheless, despite this aug- mentation in the process of combustion the body temperature is scarcely raised, but a further proof of heightened combustion was furnished by the loss of weight of the animals used in these experiments. A little guinea-pig, for instance, lost under ordi- nary conditions 6 grammes in weight in sixteen hours; when ex- posed to the action of high-frequency currents it lost 30 grammes in the same time. After that when left to itself it recovered the lost weight in 2 hours. Berlioz 2 ) tested the urine of 280 patients who were under *) Zeitschr. f. Elektrotherapie unci arztl. Elektrotech., 1900, p. 59. a ) Compt. rend de l'Academie des Sc, March 18, 1895. HIGH-FREQUENCY CURRENTS 107 treatment by auto-conduction, examining in all 761 specimens. He found, first, increased diuresis and better elimination of the excreta; secondly, increased organic combustion; thirdly, the proportion between uric acid and urea approached nearer the normal ( 1 : 40) . Apostoli observed with his patients increased diuresis and excretion of urea, increase in the percentage of oxy- hemoglobin in the blood, better capacity for work and walk- ing, etc. Haemospectroscopic analysis by Henocque's method shows the vigorous effects of these currents on nutrition change. The process of nutrition is both stimulated and regulated. Tripet a ) made researches on the influence of high-frequency currents on the reducing power of oxyhemoglobin. He found this power increased in 37 cases of patients suffering from de- fective metabolism ("rheumatism"). In 10 cases of diabetes where the reducing power was much augmented before treatment it became lowered by high-fre- quency currents. In 6 cases marked by general organic decay the treatment was unsuccessful. Guillaume -) also pursued investi- gations on the lines of Tripet. His patients were affected with arthrodynia, sciatica, chlorosis; in them the quantity of oxy- hemoglobin was increased together with its reducing power; often, too, the general health became improved. This improve- ment, however, was partly due to the modified nutrition, as was shown by the analysis of the blood and urine. In any case the good effects cannot be ascribed to the high-frequency currents alone. The inhalation of ozone acts in the same way on haemo- globin (Labbe), and it is well known that high-frequency cur- rents are always accompanied by the production of ozone. Lacaille '■') found that in his cases the quantity of urea ex- creted while the patients were under the influence of auto-con- duction increased from 1 1 grammes to 43, and even 60 grammes. Denoyes, Martre and Rouviere 4 ) found that under the influ- ence of high-frequency currents the daily quantity of urine ex- creted increased in the same proportion as did the urea, uric acid, ,*) Acad. d. Sc. June 25, 1900. 2 ) Gazette des Hopitaux, February 7, 1901. 3 ) Bullet, offic. d. 1. Societe fr. d'electrotherapie, March, 1900. ') Compt rend de I'Acad. d. Sc, July 1, Kim. 108 RADIO-THERAPY nitrogen, phosphates, sulphates and chlorides. The increase varies with different people, and is maintained to some extent for 3 days after suspending treatment. G. S. Final and G. Vietti 1 ) also found in two cases that d'arsonvalisation increases the total amount of nitrogen and phosphates excreted. These statements of d' Arsonval and his pupils have, how- ever, not been generally confirmed. Guilloz enquired into the tissue change in muscles, and could not observe any increase in the assimilation of oxygen brought about by auto-conduction. He does not, however, doubt the results of d' Arsonval' s enquiries, which indicated an increased assimilation of oxygen in the body, but maintains that this in- crease cannot be due to increased oxygenation in the protoplasm. L. Querton -) found not the slightest increase in the output of carbonic acid by the use of alternating currents of high-fre- quency and tension. Reale, Renzi and V'inai l ) were of opinion that Tesla's cur- rents considerably increased the oxygenation of the body by pro- moting the elimination of uric and phosphoric acid. Querton") observes that d' Arsonval does not mention if the guinea-pigs employed in his experiments were fed during the process, or if the temperature remained normal. /. E. Baedeker 4 ) reports that rabbits which were subjected to the auto-conduction method showed an increase in the rate and depth of respiration, and along with that an increase in respiration-quantity (from 6,140 to 1 1,000 c.cm.) . This effect was maintained for five minutes after the operation, but gave way after fifteen minutes to normal conditions. In the case of other animals the respiration was in no way affected. A. Loewy and T. Colin 5 ) made experiments on the respira- tion of eight persons. They found "in one case an increased consumption of oxygen, which exceeded the normal physiological a ) Giorn. d. elettr. medic, 1. 2, p. 61. = ) Ann. d'electrobiologie. Vol. Ill, p. 14. :i ) Institut Solvay, 1899. 4 ) Wiener Klinik, Vol. XXVII. Nos. 10 and 11. 6 ) Berlin, klin. Woch., 1900, No. 34. HIGH-FREQUENCY CURRENTS 109 limits of 6 per cent, by 12.6 per cent., in another case by 19 per cent." N. Spasski 1 ), on the contrary, found a decreased assimila- tion of oxygen and of carbonic acid and a decrease in the ex- halation of aqueous vapour in animals which underwent general d'arsonvalisation; he therefore denies any effect on the inter- change of gases by this proceeding. The third important property ascribed by d'Arsonval to high-frequency currents is their influence on the vaso-motor sys- tem. When a rabbit is subjected to the currents it will be ob- served that the vessels on the animal's ear rapidly dilate, just as they do after section of the sympathetic nerve. This phenome- non is succeeded by marked contraction of the vessels. The blood pressure of a person undergoing general d'arsonvalisa- tion, as shown by the sphygmograph or sphygmomanometer is seen first to fall and to rapidly rise. The same thing is shown by a mercury pressure gauge brought into contact with an artery. D'Arsonval observed that the blood issuing from an incision in a rabbit's foot flowed more freely after the action of high-fre- quency currents. But these statements of d'Arsonval are also not generally confirmed. Carvalho found no change in the blood pressure after auto- conduction, neither could he observe any motor or sensory reac- tion. But when a very strong current was directly applied to the skin the sensibility of the latter became affected, and at the same time the blood pressure decreased. He obtained the same motor and sensory reactions with muscle-nerve preparations from frogs as are to be obtained from other kinds of currents. Moutier -) states that he decreased arterial pressure by means of auto-conduction, which is precisely the opposite of d'Arsonval' s finding :! ) . The same author, 3 ) however, produced an increased arterial pressure of 2 to 3 cm. by applying the effluvium from the resonator along the spinal column. ') Le Physiologiste Russe, Moscow, iK't'i; quoted by Baedeker, 2 ) Soc. medic.-chirurg., December m. [899. ') Bulletin offic. ;:?■ ■"-&/;>;: ■> v»/v/s///s/. •:•>.»/.• •">;/7i7777y Fig. 45. the outer side of the left fore-paw; here also there were bald places. It was found that the latter places had been in contact with the metallic fastening of the case during the experiment, for from time to time sparks had been observed striking be- tween these parts of the body and the metal. On March 19th a completely bald white patch 3-4 mm. in width was observed on the skin corresponding to the hori- zontal arm of the cross of metal points. There were, more- over, three bald spots the size of a lentil, arranged in a straight line and corresponding to the vertical arm of the cross. Be- HIGH-FREQUENCY CURRENTS 125 sides these spots the rest of the skin coinciding with the aper- ture appeared but sparsely covered, and there were numerous places the size of a kroner which were quite destitute of hair. The skin itself appeared quite normal, with the exception of some few excoriations the size of a pinhead; the latter were probably due to very strong sparks. Fresh hair began to grow again in the course of a week on all the places except those corresponding to the cross; in the latter situation about four weeks elapsed before there was any recovery of hair. Exp. 5. March 21st, 1900. The animal was now so placed that its left Piank coincided with the aperture in the case; in front of this case the same electrode was fixed, at a distance of 1 cm. The electrode was con- nected with the coil terminal of an Oudin's resonator; the latter again was in connection with a d' ArsonvaV 's condenser and the spark-coil /. The primary current of the coil was of 12 volts and 2 to 3 amperes, the rate of interruption 16 per second; time of exposure, 10 min- utes. By this arrangement much brighter sparks were induced than in the case of the previous experiment. On the following day a scab of dry blood the size of a lentil was visible on the exposed area of skin ; the operation was repeated under the same conditions on March 22nd and 23rd. On March 24th the animal's coat showed the same changes as in the case of direct polar discharges from the coil, i. e., loosening and falling of the hair and clogging together of the woolly undergrowth. The experiments were continued on March 24th, 25th and 26th. By the latter day the area of skin corresponding to the electrode appeared almost bald; the rest of the hair, moreover, coinciding with the aperture of the case had become very thin and loose. The skin itself appeared quite normal during the whole experiment, except for the above-men- tioned excoriation, which soon healed. In this case, also, fresh hair did not appear until the expiration of some weeks. 126 RADIO-THERAPY The above experiments conclusively proved that in animals the hair can be made to fall by applying spark-discharges, whether in the form of a direct polar discharge or as the efflu- vium from a d'Arsonval-Oudin's apparatus. (b) Experiments on the Action of Spark-Discharges on Bacteria. The organism chosen for these experiments was staphylo- coccus pyogenes aureus, this possessing an average capacity for resisting deleterious influences. Exp. 6. April 3rd. A small portion from a fresh culture of staphylococcus pyogenes aureus was taken on a strip of platinum, and with this the nutrient agar of 2 Petri's dishes A and B were inoculated. Culture A was deposited for 24 hours in the incubator, and served for control purposes; culture B was uncovered and ex- posed to the electrode employed in Exp. 2 at a distance of 1 cm., the electrode being connected with one pole of the secondary coil of a Ruhmkorff's apparatus. The primary current was of 2 amperes and 12 volts; there were 16 interruptions per second. The culture was treated to the sparks for 15 minutes, a metal dish being afterwards placed beneath it and earthed by means of a wire; the culture was then exposed to the discharge for 1 $ minutes more, and after that placed in the incubator for 18 hours. April 4th. Culture A shows a well-developed growth; culture B shows very slight signs of growth. In the middle of it, indeed, there is an absolutely sterile patch the size of a kreutzer. This area corresponds ex- actly with the middle portion of the metallic electrode, from whence most of the sparks had been seen to strike. The experiment was repeated several times, and the conclu- sion appeared justified that the effect of direct sparking is to hinder the development of cultures of staphylococcus pyogenes aureus. The object later was to disperse the spark-discharge over HIGH-FREQUENCY CURRENTS 127 a large surface, making it everywhere of equal intensity. The cross-shaped electrode was, therefore, dispensed with, and a me- tallic brush 4! cm - by 2 cm -> the construction of which was like that of the brush electrodes used in general faradisation, was employed (electrode II) ; or a faradic brush having a diam- eter of 1 cm. was used (electrode III). Exp. 7. April 4th. Three cultures, A, B, C, are made on nutrient agar from plate A of the last experi- ment, a streak 2 cm. in width being inoculated in each in- stance. Culture A is placed in the incubator; electrode II is placed over the middle of cultures B and C so that its longest diameter coincides with that of the streak of bacteria. Culture C is electrically earthed; distance of the electrode, 1 cm.; primary current, 2 amperes, 12 volts; interruptions, 16 per second; time of exposure, 20 minutes each. Culture C is seen to receive stronger sparks; after the experiment each culture is deposited in the incubator for 18 hours. April 5th. Culture A has developed well, also cul- ture B, the latter showing a uniform growth. Culture C, on the other hand, shows even to the naked eye a bare strip 8 mm. in length, corresponding to the middle of the electrode. This experiment shows that by earthing the current the de- velopment of cultures of this organism is materially arrested. Exp. 8. Three streak-shaped cultures of the same organism are made on three agar plates, as in the last experiment \A, B, C) . A, the control culture, is placed in the incubator; a fourth culture I) is made in a cross- shaped manner. Culture B is earthed by a wire, elec- trode II being placed opposite the middle of the streak at a distance of 3 cm. An ordinary brush electrode (III) is placed opposite the middle of culture C, at a distance of \ cm., but C is not earthed. J) is arranged in such a way that the centre of the cross is situated immediately under electrode II, at a distance of 1 cm. I) is electri- cally earthed. B and I) are exposed for 20 minutes each; C for 30 128 RADIO-THERAPY minutes; primary current, 2 amperes, 12 volts; interrup- tions, 16 per second; after the experiment all the cultures are placed in the incubator for 18 hours. The object of this experiment was to discover whether the distance of the electrode counts as a material factor, also whether the absence of proper electrical earthing may be com- pensated for by longer time of exposure and shorter distance of the electrode, and, finally, whether the area of the sterile zone is proportional to that of the active surface of the elec- trode. April 6th. The result of experiment 8 is as fol- lows: A seemed to be well developed; in B also no ar- rest of development could be noticed; C shows a spot of deficient development in the centre; D an absolutely sterile spot the size of a kreutzer in the centre. These results clearly show that the bactericidal action of spark-discharges rapidly decreases as the distance of the elec- trode from the cultures increases; further, that absence of proper electrical earthing may be to some degree compensated for by more prolonged exposure and shorter distance from the electrode. In the case of culture D the experiment shows that elec- trode II was not adapted for equal dispersion of the spark-dis- charge. The next experiment was undertaken with the object of find- ing whether stronger currents and longer exposures can com- pensate for greater distance between the electrode and culture. Exp. g. April 6th. In 3 Petri dishes, A, B, and C, ribbon-shaped cultures of the same organism were made on agar as before; A, the control culture, is placed in the incubator; B is exposed to electrode II, at a dis- tance of 3 cm., being duly earthed. Primary current (from the main), 4-6 amperes, no volts; rate of inter- ruption, 16 per second; time of exposure, 20 minutes. C is also earthed and placed so that the middle of its culture streak is at a distance of 3 cm. from electrode II, and exposed for 45 minutes. Primary current, 2 amperes, 12 volts; interruptions, 16 per second. Each HIGH-FREQL ENCY CURRENTS 129 culture is placed in the incubator for 18 hours after the experiment. April 7th. J is well-developed; B and C show in their centres a sterile patch, that of B being the more conspicuous. This experiment shows that, in spite of greater distance of the electrode, the desired inhibitory effect on the organism can still be attained by prolonging the exposure and increasing the strength of the primary current. Exp. 10. In order to investigate the manner in which the conduction of electricity to the floor takes place, capsule B of the last experiment was placed, not directly on a metal plate as before, but a sheet of black paper was inserted between them. During the experi- ment powerful sparks could be seen flashing up and down along the walls of the Petri dish. After the ex- periment the paper, when held up to the light, showed a circular line, consisting of numerous tinv holes, the ar- rangement of which exactly corresponded with the out- line of the base of the glass dish. Thus the sparks had evidently not struck through the bottom of the dish, but had taken their way from the surface of the agar over the edge of the dish, so transfixing the paper. The above experiments clearlv prove that spark-discharges have the effect of hindering the development of culrures. It now remained to be seen whether they were also able to destroy cultures already grown. Exp. 11. April 9th. Two Petri dishes, A and B, were each inoculated in a cross-shaped manner with the same organism ; A serves for control purposes; B is cov- ered with a sheet of paper and placed in electrical con- tact with the floor. Electrode II is fixed above the paper at a point coinciding with the centre of the cross. Primary current, 46 amperes, no volts, 60 interrup- tions per second. An isolated spot of a well-developed two-days old culture (Exp. 9) E is placed opposite the bare end of the wire, at a distance of \\ cm., and exposed for 20 130 RADIO-THERAPY minutes; primary current, 2 amperes, 112 volts; inter- ruptions, 16 per second. Afterwards a small part of this irradiated portion is removed on a strip of platinum and an I-shaped figure drawn with it on a fresh nutrient agar E; from a non-exposed portion a II-shaped figure is drawn on the same agar E; all the plates are then placed in the incubator for 1 8 hours. April 10th. A is well developed; B is also well de- veloped, but shows in its centre an absolutely sterile spot the size of a pfennig; the / and the / of capsule E are also well developed; no difference can be discerned between these respective growths. From the first part of this experiment we may conclude that the discharges have a deleterious action on organisms, even through a paper diaphragm. The sheet of paper showed nu- merous punctiform holes in the centre. In the second part of the experiment any destruc- tive effect on grown-up cultures had failed to show itself. Exp. 12. April 11th. A colony of a culture of the same organism two days old, the size of a pinhead a is placed half a centimetre below electrode II; this brush electrode is connected with apparatus II; 20 min- utes' exposure is given. The same is done with a second colony (b) for 10 minutes. Then "I" from (a), "II" from (/>), and "III" from a non-exposed portion of the colony are grafted on fresh agars, and these three plates (I, II, and III) are deposited in the incubator for 18 hours. During the sparking, which was extremely vivid, the colony and its immediate surroundings assumed a bleached appearance; this vanished after an hour or so and was replaced by a brownish hue; similar changes, but less marked, were observable with colony b, which had not been so long exposed. April 1 2th. Only the last of the plates which had been deposited in the incubator shows a III formed by colonies; the others are absolutely sterile, showing only HIGH-FREQUENCY CURRENTS wi j the furrows of the I and II in the agar. The spots a and b on the exposed plate appear more sterile than their surroundings. Exp. i j. April i 2th. Exp. 12 is repeated, but at a distance of 1 -A cm. from the electrode. April 13th. The marks I, II and III on the three plates show a uniform development of bacteria; thus the greater distance of the electrode had counteracted the effect of the discharge. Exp. 14. April 13th. The general arrangement of Exp. 1 2 is adopted, but a larger colony of culture A, in the shape of a streak 1 cm. in length and 2mm. in breadth, is exposed for 20 minutes. From this an I-shaped inoculation is made on plate B; also a II- shaped inoculation from a non-exposed portion is made on the same plate. April 14th. I and II on plate B are uniformly and thickly covered with bacteria. Frequent and careful repetitions of Exp. 12 showed, how- ever, that small colonies the size of a pinhead may be destroyed by a 10-minutes' exposure under the above-described conditions. The failure of Exp. 14 may, therefore, be ascribed to a too short exposure of so extensive a colony. It follows from this that by employing sufficiently strong high-tension primary cur- rents and a sufficiently quick rate of interruption , spark-dis- charges can be produced which, with the electrode at a moderate distance and a comparatively long exposure, can destroy bac- terial cultures which are several days old and fully developed. In the later experiments the current in the primary coil was so directed that the disc of the spark-gap was always cathode ( — ) and the point anode ( + )• (Sec p. 64.) The object of enquiry now was to discover whether positive and negative discharges have the same physiological effects. Exp. 75. April 13th. On a plate of agar (A) two colonies of the organism are deposited in the shape of two parallel streaks, each about 1 cm. wide (i, 2). The plate is earthed and the middle of each streak exposed to the brush electrode for 1 5 minutes, at a distance of i 3 2 RADIO-THERAPY i cm. ; the electrode is in connection with the anode (point) in the case of streak i, with the cathode (disc) with streak 2; primary current, 2 amperes, 12 volts, 16 interruptions per second. During the experiment a marked difference can be discerned in the character of the two discharges. The sparks from the negative pole are thrown in a shaft directly and vertically on the portion of the agar near- est to the electrode. They always occupy the same site; the discharges from the positive pole, however, are seen jumping from one metal point of the electrode to the other, and show a tendency to reach the circumfer- ence of the electrode. The same procedure is repeated with a second plate B, which is exposed for only 8 minutes. After both experiments both plates are deposited in the incubator for 18 hours. April 14th. Both streaks on plate A are well de- veloped, but show a sterile region in their centre. This in the case of streak 1 is seen in the shape of a clear circular spot the size of a lentil ; streak 2 shows in its centre more irregular sterile streaks and foci. On plate B only streak 1 shows a small circular ster- ile patch; streak 2 is nowhere interrupted, but uniformly covered with the growth. This experiment shows that the bactericidal effect of posi- tive spark-discharges is not so powerful as that of negative; also that the action of the latter is limited to a smaller area. Further repetitions and control experiments confirmed these conclusions. Exp. 16. April 25th, 1900. A streak inoculation is made on two agar plates {A and B) . A brush elec- trode in connection with d'Arsonval-Ondin's apparatus is fixed opposite the middle of streak A at a distance of 1 cm. Primary coil current, 2 amperes, 12 volts; inter- ruptions, 16 per second. The brush electrode is also fixed at the same dis- tance opposite the middle of streak /?, but connected with HIGH-FREQUENCY CURRENTS 133 the cathode of the coil; both plates are earthed, and exposed for 5 minutes each. April 26th. The growth on B is well developed, but shows a sterile spot in its centre; streak A is uni- formly developed. Exp. i/. April 26th. A streak-shaped colony of the organism in a Petri's dish is treated in the middle with discharges from a d' Arsonval-Oudin' s apparatus for 2 5 minutes. April 27th. The streak shows a sterile patch in the middle. These last experiments show that spark-discharges from d' Arsonval-Oudin* s apparatus act in the same way on bacteria as direct polar discharges from the coil, but that the intensity of action of the latter is greater. Exp. 18. April 27th. Two streak-shaped cultures of the organism are made on agar; the middle one, plate A, is exposed at the distance of 1 cm. to a brush electrode conveying the discharges of a secondary cur- rent, which is induced by a primary current of 3 to 4 amperes, 12 volts, and 16 interruptions per second. The middle of the second streak B is exposed to the sparks from a primary current of 3 to 4 amperes, 110 volts, and 16 interruptions per second. Time of ex- posure in each case 3 minutes, followed by incubation for 18 hours. April 28th. Both cultures show uniformly well- developed uninterrupted streaks of organisms. Exp. iq. The last experiment was repeated, this time with a longer exposure, viz., 10 minutes; both streaks now show equal-sized sterile patches. When the time of exposure was varied in still other ways no difference was found in the action of primary currents of varying tension, hut of equal intensity and rale of interruption. These findings are quite analogous to the results of a series of experiments made by B. Walter. 1 ) The latter found that y ) Fortschr. auf dem Gebiete der Rontgen trahlen, Vol, II. p. 31. 134 RADIO-THERAPY the amount of tension obtaining in the circuit of a primary cur- rent has no direct effect on the length of spark evolved. 1 ) Exp. 20. April 27th. Two streak cultivations of the organism are made on agar plates; the middle part of one (plate A) is exposed to the spark-discharge from a brush electrode at a distance of 1 cm. The electrode is in connection with a secondary circuit induced by pri- mary currents of 2 amperes, 12 volts, and 16 interrup- tions per second. Plate B is subjected to the same treat- ment, with the exception that in this case the primary current is only interrupted 8 times per sec- ond. The plates are earthed in both instances. Time of exposure 4 minutes, followed by incubation as be- fore. April 28th. Plate A shows a well-developed col- ony, with a sterile patch in the centre; the growth in the case of plate B is absolutely uniform. We may conclude that the rate of interruption of the pri- mary current is an important factor concerning the effect of the spark-discharge. Exp. 21. This is a modification of the last experi- ment. The rate of interruption is again 16 per second, but the intensity of the primary current is altered from 1 to 4 amperes by varying the resistances and raising the mercury vessel of the interrupter. The result showed that a colony of bacteria exposed to the discharges from a current of 1 ampere for 8 minutes was not hindered in its development; whereas, the latter event occurred when another colony was exposed to a current of 4 amperes un- der precisely the same conditions. Exp. 22, April 30th. A square piece of annealed copper sheeting 1 sq. cm. in size is placed on the floor of a sterile Petri dish (Fig. 46 K) ; from the edge of this piece of metal a copper wire B leads to the side of the dish, and eventually to the floor. An ordinary nutrient agar medium is placed on the copper sheet, and 1 ) Fortschr. auf dem Gebiete der Rontgenstrahlen, Vol. II, p. 31. HIGH-FREQUENCY CURRENTS 135 after coagulation is uniformly covered with a small quantity of the organism. Over the colony the follow- ing arrangement is placed: A disc of glass 6 cm. in di- ameter and ih cm. thick, with a central hole 2 cm. in diameter, is supported by three glass pedestals; on the upper surface of the disc a sheet of paper (P) is at- tached with sealing-wax so as to cover the central hole; on this paper a circular piece of fresh human skin (//) K Fig. 46. is placed. The edge of the skin does not extend quite to that of the glass disc ; the hole in the latter is arranged just above the copper sheet. Above the whole a brush electrode is fixed at a distance of \ cm., and con- nected with the negative pole of the secondary circuit. Primary current, 4 to <; amperes, 1 10 volts; 100 inter- ruptions per second; time of exposure, 20 minutes. During the whole experiment a copious discharge of sparks took place between the perforation in the glass disc and the copper sheet. After the experiment the surface of the skin appeared slightly singed within an area coinciding with the aperture in the glass disc; the paper showed a multitude <>t small holes with scorched border. The glass disc was then removed; the surface of the nutrient agar showed no evident changes; the 136 RADIO-THERAPY Petri dish was then closed and placed in the incubator for two days. On May 2nd the culture presented the appearance shown in the photograph (Fig. 47). The agar is seen to be completely sterile in the region corresponding to the piece of copper sheeting and its wire; everywhere else the nutrient medium is seen to be uniformly covered with a well-developed growth. This experiment proves that, even by interposing a piece of human skin, living bacteria can be absolutely prevented from developing by treating them with negative polar discharges of high-tension induced currents. The experiments hitherto described were intended to shed light on the particular circumstances under which the bacteri- cidal effect of the electric discharge takes place. We now proceeded to test the action of polar discharges on various other kinds of bacteria, dealing especially with those micro-organisms which bear a causal relationship to certain dis- eases of superficial parts of the body. Exp. 23. April 20th. Two streak-shaped colonies (a, b) of a culture of typhus bacillus are made on nu- trient agar in a Petri dish A, the dish is placed in the incubator for 36 hours. After this time a uniformly Fig. 47. Fig. 48. Fig. 49. well-developed growth is seen in the sites of inocula- tion; streak a is now exposed in the central part to the negative discharges of a secondary current, which latter is induced by a primary current of 2 amperes, 1 10 volts, and 100 interruptions per second. Discharges are pro- HIGH-FREQUENCY CURRENTS 137 jected from a brush electrode at a distance of ', cm. The Petri dish is electrically earthed; time of exposure, 10 minutes. After the experiment a small quantity is taken from the exposed portion (which appears rather dry) and an [-shaped figure is inoculated with it on sterile agar B. A portion is also taken from the non-exposed streak b and a U-shaped figure inoculated on B ; both dishes are then placed in the incubator. April 2 1 st. Streak a in dish A shows a small hol- lowed spot in its midst; otherwise it is uniformly cov- ered with growth. On the agar of dish B the furrows made by the "I" are completely sterile; on the other hand, the "II" is everywhere covered with thickly- grown colonies. Exp. 2-j.. April 25th. The middle (1) of three cultures of diphtheria bacilli several days old is exposed to the negative discharge of a secondary current through a brush electrode; primary current, 2 amperes, no volts; 100 interruptions per second. The culture ves- sel is electrically earthed. From the exposed portion "I," as in experiment 22, is drawn on a second agar B ; also on the same agar a "II" is drawn with a non-ex- posed portion of culture 2. Both plates are then placed in the incubator. April 26th. Streak 1 in plate A shows a slightly brownish colour in its centre; the I in plate B is com- pletely sterile, the II thickly covered with colonies (Fig. 49)- Exp. 25. April 25th. Exp. 23 is repeated with the same arrangement, but this time cultures of aphtha' two days old are used; the results are quite similar to those in the case of the diphtheria bacilli. Exp. 26. April 25th. The same procedure is adopted with cultures of anthrax two days old, which are treated by direct negative polar discharges from a brush electrode. The first experiment gives negative results; acting on Prof. Weichselbaum's advice, the colony is moistened with sterile bouillon. Vivid sparks ensued, 138 RADIO-THERAPY with the evolution of moist heat, in which the organisms perished more easily. By these means their destruction is achieved. Exp. 27 '. May 1 2th. A culture of tubercle bacillus four months old, cultivated on glycerine agar in a test tube (A) and well developed, is treated as follows: A wire in connection with the negative pole of a sec- ondary coil perforates the woollen plug in the test tube so that its end is placed vertically and at a distance of Fig. 50. 4 mm. above the culture. Outside the test tube and op- posite the wire a small sheet of metal is fixed; a wire connects the latter with the floor; primary current, 2 am- peres, 1 10 volts; 100 interruptions per second. Expos- ure is continued for 10 minutes, during which time sparks are seen freely striking through the tube in the di- rection of the metal strip outside. (The surface of the nutrient medium was placed in a slanting direction with- in the tube so as to be traversed by the sparks in HIGH-FREQUENCY CURRENTS 139 their passage.) After the experiment the exposed por- tions of culture are apparent as two dark-brown spots the size of a lentil. (Fig. 50.) From these spots a small quantity is taken on a platinum spatula, mixed with a few drops of sterile bouillon, and a sterile sloping surface of nutrient glycerine agar in test tube / inoc- ulated with it; in the same way a portion of culture A which had not been exposed to the discharge is inocu- lated on a third agar (test tube //). These three test tubes are then closed with plugs of cotton wool covered with gutta-percha tissue and placed in the incubator. After three weeks (June 2nd) they were inspected. Test tube A shows four sterile places exactly like each other; test tube /, on which the irradiated portion had been ingrafted, shows the surface of the agar to be com- pletely sterile ; test tube //, however, in which non-ex- posed portions had been inoculated, shows several well- developed colonies (see Fig. 50). Exp. 28. A culture of favus, in three well-devel- oped streaks on agar and a fortnight old {A) , is exposed in the centre of its middle streak to negative discharges from the brush electrode at a distance of \ cm. for 15 minutes; primary current, 2 amperes, 1 10 volts, 100 in- terruptions per second; earthing of the current. The exposed portion is then moistened and mixed with ster- ile bouillon and "I" of this is inoculated on a second agar B. Also a "II" of one of the other non-exposed streaks is inoculated on B. Both vessels are then closed and placed in the incubator. Three days later the "I" on vessel B appears sterile; the "II," however, is thickly grown over with colo- nies. In addition to the preceding experiments, experiments 23 to 28 show that it is possible by direct polar discharges striking from metal (end of the conducting wire, or brush electrodes) to prevent the development of bacterial cultures; also, under suitable experimental conditions, to absolutely destroy even well-developed colonies, several days old, of staphylococcus i 4 o RADIO-THERAPY pyog. aur., typhus bacillus, diphtheria bacillus, anthrax bacil- lus, aphthce, tubercle bacillus, and achorion Schonleinii. We must not, of course, assume too much from the results of the last two experiments, since it is quite possible that these results were merely accidental in view of the difficulty presented in the cultivation of these kinds of bacilli (tubercle bacillus, achorion Schonleinii). The results of the other experiments, however, may fairly be regarded as conclusive, since in their case no difficulty of this kind exists. Some reports on the action of electricity on bacteria already exist. Mendelsohn 1 ) had shown that the gal- vanic current is capable of destroying micro-organisms. Apostoli, 1 ) Laguerriere,' 2 ) Prochownik and Spdth 3 ) as- cribed this effect to the electrolytic action of the current. Some authors ascribed similar effects to the inducing properties of electricity; especially Spilcker and Gott- stein*) Buret and Froscani. b ) The statements of Spilcker and Gottstein were disputed by Friedenthal 6 ) and Kriiger. 1 ) Klemperer, 8 ) Kriiger, ) and Smirnow 10 ) made anti-toxines from bacterial toxins by treatment with con- stant currents of 80 to 100 m. a.; d'Arsonval and Charrin 1X ) succeeded in converting the toxins of pyo- cyaneus and diphtheria bacilli by the electrolytic action of high-frequency currents. Bonome and Vial, 12 ) Meade Bolton and II. D. Pease 13 ) confirmed d'Arson- 1 ) Cohn's Beitnige zur Pflanzenphysiologie, 1879; quoted by Gottstein and Labarsch-Ostcrtag, 1897, p. 82. 2 ) Sem. med., 1890. 3 ) D. med. Wochenschr., 1890. 4 ) Centralbl. f. Bakt., Vol. IX. 6 ) Quoted by Labarsch-Ostertag, 1897. 6 ) Centralbl. f. Bakt., Vols. XIX and XX. 7 ) Zeitschr. f. klin. Med., Vol. XXII. 8 ) Ibid. Vol. XX, p. 165. ») 1. c. 10 ) D. Med. Wochenschr., 1894, No. 30. ") 1. c. u .) Centralbl. f. Bakt., Vol. XIX, p. 849. M ) Journal of Experimental Medicine, 1896, Vol. I, No. 3. HIGH-FREQUENCY CURRENTS 141 vol and Charrin's experiments on the conversion of tox- ins into anti-toxins, but stated that bacteria themselves were not in the least influenced. Marmier 1 ) repeated the experiments and came to quite other conclusions. He believed that by the electrolytic decomposition of the sodium chloride contained in the culture fluid hypo- chlorites are produced which destroy the toxins. He found that by employing d'Arsonval and Charrin's method the diphtheria toxins were heated in 12 min- utes to 8i° C. Tolomei 2 ) enquired into the effects of direct sparks on acetic fermentation. When sparks from a Rithm- korff's apparatus strike the surface of the fermenting liquid, some arrest in the development of the organisms occurs in the case of fairly strong discharges; the liquid, however, is not sterilised, for after stopping the dis- charge the fermentation proceeds again, though to a less extent. According to the report of Destot's and Dubard's papers, read before the Congress on Tubercu- losis, Paris, 1898, bacteria can be destroyed by static electricity. How are these negative discharges of high-tension induced currents, which have proved to be so efficacious, to be used in practice? The use of the apparatus in the manner described for the foregoing experiments is obviously out of the question ; for one thing the pain would be considerable, and the surface of the body, if irradiated in this manner, would be almost cer- tainly damaged. Moreover, the discharges would be applied over too small an area. Many experiments had been made with the object of dis- persing the spark-discharge over a larger surface, with nega- tive results. In no case could a simultaneous discharge be in- duced from all points of the surface of the electrode. The au- thor made a series of photographs of discharges from the electrode in the following way: ') Annates de Pinstitut Pasteur, [895, p. 533! 1896, p. 468. 2 ) L'Orosi, Vol. XIII, p. 401-409. Rcf. Centralbl. f. Bakt., Vol. IX, p. 540. 142 RADIO-THERAPY A bromide of silver collotype film was placed in a dark room on a metal plate, the latter being earthed. An electrode was fixed at a distance of i cm. above the middle of the collo- type and a current passed from the coils. The time of exposure amounted to only a few seconds; with a longer exposure the whole collotype would have been diffusely blackened. In this way a graphic picture was obtained of the positive discharges which were seen to flow off in all directions towards the metal plate (see plate, Fig. i). Another picture showed the more constant course of negative polar discharges, which always keep the same situation and follow the shortest course to the metal plate (see plate, Fig. 2) . Pictures of the discharges from brush electrodes (plate, Fig. 3), also those from pencil electrodes (Fig. 4) , show very distinctly a series of round spots where the sparks successively struck the film. From these photographs, as well as from inspection of the process of sparking itself, it be- came quite clear that none of these electrodes would quite meet the case. In consideration of the fact that in all these experi- ments good conductors had been employed, the author now de- termined to try bad conductors. Exp. 2Q. A piece of wood was placed within the lumen of an ordinary wooden bobbin and connected with the conducting wire of the negative pole. The bobbin was fixed above the collotype in the same way as before. The negative, on being developed, showed a bright circle corresponding to the base of the bobbin, with a completely blackened surrounding. This blackening was evidently caused by the quiet (invisible) discharges from the bobbin. This experiment suggested the following : Exp. 30. By Prof. Valenta's advice the wooden electrode was shaped like a cylinder, the thickness of a thumb, with its ends rounded; this was placed in a glass receptacle which left only that side free which faced the collotype; the conducting wire was conveyed through the glass to the electrode. The photograph obtained by the use of this apparatus ap- peared distinctly more promising. In addition to a number of HIGH-FREQUENCY CURRENTS 143 spots corresponding to the varying position of the spark-shaft, there was a rather diffuse and more uniform action, as shown in the plate (Fig. 5). Instead of an imperfect conductor, such as wood, a thor- oughly bad conductor, glass, was now chosen. Experiments with glass alone failed. An electrode was now contrived (Exp. 31) by filling a test tube with water, closing it with a cork, and conveying the conducting wire through this cork to the surface of the water. It was soon seen that one's object had been more nearly attained; discharges proceeded from the lower end of the test tube in a regular and uniform manner, in the form of a number of thin blue rays streaming oft simultaneously. The photograph, too (see plate, Fig. 6), gave satisfactory results — the discharges had produced a diffuse circular blackening figure, which showed only an insignificant bright spot in the centre. (The plate, of course, shows the photographic process reversed, i. e., the black spots are white, and vice versa.) The last defect was removed when, instead of the test tube, a small glass flask of about 8 mm. in diameter was employed (Exp. 32), and arranged as the test tube had been. Dis- charges from this instrument gave a perfectly uniform and simultaneous effect. Their photograph appeared as a circular uniformly blackened disc (see plate, Fig. 7), the diameter of which amounted to about 8 cm., that is, about 10 times the diam- eter of the electrode. These diffusely radiating discharges, which cause but feeble light effects, have been known for a long time; the peculiar light effects which are seen in the dark on mast-tops, the ends of light- ning rods, tree-tops, etc., which were named after Castor and Pollux by the ancients, and called St. Elmo's lire in our times, belong in the same class of phenomena. Points which are ap- proached to a conductor charged with electricity collect this electricity in a high state of tension and part with it to the surrounding air. The electricity thus imparted to the air is repelled by that of like kind still remaining in the points, and leads away the electricity accumulated on the conductor; thus the result is the same as though the electricity streamed directly from the points. When the eleetrieit\ streaming oft points in 144 RADIO-THERAPY this manner is conducted to the ground, the appearance of a bluish vapour is produced; when, however, the space between the point and the earthing wire is increased, the electricity streams away almost invisibly: it is now more readily discernible by the sense of touch than that of sight. Exp. 33. An investigation now took place of the action of negative polar discharges from the last-men- tioned (flask) electrode when directed towards an earthed metal plate; also as to their behaviour when a glass plate is inserted between the electrode and the metal plate. The following table gives the results : Flask-Electrode Glass-Plate Earth-Conduction Flask-Electrode I Earth-Conductor 3- 4- Contact of the electrode with the glass plate gives a powerful dif- fused blue light, from which no other visible rays stream off. When the electrode is gradually removed the light becomes con- centrated into numerous blue rays, with one central brighter ray. With still greater distance of the electrode, the central ray becomes brighter and more pronounced, while the other rays become cor- respondingly feeble. With still greater distance the central ray also disappears ; a dif- fused bluish halo is now seen round the electrode. 1. Contact of the electrode with the metal plate gives numerous but weaker luminous rays. 2. With the electrode a short dis- tance from the plate, one thick luminous ray appears. 3. With the distance increased numerous weak, but still luminous, side-rays appear surrounding the central ray. 4. With the distance still increased, the central ray disappears, and 5. The electrode appears surrounded by a bluish luminous halo. Exp. 3J. Similar phenomena were observed when the electrode was only half filled with water, in which the end of the conducting wire was immersed. Exp. 55. The experiment was repeated with the electrode empty. With the electrode in contact with the glass plate a feeble light was seen; this disappeared as the electrode was removed. Precisely the same effect was produced when the metal plate was substituted for the glass plate. Exp. 36. In order to decide whether the size of the electrode has anything to do with the quality of the dis- HIGH-FREQUENCY CURRENTS 145 charge, a spherical electrode filled with water was used, 4 cm. in diameter. With this apparatus no such dis- persion of the discharges could be effected as with the smaller electrode. When the electrode was placed 1 cm. from the glass plate, about a dozen thick bluish rays were seen striking from its base. As the electrode was approached still nearer to the plate the rays became thinner and gradually brighter. Exp. 3J. In order to decide whether these dis- charges caused any sensation of pain or touch, the back of one's hand was approached to the electrode in action (electrode VI). At a considerable distance even the hand had the sensation of being breathed upon; this sensation increased as the hand was brought still nearer to the electrode, and at a distance of 1 \ cm. a spark struck the skin. There was absolutely no feeling of pain. Repeating the experiment with the larger water- sphere electrode (electrode VII), a faint sensation as though the skin were being stroked with hair was felt even at a distance of half a meter. This phenomenon occurred when the hand was moved in any direction within this radius. The effects of uni-polar discharges of high-tension induced currents differ slightly from those of high-frequency currents. In the form of a simple spark-discharge they produce a small wheal on the skin, which shows as a white spot well defined against hvperarnic surroundings. Sparking of this kind causes a smarting, burning sensation; afterwards the sensibility of the skin for further shocks rapidly diminishes. When the discharge is converted into a "quiet" one, the skin becomes first red and then bluish, slightly swollen and (edematous. Sensibility is mostly altered in the direction of analgesia; sometimes, how- ever, the reverse occurs. Exp. 38. A rabbit, whose coat was perfectly fast, was placed in a wooden receptacle as before, and the left side of its chest exposed to diffused negative polar discharges from the water-sphere electrode VI at a dis- tance of 4 cm. Primary current, 3 amperes, 110 volts, 146 RADIO-THERAPY ioo interruptions per second. No earthing of the cur- rent. Time of exposure, 30 minutes. No visible sparks were evident during the whole experiment, and the animal showed no signs of discomfort. The treatment was continued in this way for 8 days (June ist-Sth). The animal, which for want of proper i 1 JmSk i ^lr « : Kfeg. *%"*, ■$ -0* ; v '^-:, ' . * Fig. 51. accommodation had to be kept in a very warm room, failed gradually in health and died on June 8th. By this time, however, changes were seen in the fur exposed to the discharges; these changes exactly cor- responded to those produced by direct spark-discharges : thinning of the hair, bald spots in places and clogging of the woolly undergrowth in others. (Fig. 51.) Exp. 3Q. April 26th. A Petri dish containing nu- trient agar is uniformly covered with a culture of staphy- lococcus pyog. aur. The test-tube electrode is fixed at a distance of 1 cm. above it. The apparatus is earthed. Primary current, 2 amperes, no volts; 100 interruptions per second. No direct sparks are visible; a bluish halo of "quiet" discharges surrounds the electrode. Time of exposure, 25 minutes. The Petri dish is afterwards placed in the incubator. April 27th: The centre of the nutrient agar shows a sterile circular patch the size of a HIGH-FREQUENCY CURRENTS 147 kreutzer; elsewhere a thick uniform growth is seen (Fig. 52). Exp. 40. April 26th. Exp. 39 repeated without the earthing of the current; exposure, 35 minutes. The result was the same as in Exp. 39. Exp. 41. May 5th. Two agar plates, A and B, are uniformly inoculated with anthrax bacillus. A, the control-plate, is placed in the incubator; B has its central portion exposed to electrode VI and is earthed. Primary current, 24 amperes, 110 volts, 100 interrup- tions per second. Exposure, 20 minutes, followed by incubation. May 6th. A shows well-developed colonies; B shows a central sterile patch and colonies only round its border. Exp. 42. May 9th. Plate A of the preceding ex- periment, now a culture 4 days old, is exposed in its cen- tral portion to the water-sphere electrode for one hour; the discharge is invisible. From the centre of A an "I" is marked on a second nutrient agar in dish B, while from the periphery of A a "II" is marked also on B. Fig. 52. Fig. 53. — Control-plate A (Exp. 43). May 10th. Both marks, "I" and "II," on dish B are completely and uniformly covered with growth. The discharge had, therefore, been unable to destroy the in- oculation from ./. Exp. 43. May 10th. Two agar plates, ./ and II, are covered with anthrax bacilli and placed in the incu- 148 RADIO-THERAPY bator. After 8 hours B is removed; it shows a slimy, delicate Him throughout its surface. A cover-glass preparation is made from this and stained with Moel- ler's carbol fuchsin-methylin blue, to show the spores. These and the bacilli are seen under the microscope to be very abundant. The central portion of B is now ex- posed for i{ hours to electrode VI (the water-sphere), conveying quiet negative polar discharges. Primary current, 2 amperes, 1 10 volts, 100 interruptions per sec- ond. Afterwards an "I" from this exposed portion is marked on a third dish C, while a "II" from its periph- ery (unexposed) is marked also on C. B and C are then placed in the incubator. On the following day A is seen to be copiously cov- ered with colonies. B is seen to be sterile, with the ex- ception of some scanty colonies round its border. 7 he "I" on plate C is only seen by its furrow; it is quite ster- ile. The "II," on the other hand, is well marked with bacterial growth (see Figs. 53, 54, 55). Summing up the results of the last experiments, we see that by suitable appliances we can transform direct spark-discharges 1 i Fig. 54. Fig. 54.— Plate B (Exp. 43). Fig. 55. Fig. 55.— Plate C (Exp. 43). into quiet discharges, whereby they lose somewhat in their effective power; that in order to make the effect of these quiet discharges equal thai of direct sparking the exposure must be prolonged ; that the quiet discharges from the water-sphere electrode have a larger sphere of action. The physiological effects of these quiet discharges exactly HIGH-FREQUENCY CURRENTS 149 Fig. 56. corresponded with those of direct spark-discharges: they caused hair to fall off, they prevented the development of bacteria, and they destroyed the already-developed colonies of anthrax ba- cilli. Electrical conduction to the ground was advantageous in this instance as before. Direct observation of the phe- nomena themselves and comparison of the effects of quiet discharges and direct sparking suggests the idea that, just as the thick shafts of sparks become divided into several feebler rays, so also the physiological effect becomes weakened, but on the other hand spread over a wider area. The painlessness of quiet discharges is certainly a practical point in their favour. In using the water-sphere electrode it must be very gradually approached towards the object. The author had a special apparatus made for him by Messrs. Schul- meister & Ott, Vienna (see Fig. 56), which enables this to be attained very efficiently. Exp. 4J. May 17th. A cover-gla^s preparation of anthrax bacilli is made, and the spores shown by suitable staining. The microscope reveals an abundant culture of spore-bearing bacteria. A small quantity is, therefore, taken from the culture and mixed with 1 c.cm. of sterile bouillon. The test tube containing this mixture is placed for one day in the incubator; typical anthrax-colonies are seen to develop. Three drops, therefore, are taken of the culture and placed in the cen- tre of a sterile and empty Petri dish. This latter is then exposed to direct sparking for 15 minutes. Brush- electrode 1 cm. distance; earth-conduction; primary cur- rent, 2 amperes, 1 10 volts, 100 interruptions per second. After the sparking a trace of the culture so treated is taken on a sterile platinum point and an "I" drawn with this on a sterile agar B. On the same agar i 5 o RADIO-THERAPY a "II" is drawn from the non-irradiated bouillon-culture in the test tube. B is then placed in the incubator. May 1 8th. The "I" in B is sterile; the 4l II" shows well-developed bacteria. From this experiment it follows that micro-or ganisms , even when suspended in liquids, are susceptible to the destructive effects of spark-discharges. When the conducting wire of a d'Arsonval-Oudin's appa- ratus in action is observed in the dark, bluish rays (brush-dis- charges) are seen to strike from it at right angles in its entire length. The rays are very similar to those of our water-sphere electrode, and they evoke similar sensations in the skin. In order to discover if these rays were the cause of the well-known phenomenon — the illumination of an incandescent lamp placed within (but not in contact with) a metallic spiral traversed by high-frequency currents — the following experiment was made: Exp. 45. Within such a spiral a large pasteboard cylinder was placed, covered above and below with glass plates. Within this cylinder two spirals of wire with an incandescent lamp between them were sus- pended. As soon as high-frequency currents were sent through the solenoid the lamp began to shine. Since thick pasteboard, such as was used in this in- stance, prevents the passage of brush-discharges (as the author had proved by other experiments), we had clear- ly to deal here with an induction-effect within the cylinder. The question now arose, had this inductive action any role in the destruction of germs by high-frequency currents ? Exp. 46. Diffused cultures of staphylococcus pyog. aur. are made on two nutrient agars (with sloping sur- faces) contained in test tubes. Culture A is for con- trol purposes. Tube B is wound round, opposite the agar, with four turns of thick insulated copper wire. The ends of this wire are attached to the first and last winding respectively of a d'Arsonval's solenoid D. D'Arsonval states that within a spiral of this de- HIGH-FREQUENCY CURRENTS 151 scription sufficient heat is developed to boil mercury in the bulb of a thermometer. Consequently the spiral and test tube are placed in a vessel of ice-water. The apparatus is then set working and the culture in the test tube exposed for 45 minutes to the action of high- frequency currents. A mercury-thermometer immersed in the tube regis- tered io° C. throughout the experiment. After the exposure of the tube in this way both A and B were placed in the incubator. On the following day both agars were found thickly and uniformly covered with colonies. The experiment showed that high-frequency cur- rents have no bactericidal effect which can be referred to induction. Exp. 4J '. In order to examine the action of spark discharges on the blood-vessels a frog was curarised. A fold of mesentery was then arranged over a perforated cork — as is done in examinations of the blood-circulation — and exposed to the direct discharges from apparatus /. Under the microscope a vessel was seen, from which the diagrammatic sketch (Fig. 57) is taken. Afissure (Schl.) is seen in the front and hinder walls of the vessel; the direction of this fissure is perpendicular to that of the path of the discharge. The walls of the vessel must in some way have become fused together round the fissure, for no signs of extravasation were to be seen. The diverted course of the blood-stream is shown in the sketch. This condition obtained for nearly 48 hours. In order to examine the histological changes which take place in living skin exposed to spark-discharges, Exp. 48 was undertaken. A rabbit was anaesthetised and a portion of its skin treated for 3 minutes to the powerful sparks from JnPwXPooy ,/Sfchl. Fig. 57. 1 5 2 RADIO- THERM P Y apparatus /, using the negative polar current. A second por- tion of the skin was exposed to sparks from apparatus //, and a third, for the same time, to the effluvia of a d'Arsonval-Oudin's apparatus. Although the animal was deeply anaesthetised, breathing but superficially and showing no conjunctival reflex, it responded instantly to the first spark-discharge and made ef- forts to escape. The prompt appearance of these stimulating effects of high-tension induced current discharges is a point of practical significance. After the experiment small extravasations of blood were seen on both portions of the skin which had been exposed to spark-discharges. The animal soon recovered from the effects of the chloroform and appeared quite healthy. A day later it was killed, and the exposed portions of its skin deeply excised and prepared for microscopic examination. (c) Histological Investigations. The specimens of skin were hardened in Mueller formol, embedded in celloidin, and cut at right angles to the surface. Horizontal sections were made of the piece which had been treated by the discharges from apparatus //. The sections were stained with haemalum-eosin, ha?motoxylin-eosin, poly- chrome methylene-blue, and also after the methods of Tanzer- Vnna, Weigert and van Giesson. Specimens of skin which had not been subjected to the experiments were similarly prepared for purposes of comparison. Examination even by low power showed that changes had occurred. These changes were localised in the upper layers of the skin in the form of a focus; with increasing depth they were spread out over a gradually increasing area. In the stratum mucosum a cell-infiltration appeared, which contrasted well with its surroundings (see Fig. 58) . This small cell infiltration separated the cellular tissue of the rete malphigii, partly taking the place of the latter in both its upper and lower layers. The infiltration consisted entirely of poly- nuclear leucocytes, thickly clustered in the upper layers and here hardly distinguishable from each other, while in the lower lay- HIGH-FREQUENCY CURRENTS i53 ers of the infiltration the cells could be readily defined, and were seen to contain numerous eosinophile granules in their proto- plasm. Further important changes were found, at varying depths, in the pars papillaris and pars reticularis. Here, even with the '.-.*".'.-' •- n "■■ -r- w .fgssi »i- ■■ ■: » V %W > - --. 60 1 Fic. 58. low power, an infiltration with red blood-corpuscles was evi- dent; this filled the interstices of the tissue in the form of streaks, and surrounded the hair- follicles like a web. This was plainly shown in the horizontal sections of specimen //. The infiltration was evidently a hemorrhage into the cuticular tis- sues. 154 RADIO-THERAPY M Here and there on the surface of the epidermis were crusts of necrotic material; cell elements were visible here also, which proved to be red corpuscles. Still more striking were the conditions obtaining in the blood- vessels. A casual inspection even showed marked vascular dilatation, the veins especially being widely dilated and gorged with blood. These vascular changes were more marked in the deeper layers of the corium. The vessel walls showed especial changes in the case of the arteries (Fig. 59). In some of these the intima appeared so thickened that it occupied the greater part of the lumen. In the intima and media b peculiar round spaces / / (vi) the size of a cell- nucleus were visible; these spaces were packed to- gether (14 or more being seen in some sections), partly raising the intima from its underlying layer, so that it was only con- nected by septa with the rest of the vessel-wall. Examination by the high power showed that the spaces were not really formed by the raising of the intima from the elas- tica,but by vacuole degeneration of the cells. They are, moreover, not arranged purely concentrically, but quite irregularly, being here adjacent to and there remote from the vessel lumen. The spaces (vacuoles) were, as has been said,, also visible in the media (vm), but to a less extent. The formation of vacuoles to the extent just described was only seen in a few sections; most sections showed only two or three vacuoles. The nuclei of some of the cells within the vicinity of the vacuoles possessed a peculiar property. Whereas the nuclei of other cells took the stain readily and appeared finely granulated m Fig. 59. HIGH-FREQUENCY CURRENTS 155 and dark, these nuclei remained light-coloured and homogene- ous, showing no traces of granules, but rather having the appearance of drops of oil or water. Where nuclear granu- lation was seen this was coarser and more marked than that of the cell-protoplasm. The granules were mostly arranged at the periphery, leaving the centre clear, with perhaps several vacu- oles there situated. Many cell-nuclei in the hair root-sheaths showed similar peculiarities. Many of the hair-sheaths were empty; a few still contained hair, and in these no abnormality could be observed. Pigment was formed in clumps in parts of the upper cuticu- lar layers; it did not appear to be increased in quantity. In the sections stained with orcein, according to Tdnzer-Unna's method, elastic fibres were visible amongst the connective tissue, both of the pars papillaris and pars reticularis. Where the haemorrhages obtained, these fibres were sometimes pressed apart from one another and destroyed. Mast-cells, plasma- cells, and giant-cells were not seen in any specimen. Summed up, microscopical examination revealed mainly (a) small-celled infiltration in the deeper layers of the epi- dermis, (b) extensive extravasation of blood, (c) vacuolisation in the intima of the arterioles. Comparing these facts with what Gassmann observed in a case of Roentgen-dermatitis, we are first struck by the similarity in the condition of the vessel walls in both instances. Ultra- violet light, moreover, as Glebowsky proved, produces similar changes in the cell-protoplasm. There can be no doubt that in our case these changes may be ascribed to the electric discharges; this was proved by comparison with sections of skin which had not been so treated. Moreover, only those vessels which were within the range of the discharges were affected; other vessels in the same preparation were free from change. The author cannot decide whether the vacuolisation must be considered as due to the direct mechanical action of the sparks, or whether it is a degeneration caused by electricity itself; the latter, however, appears to him to be more probable. A second important change in the exposed skin is rcpre- i 5 6 RADIO-THERAPY sented by the haemorrhage. It is quite possible that this phe- nomenon may bear some relation to the marked pigmentation following Roentgen-radiation; that is to say, the electric dis- charges from the Roentgen-tube may cause haemorrhage, fol- lowed by the deposit of haemosiderin. The above-described transformations, sometimes more marked in one respect than in the others, were seen in all the sec- tions made from the three portions of skin which had been treated by discharges from different apparatus. We may as- sume, therefore, that high-tension discharges, of whatever ori* gin, produce physiological effects which are identical as regards their quality and differ only in their intensity. Many authors state that not only the cells of vessel walls, but, under certain circumstances, other structures are trans- formed in like manner. Thus, on reviewing the literature of the subject we find that several botanists speak of the disorganisation of protoplasm under the influence of electricity. Klemm 1 ) mentions swelling of the protoplasmic layers and fibres and plentiful production of vacuoles of an indefinite size. Pfeffcr 2 ) states that the nu- clei are more sensitive to electrical influence than the unformed protoplasm. In the case of tradescantia the nucleus swells al- most to twice its original size, becomes circular, and then sud- denly collapses and becomes irregular in its outline; it often takes a stain before the body of the cell colours at all. Kuehne 3 ) and Verworn 4 ) observed that the galvanic cur- rent produces granular decay in the protoplasm of actinos- pharium, mycomycelis, polystonella and pelomyxa. Verworn traces the opacity and shrinking of the protoplasm, which is "typical of contractor-excitement," to a very fine vacuolisation (becoming froth-like and honeycombed) of the homogeneous hyaline condition which previously obtained in the protoplasm. a ) Jahrb. f. wissensch. Bot.. 1895, Vol. XXVIIT. p. 627. ') Abh. d. Saechs. Ges. d. Wiss., Nw.-math.-ph. Cf., Vol. XVI, p. 185. 3 ) Arch. f. Anat. und Phys., 1859, pp. 564 and 748.— Unters. ueber das Protoplasma, Leipzig, Engelmann. 4 ) Arch. f. d. ges. Physiol., Vol. XLV, p. 1,267; Vol. LXV, p. 47, and Sitzs. der Berl. phys. Gesellsch., Dub. Arch., 1894, P- 538. HIGH-FREQUENCY CURRENTS 157 He also observed granular destruction of the protoplasm re- sulting from alternating currents. Ronx 1 ) found that alternating currents caused migration of pigment in frog-spawn, and contractions so powerful that the ova became broken and the yolk escaped. C. Hess 2 ) explains the opacity of the lens which occurs after a lightning-stroke by the destruction of ephithelium in its capsule. A. Kiribuchi :; ) exposed rabbits' eyes to powerful spark-dis- charges. He found both in the protoplasm and the nuclei of the capsular epithelium a formation of vacuoles, which he as- cribed to electrolytic processes. All these reports go to show that the damage caused to protoplasm bv electricity consists of a loss of cohesion and a solution of its ingredients, which is probably brought about by chemical transformation ( vacuolisation) . Several authors describe changes in the nerve-cell from elec- trical stimulation. These changes are visible under the micro- scope, or show themselves in the form of "fatigue." Korybut-Daskiewicz 4 ) found an enlargement of the nuclei in the cells of the medulla which are in connection with the elec- trically-excited nerves. Hodge 7 ') found reduction in the size of the nucleus, vac- uolisation of the protoplasm, and lessened staining power. Magini 6 ) found disappearance of the nucleoli and a better staining capacity in certain cells of the anterior cornua. J' as') observed swelling of the nucleus and the cell-body, also dispersion of the nucleus and the chromatic substance towards the periphery of the cell. Lambert's*) observations ') Sitzungsb. d. k. Akad. d. Wis... Math. Nat. Classe. Abth. III. 1891, Vol. CI p. 27. and Pfiueger's Arch.. 1896, Vol. LXIII. ") Her. ophthalm. Congr. Heidelberg, 1888. ') v. Graefe's Arch. f. Ophthalm., 1.. I., i<)00. 'i Arch. f. mikrosk. Anat., [889, i». 51. 1 American Journal Psych., Vol. II. i>. 378; Vol. III. p. 53<>; Journal of Morphology. Vol. IX. p. 449. ') Compt. rend. (In II. cong. intern. Vol. II (Physiology), p. 104. 7 ) Arch. f. mikrosk. Anat. Vol. XI. p. 375. ') Compt. rend, de la Soc. de Biologic Paris, [893, P 879. 158 RADIO-THERAPY agree with those of Fas. Mann 1 ) found that the size of the cell, the nucleus, and the nucleolus increases during the stage of irritation, and that the chromatic matter is destroyed. In the stage of fatigue the size of the nucleus diminishes and its stain- ing becomes more diffuse. Lugaro's 2 ) observations agree with this. Falenza 3 ) found that after prolonged irritation of the electric organ of the torpedo-fish by high-tension and high-fre- quency currents important retrogressive changes occurred in the nerve-cells. These were shown especially in the nuclei as "chromatolysis caryorixe" and as hyperchromatosis. When the cells were adjacent to the electrode the nuclei contracted with irregular outlines and hyperchromatosis of its contents; the nu- cleoli, moreover, became absent. Parts more remote from the electrode, however, showed an increase in the volume of the nucleus, hyperchromatosis of the nuclear wall alone, while the nucleolus still remained in evidence. By the application of less powerful currents he found various changes in the nerve- cells. G. Corrado 4 ) killed dogs by the direct application of high- potential currents (400-920 volts, 10-23.5 amperes). The cur- rent was applied through broad metallic electrodes, one of which was attached to the forehead and the other to the back, near the animal's tail. With the highest tension he observed spark-shocks at the site of the electrodes, but there was always also a certain amount of burning without the formation of sparks. The autopsy revealed congestion of the meninges, the sinuses of the dura mater being engorged with blood. Often effusions of blood would be seen on the surface of the cerebrum, and on one occasion there was hemorrhagic effusion into the lateral ventricles. On the surface of the medulla ob- longata numerous ecchymoses were found. The heart in most cases was in a state of systole, especially the left ventricle. In one case bubbles of gas were found in the blood, in another *) Journ. of Anatomy and Physiology, Vol. XXIX, p. 100. ') Lo Sperimentale a 49, sect, biolog.. Florence. 1895, p. 159. 3 ) Atti della R. Accad. d. Sc. fisiche e nat. di Napoli, Vol. VIII, ser. 2. 4 ) Ann. d'electrobiol.. Vol. II, 1899. p. 245. The experiments made by this author are very similar to those printed later by S. Jellinek. HIGH-FREQUENCY CURRENTS 159 they were in the meninges of the medulla, while in a third case they occupied the cerebral fissures. Corrado described in the first place marked alterations in the body of the nerve-cells. Many nerve-cells could be recognised through Golgi's method of staining, or by convergence of nerve fibres towards them. Most of them appeared globular, irreg- ular, or torn. By other methods of staining (e. g. f Nissel's) the fragments of the lacerated cells were also discernible; often the protoplasm near the well-preserved nucleus appeared gran- ular. The condition was, therefore, one of cytorrhexia. The cells of the spinal marrow were less affected than those of the cerebrum. In certain of the microscopic fields cells could be seen which were absolutely normal, in addition to those which were badly damaged. Often a cell had the appearance as though parts of the protoplasm had been expelled from one side. In the cell-body Corrado found a removal of the chromatic substance, a homogeneous powder-like condition ; in a word, marked plasmolysis. Often distinct vacuolisation was observed. The chromatic substance showed a tendency to separate itself from the remainder of the cell-body and to congregate at one side of the cell, the other side remaining uncoloured. {Cor- rado believes that the situation of the decolourised portion indi- cates the direction of the current.) In most cases the nucleus appeared changed only in its general aspect and in its volume — its outlines were angular and irregular. The chromatic sub- stance of the nuclei was either completely destroyed or left a few thready remnants near the periphery. The situation of the nucleus in the cell-body varied, but was generally somewhere near the circumference of the cell, especially at that side where the chromatic substance had collected. The nuclear membrane was sometimes torn. The nucleolus was generally uninjured, and stained well. Sometimes, however, it was destroyed; it changed its situation, traversed the nuclear membrane, and ar- rived at the periphery of the cell. The processes of the nerve-cells often showed a condition of "varicose atrophy." They were throughout fragmentary and disarranged. Not infrequently a spiral ami highly char- 160 RADIO-THERAPY acteristic condition was to be found in the protoplasmic processes of the pyramid cells in the cortex. Corrado believes that there is not only a chemical but also a mechanical action on the nerve- cells; moreover, the bubbles of gas are evolved in the interior of the cells, as in the meninges and the blood. S. Jellinek 1 ) observed that ganglion-cells in the spinal-mar- row burst and ecchymosis also resulted after the use of power- ful alternating current-discharges. Light has been shed on the mechanics of the effects of spark- discharges partly by direct observation of irradiated cultures, partly by microscopical investigation of the condition of the exposed skin. Short exposures produced an immediate drying effect on the inoculated nutrient medium; after longer exposure heat-effects were noticed — the nutrient medium became brown- coloured, swollen, and fluid. With sparking at a rapid rate, a small flame flashed up from time to time, vapours arose, and the sound of the boiling agar was to be heard. It is quite comprehensible that these two factors alone (desiccation and heat) would be sufficient to cause destruction of bacteria and perchance therapeutic effects also. Possibly marked desquamation — the result of desiccation, and perhaps also of the electrolytic destruction of the superficial layers of cells in the skin- — may explain any good results achieved in the case of acne, seborrhoea, and similar affections. Both desicca- tion and rise of temperature are inimical to the vegetative forms of bacteria. Even the spores which longer resist such dele- terious influences may be destroyed, as the author has proved, by spark-discharges from suitable apparatus. Tesla explained the heat-effects of high-frequency current as follows: A body, properly insulated in the air, becomes heated simply by connecting it with a source of rapidlv-alter- nating high-tension electricity. The body becomes heated by its electrical bombardment, through the air or through any medium of a molecular or atomic constitution. The body itself may be a good or a bad conductor; this does not materially affect the heat phenomenon. The human body happens to be a good *) Wiener klin. Wochenschr., 1902, p. 450. HIGH-FREQUENCY CURRENTS 161 conductor; when a person standing insulated in a room comes into contact with a generator of high-frequency currents his skin becomes heated by the electrical bombardment. The ex- tent of the calorific effect depends upon the dimensions and gen- eral arrangement of the apparatus. The physiological effects (e. g., lessened sensibility) may also reasonably be ascribed in part to "mechanical concussion," the mechanical action of the rapid bombardment on the tissues. Besides these factors we have, however, to consider still oth- ers; this was shown by the author's histological examination of skin treated by spark-discharges. Where the discharges had only operated for a short time, and had been produced by weak currents, merely superficial inflammation and small-celled infil- tration was discernible in the upper layer of the cutis. When, however, powerful and rapidly-succeeding sparks had been in operation for a considerable time, very marked alterations were produced in the tissues. According to Engelmann, Klemen, Davenport and others, these changes consisted in an impairment of cohesion and a so- lution of the cell-ingredients (vacuolisation) ; the latter effect is probably brought about by chemical change, the former more indirectly. Electrolytic processes can be readily understood to be going forward in the cells, and these, acting in concert with the local increase of temperature, may conceivably hinder the development of micro-organisms. Physiological investigation thus shows, 1st, that spark-dis- charges of whatever origin may induce desiccation; 2nd, heat- effects; jrd, that by these means the development of bacteria may be hindered; 4th, that in all probability an electrolytic, and $th, a mechanical action are to be ascribed to them. We must also bear in mind the possible action of the actinic light-rays (blue, violet, ultra-violet) which accompany the sparking phe- nomena, the freely-developed ozone, and the remote effects of the electric waves themselves. It is theoretically possible that by means of the local action on the skin indirect effects may be attained on the whole organ- ism. The passive hyperaemia induced on the body surface might, were a sufficiently large area treated at once, result in the 162 RADIO-THERAPY relief of congestion in deep-lying organs. Thus in the case of d'Arsonval's method of auto-conduction, could it be proved that really efficacious high-tension discharges take place between the solenoid and the body of the patient (and the author himself has never been able to verify this), one would be the better able to understand the beneficial effects claimed for this method. The same physiological effects on the skin can be obtained by the use of strong discharges from a static machine, or from a Roentgen apparatus. If these act on a large surface of the body for a considerable time one may also, for the above-stated rea- sons, expect some effect upon the general organism. In this sense the action of these electrical methods of treatment is prob- ably comparable with that of hydro-therapeutics and light-treat- ment. Each aims at a local irritation of the skin. The thera- peutic effects of faradic currents are probably also to be ex- plained in this way; here also we are dealing with the dis- charges of induced currents, albeit very weak ones, applied to the skin. As regards the remote (electrolytic) effects of high-fre- quency discharges, these are probably, on account of the low intensity of the currents employed, inferior to those produced by the employment of direct spark of brush-discharges at the exposed surface. Arguing from the results of his own experimental and his- tological enquiries, and comparing these with the findings of other investigators, the author came to the following conclu- sions regarding the mode of action of electricity: There is no hard and fast line to be drawn between the bio- logical effects of statical, faradic, and high-frequency electricity. Any differences which may exist depend simply upon the strength of current employed in any particular instance. The effects are mechanical, electrolytic, and thermic; the most im- portant action of electricity on the tissues is to be found in its disorganisation of living protoplasm (vacuolisation degener- ation). When the electrical discharges are of high intensity the effect will be manifested not only at the site of their appli- cation, but also in remoter regions of the body to which the current has been conveyed. Thus in addition to local cell HIGH-FREQl ENCY CURRENTS 163 destruction at the site of impact we may get disorganisation in the cell-tissue of more remote vital parts (as in death from cur- rents from the main or from lightning, where we may get hem- orrhages into the tissuesof the central nervous system in addi- tion to local effects at the part struck). When, however, the intensity of the current is low, the effects are merely local, pro- ducing anatomical changes in the skin and nerve fibres, though sometimes functional effects (convulsions) may also be pro- duced. Further histological investigations are required before it can be decided whether the good results claimed for the treat- ment of internal diseases by the application of electricity which possesses no great intensity are to be ascribed to the direct influ- ence of that electricity on deep-lying organs, or to the local irri- tation of superficial tissues (the skin, the sensory nerves) where- by secondary changes (depletion, nervous reflexes, etc.) are evoked in deeper parts. The author himself inclines to the latter view. The author believes that the local irritation of the nerve- terminals by electrical discharges plays a considerable part in ordinary electro-therapy. It appears to him very unlikely that ordinary faradic induced currents of low intensity can have any influence on remote organs, even if it be presumed that they are conveyed to those organs along the nerve trunks. But the strong local action of alternating-current discharges as applied by the brush-electrode must be regarded as therapeutically im- portant; this action may be compared with that of chemical irri- tants, though it is possibly more powerful than that of the latter. The application of constant galvanic currents, how- ever, if these be of fair intensity, must have some derivative effect; at the site of the electrodes considerable electrolytic action and signs of irritation in the superficial tissues are mani- fest. The latter show themselves by more or less marked ery« thema, often followed by pigmentation. If a powerful galvanic current be passed through the tissues it may produce marked destructive changes. Conceivably by these diseased tissues fibres or cells might be destroyed, and so prepared for absorp- tion. The above considerations may serve. t<> explain the good 1 64 RADIO-THERAPY effects of faradic brush-applications in cases of neuralgia, etc., of galvanic treatment in cases of painful or tender regions in the spine. The shocks produced by current-interruptions are certainly of importance in a therapeutic sense. Any sudden disturbance of the electrical equilibrium of the body probably acts physio- logically. In this way also the body may be possibly affected by being placed in any field of electric vibrations. Undoubt- edly the sudden opening and closing of currents acts as a pow- erful stimulus on nerve terminals; this may be transmitted along nerve trunks to the muscles, and so excite contraction. It would appear quite reasonable to apply this property of electrical, and especially faradic, currents to medical purposes. Many authors have proved that electric vibrations produce certain effects on living tissues. R. J. Danilewsky 1 ) showed by a series of experiments that many tissues and organs (nerves, muscles, the brain, the organs of sense, protoplasm in general) are affected when placed within an electric field, even when the electric source is some distance from the organism and not in direct connection therewith. This inductive action undoubtedly exists also in the case of an organism placed in a field of atmos- pheric electricity. Electrical waves or rays cause physiological effects even at considerable distances, and partition walls of wood or even stone cannot prevent these manifestations. The physiological effect shown by increased irritability, restlessness, or a feeling of oppression, according to the intensity of the elec- trical action and the circumstances under which it is produced. In all these instances the essential condition of electric stimula- tion is the oscillatory character of the electric field. Radzikowsky *) Chatzky*) Kurella*) and others have made similar observations. Capriati^) obtained in this way (through the agency of the electric field) an influence on the ') Centralbl. f. Physiologie, XI, No. 19, 20. See also Compt. rend, du XII Congr. intern., Moscow, Vol. II, Section II, p. 59. 2 ) Quoted by 6". Jellinek, Wr. klin. Wochenschr., 1902, p. 450. 3 ) Zeitschr. f. Elektrotherapie u. aerztliche-Elektrotechnik, June, 1900. 4 ) Ibid. 5 ) Ibid. HIGH-FREQUENCY CURRENTS 165 development of tadpoles; while Selim Lemstroem l ) and Ber- thelot '-) observed an effect on the growth of plants. The detailed account given of the foregoing experiments shows that d'Arsonval-Oudin's apparatus owes its efficiency mainly to the action of spark-discharges on the skin. At the same time the possibility cannot be ignored that the electric- waves sent forth by the apparatus may have some conceivable effect on other organs. This latter effect might then be applied for medical purposes, as d'Arsonval intended. Could the existence of such an action be definitely proved, the method of d'arsonvalisation might fairly be ranked amongst other radio- therapeutic procedures. § 25. The Therapeutical Application of High-Frequency Currents. Soon after the publication of d'Arsonval' s researches, his method became exploited by many writers as the best for all sorts of diseases, both internal and external. Of late, however, there has been a marked change of opinion, and the earlier enthusiasm has given way to scepticism. The reason for this is probably to be found in the fact that in many cases repetitions of d' ArsonvaV s experiments gave negative results. Clinically, too, results fell far short of what had been expected; conse- quently in some quarters the whole method received unqualified condemnation. This attitude is by no means justifiable, nor is it fair to stig- matise all d'Arsonval's deductions as incorrect. The author is bound to confess that he obtained no more success than many others who experimented on "auto-conduction"; nevertheless he is of opinion that his failures were probably due to certain de- tails lacking in his technique, and more especially to deficiencies in the currents he employed. The statements of the man to whom we owe so many important discoveries are not to be dis- regarded in so off-hand a manner. It would, however, be very desirable if d'Arsonval would give us minuter details of the 1 1 Elektrotechnisi h< /'it.. 1899, X". 4. 1 Quoted by S. Jellinek. 1 66 RADIO-THERAPY arrangement of his experiments so that they could be repeated under exactly the same conditions. As regards the utility of these currents in medicine, there can be no doubt that they are successful in dealing with certain affections where other methods have failed. Apart from their value in asthenic conditions of the nervous system, their bene- ficial effects in certain local and superficial affections is beyond dispute. These good effects are quite on a level with those pro- duced by faradic and static apparatus. Indications. D' Arsonval infers from his bacteriological experiments that d'arsonvalisation produces a direct stimulant effect on the vital processes in the cell-protoplasm while exerting no influence whatever on the nervous system. Previous methods of electrifi- cation acted directly on the nervous system and only indirectly on metabolism by the medium of sensory, yaso-motor, and nutri- tion-nerves. Apostoli says d'arsonvalisation "is a medicament for the cell and a powerful modifier of the general nutrition, which it can at once promote and regulate." D' Arsonval and his pupils, M. Benedict and others, acting on the results of their physiological experiments, laid down the following indications for the employment of high-frequency currents : i. The production of analgesia in minor operations and the relief of superficial neuralgia. 2. Those diseases which are due to defective tissue-change (Bouchard) : Diabetes, mellitus, gout, rheumatism, obesity. 3. Parasitic diseases (tuberculosis). 4. Diseases of the nervous system. 5. Various local diseases of the skin and mucous membrane. /. Analgesia. The high-frequency method can scarcely be recommended for anaesthetic purposes in the case of surgical operations. Indeed, its analgesic effect would appear to be but trifling at the best. What there is may be accounted for partly by the HIGH-FREQUENCY CURRENTS 167 mechanical concussion-effect on the tissues partly by the local anaemia caused by the discharges, by which the sensory nerve- endings suffer in nutrition. Baedeker 1 ) states that in his case d'arsonvalisation caused impaired sensitiveness lasting for five minutes; this was succeeded by hyperaesthesia and increased sen- sibility for temperature. Cruet and Oudin, 2 ) Requier and Dids- bury '') recommend the process as an anaesthetic for dental surgery. They stipulate that the current be of 150 to 300 ma. intensity. Dr. Bum has recently experimented in the author's establishment with Oudin's effluvium for tooth extraction. Sometimes the patients said that they felt less pain, but results were often negative: it is, however, interesting to note Bum's observations that bleeding was diminished. 2. Diseases Associated With Defective Metabolism. D'Arson-val reported to the Academie des Sciences (July 6th, 1896) that he had been successful with two cases of dia- betes and one of obesity. The patients stood in a foot-bath in which one pole was immersed, the other — a forked electrode — was held in the hand. In the first case of diabetes the daily amount of urine fell in 42 days from 11 litres to 7; the sugar from 620 grm. to 180 grm.; arterial pressure, the pulse-rate, and the temperature were raised. The body-weight at first rapidly decreased, but soon advanced again. Treat- ment: daily sittings of 10 minutes. In the second case also there was a diminution in the sugar-secretion; here, however, the treatment was not so well borne, but left a feeling of lassitude. In the third case (a fat cabman, weighing 130 kgrm. and having irregular action of the heart) daily sittings of 10 minutes were given; later, as the patient complained of dyspnoea, the sittings were reduced to 3 ') Loc cit. ') Soc. franc, d'electrotherapie, 1898. ■) Lc progres med.. Vol. XIV, No. 13- 168 RADIO-THERAPY minutes. In this case an increase was noted in the amount of urea secreted. Apostoli 1 ) asserts that he has obtained splendid results by means of general d'arsonvalisation in cases of this class. He treated 518 patients, giving altogether 12,728 sittings and noted invariably: Gradual improvement in the general health, increase of energy, return of the appetite, better sleep, improved digestion, an improvement in the patient's temper, better working and walking capacity. Arthritis and chronic rheumatism improved rapidly after the "auto-conduction" in from 4 to 30 sittings; movement became easier and painless. According to Apostoli, high-frequency currents are injurious in acute rheumatism, not very efficacious in subacute rheuma- tism, but excellent for chronic rheumatism; they are good, more- over, for obesity and asthma (which is said often to accompany arthritis), anaemia, chloraemia, and diabetes. He states that in the case of the latter sugar is "often diminished"; in many cases where the sugar was not lessened in amount, the general health was nevertheless improved. Similar opinions are offered by Th. Guilloz. Moutier) states that he has cured two patients with urinary calculus in 25 sittings held 2-3 times a week (auto-con- ductions followed by "static baths" and gentle discharge-cur- rents of 20-30 minutes). After the first few sittings stones are said to have been voided in masses (a doubtful testimony in favor of high-frequency currents). Moutier also reports the cure of two cases of biliary calculus. Laquerriere 3 ) speaks well of the method in the treatment of diseases associated with defective tissue-change. On the other hand, T. Colin and Loewy, also Doumer 3 ) state that they have observed no improvement in the case of diabetes. Baedeker treated three diabetics in the large solenoid. The sugar was not altered in amount thereby, but some trouble- some symptoms (pruritus, dryness in the throat) were relieved. 1 ) Compt. rend, du XII Congr. internat. de medicine, Vol. II, Sect. 4a, p. 69. 2 ) Annales d'electrobiologie, Vol. II, p. 47. 3 ) Ibid. Vol. III. HIGH-FREQUENCY (.1 RRENTS 169 Kindler 1 ) also only obtained negative results with these affections. Th. Guilloz 2 ) reports that a case of obesity which had much improved under the direct continuous current again put on Hesh when high-frequency currents were applied by auto-con- duction. Moutier 3 ) remarks that d'arsonvalisation effects no real loss of weight in obesity, but a general decrease in corporeal bulk, the tissues increase in density. Foveau*) found d'arsonvalisation ineffective in obesity but states that thyroid treatment is better borne in conjunction with it. Doumer 5 ) stated at the Congress for Radiology, 1900, that there existed unanimity of opinion as to the ineffectiveness of d'arsonvalisation in diseases associated with defective tissue- change. The author's own experience in this direction has not been very extensive. He has treated some cases, which would be classified among the "arthritis" group by the French school, by means of auto-conduction, but has seen no very definite re- sults. Now and then it is true that patients declared them- selves feeling better, but these were generally neurotic indi- viduals who were probably under the influence of suggestion. Nevertheless he thinks it quite possible that d'arsonvalisation, as well as any other form of high-tension electricity, may exert a favorable influence on this kind of disease. Beneficial effects in the case of internal disease might reasonably be looked for, bearing in mind the counter-irritation produced by the currents on the skin. Where the skin surface treated is fairly large, one might assume that by making it hyperaemic the blood-supply of internal organs would be somewhat modified. The local irrita- tion of the skin plays a considerable part in the often successful treatment of these diseases by water or light. This local irrita- tion is, of course, quite insignificant in the treatment by auto- 1 ) Annales d'electrobiologie; Vol. III. 2 ) Collar. g., pruritus, dynamic electricity may play a lesser part; in the main, however, the mechanical effect of the sparking must be considered as the chief factor. Proof of this may be found in the fact that when the electrode is kept tightly pressed against the skin no alteration takes place in the lesion; results are only obtained when the electrode is kept at some little distance away, so that sparks bombard the skin. In the first case, dynamic electricity alone is operating, while in the second we have the addition of static discharges. Already this method of applying high-frequency currents has found a large field in dermatology. Oudin, Bollaan and others have used it successfully for molluscum contagiosum, psoriasis, eczema, pruritus, impetigo, herpes zoster, furunculo- sis, acne, acne rosacea, seborrhcea, sycosis, tuberculosis of the skin and venereal warts; Oudin and Barthelemy for keloid; Bis- serie, Bordier, Gaston, Cliabry and Rieder for alopecia areata; Pearsons and Riviere for epithelioma ; Bisserie for lupus ery- thematosus, and Brocq for atrophia cutis, etc. *) Fortschr. d. Medicin, 1901, No. 1.3. HIGH-FREQUENCY CURRENTS 175 Thus we may see that many writers claim to have achieved good results upon ulcers and parasitic affections of the skin by this method, which combines high-tension electricity with spark- discharges. Lupoid, trophic, varicose and venereal ulcers, impe- tigo, acne, furunculosis, gonorrhoea, and alopecia areata (which most of these authors regard as a parasitic disease) are said to have been cured in this way. We may therefore regard parasitic skin diseases as suitable for this particular mode of employing high-tension electricity. The author's own experience is as follows : By the use of spark- discharges, however produced (whether from high-frequency apparatus of static machines, etc.), he has obtained a distinctly good effect upon ulcers. The earliest sign has been a drying and cleansing of the ulcer base. With lupus ulcerations he ob- served after a few days a tendency towards healing, even in obstinate cases. But, while acknowledging this improvement, he feels bound to state that up to the present he has not suc- ceeded in absolutely curing an ulcer of infective origin by this process. Together with Schif, he treated a soft chancre in this way, with the view of testing the parasiticidal action of spark- discharges. The same effects were observed as with lupus ulcer- ations — a cleansing and drying of the ulcer-base. Nevertheless the ulcer showed no tendency to heal quicker than usual, and after 6 sittings the treatment was abandoned in favour of the iodoform method. The impression gained was that at the best the high-frequency method in this case was no improvement on older methods. Brocq 1 ), Bisserie 2 ) and Gaston obtained a temporary and slight improvement with lupus vulgaris; even this, however, was not lasting :i ). Probably the morbid infiltration in these cases is too deep- seated for the spark-discharge, which loses its effect at the sur- face. The author's microscopical investigations lend support to this theory. 1 ) Traitement des dermatoses, Paris, 1898. 2 ) Journ. des malad. cutan., 1898. p. yj2. 3 ) Chisholm Williams (meeting of British Medical Association, Man- chester, 1902) reports that he cured a case of facial lupus by general d'arsonvali.sation. This experience appears to be unique. 176 RADIO-THERAPY With a suitable arrangement of the apparatus {sufficiently powerful currents, etc.) the discharges may be made to pene- trate very deeply {see the experiments quoted on p. IOQ and I2Q; according to Flemmings reports (quoted by Strebel), alternating currents of lesser frequency, e. g., ioo per second, penetrate about 26 mm. into copper, while those of 1,000,000 per second penetrate only T V mm. Those of slower rate can penetrate various media, including human skin, and exert vig- orous bactericidal effects of some depth. It has, however, not proved possible as yet to use the apparatus necessary for this penetration in practice. The author's experience of high-frequency currents in the treatment of alopecia areata is not quite in accordance with that of other writers. Many of them claim to have cured this dis- ease by faradic and static electricity and by d'Arsonval's high- frequency currents. The writer treated a boy suffering from alopecia areata by uni-polar discharges on a bald plaque. After some time lanugo appeared, but on the whole the result was quite inconclusive. Schiff afterwards treated the same patient by Ehrmann's method of faradisation, but without success. Since that time the author has often repeated the experiment, but with no better results. Assuming that the treatment has been successful in some cases of alopecia areata — and the bona fides of other workers is not to be questioned — the question arises, is the good effect due to the destruction of micro-organ- isms, or to the counter-irritations and consequent increased blood-supply to the definitely-acting hair papillae? Before leav- ing the subject of the treatment of alopecia areata by high-fre- quency currents, we may refer to an observation by Neumann, who aptly states that decided proof of the efficacy of the method can only be looked for in a universal alopecia of several years' standing, in which the possibility of spontaneous healing is prac- tically excluded. It would appear desirable that experiments should continue in this field. Processes which are undoubtedly infective in origin (such as trachoma) should be subjected to this treatment. A second group of skin-diseases which are benefited by high-tension electricity is to be found in those disorders which HIGH-FREQUENCY CURRENTS 177 are characterised by hypertrophy of the fibrous tissues and chronic cell-infiltration of the cutis. From many reliable sources come reports of success with keloid, cicatrices, sclerema circum- scriptum, and elephantiasis by these means. Bisserie, whose authority is beyond question, gives an account in a notable work x ) of the treatment of 62 cases of lupus erythematosus, 33 of which were completely and permanently cured by high-fre- quency currents. Jaquot, too, cured 39 cases out of 56 with this disease. These results are probably to be explained by the electrolytic effect on the tissues by the high-tension electricity; again we must count as favourable factors the heat-effects, the mechanical effects ("electrical massage"), the mechanical destruction of im- portant parts of the diseased tissue, and the decreased nutrition of the morbid growth which results from alterations in its vas- cular supply. The author himself had a case of lupus erythemato- sus of the face under treatment, in which his experience agreed on the whole with that of Bisserie. A dark-red erythema first appeared, not only in the lesion itself, but forming a border \v cm. in breadth around it. The scales and crusts gradually left the diseased site. Then the erythema began to diminish, finally disappearing alto- gether. Some pigmentation was left behind. The treat- ment could not be continued, unfortunately, as the pa- tient failed to attend. We may note the fact that Roentgen-treatment with hard tubes, in which high-tension electricity probably plays an impor- tant part, succeeds also with this class of disease (elephantiasis, lupus erythematosus). The third important indication for the application of high- tension electricity is to be found in pruritus and pruriginous af- fections generally. The author, in company with others (Brocq, Bisserie, Ler- eddc, and even Strauss, who believes this to be the only legiti- mate use of high-frequency currents) has observed a favourable ') Journ. de Medicine el de Chirurgie pratiques, February 25, 1901. i 7 8 RADIO-THERAPY effect in most cases of essential and symptomatic pruritus (e. g., in jaundice and eczema) by means of high-frequency currents, faradic electricity, and uni-polar discharges from a Ruhmkorff's coil. The distressing itching is markedly relieved, sometimes in a comparatively short time (after 5 sittings). The author has .not been able to histologically examine a portion of the treated skin and so determine the cause of this success, but clinical obser- vation and theoretical reasoning would support the idea that the production of heat and the mechanical impact of the sparks are of importance. Possibly, too, the stimulation of the local circu- lation, the counter-irritant effects of the spark-discharge and its mechanical or electro-chemical influence on the peripheric nerve- terminations are to be considered. The relief of the pruritus of impetigo, eczema, etc., may be explained by the destruction of the denuded nerve-endings. But the whole question requires further and more exact investigation for its elucidation. Polar discharges from high-tension induced currents em- ployed in this way have a distinct depilatory effect. This was confirmed by Schijf l ) by experiment on his own cuticle, and also by Kaiser 2 ). Disturbances of the circulation in the skin are successfully treated by the discharges from an Ondin's reso- nator. We have already seen that the effluvium causes some local anaemia from vascular spasms; this property may be utilised in the treatment of paretic conditions of the skin capillaries. Thus the high-frequency currents may be used with advantage in the treatment of chilblain and certain other angioneuroses. The author, in company with Thielee, Baudet, and others, has seen very good results with perniones, especially as regards the relief of itching. It must be noted that the same success can be ob- tained by using electrical discharges which are otherwise pro- duced; for instance, faradic currents have the same effect. This was first proved by Ga u tier. We have already mentioned (p. 160) the use of spark-discharges in producing desquamation of the epidermis (for cases of acne, seborrhea, ephelides, chloas- ma). The author has seen definite though not very extraordi- nary results achieved in this way. J ) K. k. Gesellschaft der Aerzte Wien, Dec. 14, 1900. 2 ) Wiener klin. Woch., 1901, No. 31. HIGH-FREQUENCY CURRENTS 179 Some writers speak well of the use of high-frequency cur- rents in affections of the mucous membranes. Thus E. Doumer, 1 ) R. Sudnik*) and Stembo, 3 ) mention good effects in cases of haemorrhoids, which they describe as antiphlogistic and "resolving." The former effect — the antiphlogistic — is said to relieve the congestive symptoms after a few sittings, while the "resolving" appears later, but is seen in even old and inveterate cases. Doumer, moreover, mentions extremely good results with fissura ani, which he states is cured in from 2 to 6 sittings of 3-6 minutes each. Tschdanow*) made extensive trials of the method in 85 cases of fissura ani with very good results. He used bi-polar discharges, without resonator, curing his cases after 1 5-30 sit- tings applied every other day. The pain was first relieved, then the straining, later the sphincter-spasm, the difficult defalcation, and the bleeding. The fissures healed perfectly in every case. R. Sudnik "') reports that he has used high-frequency cur- rents successfully in conjunctivitis granulosa and in blenorrh(Ea urethras with paraphimosis. He treated gonorrhoea by wrapping the penis in cotton-wool covered by a zinc-plate, to which the currents were conducted. Or the penis was placed in a glass tube with a metallic bottom, and containing boracic lotion; the metallic bottom was then conducted with one end of the sole- noid, the other end being joined to an electrode placed over the perineum. He treated the urethro-vaginitis of women by intro- ducing a moist plug of cotton-wool into the vagina and connect- ing it with one end of the solenoid, the other end being connected with an electrode applied to the hypogastrium. By this pro- ceeding the micro-organisms are said to be killed; nevertheless, the discharge is not completely removed. Application of the currents to the perineum is said to suppress inflammation of the back part of the urethra in recent cases. From other experiments Sudnik infers, moreover, that the antiphlogistic action of high- ') Ann. d'electrobiologie, etc., [898. J ) [bid. 1899. 1 Deutsch. med. Wochenschr., 1902, No. 8. ' i Botkin's Hospital zeitung, 1900, X". .v> B ) Ann. d'electrobiologie, Vol. II. p. 3*3- i8o RADIO-THERAPY frequency currents is useful in boils, buboes, orchitis, and acute articular rheumatism. Doumer 1 ) confirmed Sudnik's opinion. He found that in gonorrhoea the inflammation was rapidly sup- pressed, while the discharge and pains soon disappeared. The reader is referred to an earlier description for the technique of the method of local application (see Fig. 60). It Fie 00. is sometimes advisable to apply the currents daily; at others twice or thrice a week will suffice. The sittings may vary in time from 2 to 10 minutes. The operator must be guided always by the reaction seen on the skin. As a rule, several weeks are re- quired for a cure, if this be attainable. Bisserie gives 70 sittings as the utmost required for the treatment of lupus erythematosus. For other diseases, however, such as pruritus and eczema, even from 3 to 5 sittings may suffice. Summary. In the a" ' Arsonval-Oudin method of treatment we have clearly one which utilises both electrical waves and static dis- charges. We have seen that while the high-frequency currents l ) Congr. intern, d'electrobiologie, August 1, 1900. HIGH-FREQUENCY CURRENTS 181 produced by the present-day apparatus give us physiological and therapeutic results which are somewhat indefinite, the re- sults obtained from the static discharges of Oudin's resonator may be more exactly demonstrated. We have thus to deal mainly with effects which are quite similar to those produced by faradisation and franklinisation. The only difference is one of degree, corresponding to the dif- ference in current intensity of the several apparatus. From a survey of the physiological and clinical effects of high-tension electricity (including the discharges from induc- tion-, influence-, and d'Arsonval-Oudin's apparatus) we may say: That this method possesses many advantages in common with Roentgen-therapy; thus it dispenses with dressings and causes little pain, the sittings last but a few minutes each, so that no great sacrifice is demanded from the patient, and finally that the cosmetic results are very good. We have seen that the method possesses certain valuable properties (bactericidal, desiccating, anti-pruritic) which are of advantage in several skin-diseases; we have found, however, that its virtues are not so pronounced that older and more ap- proved methods may be disregarded. Nevertheless, due atten- tion must be paid to a new department which has undoubtedly enriched our therapeutical resources, trusting that in time it may receive the improvement and scientific development which it now so greatly lacks. • The treatment by monopolar voltaic currents should probably he included in radio-therapy. Narkiewicz- Jodko and Colombo utilise the cathodal waves from a Rithmkorffs coil for curative purposes. The operator holds in his hand a test-tube containing liquid in which the anodal terminal (a copper plate) is immersed. The operator then strokes the patient with the other hand. The patient thereby receives electrical waves from the cathode, and becomes charged with negative electricity. It is said that by this method the same results are achieved as by d'/lrsonval's auto-conduction process '). ') Bull< tino della R. Accad. di Roma, [890/. 1 82 RADIO-THERAPY Appendix. §25. In the treatment of the so-called "permeating electric- ity" method of E. K. Mueller (Zurich) the patient is exposed to the influence of a magnetic field of high intensity produced by a powerful wave-forming current. The apparatus consists in the main of a wire spiral of over 200 windings traversed by a current of high intensity (20-60 amperes) but low tension and frequency. By these means a magnetic field of low frequency, but high intensity, is produced; the lines of force in this magnetic field penetrate the body which is to be treated. The wire spiral surrounds a core composed of layers of para- magnetic material (soft iron, nickel, etc.), and containing a cen- tral space for system of cold-water circulation. The coil itself, moreover, is provided with a cooling arrangement. The coil may be supplied with a continuous or an alternating current. The current merely needs to vary periodically in in- tensity, its direction being immaterial. This undulating supply- current, whether continuous or alternating, will always produce alternating currents in the windings of the coil by self-induction, and these in turn will create an undulatory magnetic field. The para-magnetic core is not absolutely essential, but it enhances the magnetic effect. According to Rodari, 1 ) the treatment has the reverse of the stimulating action on the organism produced by d'Arsonval's method. The effect is said to be mainly on the nervous system. Rodari gives the following indications for its employment: 1. Peripheric nerve diseases (neuroses) : neuralgia of the trigemi- nal, occipital and temporal nerves; diffuse headache; migrain; neuralgia of the brachial plexus, of the intercostal nerves; sciat- ica; conditions of a neuralgic nature, especially writers' cramp, cramp in the calf; also lumbago and muscular rheumatism. 2. Central neurosis: irritative forms of acquired neurasthenia with insomnia. 3. Sensory disorders of internal organs: angina pectoris, hyperalgesia of the gastro-intestinal tract. 4. Local *) Berlin, klin. Woch., 1901, Nos. 23 and 24. HIGH-FREQUENCY CURRENTS 183 acute gout. 5. Ataxia and the shooting pains of tabes dorsalis. Since the publication of these indications another has been added to the list, viz.: 6. Subacute articular rheumatism. S. Kuznitzky 1 ) reports the cure by this method of an obsti- nate lumbago, which disappeared after 5 sittings of 20 minutes each. A valuable St. Bernard dog suffering from palsy of the hindlegs is said to have been cured in 3 sittings. P. Ishewsky 2 ) states that his investigations show that an electro-magnetic field produced by alternating currents of high-frequency and high tension causes considerable changes in the organism and in the skin. He noted especially increase of blood-pressure, the pulse becoming slower and fuller, and the respiration less frequent and deeper, while the sensibility of the skin for percep- tion of space and faradic irritation became heightened. More- over, he found a striking increase of general liveliness on the part of the patient, and rapid recovery from the effects of hard mental work. We may conclude from this that an undulating magnetic field does not act soothingly in Rodari's sense, but rather as a stimulant, like d' ArsonvaV s alternating currents. Here, too, the disturbing effects on the electrical equilibrium act as physiological irritants (see p. 164). That magnetism is under certain circumstances capable of exciting similar physical phenomena to those produced by the other kinds of "radiation" treated of in this work may be proved by Ph. Braham's 3 ) experiment. Tn this a sensitised photo- graphic plate is placed between the poles of a powerful electro- magnet having an interrupted current; a similar impression is made on the plate as by ordinary light, a black portion appear- ing on development corresponding to the part situated directly between the poles. Grenee 4 ) has made similar observations; Ch. Graf;') on the other hand, was unable to confirm these experiments. *) Aerztlichc Rundschau, Munich, 1901, No. 50. 2 ) Nachr. d. kais. Militaer. med. Akad., Petersburg, 1901. No. 3. ') Phot. News, 1889, p. 620. l ) Ibid. [889, p. 751. B ) Phot. Chronik., 1X09. p. 82. 1 84 RADIO-THERAPY The following experiments are more reliable : D'Arsonval (Compt. rend. Acad. d. sc., Vol. 126, p. 919) states that the eye is affected as by light when it is brought into an electro-magnetic field. Dr. Beer has recently confirmed this observation. Even in the year 1857 the well-known dis- coverer of the "Od," Baron Reichenbach, declared that "sen- sitive" subjects have a sensation of bluish phosphorescence under the influence of the north pole of a powerful electro-magnet, combined with the sensation of a refreshing breath of wind; under the influence of the south pole there is the sensation of yel- lowish phosphorescence and of a tepid enervating current of air. According to Hermann's 1 ) researches, animal substances are diamagnetic. Plaecker 2 ) found that when blood was brought into a mag- netic field, there was a repellent effect amongst the corpuscles. Milk showed the same phenomena with its fat globules. Ch. Fere' 6 ) tried to prove by experiment that a magnet is capable of increasing muscular power; at first the power is said to diminish, then to increase. North and south poles act alike. Many other physiological effects have been ascribed to mag- netism ; the statements are mostly, however, from unreliable sources, and will not bear investigation. ') Pfiueger's Arch., Vol. XLIII, pp. 217, 218. 2 ) Pogg. Ann., 1848, Vol. LXXIII, p. 549. 3 )- Soc. d. biologie, 1902. III. TREATMENT WITH X-RAYS. TREATMENT WITH X-RAYS. The X-Ray Mel hod 1 ). § 26. Cathode and Roentgen-Rays. We have already seen that air offers great resistance to the passage of electricity, which can only be overcome by very high tensions. If one discharges an electric machine or a Rulnnknrff's coil through a medium of rarefied gas, one obtains a greater spark- length with the same potential -) . By lessening the density of the air, therefore, the resistance opposed to the passage of electricity is also lessened. The pressure of a gas, as is well known, is measured by the height in millimetres of a column of mercury which it counterbalances. Normal atmospheric pressure — called "atmosphere" — is the pressure equivalent to ') Literature: E. P. Thompson and IV. A. Anthony, Roentgen-rays and phenomena of the Anode and Cathode. New York, 1896. — Fortschritte auf dem Gebiete der Roentgenstrahlen, Hamburg, Jahrg. I-V. — /. M. Eder, Jahr- biicher fur Photographic, etc. Jahrg. X-XVI, Halle bei Knapp. — Pusey, Roentgen-rays in the treatment of skin disease, etc. Journal of cutaneous and genito-urinary diseases, July, 1900. — Annales d'electrobiologie, Jahrg. I. II, III. IV. — Kalischer, Streifzuege (lurch das Gebiet der X-Strahlen. ElektroUchni>che Zeitschrift, 1898, H. 24 U. — Magnus Moeller, Der Einfluss des Lichtes auf die Haut, Stuttgart. — Buettncr and Mueller, Technik und Verwendung der Roentgenstrahlen, I and II, Aufl., Halle bei Knapp. — L'annee electrique der / ; <<7v<;;< '.. Die Einrichtungen zur Erzeugung in r Roentgenstrahlen, Berlin, 1899. — Londe, ./., Traite pratique de Radio- graphic et de Radioskopie, Paris, [898. ') Electricity traverses a "Torricellian" vacuum with the production of light phenomena. 1 88 RADIO-THERAPY 760 mm. of mercury. In a vessel whose atmospheric con- tents have been reduced by means of a pump to 1 mm. pressure, there remains but ,| - ¥ part of the original quan- tity of air. In order to utilize highly-rarefied gases and vapours for these purposes, Gassiot, Pluecker, and Geissler sealed them in tubes and globes of glass. The glass vessels were first provided with platinum or aluminium wires arranged in suitable places as electrodes, and these latter connected with the secondary termi- nals of a Ruhmkorf coil. The electrode conveying positive electricity is known as the anode; that which conveys negative electricity is the cathode. The electrodes are not invariably simple wires; they are fashioned according to requirement in the form of plates or rings. A high-tension current can easily traverse a tube exhausted to an atmospheric pressure of 3 mm., causing its contained gas to glow 1 ). Entirely different light-phenomena, however, are seen at the electrodes ; the negative terminal is covered by a thin light layer, then follows a darker space — the dark cathode-space — which is again succeeded by a light band — the light cathode- band. From this glowing light rays extend with diminishing brightness towards the anode. Then follows a dark space, behind which the positive light begins. This consists of a great number of alternately dark and light bands. The electric glow-light in vacuum tubes is now gen- erally looked upon as a kind of fluorescence — or phos- phorescence — phenomenon of the gas, which glows under the influence of the negative electrical particles, the cathode-rays which are thrown off by the cathode. H. Ebert 2 ) shewed that the properties causing the visible phenomena of light continue after cessation of the light, yet remain so effective that they considerably influence the succeeding discharge and its characteristic appear- *) Wiedemann proved (Wiedemann's Ann., V, p. 500, 1878; VI, p. 278, 1879) that the gas begins to glow at a temperature below ioo°. We must, therefore, assume that the electric discharges act directly on the "ether." (See also the Electron-theory.) ") Wiedemann's Annalcn, 1899, d. LXIX, p. 372. TREATMENT WITH X-RAYS 189 ances. These after-effects appear mainly to be due to the continuance of certain charges, which, during the process of discharge, are communicated to the gas. It is principally in the zone of gas around the cathode that these after-effects are manifested. If the current is passed for a long time in the same direc- tion through the glass vessel, the wall of the latter, which faces the negative electrode, becomes covered with a metallic deposit from the electrode. If the air be gradually exhausted from a Geissler's tube, the light first begins to disappear from the cathode, where soon a luminous point only remains, then from the anode, and finally altogether. On the other hand, the vessel wall begins to fluoresce, between _Jo and yuVo mm. pressure, the light being green or blue, according to the nature of the glass. This fluorescence is caused by a certain kind of rays proceeding from the cathode. They were discovered by //'. Hit tor f in 1869 1 ). These rays, whose study was continued with such suc- cess by Goldstein, Hertz, Lenard, Crookes, roller, Wiedemann and others, proceed from the cathode. Goldstein called them cathode-rays, Crookes "radiating waller." Their cathodal origin may be assumed from the fact that only that part of the tube-wall fluoresces which is directly opposite to the cathode. They have not the pozver of penetrating glass, bat are trans- formed into heat. In other words, they become completely ab- sorbed as soon as they strike the wall of the tube. These cathode-rays proceed in a perpendicular direction from the sur- face of the cathode, quite independently of the anode's position. If, therefore, the cathode be shaped as a concave mirror, the rays become focussed in some spot, and here the temperature may reach such a height that any body encountered at this focus begins to glow. Again, the tube-wall may be so softened by the heat as to become broken through by the external atmospheric pressure. Substances which fluoresce well in ordinary light show the phenomenon in a still higher degree under the influence of cathode-rays. The effect of rays proceeding simultaneously ') ^°gS- Ann., CXXXVI, pp. i. 97. 190 RADIO-THERAPY from several cathodes is very remarkable. They mutually di- vert each other, as can be seen from the fluorescence on the tube- walls. Crookes introduced a metal cross in the path of the rays. He found this arrested all the rays striking it, giving a shadow of the cross on the wall of the tube, and thus incidentally fur- nishing proof positive that these rays proceed in straight lines. A powerful magnet has also the property of deflecting cathode- rays, as can be easily demonstrated by first bringing a shadow- casting body in their path. E. Wiedemann and Ebert observed that this deflection is fan-shaped 1 ) . The shadow always takes another position and shape '), according to the position of the magnet. Cathode-rays seem also to possess a motive power. If they impinge on a lightly-hung fly-wheel, the latter begins to move. Not only the glass of the tube, but also nearly every (non-metallic) body with which they come into contact is made to fluoresce by cathode-rays. The colour of this fluorescence de- pends upon the nature of the body. Moreover, these rays have an active effect upon photographic plates. Becquerel and Gold- stein found also that the rays have the power of imparting vivid colour to certain colourless salts. This property E. Wiede- mann and G. B. Schmidt believe to be due to a reducing action. Goldstein found that not only "alkalihaloid" salts, but also sul- phates, phosphates, and carbonates were coloured if first power- fully heated. Radium-rays, ultra-violet light, and Roentgen-rays (Holzkneeht) are capable of producing the same colour effects. 1 ) Sitzungsber. der phys.-med. Soc. zu Erlangen, December, 1890. = ) It is interesting to note that Prof. Goldstein, of Berlin, described two kinds of cathode-rays in 1866 — those which can be deflected by a magnet and those which cannot. The latter, as we shall see, are the Roentgen-rays. Lenard (Vortrag v. d. Gesellsch. Deutsch. Naturforschr., Frankfurt, 1897) found that this penetrating power of cathode-rays decreases the more they are diverted by a magnet. He could not deflect the external cathode-rays (Lenard-rays) magnetically. Lenard also demonstrated the fluorescence within the tube caused by the rays, their power of penetrating opaque bodies, their increase of the electric conducting-power of air or gases which they traverse, and their photographic action (Goldstein). The greater the electric force employed in the production of these rays, the less are they capable of being deflected from their course. TREATMENT WITH X-RAYS 191 Most bodies, especially metals, are opaque to cathode-rays. Aluminium, however, as Hertz has shown, is an exception. Lenard 1 ) made tubes of this metal so that the cathode-rays could penetrate the tube-wall, and thereby be more carefully examined. The so-called channel-rays radiated backwards by a perforated cathode, which were discovered by Goldstein, do not, according to Jl'chnelt, originate at the cathode, but are merely positive ions which have traversed the cathodal perforations. Otto Berg 2 ) satisfactorily proved that these channel-rays are in reality anode- rays. In the year 1895 Wilhelm Konrad Roentgen *) found that from the site of the vacuum-tube which is struck by the cathode- rays, a new kind of rays emerges which are not visible to the human eye, but which possess the same properties which Lenard found in his "external cathode-rays." If one deflect the cathode- rays within the tube by means of a magnet, then the new part of the vessel-wall struck by them becomes also the site from which these new rays emanate. Roentgen showed that these rays, which he called X-rays, but which are also known as Roentgen-rays in honour of their discoverer, penetrate the glass-tube, proceed in straight lines, and have an actinic effect upon photographic plates. He also showed their remarkable power of exciting fluorescence (as, for instance, in a screen coated with barium- platino-cyanide) . The bulk of the fluorescence in a Roentgen-tube is caused not by the cathode-rays themselves, but by the X-rays to which they give rise. If one brings a piece of glass near an active Roentgen-tube covered with black cloth in a dark room the piece of glass begins to fluoresce {IV alter). A fact of great practical importance established by Eder and ') Wiedemann's Annalen, 1804, 51, 225. and [897, <>.?. 257,. 2 ) Wiedemann's Ann., 1899, Bd. LXVIII, p. 688. 3 ) Einc ncuc Art von Strahlen. Stabel'sche Hof- und Univ.-Buchhand- lung, Wurzburg, 1895. 192 RADIO-THERAPY • Valenta 1 ) is this: one can only obtain good photographic results with these rays by using gelatine plates. A collodion- plate is comparatively insensitive. The effect of X-rays, as is the case with ordinary light, decreases with the square of the distance. X-rays penetrate objects which for ordinary light- rays are opaque with even greater facility than cathode-rays'). Thus, for instance, a thick book, a double set of playing cards, thick blocks of wood, etc., are easily penetrated by X-rays, as is glass by ordinary light. Since, as has been before mentioned, photographic plates proved sensitive to X-rays, Roentgen found that he could take photographs in a lighted room with a plate hidden in a wooden case or paper bag. Speaking broadly, one may say that the lighter the specific gravity of a body, the more transparent is it to X-rays. On the other hand, a body's opacity for the rays increases with its density, though not in the same proportion. Variations in the density of a given body give, therefore, varia- tions in its capacity for penetration. V. Novak and O. Side;'') also V oiler and Walter, 4 ) proved that the transparency of a body for X-rays depended less upon its density than its atomic weight. Eder and Valenta found that almost all organic bodies are transparent to X-rays when they do not contain any heavy metals, but consist only of carbon, hydrogen, nitrogen and oxygen. From the important transparency-data published by the above-mentioned investigators it is seen that magnesium-ribbon (,'„- and \ mm.) is easily penetrated, also tin-foil; with strips of the latter of o.i to i mm. thickness they succeeded in making graduated transparency-meters, recalling some of the photo- J ) Eder und Valenta, Versuche ueber Photographie mittels der Roent- genstrahlen. Wien und Halle, 1896. ") It must be noted that other kinds of rays are known which pene- trate opaque bodies. For instance, a dark iodine-bisulphide of carbon solu- tion allows radiant heat to pass through it without loss. Again, electric waves, as we have seen, penetrate solid bodies. The penetrating power of cathode-rays with certain media has already been mentioned. 3 ) Zeitschr. f. phys. Chemie, 1896, 19, 489. 4 ) Zeitschr. f. angewandte Chemie, 1897, Heft 15. TREATMENT WITH X-RAYS 193 meters used in photography. Copper and silver in layers of 0.1 to 0.2 mm. thickness are not quite opaque. On the other hand, lead, platinum, and gold are highly opaque, as are also zinc (as thin plate), nickel, iron, and especially mercury. It is interesting to note that rock-crystal is not much more transparent than crown-glass, and that flint-glass stops X-rays even more than crown-glass. Glass with a thickness of 1 mm. weakens the rays (even if one uses the purest crown-glass or "solinglass") , and much more than an aluminium plate of the same thickness. On the other hand an aluminium plate 1 cm. in thickness affords a very con- siderable resistance. Hence, it follows that in estimating the transparency of a body for X-rays one must take into account not only its atomic weight, but also its thickness. A body, therefore, which in thin layers may be comparatively trans- parent to the rays, becomes in thicker layers quite opaque. This was well shown in the photograph of a cameo taken with X-rays by Eder and Valenta, the different gradations of thickness being well marked. Layers 1 mm. thick, of bone or mother-of-pearl, absorb the rays about as much as glass. A layer of flesh 1 cm. thick is as transparent as a layer of bone 1 mm. in thickness. Horn is similar to flesh in this respect. Wood, even in thick pieces, is very transparent; soft wood is more so than hard. Caoutchouc, wax, strong leather, woollen cloth, linen, dressings for wounds, mica, and celluloid are all very transparent. Car- bon, in the form of coal, charcoal, soot, black-lead, or diamonds, is very transparent. Of phosphorus, selenium and sulphur, the first has the greatest penetrability, and the last the least. Accord- ing to Marangoni, 1 ) lithium is the most transparent of all metals for X-rays. According to Chabaud 2 ) and Sehrwald, the addition of halogene to the organic molecule greatly in- creases its opacity in this respect. This effect is particularly well seen in the case of chloroform, bromoform and iodoform. Very dark shadows are cast by clear solutions of bromoform, also by liquid tetrachloride of carbon. Since these combinations l ) Atti K, Ace. dei Lincei (5) 5. 2. Sem., 1896, page 403, ') C. R. 122. 1896, p. 237, 1 94 RADIO- THERAP Y are mostly penetrable by ordinary light-rays, they afford, as Sehrwald observes, a very good filter for X-rays 1 ). As re- gards liquids, water and bi-sulphide of carbon are very trans- parent to the rays. Others again are somewhat more opaque, e. g., blood and, as the author has himself observed, solutions of sulphurated hydrogen. If one wraps the vacuum-tube in black cloth in order to ex- clude all visible light-effects, and places near the cathodal-ray region a screen coated with some fluorescent body (the best is Danum-platino-cyanide) , the latter at once begins to shine with a light-green radiance when the tube is in a state of activity. If one then places between the tube and screen a body whose dens- ity varies in parts (e. g., a boot with iron nails, a box of weights, a human hand), the dense portion will be found to cast deeper shadows than the more transparent. It is to this property, their power of easily penetrating softer parts, while others, such as bones, are more opaque, and metals (foreign bodies) absolutely so, even varying gradations of shadows being corresponding to tissues which are air-containing or otherwise, rich in blood or the reverse, that the X-rays owe their enormous value in medical diagnosis. As regards the chemical effect of X-rays per se opinions are much divided; while many investigators (for instance, Hemp- tinne) are inclined to deny the existence of such an action, others arguing from certain facts take an opposite view. P. Villard 2 ) is to be included among the latter. He noted that glass is coloured violet by X-rays, whereas cathodal rays blacken it. Roentgen thought it probable that his rays are capable of exerting a heat-effect, since they certainly possess the power of producing light-phenomena (fluorescence). He found also that they are not refrangible — they are not deflected by mica, rubber or aluminium prisms or lenses. Moreover, he could not suc- ceed in finding any very definitely marked reflection of the rays; on the other hand, he found that a photographic dry-plate ex- posed with its glass side towards the vacuum-tube and bearing 1 ) Naturwissensch. Rundschau, II, 1896, p. 50,3. 2 ) Poggendorf's Beiblattcr zu den Annalen der Physik, 1900, p. 135. TREATMENT WITH. X-RAYS 195 bright strips of aluminium, iron, platinum, tin and zinc, on the film-side, gave on development darker patches corresponding to the last three metals. The actinic effect was particularly marked under the zinc-strip, while the aluminium had absolutely no effect whatever. It would seem, therefore, that lead, platinum, and zinc do to some extent reflect the rays. Later on, Cur* michael of Lille succeeded in reflecting Roentgen-rays by means of steel-mirrors. Roentgen showed that X-rays are entirely dif- ferent from cathode-rays, and cannot, like the latter, be deflected by a magnet. It has been found no more possible to bring X-rays to a condition of "interference" than to deflect, refract, or polarise them. On the other hand, they are found to have a discharging effect on electrified bodies. The leaves of a charged electro- scope rapidly fall together if the instrument be brought within the field of an X-ray tube. According to H. Starke? ) this action of X-rays is to be compared with the similar effects produced by ultra-violet and Becquerel-rays. The action of ultra-violet light is confined to the cathode; Roentgen-rays, however, have the same effect whether they strike the positive or negative electrode. The effect on both poles on the part of X-rays is perhaps only an apparent one. According to Sagnac, solid bodies which are struck by X-rays emit new rays having similar properties. These secondary rays likewise favour an electrical discharge. It is therefore possible that the anodal effect is to be attributed to the secondary rays emitted by the irradiated anode towards the cathode. Sella and Majorana ") found from a series of experiments that the discharge depended largely upon the nature of the irra- diated body. The discharging effect of X-rays increases, ac- according to /. /. Thomson;) Right*) and Roentgen, with the atmospheric pressure on the charged body. Roentgen maintains that it is the air itself which, excited by the X-rays, brings about the discharge. ] ) Wiedemann's Ann.. iSo*. Bd. LXVI, p. [OO9. ») Atii della R. Ace. dei Lincei (5) 5. T Sem., [896, p. 116. ') Electrician, 39, 7 F( b . [896, p. i- '■ 260. 200 RADIO-THERAPY tron against a solid body sends an explosion-like electric wave into space, just as a projectile at the moment of impact emits a sound-wave. Wiechert thinks it not unlikely that Roentgen-rays may be electro-dynamic wave-movements, manifested as a series of short, rapidly-succeeding waves. The real carrier of these wave-movements is the all-parading ether. Walter?) Batelli and Garb as o, 2 ) Michelson, 3 ) Muraoka, 4 ). Vosmaer, Ortt") and other scientists regard Roentgen-rays as cathode-rays which have given oft their charge at the tube-wall or at the anti-cathode from whence they spring, thereby gaining in power of penetration. They are therefore cathode-rays sifted, as it were, by the media through which they pass. Assuming that Roentgen-rays are themselves non-electri- cal, we can the more readily understand that on the one hand they tend to discharge an electrified body, and on the other hand, like all non-electric or non-magnetic bodies, they are not de- flected by a magnet. Wehnelt's*) observation again, that the production of X-rays depends on no factor so much as the presence of rapidly-suppressed discharges, that is to say, a dis- turbance of electrical equilibrium giving rise to powerful electric waves, induces B. Donath "') to assume that there is some con- nection between Roentgen-rays and electrical waves, and that the former are electrical waves of the most diminutive wave- length. It is very likely that, just as white light is composed of various colours, Roentgen-rays may also be of various kinds, which differ from each other in their penetrative power as well as in their physical and physiological effects. We shall examine this question more closely when speaking of vacuum-tubes. *) Fortschr. a. d. G. d. Roentgenstr., Bd. II, H. 4. 2 ) Nuov. Cim. (4) 3, 1896, p. 299. s ) American Journal of Science (4) 1, 1896, p. 314. 4 ) Wiedemann's Ann., 59, 1896, p. 773. r °) Nature, 56, 1897, p. 316. °) Wiedemann's Ann., 65, 511, 1898. ) B. Donath, Die Einrichtungen zur Erzeugung der Roentgenstrahlen, Berlin, 1899. TREATMENT WITH X-RAYS 201 § 27. Vacuum Tubes. A vacuum-tube is an apparatus in which electrical energy is transformed into Roentgen-rays. The quality of the rays de- pends upon: 1, the kind of electrical energy employed; 2, the condition of the tube. The intensity of the rays increases with the quantity of electrical energy consumed. Consequently not only higuer ten- sion, but also greater current-intensity, causes a more powerful emission of X-rays. The condition of the tube is always a factor of prime im- portance for the production of an abundant, strong, and con- stant supply of X-rays. It was the caprices of tubes and their slight resisting capacity which accounted for so many failures in the earlier history of X-ray work. The earlier forms of Crookes' tubes were pear-shaped or cylindrical. The cathode was button-shaped, or later on con- sisted of an aluminium disc or concave mirror (Fig 61). A pin or ring of aluminium was first used for the anode; later on the latter was shaped in the form of a plate fitting in a side- chamber of the tube. Now in these earlier forms of tube the most effective rays pro- ceeded from a comparatively large and curved surface. Con- sequently they were lacking in power, and gave only ill-defined shadows of an object. The portion (From A. Londe, Traite pra- of the glass bombarded by the tique de Radiographic. Paris. & • 1898, p. 61.) cathode-rays again was very liable to become over-heated, whereby it softened and gave way under the external atmospheric pressure. Fortunately the production of X-rays is not solely dependent upon the impact of cathodal-rays on glass — on the contrary, other materials are just as suitable, or even more so. Roentgen soon found that his rays could be emitted from a platinum surface, and here he was dealing with a material which withstood high degrees of heat and was there- fore all the more suitable. In order that clear shadow-pictures Fig. 61. 202 RADIO-THERAPY may be given, the source of the rays must be in the form of a point, or at least very small, and this requirement was met by employing an aluminium concave mirror as cathode. On these principles Roentgen, Jackson and others con- structed the so-called focus-tubes; these marked an era in X-ray work. Focus-tubes are so arranged that the rays produced in them proceed from one point only, whereby considerably greater intensity is attained. For this purpose, as mentioned above, an aluminium concave mirror is used as cathode. A small platinum plate — the anti-cathode — is now fixed between the disc-shaped anode and the cathode, opposite the centre of the latter. This anti-cathode is so placed that it coincides with the apex of the cone of cathodal-rays from the concave mirror, and these rays, moreover, strike it at an angle of 4^°. Since every solid body struck by the cathode- rays becomes the source of Roentgen-rays, these latter are emitted at once from the focus-point on the anti- cathode. This point emits X-rays in all directions, though most powerfully in the half of the tube-space corresponding with the cathode. (Emission of X-rays, however, takes place in the op- posite direction as well, through the platinum-plate of the anti- cathode. The fluorescent screen at once proves that the rays are evolved also from the dark half of the tube. The glass walls of the tube and the secondary anode also emit X-rays.) By this ar- rangement excessive heating within the tube is obviated. The anti-cathode in these tubes is generally so arranged that by means of a connection with the anode it may be turned into a secondary anode. Thereby the tendency towards destruction of the platinum is minimised. In many tubes (those, for instance, of the Allg. Elektricitats- Gesellschaft, Berlin), while the cathode is made as above de- scribed, the anode itself is made to form the anti-cathode by making it carry a platinum mirror set at an angle of 45 °, from which the X-rays emanate. If, however, the anti-cathode is made to work in this way as anode also, the tube soon becomes blackened by the dispersion and precipitation of platinum-par- ticles on the vessel-wall ; this does not occur where the anti- cathode is insulated. The coating of platinum-particles has an affinity for absorbing gases, and so seizes on the traces of air TREATMENT WITH X-RAYS 203 left within the tube. According to JJ'ild, the cause of this dis- persion of platinum-particles from the anti-cathode is explained by the fact that the latter is always surcharged with negative electricity, and becomes, indeed, a secondary cathode, which de- velops its own rays. These, according to the "bombardment- theory," are a current of material particles flung oft by the cathode. The '"penetrator" of Messrs. Watson Cff Sons is a globe with two long tube-shaped processes which contain the electrodes. The cathode is shaped like a concave mirror, and the anode-wire, which terminates in a ring, is placed in a sep- arate glass tube. A prolongation from the latter supports a platinum mirror (the anti-cathode), which is thus insulated from the anode-wire. The cone of cathode-rays has to pass ZS* Fig. 62. (From A. Londc, 1 c, p. 64. through the anode-ring before it strikes the anti-cathode (Fig. 62). Richard Mueller-Uri of Brunswick constructed a Roentgen tube giving its effect within a small and strictly limited area and with small current-quantities. The cathode, supported on a long stem, is contained within the cylindrical part of the tube. The anode — an aluminium ring — is placed in the middle or wider part of the tube. Opposite to it the secondary anode (reflec- tor) is fixed; this is contained within the globular end of the tube, which is cone-shaped. The peculiarity of the tube consists in this situation of the reflector at one side, with its finger-like encasement. The rays from it act only upon an area the size of a thumb-nail. The efficiency of an X-ray tube is limited by the fact that when the cathode-rays have attained a certain intensity, the anti-cathode gets red-hot. As a result of this the glowing 204 RADIO-THERAPY platinum parts with a certain amount of absorbed gas, whereby the degree of vacuum in the tube becomes altered. Again the dispersion of the platinum in the form of fine particles, as men- tioned above, is considerably augmented. By these two means the tube is gradually rendered useless; and it is not always safe, therefore, to work the coil at its full capacity and so. supply to the tube more energy than it can properly deal with. In order to prolong the "life" of a tube, F. Kurlbaum 1 ) covers the anti- cathode with platinum-black. This material parts with heat much more freely than sheet platinum, and therefore is much less liable to become red-hot. Many makers, with the idea of obviating this excessive heating of the anti-cathode, construct the latter of comparatively large blocks of copper {voltohm tubes), or provide it with a layer at the back consisting of some substance which has a greater heat-capacity and a larger radiating-surface {Max Levy, Dessauer) . This black layer of insulating material (porce- lain) is intended on the one hand to retain the heat, so that the platinum-mirror gets into the glowing state, in which it evolves the greatest quantity of highly-penetrative rays. At the same time this kind of anti-cathode, even when heated, only parts with very small quantities of gas, so that the vacuum is not altered very much. Max Levy believes that a second function of the insulating material is to be found in its power of storing a large portion of the energy developed on the anti-cathode. In order to cope with powerful current-supplies having rap- idly-succeeding interruptions — such as, for instance, obtain when using the electrolytic interrupter — tubes have been made with cooling-chambers adjoining the anti-cathode. These chambers contain cold water, which absorbs the surplus heat, and moreover tends considerably to diminish the dispersion of the platinum. The water in tubes of certain kinds is kept circulating through a system of tubing, whereby a stream of cold water is constantly in relation with the anti-cathode. In another and still better system the anti-cathode is formed by a platinum-mirror fixed at the bottom of a glass vessel containing water. The water does *) Elektrotech. Zeitschr., 1900, p. 237. TREATMENT WITH X-RAYS 205 not require renewing, since the tube works efficiently even with the water at boiling-point (Dr. Walter, Fig. 65). These appliances prevent in a great measure any increase in the vacuum of a tube, which would, other things being equal, be inevitably accompanied by some loss of efficiency. For if the platinum be allowed to glow very much, it has a well-known tendency to absorb gases on cooling, and so heighten the vacuum 1 ). Now the quality of the X-rays depends very largely upon the degree of the tube's vacuum. With the heightening of the latter the tube is said to become "hardened"; it offers a greater resistance to the passage of the discharge, and while the radiation gains thereby in intensity, it also gains in penetrative power. If, for instance, working at a certain vacuum, the tube gives a sharp silhouette of the hand (since the X-rays only pen- etrate the fleshy parts, but are absorbed by the bones, as is the case with soft tubes), it will be found on increasing the vacuum that one obtains rays which penetrate all the tissues almost equally well, whereby constant effects become lost (hard tubes) . We see, therefore — a fact which was soon discovered in X-ray work — that by varying the degree of vacuum, we can also vary the penetrative capacity of the rays. Edcr and Valenta 2 ) observed in 1896 that the effectiveness of tubes varied with their degree of vacuum; Porter*) classi- fied X-rays as follows: Rays which penetrate the flesh easily but bones with difficulty (X x -rays) ; those which are largely ab- sorbed by flesh (X L .-rays) ; and those which penetrate both bones and flesh equally well (X-rays). Albers-Schoenberg*) recognised four degrees of vacuum: 1, hard (grey) ; 2, medium-soft (grey-black) ; 3, soft (deep- black) ; 4, very soft 5 ) . Here the intensity of the shadow of the metacarpal bones on the fluorescent screen is taken as an index. ') With a high degree of vacuum the tube sometimes explodes under the atmospheric pressure. 2 ) Versuche ueber die Photographie mittelsl der Roentgen Strahlen. Wicn und Halle, [896, p. 5. Amu. ■) Cit. bei /•:. Valenta, Oesl Chemikerztg., I. Nr. 1. [898. *) Fortschr. a. d. Geb. d. Roentgenstr., Bd. IN. 11. 4. p. 14.^ 6 ) Kienboeck distinguishes yet another, a fifth grade, the "over-hard" tube. (Wr. Klin. Woch., 1900, No. 50.) 206 RADIO-THERAPY Contrasts are more with "soft" tubes, as mentioned above, than with hard ones. According to Gassmann and Schenkel, 1 ) the degree of hardness of a tube is best determined by means of the skiameter. This, however, only measures the penetrative power of the rays, and not their intensity. Two tubes having an iden- tical penetration capacity may act very differently upon a pho- tographic plate; moreover, one and the same tube, given a fixed degree of hardness, produces very different radio-chemical ef- fects when worked with different strengths of currents. In order to estimate their intensity, one is obliged to examine the effect of the rays on the fluorescent screen. Gassmann and Schenkel pro- pose gauging the skiameter by having the tin-foils of a de- termined thickness and counting the number of foils required to just block out the rays. Of course, the apparatus would have to be worked at a definite distance, say 30 cm., from the anti- cathode. Benoist (seep. 245) constructed his radio-chro- mometer very much on these lines. Acting upon the hypothesis that the degree of pene- tration of X-rays for different bodies depends not only upon their thickness, but upon their atomic weight, the author has for some time past been engaged in the con- struction of an instrument consisting of a graduated series of substances of different atomic weights for this purpose. W . Kaufmann 2 ) found that the velocity of the cathode- ray particles is proportional to the square-root of the tension- difference between anode and cathode. Since in order to work hard tubes higher tensions are re- quired, it may be presumed that in these tubes the cathode-ray particles move with considerable higher velocity and conse- quently bound with greater force against the anti-cathode than is the case with soft tubes. It must be here noted that the degree of hardness of many tubes alters perceptibly during their use; moreover, the extent and time of the appearance of this change varies with different 1 ) Fortschritte auf dem Gebiete der Roentgenstrahlen, Bd. II, H. 4, p. 131. 2 ) Wiedemann's Ann., 61, 544, 1897, and 62, 596, 1898. TREATMENT WITH X-IUYS 207 tubes and apparatus, so that no hard and fast rule can be laid down as to the degree of hardness permissible for radio-therapy. The glass wall of a tube absorbs a considerable amount of the rays, thereby diminishing their effect. In order to do away with this loss, Colardeau made a tube in which the site where the rays are emitted is only ^ millimeter thick. The life of the tube is further prolonged by a communicating side-chamber of great capacity (Fig. 63). The Allgemein. Elektricitaetsgesellschaft also construct a tube having a very thin wall where the rays appear and have Fig. 63. Colardeau' s tube. their greatest intensity. This region lies at right angles to the axis of the tube. At Stuetzerbach in Thiiringen, Messrs. Greiner &? Fried- richs make tubes of borax-glass, which are very transparent to X-rays and fluoresce with a blue colour; while Seguy and Gunde- lach make theirs of a glass containing powdered potter's earth and "chlordidymium." This glass fluoresces red, and allows double the ordinary amount of rays to pass. After prolonged use a Roentgen-tube begins to lose in effect- iveness. This is partly due to the electro-static charging of the tube-wall, a fact which is readily proved. It has been supposed that the gas-molecules within the tube are driven towards the 208 RADIO-THERAPY wall as a result of electro-static attraction, whereby the central part of the tube becomes of higher vacuum. Efforts have there- fore been made to obviate this change of vacuum by removing the electro-static charge. Porter, 1 ) with this object in view, placed a wire ring around the tube in the plane of the cathode-mirror. This ring was brought as near as possible to the outer surface of the tube, without actually touching it, and was "earthed" by means of a connecting wire. By this arrangement constant discharge from the tube-wall is effected. The same result is attained by covering the cathodal part of the tube with tin-foil and fitting an "earthed" wire ring over the latter, or again by covering the cathodal region with a wooden cylinder, whose inner wall is kept moist. Other means are also available for prolonging the life of the tube. Thus the air-molecules attracted to the metallic coating of the tube-wall may be dispersed by warming the latter. This method, however, proves effective only for a few times and for short periods. Again the so-called adjustable tubes have been constructed, which are founded on two systems. In the first of these, sub- stances are placed within the tube, or side-chamber, which give off gases on being heated. Crookes varied the tube vacuum by means of a piece of caustic potash in a side-chamber. This absorbs the last traces of moisture left within the tube, thus raising the vacuum. On heating the potash, however, a certain amount of vapour be- comes liberated, whereby the vacuum can be lowered. In the latest tubes of this class, the heating of the potash is effected automatically through the agency of the discharge-spark, which, when the vacuum is too high, jumps across and outside the tube. In the "Queen self-regulating-tube" made by Queen &? Co. of Philadelphia, also in those of C. F. Mueller of Ham- burg, and E. Ducretet of Paris (Fig. 64), there is some caustic potash placed within a secondary tube R, which is attached to the main tube. When the vacuum in the latter becomes too *) Nature, 54, 149. 1896, TREAT M EST WITH X-RAYS 209 high, there is too much resistance offered here to the passage of the current from the poles A and K. Consequently the current passes through / to the side-tube, which is also a vacuum-tube in which m represents the cathode. The apex of the cathodal-ray cone from ;;/ coincides with R y whereby the caustic potash be- comes heated and emits vapour; this vapour passes into the main tube and so lowers its vacuum and resistance. An adjustable lever E is in connection with the side-circuit, which permits the intro- duction of a larger or smaller spark-gap. With the lever at some distance (5 to 7 cm.) from the cathode of the main tube, the latter works "harder," at a less distance (1-3 cm.) we have a constantly lower vacuum, and the tube works "softer." At any time when the resistance of the main tube becomes greater than ^^ Fig. 64. that of the spark-gap the current passes through the side-circuit and heats the potash. The presence of sparks, therefore, in the spark-gap shows that the automatic-regulating process is pro- ceeding. In the latest types of tube made by C. II. F. Mueller of Hamburg (Fig. 65) a loop is attached to the lexer C. To this, if it be required to quickly lower the vacuum, the negative pole of the coil is directly attached, so that the current can be sent in its full force through the secondary tube. It is generally advis- able, however, to begin with weaker currents. The last-mentioned tube has also a device for "hardening" it. This is useful when the "softening" has by accident been 2IO RADIO-THERAPY carried too far. In order to harden the tube, the positive wire from the coil is not connected with the secondary anode G of the main tube, but with the spiral-shaped electrode / of the side-tube, care being taken that the brass lever E is not in contact with the cathode K. If now the current be turned on (in the same direction as for softening), metallic par- ticles from the spiral / are freely driven off against the wall of the side-tube, whereby some of the gaseous contents of both tubes become also bound to the vessel-wall and the vacuum of the main tube is raised. Another method of control- ling the vacuum tubes is founded on the principle of osmosis. Here one utilises the property which heated platinum possesses of being penetrable by hydrogen. For this purpose the main tube carries a side-chamber terminating in a platinum tube closed at the end (Fig. 66). If the vacuum be too high, one heats this platinum over a Bunsen- or spirit-flame till it be- comes red-hot. Hydrogen gas from the flame now permeates the platinum and so gains access to the interior of the main tube, the vacuum of which is thereby lowered. This process may be carried out while the tube is working, so that the degree of vacuum can be gauged by the colour of the fluorescence. When the latter begins to show a bluish tint the heating opera- tion should be suspended, for now the vacuum is evidently very low. According to B. Walter 1 ) and Lester Leonard, 2 ) the Fig. 65. 1 ) Fortschritte auf dem Gebiete der Roentgenstrahlen. Bd. I, p. 84. 2 ) Ann. d'electrobiolog., Bd. Ill, p. 481. TREAT M EXT WITH X-RAYS 21 I degree of vacuum of a Roentgen tube may be at once gauged from the spark-length of the electrical tension necessary for its excitation, so that one may speak, of the "spark-length" of such a tube. Since the electrical resistance of a tube depends upon its vacuum, while the same factor controls the penetrating power of the rays, one will in the measure of the resistance possess also a relative measure of the quality of the X-rays. The spark- length of the coil supplies this measure, since the spark jumps across the secondary current-circuit and is parallel to the dis- charge-path within the tube. (See Spintemeter, page 245.) The metallic lever on the automatically-regulated tube (Figs. 64, 65) affords a means of varying the vacuum of the tube by modifying the resistance of the secondary current-cir- cuit, which again influences the resistance and the vacuum of the tube. As the lever approaches or recedes from the cathode, Fig. 66.- -Friedrich Dessauer's adjustable tube. the resistance in the secondary current-circuit is accordingly in- creased or diminished. By using a self-regulating tube one can work, throughout the expose, with X-rays which are of even quality. According 212 RADIO-THERAPY to Leonard, a "soft" tube corresponds to a spark-length of 2-5 cm. at the coil; it allows a current of great energy to traverse it. The same authority defines a "hard" tube as one requiring a spark-length of 5 cm. and more at the coil. It sometimes hap- pens that on reducing the vacuum of an over-hard tube the proc- ess is carried too far and the tube made too soft. Such a tube is useless for work with a JVeluielt's interrupter. On first clos- ing the circuit, a temporary yellowish-green illumination of the tube is seen, with violet circles and shadows, but after that there is no further fluorescence. The author has remedied this defect by lengthening the platinum-pin of the interrupter; or should this prove ineffective, by placing another tube (a hard one) in front of or behind the over-soft one. On sending a strong cur- rent through both tubes, at first a slight violet glimmer is seen in the soft one. Later on a violet line appears between cathode and anti-cathode, and this is succeeded by greenish fluorescence which gradually gains in intensity, the violet being lost; when this happens sparks appear in the spark-gap of the coil. By serial connection of hard and soft tubes in this way the author has moreover at times succeeded in restoring over-hard tubes. Very hard tubes can also be got to work for a time by removing the wire connecting anode and anti-cathode. The adjustable tubes made by W~ A. Hirschman and Max Levy of Berlin are founded on another principle. In these there is a contrivance where- by minute quantities of air are allowed to enter the tube when it has become over - hard. Fig. 67 represents such a tube. By turning the valve-screw V , which is kept tightly closed at other times by atmospheric pressure, a minute quantity of Fig. 67. — Roentgen-tube, by W . A. Hirscluiiaiin, Berlin. TREATMENT WITH X-RAYS 213 air gains access to the tube and so softens it. These tubes also possess an appliance E for letting air escape from them, whereby it is possible to harden soft tubes while they are work- ing. This is managed simply by lifting the spring F with a glass rod away from G till no sparks jump across. The globe E is, it should be mentioned, coated with a layer of finely-divided platinum, which absorbs air while the current is passing. The anti-cathode is in this tube provided with a water cool- ing chamber L. If the character of the X-rays changes, the situation of the focus-point of the cathode-rays will also change. The ideal is to have one point on the anti-cathode, which is at the same time both the focussing-point of the rays coming from the concave mirror and the point of origin of the X-rays. In most tubes, however, the X-rays do not emanate from a point on the anti-cathode, but from a surface of variable size. This surface is at its smallest when the tube possesses a certain de- gree of vacuum. The need, therefore, existed for some arrange- ment whereby the cathode-rays could be accurately focussed at one point in the anti-cathode. Moreover, the X-rays must pro- ceed from one point only, and this point must remain fixed, even though the penetrating capacity of the rays may alter. For exact work again those rays which exist apart from the main body of rays — the so-called "wandering rays" — must be elimi- nated, and one should be able to regulate the quality and the penetrating capacity of the rays during the expose as desired, and that without admitting or expelling air. With these ideals in view, a tube has been constructed by Gundelach and Dessauer. Gundelach utilises an observation made by Hittorf and Puluj to the effect that the static charge of a glass tube hinders the free passage of the cathode-rays. When cathode-rays traverse a tube the latter becomes statically charged, whereby the progress of further cathode-rays is im- peded. If the tube be narrow, the cathode-rays may be alto- gether suppressed. If, however, it be somewhat wider the rays pass through, keeping as far away as possible from the sides of the tube and becoming concentrated into one single ray which runs in the line of the tube's axis. This concentrated ray will strike the anti-cathode somewhere, and X-rays will be evolved 2I 4 RADIO-THERAPY with almost mathematical precision from this point. Gundelach placed a metallic covering over his tube, which considerably heightens the effect. This metallic mantle has another function. The site where the X-rays strike it has an area about the size of a pfennig-piece. This area allows all the regular rectilineal rays to pass, but completely obliterates all "wandering" rays. F. Dessauer had, however, noticed that the quality of the rays changes in certain tubes according to whether one uses the anti-cathode and secondary anode conjointly or not. In the former case some tubes were considerably softer. Acting on this observation, tubes were made (Fig. 68) with a variable spark-resistance between the external poles of the anti- Fig. 68. — Adjustable tube by Gundelach and Dessauer. cathode and anode. By means of a vulcanite handle the spark- gap could be increased or diminished, so that any desired cur- rent-quantity could be supplied to the secondary anode and the penetrating capacity of the rays controlled. Wild and Walter 1 ) have shown that Roentgen-tubes are adversely affected by the closing currents of the coil, which give wrong current direction. The presence of this reversed closing- current is shown by the interspersion of spots, rings, and shadows in the green fluorescence of the tube. Experience soon showed that in order to be able to properly regulate soft tubes, as well as to free them from closing-current *) Fortschritte auf dem Gebiete der Roentgenstrahlen, Bd. II, p. 6o. TREATMENT WITH X-RAYS 215 effects, the primary coil should be constructed with variable self- induction. The latter can then be readily increased for these soft tubes x ) . For this purpose coils are made as directed by B. IT alter, in which the primary winding is composed of several sections. By means of a special cross-connecting arrangement the current may be made to flow through one, or to increase the self-induction, through two or more of the sections. Another method of banishing the closing-currents from the tube consists in introducing the so-called Drossel tubes to the secondary current-circuit of the coil. The cathode-rays, accord- ing to Pulnj, that is to say, the electric discharges in a vacuum- tube possessing a free and an enclosed electrode, go only from the latter to the former, since a greater resistance is opposed to the passage of a discharge in the reversed direction. The Dros- sel-tube takes advantage of this fact. It offers no special re- sistance to the "opening" induced currents, but, on the other hand, "closing" currents, which pass in the opposite direction, are practically suppressed. The Drossel-tube is connected directly to the Roentgen-tube, being itself in connection with the positive wire from the coil. As a rule, the Drossel-tube itself is provided with an appliance for regulating its vacuum. (Dr. Max Levy's, F. Dessauer's and Chabaud's tubes.) The author's own experience with Roentgen-tubes leads him to prefer those which are regulated on the "osmosis" principle. These tubes he has found practically indestructible, and has in- deed had two of them in constant use for .five months, working daily for several hours, without finding them suffer any dete- rioration. He has found the ordinary non-adjustable short-lived tubes so very troublesome that he has discontinued using them. § 28. Some Practical Hints on the Installation and Use of X-Ray Apparatus. When buying an X-ray outfit, the current source must be the first consideration. Primary currents are no longer used. Most ') See page ()2 fT. 2l6 RADIO-THERAPY tubes are now worked by accumulators, or by currents, contin- uous or alternating, from the town supply. In rare instances static machines (see p. 17) are used to supply the current, and here the installation is perhaps the simplest. These generators, however, cannot as a rule be recommended on account of their comparatively feeble capacity. Presuming some system of accumulators to be selected, the first thing to ascertain is what current-strength and what tension are required by the coil. Supposing 1 2 volts to be necessary, at least 6 cells must be provided. It is, however, better to use an accumulator somewhat larger than this, as small accumulators suffer if too great a demand be made upon them. It must be remembered also that the charge of the cells falls after use below 2 volts, and, moreover, various auxiliary apparatus has to be connected with the current-circuit. The following table of the Allgemehie Elektricitaets-Gesellschaft, Berlin, shows the lowest tension necessary for a coil in order to maintain the maxi- mum spark-length. A mercury-interrupter is supposed to be used which interrupts the current 18 times per second, the dura- tion of current-opening and current-closing being identical. Spark-Length Minimum Tension in Volts Minimum of Cells required in Battery For Roentgen-Ray Work of Coil in Cm. Minimum Tension Number of Cells 18 23 28 33 43 54 65 75 12 14 16 20 24 28 32 40 6 7 8 10 12 14 16 20 16 16 20 24 28 32 40 4 s 8 8 IO 12 14 16 20 24 With a quicker rate of interruption more cells are required, or the coil will not be worked at its full capacity. Charging the Accumulators. This must be done at a certain current-strength only, which is denned by the maker of the cells. Primary elements, or a thermo-pile, or a dynamo-supply, may be used for this purpose, but the first two should only be used when the last-mentioned method is not available. Generally 2 Bun- TREATMENT WITH X-RAYS 217 sen-elements are required to charge a single cell, so that an accumulator of 6 cells requires 12 elements for charging. When using a thermo-pile, the battery requires first connect- ing with the gas-supply, and it is important to see that all the lights are burning. Since a thermo-pile only furnishes low-ten- sions, the accumulator must be provided with an arrangement whereby all the cells may be connected in parallel; in this man- ner, as is well known, the tension of the battery is made no greater than that of an individual element. After the thermo- pile has become heated, its + terminal is connected with the + terminal of the accumulator; the — terminals are similarly joined. Charging an accumulator in this way takes a consid- erably longer time than in the manner next described. I he best method of all is to use the continuous current from a dynamo. The poles on the conducting-wires from the latter must be first determined. The following chemical methods may be adopted for pole-finding: {a) By dipping the ends of the two wires into dilute sulphuric acid, say the contents of a WehneWs interrupter. The negative wire shows a free development of gas, whereas the positive wire remains practically free from gas, but is coated with a black deposit of copper oxide, (b) By bring- ing both wires into contact with a piece of paper moistened with potassium iodide solution. The positive pole is indicated by a black stain. Wilke's "pole-finding paper," which is treated in the same way, gives a red stain at the site of the negative pole. This paper may be purchased from the trade, bound in booklets. (c) A small apparatus can be obtained which consists of a small tube filled with a liquid into which platinum wires project from either side. If these be connected with the conducting wires the liquid becomes dyed red at the negative pole. The colour disappears on shaking the tube. When the pole signs are not marked on the accumulator, the positive electrode may be known by its brown, and the nega- tive by its grey colour. Care must be taken when charging, that the positive and negative electrodes are in connection with the corresponding terminals of the supply current. In order to protect the accumulator from damage by too strong a supply-current, a rheostat and amperemeter must be 218 RADIO-THERAPY first introduced into the circuit. Or a series of incandescent lamps of definite size, connected in parallel, may be used as re- sistance. In this case no amperemeter will be required. The current-consumption of a lamp is at the same time a measure of the current-strength which it allows to pass through. If, for instance, a lamp of the series works at 98 volts and 25 candle- power and uses 1 ampere of current, it will, where there is par- 1 1 1 lllll + + III 1 1 - m : j ( )Oc 3: X Fig. 69. — Scheme for the arrangement of incandescent lamps as front-resist- ances in the charging of accumulators. (After Max Kohl, Chemnitz.) allel-connection (Fig. 69), allow just as much to reach the accumulator. A second lamp passes a second ampere, and so on. When the accumulator is not properly connected, the lamps burn more brightly than usual. A lead-fuse placed in the cur- rent circuit and calculated for the maximum current-strength protects the lamps from destruction. As a rule the current-strength should be maintained at an even level during the process of charging. In no case should too great a current-strength be used, or the cells will be damaged, and towards the end of the charging the strength of the supply should be allowed to fall 30-50%. If too feeble a current be used, the time required to charge the cells is unnecessarily pro- longed. The charging of the accumulator must be allowed to proceed until a moderate amount of gas is developed in the cells. Notice should be taken if the formation of gas is equal in all the cells; should one of them be deficient in this respect, it will probably be found that short-circuiting has occurred, owing to the presence of conducting media between the electrodes. These should be removed by means of a glass-rod, and if the trouble cannot be removed in this way the cell should be withdrawn. Hermetically sealed vessels which may enclose the electrodes should be opened during the process of charging, e. g. } by re- moving plugs. When discharging an accumulator the current-strength used TREATMENT WITH X-RAYS 219 must not be allowed to exceed certain limits, which are defined by the manufacturer. At the beginning of the discharge the tension of each cell averages 2 volts; later on it suffers a gradual decrease, while as the cell approaches the stage of exhaustion this loss of tension becomes more rapid. The discharge limit is reached when the terminal tension of each cell drops to 1.83 volts. A cell should never be worked down to 1.8 volts or its durability will be impaired. The following points should also be borne in mind when working Roentgen apparatus from accumulators : A fully charged accumulator standing idle discharges itself in the course of 2-4 weeks; consequently it requires periodical charging whether in use or not. The liquid in the cells requires renewal from time to time, either with distilled water, or fresh acid and water of the original strength. Accumulators must be moved with great care and guarded Fig. 70. — Scheme for Roentgen apparatus worked with accumulators. (After B. Donath, c. p. 91.) from shocks. They must never be used too long at a time, and must be frequently recharged. When connecting the accumulator with the coil (Fig. 70), one of the poles of the battery is joined by wire with one of the 220 RADIO-THERAPY terminals (« 2 )of the primary coil. The second battery-pole should first be connected with a lead-fuse, the latter with an amperemeter (Ap), a rheostat (//\), and a current-interrupter (A t ) which is in connection with the other terminal («j) of the primary coil. A volt-meter {V) is arranged in a side-circuit (par- allel), the function of which is to indicate the tension in the accumulator. For use with a Neef's hammer, the above ar- rangement is quite sufficient, but in most cases quicker inter- rupters are employed for therapeutic purposes, so that the second battery (B 2 ) will be required for working the interrupter. One of the poles of this battery is connected with a terminal (wj) of the motor working the interrupter. Between the other bat- tery-pole and the second motor-terminal (m 2 ) a current-inter- rupter (A 2 ) and a rheostat (JF 2 ) are introduced, by means of which the rapidity of the interruptions may be regulated. In addition to the terminals m x and m 2} there are three further pairs of terminals at the interrupter board. Of these, the first pair, n x and n 2 , receive the main current for the primary coil, the second pair, />, and p 2 , are joined to the poles of the primary coil, and the third, K x , K 2 , are connected with the terminals of the con- denser. The condenser is in connection with both sides of the site of interruption, its function being (p. 57) to re- ceive the electrical quantities which are produced here by the extra-current. The switch between « a and n 2 enables one to change the direction of the current at any time. The wires con- necting these parts of the apparatus must be well-in- sulated thick copper cables. The apparatus should be worked with a continuous current supply of 1 10 volts wherever this is to be obtained. Apart from the fact that a cheaper form of apparatus may be used with a lighting-circuit, no restriction is placed upon the choice of an interrupter, and the whole plant can be worked more efficiently. Fig. 71 shows a scheme for the arrangement of a Roentgen apparatus worked from the lighting-circuit. From the main cable, shown at the top and left-hand side of the sketch, two wires branch off — a thin wire L, for working the interrupter, and TREATMENT II I Til X-RAYS 221 a thicker wire E. for the coil. Resistances {AW and RJJ') and switches (A) are situated in the course of both wires; E 2 more- over possesses an amperemeter {Ap) and a volt-meter (/') in a side-circuit. Where a WehneWs interrupter is used, the main lighting- circuit is in direct connection with the primary coil (Fig. 72), Fig. 71. — Scheme for installation of Roentgen apparatus worked from a con- tinuous lighting-current. (After B. Donath, 1. c, p. 96.) and provision is only made for a lead-fuse (5), a rheostat {.III'), an amperemeter (Ap), and a current-break (A). Care must be taken that the positive pole of the main current is in connection with the platinum pin of the electrolytic interrupter, the negative pole being in connection with the lead plate of the same. When working the Roentgen apparatus with a mercury break the lull current may be used for the motor; the tension of the main circuit is, however, too high for the coil itself. High tensions cannot be employed because of the excessive amount of sparking which would occur at the interrupter; whereby the latter would be soon destroyed. Moreover, with 222 RADIO-THERAPY high tensions the current-strength in the primary coil would reach such a dangerous height with each current-closure that there would be injurious heating of the coil and damage to its Fig. J2. — Scheme for an apparatus with electrolytic break. (After B. Donath, c, p. 96.) insulation (B. Donath). Resistances have therefore to be pro- vided which are capable of absorbing the greater part of the energy supplied. To regulate the current-supply, resistances are usually em- ployed which reduce the tension to 35 — 5 volts and the current strength to about 3 amperes. As has been before mentioned, the higher tension of the main current can be used direct for the motor of the mercury interrupter. The motor is situated in a branch-circuit from the main (See Fig. 71). In order to facil- itate their manipulation, all the connecting, regulating, and measuring apparatus belonging to the Roentgen outfit are gen- erally mounted on a wooden or marble slab fixed to the wall at a height convenient for the operator. In the latest types of Roentgen apparatus, with electrolytic interrupter and variable self-induction for the primary coil, the controlling mechanism is arranged on a small table, fixed on wheels so that it can be moved to any place desired (Fig. 73). The apparatus, more- over, possesses resistances which are capable of the most delicate regulation, and on the table every combination can be produced between the various electrodes of the interrupter. TREATMENT WITH X-R.IYS 223 and the different divisions of the primary coil (apparatus by Siemens c> Halske, Richard Scifert & Co., Max Kohl, etc.). The interrupter may be placed at some distance if its noise inconveniences the patient. When working with a turbine-inter- rupter the conducting wires from the coil may be passed through two holes in the wall to the vacuum-tube in an adjoining room, where the patient sits. Thus all noise is obviated, and a nervous patient is spared the sight of formidable-looking apparatus. A switch in the operating room controls the whole apparatus. In case a d' Arsonval-Oudin' s apparatus is intended also to be worked with the X-ray coil, the arrangement should be as Fig. 73. — Roentgen apparatus by Siemens & Halske. in Fig. 60. An earth-wire can be laid between the two wires going from the secondary coil to the inner layers <>t the Leyden jar. This earth-connection should go not to the gas, but the 224 RADIO-THERAPY water-pipes, since the former are often in the vicinity of the electric-light cables. The apparatus for the production of uni-polar discharges with Ruhmkorf's coil will not work with IVehnelt's interrupter. In cases where a continuous current-supply is not to be had, but where an alternating or rotary current alone offer, three courses are open for Roentgen work: i. An electrolytic interrupter may be used. In this case the platinum-pin is made a little thicker, to cope with the increased wear and tear. Siemens cif Halske make a Wehneli 's interrupter which may be used in direct con- nection with an alternating current-supply. A spark-gap is in- troduced into the secondary circuit, which only allows the inter- ruptions arising from one phase of the alternating current to in- fluence the tube, those of the other phase being equalised in the spark-gap. 2. By means of a turbine-mercury-interrupter. With this apparatus the current is always closed in one and the same half of the current-phase, so that only waves of the same direction enter the primary coil; consequently their effect is iden- tical with that of an interrupted continuous current. As already mentioned, the turbine-interrupter must be first regulated by hand by means of the fly-wheel. The number of interruptions exactly equals the number of periods of the alternating current. 3. The most advantageous plan is to transform the alternating or rotary current into a continuous current. This is done by means of a motor, which is coupled to a continuous-current dynamo; the latter supplies the current for the Roentgen appa- ratus. (A transformer must also be used in case the continuous current supply has a very high tension, say 440-500 volts.) The commutator must always be properly arranged, so that in the spark-gap of the coil sparks jump from the point (anode -f-) to the centre of the disc (cathode — ). Where the commu- tator is wrongly placed the sparks jump from the edge of the disc (see Fig. 23) to the point. The tube must be arranged so that its anode is in connection with the positive pole of the coil, while its cathode (the concave mirror) is joined to the negative pole. The wires connecting the tube with the coil may be thinner than those joining other parts of the apparatus. Many kinds TREATMENT WITH X-RAYS 225 of insulated wires are on sale with the object of preventing the patient or operator from electric shocks. The author has found none of these really effective; he now uses plain copper wire. The only thing necessary is to avoid coming too close to the wires. What should be the position of the tube with regard to the patient? The first thing is to ascertain where the most effective Roentgen-rays are evolved from the tube. This a fluorescent screen or photographic plate soon shows. By bringing either of these close to an active tube, not only the contour of the irra- diated field, but its most intensive area can be seen. The latter, in the case of most tubes, lies round a line proceeding from the point on the anti-cathode (coinciding with the apex of the cathode-cone) at right angles to the tube-axis. In some tubes, however, the most active zone lies around a line at right angles to the anti-cathode itself. In the first case the tube should be placed parallel to the object to be exposed, and then moved until the middle of the sphere is exactly opposite that object. In the second instance, the tube must be turned until the anti-cathode is parallel with and exactly opposite the object. An apparatus with the electrolytic break is easily placed in action. The resistances at the rheostat are first disconnected, and the length of the platinum-pin is regulated by means of the screw according to requirement. Should the interrupter fail to act there may be various causes, of which the following are amongst the commonest. a) The lead-fuse may have melted, requiring renewal. The fuse must not be replaced by a stronger one, or a copper wire, as by so doing the wires would become red-hot with too powerful a current. 7 he insulation of the supply-cable must be looked to at the first opportunity. b) A gas-bubble may be fixed at the platinum point, in which case it should be dislodged by tapping or shaking the lid. c) The tube may be too soft, or, where no tube has been connected, the spark-gap in the secondary circuit may be too small. To obviate this difficulty a harder tube may be em- ployed, or the original tube may be hardened by reversing its position for a few seconds (see also p. 212). 226 RADIO-THERAPY d) The acid in the interrupter may be too hot, requiring the addition of colder acid. The liquid again may be too con- centrated. The best proportion of acid is I in 20 ( 1.06 specific gravity, = 8° Beaume). e) The porcelain may become too hollowed around the platinum-pin after prolonged use, needing replacement. The current must be turned off at the main switch, not at the rheostat. When using interrupters which are not actuated by the pri- mary current itself they must first be set going before sending the primary current through the coil. When disconnecting the apparatus the procedure must be reversed. Should it be found that the current is passing in the wrong direction through the tube (which is at once seen from the character of the fluorescence), the current-reverser must be used- imme- diately. The interrupter may be regulated by ( 1 ) altering the po- sition of the contacts in the rheostat in the case of turbine- and mercury-jet-interrupters. (2) The make and break may be modified in mercury-motor-interrupters by raising or lowering the mercury vessel. (3) The intensity of the primary current may be regulated by means of its own special resistance. The following practical points are important: No wires should be left lying about on the floors or tables in the operating room; all wires which are not in use should be put tidily away, and the operator must not indulge in gesticulations with wires in his hands. Wires from the coil to the tube must not be allowed to lie against the former. The coil should stand somewhere away from the window, otherwise in the summer there will be a risk of the sun's heat melting the paraffin insulation of the windings. If the temperature be very high, the coil should be cooled with damp cloths, or by using an electric fan. Great care should be taken that the apparatus be not set working while anybody is busy with the wires; moreover, no bystander must approach too near the conductors from the sec- ondary coil while the latter is in action. The spark-gap of the coil must never be extended beyond its TREATMENT WITH X-RAYS 227 limit of capacity, even with the tube in position. Otherwise, if the resistance between the terminals be too great, there is a risk of short-circuiting through the insulation of the coil. It is much better to have the spark-gap somewhat shorter than absolutely necessary, for in this way a kind of safety-valve is provided; in case the resistance of the tube becomes too high, the discharge does not take its way round the tube or through the coil-insula- tion, but finds vent in the spark-gap. Where the platinum contact of a platinum break becomes fused, it may be necessary to use a Hie to the place, or a fresh "hammer" may have to be provided. The motor working a mercury-interrupter requires cleaning and oiling daily. When not in use, the copper rod dipping into the mercury must be removed from the latter — otherwise an amalgam will form. Plugs of cotton-wool should be placed in the oil-holes to prevent them leaking. The motors should be seen to from time to time, lest they get overheated. This may happen if they are worked too long at a stretch, especially if too strong a current be used; the result may be some damage to the insulation. Again, if a layer of spirit be used over the mercury in a mercury-break, there is some danger of it becoming ignited. The author has found water better to use for this purpose. Not only is it free from risk of firing as compared with spirit or petrol, but the appara- tus is more easily cleaned afterwards. This is readily done by placing the mercury-vessel under a strong jet of water, which washes the muddy accumulation away and leaves the mercury clean. This process should be repeated daily. A turbine-interrupter does not require cleaning quite so often; once a fortnight should suffice. The pure alcohol should first be poured off and placed aside in a vessel. What is left in the interrupter should be poured into an iron bowl, and the resi- due of alcohol ignited. When the alcohol has burnt away clean mercury is left lying on a layer of muddy debris. The mercury should be poured off and the mud stirred with a stick, whereby the rest of the mercury separates and is ready for collecting. The whole process should be completed in the open air on account of the poisonous mercury fumes evolved. Do not neg- lect after this operation, or after much handling of the leaden 228 RADIO-THERAPY masks (see later) , to always wash the hands with soap and water so as to avoid lead or mercury poisoning. It is advisable to remove the electrodes from the acid when an electrolytic interrupter is not in use. Vacuum-tubes must be kept in a dry place, free from shocks r "~Hh „_J d Fig. 74. or risk of violent shaking. The best plan is to line the box in which they are kept with wood-wool or cotton-wool. The following articles are necessary auxiliaries for Roent- gen-therapy : 1. A tube-stand, either fixed to the wall or movable, and preferably with two arms, so that two tubes may be connected if desired (Fig 74 a) . 2. An operating-chair with adjustable head-rest (d). TREATMENT WITH X-RAYS 229 3. A small table with an adjustable top (b) . 4. A clock for timing the sittings. 5. A couch. 6. A fluorescent screen, for examining the quality of the tubes (a, Fig. 74) . If the room cannot be darkened, this screen must be fixed in a darkened box. 7. Several leaden plates \ cm. thick, thick cardboard, tapes, pasteboard masks, lead-fuses, and a variety of mechanical tools, such as pliers, files, screw-drivers, etc. § 29. The Development of the Therapeutic Employment of Roentgen-rays.') Roentgen-therapy has already undergone considerable de- velopment and has received definite indications for its employ- ment and method, whereas the theoretical investigations of the detailed physiological effects of the process has only recently been commenced, and this with comparatively small success. Consideration of this circumstance induces the author to place the chapter on Roentgen-therapy before that on Roentgen-physi- ology. Many facts, moreover, to be found in this section are of significance in a physiological sense, and will not require repe- tition later, but merely a reference to the present chapter. The origin and development of the Roentgen-therapy of skin diseases dates from an experiment made by the author in 1896 with the object of removing the hair from a large nasvus pig- mentosum pilosus in a girl. This experiment was prompted by a newspaper article in June, 1896, in which it was reported that a man working with X-rays became afflicted with a dermatitis accompanied by extensive loss of hair from the head; further by an article appearing soon after that in No. 30 of the "Deutsch. Med. Wochenschr.," from the pen of Dr. W . Mar- cuse of Berlin, who noticed the same effects after a fortnight's radiation on the head of a young man. ') A lucid account of Roentgen therapy is given in the excellent .article by I Icrr Prof. Kopp in the Handbuch der physik. Therapie Th. II, Bd. 1. 23 o RADIO-THERAPY The author made the following arrangements for this experiment 1 ) : A Ruhmkorfs coil by Reiser and Schmidt of Berlin, having a 25 cm. spark-length, was worked from accumu- lators, and vacuum-tubes which had been proved to be rich in X-ray powers were used. The tubes were capable of giving a Roentgen photograph of a man's hand at a distance of 15 cm. with one minute's exposure, and the fluorescent screen was used from time to time to prove their proper working. These tubes possessed platinum anti-cathodes and aluminium electrodes, and the most serviceable of all were found to be those of Messrs. Frister of Berlin. Ordinary Hittorfs tubes were only used in those experiments where it was desired to ex- clude the cathode-rays as far as possible. The child was made to sit with its back bared, and the tube was placed at a distance of 10 cm., so that the zone richest in X-rays coincided with the nape of the neck. In this way a large part of the na?vus from the scalp down to about the middle of the dorsal spine was irradiated. At first a thick leaden mask with an aperture corresponding to the area of the naevus was used; this, however, was soon dispensed with, the result of the experiment being ap- parently so doubtful. The exposure was two hours daily. The author soon convinced himself that no percep- tible heat was evolved from the tube. The child, though a sensitive one, endured the sittings extremely well and remained well and lively throughout. For the first ten days no change whatever occurred; not a single hair fell. On the eleventh day (December 3rd, 1896) the mother removed several bundles of loose hairs from the inter-scapular region, and the 1 ) Wiener med. Wochenschr., 1897, No. 10. The assertion made repeat- edly in the latter by Prof. Dr. E. Schiff to the effect that the author made these experiments under his (Schiff's) control is not borne out by facts. They were carried out independently by the author in the K. K. graphisch. Lehr- und Versuchsanstalt in Vienna; Herr Hofrath Director Dr. /. M. Eder alone assisted him with his advice in the purely physical questions. TREATMENT WITH X-RAYS 231 author did likewise. With gentle pulling, bundles of 5-10 hairs came out each time in one's lingers, with abso- lutely no sensation of pain on the part of the child. The individual hairs were thin, showing no bulbar en- largement at the root to the naked eye. A microscopic examination by Dr. Ad. Zemann showed atrophy at the roots. The skin in this region was quite smooth and showed neither reddening nor any other change. The shedding of hair continued steadily in the nape of the neck (although for reasons which will appear later the irradiation was discontinued in this region), and by the 8th of December there was an actual alopecia involving the lower part of the back of the head. From the 10th December the shedding of hair decreased in amount somewhat, though persisting for some time in lesser de- gree. On the 11th December, that is, eight days after the commencement of the hair-shedding, a dermatitis developed from two small excoriations which had already been noted on the nape. This consisted of a diffuse reddening, with here and there several small moist excoriations varying from the size of a lentil to that of a sixpence. This dermatitis disappeared after a few days' treatment with ichthyol ointment, and with it went the few remaining hairs at the nape. The back of the head and the neck and the upper inter-scapular region was then quite denuded of hair, and only a slight reddening left by the dermatitis was to be seen at the nape of the neck. It must be noted that a large portion of the bald surface had never shown the least signs of dermatitis. On the tenth day the commutator of the coil was, through an oversight, so arranged that for 15-20 min- utes no cathode-rays were evolved from the tube. When on the eleventh day the hairs began to fall it was thought possible that this result was due to "anode-rays." ') To verify this the experiment was changed. The naevus on ') Three years later O. Berg experimentally proved the existence of anode ray. (See page 191.) 232 RADIO-THERAPY the right arm, which was at some distance from the previously exposed region, was exposed for twelve days to a "reversed" tube. The results were negative. The task still remained to exclude any possible ef- fects from electric currents in the shape of spark dis- charges from the tube to the skin. With this object in view, the lowest part of the naevus was exposed to the X-rays, but between the tube and the skin a sheet of thin cardboard covered with aluminium-foil was interposed. The aluminium, which is very transparent to the rays, was suitably "earthed." This screen, therefore, while allowing X-rays to penetrate freely, acted as a dis- charger for the electricity. The experiment was begun on December 1 8th, 1896, and eight days later the hair on the irradiated area began to fall. Till the 2nd Jan- uary this shedding of hair was only small in amount, being about 5 or 6 hairs daily. After that it increased to ^-10 hairs daily. On January 5th slight erythema was noticeable, and by then the hair had almost disappeared from the middle of the field. Altogether this region was exposed for 42 hours. These three experiments clearly showed that the cause of the phenomena above-mentioned was to be found in the Roentgen-rays. Neither the anode-rays nor the high-tension electric waves could have produced the effects. Moreover, in the second series of experiments, sparks were often seen to jump from the tube to the arm to which it was adjacent, and again the hairs bristled up towards the tube (both events showing that electricity was passing from tube to skin), but no loss of hair resulted. Another point brought out by these experiments was that the comparatively thin and long hair of the scalp fell out more readily than the strong short hairs of the nwvus; in the latter situation again it was found that the fine lanugo-hairs fell more freely, and after a shorter exposure than the stouter hairs. TREATMENT WITH X-RAYS 233 Finally, it became evident that the X-rays only pro- duce their effect after a long exposure ( 1 1 to 22 hours), but that this efject is maintained for some time (S to 12 days) afterwards ; the rays have therefore a cumulative action. Was the falling of the hair due to the dermatitis alone, being analogous to the well-known alopecia symp- tomatica seen after erysipelas and eczema? Probably not, bearing in mind the late appearance of the derma- titis (seven days after the first falling of hair) and its slight character. The author published the facts con- cerning the later condition of the child's skin, and the conclusions to be drawn from the whole history of the case, in the Wiener Med. Wochenschrift, 1897, ^°- 19. From this article it may be learned that the nape of the neck showed no change till February 22nd, when a little fine down was to be seen on the occiput. These new hairs were confined to the scalp region at first, the nape of the neck remaining quite bare till March 14th, when fresh hair grew here also. In the dorsal region the changes were very surprising. This part had been last irradiated on January 15th, 1897, the total ex- posure having been about 42 hours. On January 1 8th the erythema here became more intense and all the hair fell out at the same time. On January 20th and the succeeding days the erythematous portion of the skin showed numerous small vesicles, which soon burst. Next the epithelium peeled off, leaving a large raw sur- face, which was bright red, hot and oozing freely. After a few days the inflammation became less acute. By February 6th a whiter patch the size of a child's hand was to be seen within the bright-red granulating excoriation in the region of the 9th dorsal vertebra, and from this similar streaks radiated on to the neigh- bouring surface. On this part the antral rays of the light-cone had fallen. The base of the excoriation ap- peared deepened, and at the lower border one could see two round epithelial islands. It seems remarkable 234 RADIO-THERAPY that in spite of the appearances above mentioned the child had no special pain. The chief thing complained of was itching round the borders of the excoriation, where some eczema had resulted from the irritating dis- charge. The temperature and urine were normal ! In- stead of the applications of liquor burowii cooled in ice, which had hitherto been used, dressings of ointment were now prescribed (Ung. paraffin, ung. boracic, etc.), and later on baths, but none of these influenced the der- matitis in any way. Bad nursing may also have con- tributed to the want of success, since various household nostrums were used without the author's knowledge at that time. Towards the end of February the child's general health began to suffer. She was obliged to stay in bed altogether, became pale, lost her appetite and slept badly. There was now much pain in the raw places. This pain came on often in paroxysms, especially during the night, and the attacks, lasting some fifteen minutes, were localised to the sides of the chest and abdomen. From what the child said, the pains appeared to shoot obliquely downwards towards the bladder. There was no sensitiveness on pressure anywhere. The attacks of pain, which were so severe that they always left the child bathed in perspiration, always came to an abrupt termination and were followed usually by micturition. Examination of the urine showed an acid reaction, some albumen, and deposits of urates, but otherwise nothing abnormal. By the ioth of March the white patch above mentioned became more prominent, while the surrounding excoriation became duller and of a pale red- dish-yellow colour. The base of the ulceration was considerably deeper and a delicate red flush could be seen on its (edematous borders. The ulceration proceded apace; soon the entire inflamed region was trans- formed into a large ulcer, whose uneven base was covered with dark-brown putrid shreds of tissue. The child had now a high fever and was quite prostrate, TREATMENT 1VITH X-RAYS 235 while the urine showed an abundance of albumen. With sublimate-gauze dressings and baths the patient rallied somewhat and was taken to the dermatological clinic. Here the improvement became marked in a few days and the ulcers showed signs of healing. The parents unfortunately withdrew the child from the hospital on March 29th. Further progress of the case was marked by granulation and closing in of the wound. By May, 1901, the wound was closed by a somewhat hypertrophic scar with the exception of a patch the size of a florin, which also was slowly healing. The scar next unfortunately gave way as the result of injury, necessitating further surgical aid. The following con- clusion was drawn from the progress of the case as above described. In the first place, the unexpected appearance of the ulceration gave signal warning that caution was to be observed in experimenting with X-rays. It was evident that irradiation too long con- tinued might produce disagreeable and even dangerous results. It appeared that not only the total length of exposure, but the time of the individual exposures had to be considered. On the other hand, shorter total ex- posures (20 hours or less) suffice for the therapeutic effect of epilation without causing real damage to the tissues or the organism. The cumulative effect of the X-rays constitutes the chief difficulty to be contended with in determining the proper period of exposure. It will be noted that in the case just described, the really harmful effects took two months to develop. In other cases (when the X-rays were used with a dif- ferent object in view) the author has seen the hair fall after a much shorter exposure. Other factors beside the time of exposure have to be considered, viz: the intensity of the irradiation and the distance of the tube from the skin. Since, as the first series of experiments showed, it was possible to obtain complete epilation effects lasting two months and a half, while avoiding any disagreeable 2 3 6 RADIO-THERAPY after-effects, /'/ appeared that Roentgen-rays might rea- sonably be used experimentally for the removal of hairs provided the warnings above mentioned were obeyed; apart from the fact that the effect was maintained for a considerable period, the brevity and painlessness of the treatment as compared with the other methods of dealing with hypertrichosis were a further inducement in this direction. Moreover, it seemed likely that re- sults might be made permanent, if, acting upon Kaposi's theory, one endeavoured to maintain the paretic condi- tion of the papillary vessels. This might be accom- plished by giving short exposures throughout a long period. Inasmuch as a nerve which is paralysed for some time often never recovers its function, it might be possible to so influence the vaso-motor nerves in this way that they would lose their power of providing for the nutrition of the hair follicles; in this way the existence of the hair itself would become impossible. Moreover, the epilatory powers of the X-rays might be turned to account in other skin affections, such as syco- sis and favus, where a temporary epilation is of great advantage. Experiment only was wanted to verify these hypotheses. The data obtained from the above-mentioned experiments, giving promise of a rational therapeutic employment of X-rays, induced the author to pursue his investigations in spite of warn- ings from an authoritative source (Kaposi). A definite action of the rays on the skin had been experimentally proved, and this was sufficient for its judicious employment in the treatment of skin-disease. It seemed somewhat tempting to experiment with an agent which evidently had such an extraordinary influence on the cu- ticle and which, according to later reports, had a favourable effect on the inoculation-tuberculosis of animals, as a means of dealing with local tuberculosis of the skin (lupus vulgaris). As a matter of fact X-ray therapy soon proved that in this affection very good results could be obtained, both as regards radical cure and cosmetic effect. The first report bearing on TREATMENT WITH X-RAYS 237 this question was made by Kiimmel at the Congress of the Deutsche chirurgische Gesellschaft, Easter, 1897. At the same time, and independently of Kiimmel, the author and E. Schif (to whom the publication of these experiments was left 1 )) treated and cured two cases of lupus vulgaris by means of X-rays. Soon after this, reports followed in quick succession of favourable results in various kinds of skin disease treated in this way. Thus Hahn 2 ) first employed the method in dealing with chronic eczema, Schif f 3 ) used it for lupus erythematosus, the author 4 ) for sycosis and favus, Ehrmann ') for dermatitis pap- illaris, Ziemssen 6 ) for psoriasis, SoreV) for elephantiasis, Pokitonoff ■) for acne vulgaris, Jutassy 9 ) for naevus flam- meus, Kienbbck and Holzknechl l0 ) for alopecia areata, Scholtz 11 ) for lepra and mycosis fungoides, Sjogren and Sten- beck 1 -) for epithelioma. At the present time all those diseases are regarded as suit- able for this treatment in which a temporary or permanent re- moval of hair is indicated (such as hypertrichosis, sycosis, favus) ; most writers, too, speak favourably of its employment in lupus vulgaris and epithelioma. In the case of other skin affections opinions are more divided, which is only to be expected considering the comparatively recent introduction of X-ray therapy. In many quarters the view was and still is held that good therapeutic effects are only to be obtained by first exciting powerful reactions. Many operators, indeed, make it ') Arcliiv. f. Dermatologie und Syphilis, Bd. XI.II. 1. Heft. 2 ) Fortschr. auf. d. Gebiete der Roentgenstr., Bd. II. I loft i. ) Ibid. Bd. II. Heft 4. *) Wiener dermatolog. Gesellschaft, May io, 1899. 5 ) Wr. Med. Wochenschr., rgoi, Nr. 30, 31. '' ) Aerztl. Verein Mtinchen, S June. [898, and Congress f. innere Medicin, Wiesbaden, iX<;X. 7 ) I. a Normandie Medicale, February, [898. s ) XII Intern. nir. '") K. K. Gesellsch. d. Aerzte, _' Nov., [900, and Wr. kl in. Rundschau, 1901. No. 41. 11 ) Arch. f. Dermatologie und Syphilis, Bd. I. IX. I left 3. '"') XIII. internal, nied. Congress, Paris, i. 2 3 8 RADIO-THERAPY their first aim to arouse violent inflammations. Under these circumstances it is not to be wondered at that more prudent men (Riehl, for example) , who saw some of the results of this heroic school, looked askance at the whole method. A report, however, submitted by the author to the Xllth International Congress held in Moscow, showed conclusively that under proper conditions the treatment could give the best results and yet be free from these untoward accompaniments. In view of some of the facts noted in the table below it can be seen that epilation is quite possible without disastrous effects accompanying the process. The first experiment undertaken by the author proved conclusively that the cause of the Roentgen- dermatitis lay in too intense an irradiation. Observer and Publication Dis- tance of Tubes Duration of Exposure Part Exposed Physiological Effect Remarks Sehrwald, 14 cm. 45 minutes: Abdomen: After 14 days slight Deutsche med. one exposure boy, 13I dermatitis and pig- Wochenschr., years old mentation. Falling 1896, No. 42 of lanugo-hair, lit- tle sweat secretion Marcuse, 25 cm. Once or twice Face and In one place derma- Hair grew Deutsche med. daily (5 — 10 scalp titis, in another again Wochenschr., m in.) for 4 alopecia ; the latter after 1896, No. 30 weeks no/ inflamed 3 months Conrad, — A repeated long — The moustache — Codex Medic, exposure for fell, and changed Aug., 1896 photographic purposes its colour Macintyre, — Worked for Hand Loss of hair — Nature, 1896, months with No. 1412, X-rays Vol. 55, 19th Nov. E. E. King, — Worked f or — After 5 weeks loss — Canadian Prac- i\ m onths of hair (eyebrows, titioner, daily (2-6 hrs.) beard, hand) and Nov., 1896 with X-rays nails Kolle, Once 40 min. Head Alopecia after 16 Hair grew Brooklyn Med. days ; no dermatitis again Journal, 1896, later X, 12 J. Daniel, il Once 1 hour Head Alopecia after 21 — Med. Record, inches days; no dermatitis 1896, Vol. 49, 17 TREATMENT WITH X-RJYS 239 Observer and Publication University of Minnesota, Med. Record, 1896, Vol. 50, No. 25 IV. B. Banister, Med. Record, 1897, Vol. 52, No. 4 Brora, Seances de Soc. fr. d. Phys., 1 8th Dec. ,'1896 Paul Richer and Albert Londe Forster, Deutsche med. Wochenschr., 1897, No. 5 Idem. J. Mies, Deutsche med. Wochenschr., 1897, No. 26 /. Jutassy, ( Irvosi I letilap, 1897, XLL, 24-25 Fovcau de Courmelles, Soc. de Biolog., 17th July, 1897 Freund, Wr. Medic. Wochenschr., 1897. No. 10 Idem. Dis- tance of Tubes 10 cm. o-IO cm. 1 cm. About 10-40 cm. 15 cm. 15 cm. Duration of Exposure For a consider- able period Numerous ex- posures Worked for 2-3 months daily for sev- eral h o u r s with X-rays Twice 25 min. each time Once 15 min., after 7 days 30 min. again For 16 days twice 10 min. daily Seven sittings of 2 hours each 12 days for hours each 42 hours Part Exposed Ear and scalp Abdomen, chest and neck Hand Head of a man at 30 Physiological Effect Head of a man at 40 Cheek of a girl of 23 Face, neck, chest, of a girl Skin as if frozen ; the hair had fallen out; no subjective symptoms Well-marked der- matitis; the beard became grey and fell out in parts Long after the ir- radiation the skin and hair fell off Dermatitis, falling of the fine hairs, alteration of the nails After 6 days alo- p e c i a , pigmenta- tion of the h a i r - roots, disturbed sensation of the temperature ; n dermatitis After 3 days alo- pecia, no dermatitis On the 16th day der- matitis, and alo- pecia; at the bare place no dermati- tis; disturbed sen- sibility At the places near the tube derma- titis; at those very far from it alopecia, without dermatitis Alopecia, without inflammation Remarks Back of the head of a girl of 5 Ba el; 1 the individ- ual Alopecia ; at t h e nape of the neck slight dermatitis; at the oi ciput no dermatitis A 1 pe e i a ; well- in. irked dermatitis For more than 3 mos. no after- growth of haii- After 81 days the hair start- ed growing again 2 4 o RADIO-THERAPY In a later communication 1 ) the author, in conjunction with Schiff, explained how satisfactory results had been safely ob- tained in a series of cases. The treatment is controlled by : i. Increasing or diminishing the output of X-rays. 2. The mode of administration of the same. As factors of importance in ( i ) we may note : (a) The quality of the coil, interrupter and vacuum- tube. (b) The electro-motive force and current strength employed. With regard to (2) the following are of impor- tance : (a) The distance of the tube from the object; (b) the duration of the individual exposures. In order to ascertain in the first place whether the patient possesses an idiosyncrasy in the shape of special susceptibility to X-rays (which happens now and then, according to some writers) trial exposures are given, as suggested by the author. These consist of one or two sittings of 15 minutes each at a distance of 20 cm., the rays being of medium strength; other authorities state this to be the smallest "dose" capable of causing dermatitis. The patient is then watched for three weeks. In the event of any evident reaction being noticeable in that time (though the authors never saw this happen) some modification in the exposure is called for. Patients who are undergoing treatment for hyper- trichosis are warned against pulling out the hair (a pre- vailing habit with these people) so that the extent to which the exposure should be pushed may be gauged. The intensity and quality of the rays emitted from a given tube appear to depend only upon its state of vacuum and the character of the primary current, etc., but also upon certain inherent properties of the tube which up to the present time are imperfectly understood. 1 ) Wiener med. Wochenschr., 1898, Nos. 22-24. TREATMENT WITH X-RAYS 241 The fluorescent-screen must consequently be employed as a means of estimating the intensity of the rays in a given instance. The course of events in the two lupus cases men- tioned above was as follows *) : After a time the lupus nodules became dark-red and turgid; moreover, small foci of disease became vis- ible in parts which hitherto had appeared healthy. Later on the nodules disappeared, leaving sharp-cut ulcers the size of a pin's head. The final result was as follows : The site of the nodules became occupied by reddish depressed scars, the surrounding skin being smooth and white. Where the method was employed for the removal of hairs the best therapeutic effect was obtained by expos- ing for 17-30 short sittings. Beyond an occasional slight erythema no inconvenience was felt by the patients. In several cases pigmentation was noted one or two days before the hair began to fall. This pigmenta- tion increased for the next day or two, afterwards dis- appearing rapidly within three or four days. A remark- able effect was seen in the case of several brunettes who were under treatment, the hair before it fell out becoming snow-white. In one case the pigmentary change was repeated on exposing the second and third crop of hair after the initial removal. Another note- worthy effect was seen in skins disfigured by folliculitis and scars (often the result of electrolysis). These became comparatively smooth after the treatment. In all these cases the cumulative effects of X-rays to which Freund and later Forster and others had called attention, were well seen. In the same communication arguments were given in favour of Freund 's assumption that the physiological effects of irradiation are due rather to X-rays than to electrical discharges. It was noted, for instance, that 1 ) This was outlined by Schiff in the publication already mentioned. 242 RADIO-THERAPY the epilated surface was always circular, the circle being larger when the tube was farther from the skin. This could be at once understood, bearing in mind the cone- shaped field of the X-rays as emitted from the anti- cathode. The leaden masks again completely confined the physiological effects to the area of skin exposed to X-rays, while they did not altogether protect the skin underlying them from spark discharges. If, indeed, the electric discharge were the causal factor, why should physiological effects be first manifested in the deeper layers of the skin, to be followed later by surface phe- nomena ? For in most cases the falling of the hair pre- ceded the erythema. Finally tubes of high vacuum requiring powerful currents for their working produced, slighter physiological effects than softer tubes working with much feebler currents. The writings of Kienbock, 1 ) Strutter -) and Scholtz 3 ) are of importance in the history of Roentgen-therapy. These authors insisted on the necessity of giving due consideration to the state of vacuum of the tubes employed, pointing out that "soft" tubes were more effective than "hard ones." This fact had already been referred to by the author in 1897, at the Interna- tional Medical Congress in Moscow; also in the work with Schiff above mentioned. Those works of Kienbock and the rest proved, moreover, that the author's original view, ascribing therapeutic results to X-rays rather than to electrical dis- charges, was correct. For the author had been in the mean- time led somewhat too far by experiments with spark-discharges alone, which gave results very similar to those of X-rays and led him to somewhat underestimate the value of the latter. It will be noted that a knowledge of the fact that different tubes possess different actinic effects, according to their state of vacuum, is of the greatest importance also in avoiding excessive reaction. In the earlier stages of the history of Roentgen-therapy 1 ) Wiener Klin. Wochenschr., igoo, No. 50. 2 ) Deutsche med. Wochenschr.. 1900. 3 ) Archiv. f. Dermat. u. Syph., Bd. LIX, H. 3. TREATMENT WITH X-RAYS 243 efforts were chiefly made to widen the field for its employment and to perfect its technique rather than to investigate its mode of action. The last two years, however, have seen much work of moment in the latter direction. Not only has the question as to which is the most effective agent in radio-therapy been dealt with and brought nearer to a solution, but writings are to be recorded on histological investigation into healthy and dis- eased tissues which have been under treatment, on bacteriologi- cal investigations, and experiments with protozoa and other low forms of life, all helping to a better understanding of the bio- logical effect of Roentgen-radiation. In this connection refer- ence must be made to the important works of Gassman, 1 ) Grouven, Ehrmann, 1 ) Sclioltz;') Joseph and Provazek, 4 ) and others. § 30. Method of Treatment with X-Rays. The main factors which have to be considered in X-ray therapy are : 1. The strength of the primary current. 2. The capacity of the coil. 3. The intensity of the rays and the state of vacuum of the tubes. 4. The duration and frequency of the sittings. 5. The distance of the tube from the exposed region. 6. The susceptibility of the tissue exposed. In the first place it is essential that the primary current be not of too high intensity. It must be remembered that Roent- gen-rays represent a condition of transformed electrical energy. The greater the amount of electrical energy supplied, therefore, the more powerful will be the output of the rays; moreover, the electrical discharges from the tube will be correspondingly in- tensified. The beginner should never work with currents above U-3 amperes, and even the expert should employ the greatest caution ') Fortschr. auf d. Gcbiete d. Roentgenstr., Bd. II, H. 4. *) Wiener med. Woch . [901, Nos. 30, 31. J ) Arch. f. Dermat. u. Syph., Bd. LIX, II. 3, p. 424. *) Zeitschr. f. allg. Physiologie, lid. I, 11. 2, 1902. 244 RADIO-THERAPY if compelled to work with more intense currents, say up to 6 amperes. The second condition — the capacity of the coil — must be considered in connection with the preceding one. Currents only should be chosen which give but short spark-lengths at the coil. If only a large coil is at one's disposal it should never be worked at its full capacity; if necessary, resistances should be used with the primary current, bringing down the spark-length at the coil to 15 cm. Coils whose maximum spark-length capacity is 30 cm. are the most suitable for X-ray therapy. As has been mentioned before, soft tubes are therapeutically more effective than hard ones, other things being equal. If, however, a hard tube be worked with a more powerful current, it may give as rich a supply of X-rays as a soft tube worked with a weaker current. The author arrived at this opinion as follows: An elderly neurotic woman had been treated for hypertrichosis intermittently for about a year, using hard tubes and a Kohl's coil (30 cm.) without a trace of dermatitis, the hair falling regularly after 21 to 30 sittings. The patient insisted upon the treatment being accelerated, and irradiation was then combined with ap- plications of uni-polar discharges from the coil. ' After 1 1 sittings of 15 to 20 minutes each, a somewhat intense dermatitis (without ulceration) arose, which it required some weeks to subdue. Some months later treat- ment was resumed of the skin, which still remained hairy. Two or three brief courses of treatment with hard tubes, a course consisting of 10 or 12 sittings of 15 minutes each, again produced temporarily a per- fectly smooth skin without any ill effects. The patient, nevertheless, clamoured for a stronger reaction, having noticed that the skin remained permanently smooth at the site of the former inflammation. Only one other apparatus was at the disposal of the operator, and this had clearly to be employed with great caution on account of the high intensity of its secondary currents. The hardest tube was therefore used with this appa- TREATMENT IT IT 11 X-RAYS 245 ratus, a brilliant fluorescence being the result. Nine sit- tings were given, each lasting 7 to 10 minutes, and the result was a violent dermatitis which produced an ulcer the size of a kroner piece. From the above 1 ) it may be deduced that a hard tube which, working with weaker currents, may safely produce useful results, gives altogether different effects if worked with a power- ful coil and stronger currents. Nevertheless, where only one apparatus is available, soft tubes will be found more generally useful (worked with due precaution) than hard ones. The tubes by Gundelach and F. Dessaiier, and Hirschmann, in which the vacuum can be regulated, have already been described (p. 212-214). By employing 3 sets of apparatus, Beclere'-) professes to be able to produce rays which penetrate the tissues to any required depth. The instruments used are: (1) the "ampoule a osmo-regulateur" of Villard, which is said to prolong the life of the tube indefinitely, and to allow one to control its penetrat- ing capacity; (2) Beclere' s "Spintemeter." This apparatus affords indirect evidence of the penetrating capacity of the rays through the character of the spark-discharge at the terminals of the coil. It has already been mentioned that this sparking bears direct relation to the resistance offered in the secondary circuit. With hard tubes the spark is long, being short with soft tubes. The apparatus is nothing more than the graduated wspark-gap which has been supplied for many years by certain German manufacturers, and its value would appear to be only relative. (3) The radiochromometer of Benoist. This indicates the strength of the X-rays. It consists of a thin silver plate having a broad aluminium border. The latter is divided into 12 ') Apropos of hard tubes the following case may he cited: Bernard and Rnottc (Fovcau dc Courmelles), L'annee electrique, Revue do tooi, p. 350, radiated a young man for 35 minutes with .1 very hard tube placed 15 cm. from the skin. Tin- primary currenl was one of 15 volts and .} amperes, and a 25 cm. coil was used. An aluminum plate earthed through the gas pipes was fixed between the tube and the skin. After fifteen days a dermatitis developed, which was not properly healed after ten months. 2 ) Journal des malad. cut. el syph., [902, I left 3. 246 RADIO-THERAPY sections, of graduated thickness. By means of the fluorescent screen the particular aluminium section is noted, whose shadow equals the density of shadow cast by the silver plate, and thus some measure of the intensity of the rays is arrived at. The apparatus, however, is by no means infallible, since the pene- trating power of X-rays depends not only upon the thickness, but upon the density of the body traversed. The first and third of the author's experiments quoted above show plainly that the effects of irradiation depend very largely upon its duration. While comparatively brief exposures give good results, those which are too prolonged must be regarded as highly dangerous. What is understood by too long a duration of treatment? An absolute duration of exposure must be clearly dis- tinguished from a relative one — that is, the duration of the indi- vidual sittings. The effect of one sitting of a definite duration is not the same as the effect of a series of sittings whose total sum covers the same length of time. A single exposure below a cer- tain limit has no effect. The total length of exposure necessary to produce a certain effect varies accordingly as one gives a single or several sittings. If, for example, a patient be irradiated for 50 minutes with- out interruption, the effect on the skin is much more marked than if the exposure be made for 10 minutes on five succeeding days. The fact must be especially borne in mind when working with powerful apparatus, that is to say, strong currents and tubes of high capacity. If the treatment is to be completed in one or very few sittings, powerful currents and tubes being to hand, it must be remembered that a long exposure is a most powerful agent, and that an "over-exposure" of but a few minutes only will have an important effect on the final result. In such cases, therefore, the utmost caution is necessary, and the need for this is intensified by the fact that the full effects are not seen in different individuals in precisely the same time, although the irradiation has been identical in each case. The energy of Roentgen-radiation varies inversely, as is the case with light, with the square of the distance of the ray-source. A photo- graphic plate, whose sensitive surface is weakly acted upon at a certain distance shows at half that distance an effect which is TREATMENT WITH X-RAYS 247 four times that of the former. This fact must be carefully borne in mind when arranging the position of the tube, for a difference of 1 or 2 centimetres only, when considered in con- nection with other factors (current strength, state of vacuum of the tube, relative time of exposure, etc.), may be of some importance. A proper estimation of the intensity of the X-rays employed is of the highest importance. Different methods have been advised to this end, but mostly they leave something to be desired in the way of precision. The author relies most on the character of the fluorescence as seen in the tube. In soft tubes the fluorescence is almost yellow and very copious, while in hard tubes it is greenish, transparent, and watery-looking. The amount of fluorescence afiords a fairly good means of estimating the ray-intensity. The rate of interruption of the primary cur- rent is a factor not to be overlooked, since it plays an important part in the production of physiological effects. One school of writers believes that greater effect may be had from rapid inter- ruptions, another pins its faith on slower. Upholders of the first doctrine argue that by doubling the rate of interruption in a given time the number of X-ray "waves" striking the skin is likewise doubled. Whereas the others hold that the higher current-tension obtained by interrupting more slowly is of advantage l ) The truth probably lies half-way. Up to a certain limit (40-50 interruptions per second) acceleration of the rate of interruption is attended by an increase of physiological effect. Beyond this, however, i. c, with still more rapid interruptions, the effect is not proportionately increased. Indeed, the author has found that with a turbine apparatus working at 100 inter- ruptions per second, he could obtain a certain effect with fewer sittings than when using a U'chnclCs apparatus giving 1700 interruptions per second. It is of the greatest importance to bear in mind the (act that the tissues of different individuals do not possess the same sensi- tiveness to X-rays. Many authors, it is true, deny this, though ') Gassmann ami Schenkcl, Fortschr., Bd. II. II. 4. i>. [30. 248 RADIO-THERAPY it would appear that even they have met with differences in the mode of reaction of different persons 1 ) . Other writers attribute a special susceptibility to reaction to certain parts of the body, moreover, stating that the colour of the skin and hair indicates susceptibility in some people. Thus Jutassy says that blondes are especially sensitive. Scholtz has observed that dermatitis is more apt to arise without warning on the scalp and beard than in other regions. Both Bisserie's and the author's experience is in accord with this, and the latter has further observed that reaction is more readily induced in tissues immediately overlying bone. Jutassy, Benedikt, and Kienbock noticed that children and persons who are ill-nourished are more sensitive to the rays,") also that mucous membranes, the lace and the back of the hands, react more readily than the face and the trunk. The author has not been able to verify the statement made by Hahn and Albers-Schonberg to the effect that women who wear veils have tenderer skins and are consequently more susceptible to X-rays. He has observed,") however, that skins affected with sycosis or favus, being already somewhat inflamed, are soon influenced by the rays. This has been confirmed by others (Schijf, Kienbock, Scliollz). Kienbock denies the possibility of some people possessing an idiosyncrasy which renders them prone to excessive reaction. He maintains that in every case the effect depends simply upon the amount of irradiation. The whole subject of Roentgen-therapy is still a vexed one. There are those who would deny its raison d'etre, doubting if it is really capable of producing physiological effects 4 ); others who while admitting these effects are of opinion that they sig- ') These writers do not say: "The reaction appears after irradiations," hut rather, "To obtain a certain effect n-m sittings must be given." If the mode of reaction were identical in all cases the effects produced by a given number of exposures of the same intensity would always arise at the same time. This is by no means the case. ') Hahn and Albers-Schonberg, on the other hand, believe children to be more resistant (Mi'mchen. med. Woch. 1901, 9-11). s ) Wiener med. Presse, 1899, No. 31. 4 ) Bergmann, Vers, der Naturforscher und Aerzte in Mi'mchen, 1899. TREATMENT WITH X-RAYS 249 nify dangerous damage to the body 1 ). On the other hand, those who are agreed as to the value of the method are by no means unanimous with regard to the details of its technique. Much controversy still obtains on the question of the right kind of vacuum-tube. In consideration of the fact that soft tubes have a more powerful effect than hard ones Kienbock advises the following procedure 2 ) :* An adjustable Roentgen-tube whose vacuum has Fig. 75. been brought to the "soft" or "medium-soft" stage is worked bv means of a primary current of 3-6 amperes, the interruptions being secured through a turbine apparatus at the rate of 15-20 per second. The tube must give rays capable of penetrating the thorax of an adult at a distance oi 1-2 m. This tube is fixed about 20 cm. from the skin, and from 3 to 5 sittings of 10 to 15 minutes each are given on succeeding clays. The sittings are 1 ) Oudin, Barthelemy, Sue. de Dermatog. el <1<- Syph., 3 Juli [902. 2 J Wiener klin. Woch., 1900. p. 1163. 250 RADIO-THERAPY then suspended for two or three weeks so that the reaction may develop. After all reaction has subsided the sittings are resumed as before. The author does not approve of this method, since by its adoption one hardly knows if the exposures have been pushed too far or too little. Now Kaposi 1 ) has rightly remarked that one of the chief drawbacks to Roentgen-therapy lies in this, that one is working more or less in the dark and is ignorant of what has been really done. Amongst a series of cases which were for purposes of comparison treated exactly on Kienbock' s lines the author obtained good results in two cases of sycosis; in a case of hypertrichosis again results were negative - — the exposure had been insufficient; while in a case of favus a somewhat violent inflammation set in which required several weeks to heal. The method indicated in 1898 by ScJiijf and the author, which the latter has since employed with a few modifications,-) is as follows: A Ruhmkorff's coil (30 cm.") ) is worked either from the main or from a 6-cell accumulator, the current being between U and 2 amperes, and the interruption averaging 16 per second. The tube is hard, yet one giving a good greenish flare. The tube must be so placed that the most intense rays pro- ceeding from the anti-cathode strike the centre of the region to be exposed (Fig. 75). It has been shown elsewhere (p. 224) how the region of most intense radiation may be discovered. The distance of the tube from the skin is at first 15 cm., but this is afterwards gradually decreased to 5 cm. In like manner the sittings are gradually prolonged from 5 to 10 minutes, and the part is irradiated until signs of reaction occur, when opera- tions are suspended. The author has found the following early ') K. k. Gesellsch. d. Aerzte, 27 Oct. 1899. ') Many other workers have found this method successful, e. g., Gcorg J. Miiller, Grouven, Havas, Puscy, Zechmeister, Merk, T'orok, Schein, Gaston, Vicira, Hall-Edwards, Boczar, etc. 3 ) Coils by Keiser & Schmid, Kohl, Siemens & Halske, Reiniger, Geb- bcrt & Schall and Dessaner were used. TREATMENT IVITH X-RAYS 251 signs of reaction in by far the greater number of his cases treated as above described 1 ) : 1. Intumescence of the skin. 2. Pigmentary changes. 3. Erythema. 4. Loosening of the hair. 5. Subjective symptoms. The intumescence is an early sign which is nearly always to be observed. A cheek, for example, which is being treated for hypertrichosis, appears after about three weeks fuller and rounder than the other; the skin appears tenser, a little oilier and perhaps more shining. At this stage no alteration in the colour of the skin can usually be observed. Indeed, at first the changes are not very striking and they may readily escape the notice of an inexperienced operator. They are, however, noticed by the patients themselves, who usually scrutinize their skins most assiduously; they come, therefore, to the practitioner saying that the treatment does them a lot of good, and that they "look much better than before." In cases where the sittings are prolonged for some time the intumescence is, of course, longer maintained, whereby scars and irregularities in the skin- surface are temporarily levelled, and the general appearance of the integument improved. The intumescence disappears after the sittings are suspended, but often a more lasting cosmetic effect is gained through the resulting desquamation. It must be noted that the intumescence is never sharply circumscribed, but rather diffuse, — its border cannot be exactly defined. Finally, the sense of touch is not so useful in discovering its presence as that of sight. The alterations noticeable by palpi- tation of an irradiated skin are almost imperceptible. The question naturally arises, To what anatomical changes is this clinical effect due? Behrend 2 ) assumed that the tissues become permeated with a serous exudation which not only affects the parts containing blood-vessels, but also the deeper layers of the epidermis, which ') Wiener med. Presse, 1890. No. 31 k. k. Ges. d. Aerzte in Wicn, 27 Oct. 1899. Congr. d. deutsche dermatolog. Gesellsch., Breslau, 1901. 2 ) Berliner klin. Wochenschr., 1898, No. -'.5. 252 RADIO-THERAPY becomes so soaked that the lymph-spaces between the elements of the stratum spinosum are distended. As a result the indi- vidual cell-elements are forced apart, and in the case of a violent exudation even larger spaces may be formed, filled with serous fluid and overarched by the less yielding horny layer of the epidermis, thus giving rise clinically to a vesicle. The author is not aware how far this theory of Behrend's depends upon histological investigation. It will be seen later, however, that Scholtz has verified the existence of this serous exudation into the tissues by experimenting with animals. Roentgen-radiation often causes singular pigment changes in the skin, and these may even be the first sign of commencing reaction. They may be characterised either by the appearance of freckle-like spots on the skin, or the whole exposed area may assume a diffuse, slightly yellow, brown, or greyish tint which is in most cases ephemeral. Again, pre-existing freckles or other pigmentary abnormalities may become darker, or they may in some cases become somewhat lighter in hue. It must be noted that these pigment changes very often make their appearance without erythema having preceded them; they are evidently not always dependent on the latter phenomenon. A discolouration of the hair, especially in the case of bru- nettes, has been repeatedly observed as the first sign of reaction. Sehrwald, 1 ) Gocht, 2 ) Gassmann and Schenkel 3 ) have seen depigmentation of the exposed surface with increased pigmen- tation around its border. The author has himself seen this as a later effect of Roentgen-radiation, notably in a case of lupus erythematosus treated by Schijf 4 ) . In this case the pigment seemed as though it had been displaced from the white area marking the site of the disease into its vicinity (Scliiff and Freund, Beitrage zur Radiotheraphie, Festschr. f. Hofrath, Prof. Neu- mann, page 806. The author again saw a case 1 ) Deutsche med. Woch., 1901, No. 30. 2 ) Fortschr., Bd. I, H. 1. 3 ) Ibid. Bd. II. H. 4. 4 ) Ibid. Bd. II, H. 4. TREATMENT WITH X-RAYS 253 recently, that of a young lady, a brunette, who had been treated for hypertrichosis. Dermatitis here had been followed by the appearance of pale patches in the skin surrounded by dark brown rings of pigment. One recalls the fact that freckles are particularly apt to appear on blondes, and melanoses on white animals. Ph. J. Pick, who calls attention to this fact in an able article (Vierteljahrschr. f. Derm. u. Syph., 1884, page 24), is of opinion that the pigment defect in the hair of animals with melanosis accounts for its excessive deposit in other parts. The author concluded from his researches on the physiological effects of electric discharges on the skin that pigmentary accumulations arise from haemosiderin, which in its turn is the result of haemorrhage into the tissues. S. Ehrmann 1 ) gave the following explanation of the pig- ment-phenomena, based on microscopic examination : By the direct influence of irradiation on the capillaries, the walls of which become adapted for diapedesis (not haemorrhage), hyper- emia is produced. At the same time there is a copious exudation of blood-plasma in which haemoglobin is dissolved. This explains the yellowish tinge of the hyperaemic skin. Very soon gold-coloured haemosiderin is deposited from the colouring matter of the blood in the tissue interstices. The haemosiderin is absorbed after a few weeks, until which time the skin retains its yellowish-brown tint. When, however, the sun's rays, or the X-rays, encounter a skin possessing melanoblasts (cells producing melanotic pigment, which is not formed within the cell-spaces, and is chemically different, moreover, from haemosiderin) melanin is more copiously secreted as the result of the irritation of these cells. Hence the sepia-brown discolora- tion, which may persist a twelve-month. The skin of fair-haired people as a rule contains fewer melanoblasts; consequently they usually escape this excessive brown pigmentation. ') Wiener med. Woch., 1901, Nos. 30. 31. 254 RADIO-THERAPY L. Tordk and M. Schein 1 ) have observed an abundant development of closely packed comedones after irradiation of the face. The erythema which is so often seen as an early sign of Roentgen-reaction differs in character from most erythemata. It differs, for instance, from the erythema resulting from the internal or external use of certain medicaments (erythema vene- natum) ; it has rather the character of an erythema solare. The skin looks as though it had been much exposed to the sun, or as though the patient had been amongst the glaciers. The ery- thema is at first of a delicate light colour, later on a reddish- brown tint with a slight bluish cast develops. This darken- ing of colour is probably due on one hand to the combination of erythema with pigmentation, on the other to the fact that the hyperemia is "passive." This erythema of the skin may be either diffuse or patchy. In a great number of cases loosening of the hair-shafts is the very first sign of reaction. It is quite wrong to suppose, as many have done, that this effect can only follow after other inflamma- tory phenomena have been established. A good method to dis- cover this loosening of the hair is to seize two or three shafts between the finger-tips close to the skin, then, exerting slight pressure, to slide the fingers towards the free ends of the hairs. Normal hairs are not affected by this manoeuvre, whereas loosened hairs readily fall out. To pull forcibly at one part of the hair, either with the fingers or with a forceps, is a crude and much less reliable method; it is, moreover, one which is quite useless for determining the earlier and slighter alterations in the fixity of the hair. In order that a reaction may be recognised early it is most important that any patient who is undergoing treatment for a hair affection does not shave or otherwise cut the hair short; in cases where the hair has been recently cut operations should be deferred until it has reached a certain length. Difficulties in this direction will often be encountered in the case of women who are being treated for hypertrichosis, these patients being ') Wiener med. Woch., 1902, No. 18 ff, TREATMENT WITH X-RAYS . 255 accustomed to preserve appearances by the use of depilatories or the epilation-forceps. Nevertheless, the rule must be strictly enforced, for it is impossible to tell when closely cropped hairs are really loose, the hair-roots, lacking friction on their shafts, will otherwise remain for a long time in situ, and may be only removed in the end by the lifting force of fresh-growing hairs. Under the latter circumstances the falling of the hair could give no indication whatever for the suspension of treatment. Subjective symptoms are often the forerunners of a reaction. They include itching, burning, and a feeling of tension, and are apt to be more marked by night. It is, however, in but rare instances that patients will on their own initiative mention these sensations; they regard them usually as insignificant. It is important, therefore, that they be informed of the great impor- tance of mentioning these symptoms as soon as they occur. Some- times neurotic patients who are under treatment, especially in the later stages, will suffer from an attack of intense pruritus of the exposed region often accompanied by urticaria. Should this happen, operations must be suspended. The above-men- tioned early signs of reaction are far from intense if the treat- ment is properly conducted, indeed, they often escape notice by beginners. They afford, however, a most valuable index to the more expert to the progress of events, and enable him in time to complete the treatment with safety to his patient. Reference may here be made to the fact that suspension of the sittings at this comparatively early stage almost always meets with opposition from the patient. He often begins treatment with somewhat prejudiced feelings, inasmuch as he sees nothing of what is going on, on account of his mask. Consequently he objects to resting at a time when he "hardly feels anything," and protests that he has been treated insufficiently. Hysterical women who are being treated for hypertrichosis are particularly troublesome in this respect, especially if during an earlier treat- ment they have been relieved from their hairy troubles. On no account, however, will the operator who has a proper con- ception of his responsibilities give way to these importunities. Both the methods which have been explained in full above have this in common : The object is to produce a certain effect 256 RADIO-THERAPY by means of a "normal" intensity of irradiation and period of exposure. It is true that this "normal" has been empirically determined, but it cannot be exceeded without danger. One can obtain the same final result with hard or soft tubes, weak or powerful rays, varying distance of the tube, etc., provided the "dose 1 ' be regulated accordingly. In the first method the "normal" is attained in a few sittings compared with the second; the final effect is the same in both. Whereas, however, the effect upon the skin in a single irradiation by the second method is very feeble, in the first method it is fairly strong, owing to the employment of more powerful tubes. Later experience has confirmed the author's earlier view, that by employing the first method the operator is using a strong remedy, the effects of which he may be unable to control; on the other hand, taking into consideration the different reacting power of individuals, there is the possibility of him administering a "normal" irradia- tion which the subsequent four-weeks resting time may prove to have been insufficient. An experiment by Oadin a.ndBarthele7?iy 1 ) furnished an interesting proof of this assertion. They exposed successively 12 patients under identical conditions of exposure-period, etc., to a tube whose vacuum could not be regulated. At the beginning of the experiment the tube was very soft, towards the end it became very hard. The first patient, who had been exposed to the "over- soft" tube showed no reaction whatever. Succeeding patients, as the tube became altered in vacuum, showed erythema, phlyctenular, bulls, loss of hair, and finally severe dermatitis. The eleventh patient (the tube being now very hard) showed complete loss of hair without other signs. In the twelfth patient there were no signs Avhatever. The author has already expressed the opinion 2 ) that the Roentgen treatment will only become popular amongst medical 1 ) II Congr. intern, d'electrologie et de radiologic Sept. I, 1902. 2 ) The same opinion was expressed by the author at the VII Congress of the Deutsche dermatolog. Gesellschaft. Breslau, 1901, before a large com- pany of experts. TREATMENT WITH X-RAYS 257 men when it is perfected to such an extent that by definite "doses" it produces definite effects whose presence informs the operator when he has treated the patient sufficiently and within the limits of safety. It is probably for this reason that up- holders of the "first method" of treatment have endeavoured to so modify it that it may meet the requirements, thereby bringing both methods more into line. Thus Kienbock, 1 ) who at first called our method "compli- cated, confusing, unnecessary, and tedious," has recently recom- mended, in addition to his original method, two more methods in which the total exposure is distributed over several sittings of less intensity. By these Kienbock 2 ) means daily exposures of 5 minutes ("irradiation of lesser efficiency"), or longer sit- tings twice a week ("medium strength irradiations," which pro- duce their effect in about a fortnight). Scholtz 3 ) begins with a comparatively strong exposure in order to soon bring about reaction. At the first sign of this he promptly reduces the intensity of the irradiations; these are con- tinued in mild doses until the desired effect begins to show itself. This plan is also adopted by Torok and Schein, and the author has frequently used it with marked success. V. Lion 4 ) uses medium-soft tubes, a coil with spark-length of 30-40 cm., current strength of 3-4 amperes, 30 volts tension, and 1 500-1 800 interruptions per minute. In the earlier sittings the tube distance is 30-50 cm., and the time of exposure 5-10 minutes. Later on the distance is reduced to 5-10 cm., and the exposure increased to 30 minutes. Gaston, Vicira and Nicolou 5 ) use hard tubes corresponding to a 15 cm. spark-length and to No. 6 of Bennoit's radiochro- meter. The primary current has an intensity of 5 amperes and a 25 volt tension. Tube-distance, 15-30 cm. Duration of ex- posures, 10 minutes every other day. Under this condition the 1 I 73. Versamml. d. Naturf. u. Aerzte in Hamburg, Fortschr. a. d. Gcb. R., Vol. V, Part I, p. 34. -) Fortschr. a. d. Geb. d. Roentgenstr., Vol. V, Tart I, p. 34. Archiv. f. Derm, and Syph.. Vol. LIX. Part III. p. 424. ') VII Cong. d. dcutsche derm. Gesellsch. in Breslau, 1901, ") Soc. de dermatologie ct de Syphilis, July 3, 1902. 258 RADIO-THERAPY hair begins to fall after 6-11 sittings. "Signs of inflammation were not observed." Oudin x ) gives very brief exposures, using a soft tube which is brought within 5 cm. of the skin. He exposes at first for I minute only, gradually increasing the time to 5 minutes. He continues this treatment until signs of reddening show them- selves and itching is felt. Before closing this chapter the author must once more state his opinion that in the patient's interests a plan which, while involving more time, is yet harmless, and achieves definite re- sults by gentler means, is far preferable to one which steers straight for its goal with great energy. The latter plan is unde- niably briefer, but may prove either too vigorous, in which case painful complications are in store for the patient, or insufficient, whereby much time is lost. The first plan, though more tedious, is far safer, albeit much practice and experience are required for its successful adoption. In fact, this younger branch of medical science may fairly be considered as an art. For the rest, especially in view of the varying capacities of different apparatus, the beginner would do well to proceed with extra caution. He should first test his apparatus, finding out the correct exposure by first commencing with very short sittings (say 4 minutes). Should results prove negative after three weeks, the patient should be given 3 weeks' rest. After that the sittings can be resumed, the exposure being gradually increased to 5, 6, 7, 9 minutes and so on until the desired limit is reached. The current strength and tension, the tube' distance, etc., must be as already indicated; hard tubes may be chosen if they show evident fluorescence (see p. 247) . When soft tubes are used the total exposures must not exceed 40 minutes. When once the time of exposure necessary to loosen the hairs with each series of sittings has been ascertained, one has gained valuable data for the treatment of various affections, which may now be under- taken with greater confidence. Hence, one may proceed a little more boldly, and, by modifyng the treatment in accordance with the instructions already given, hasten the cure. The best and x ) Soc. dc dermatologie et de Syphilis, July 3, 1902. TREATMENT WITH X-RAYS 259 safest plan is for the beginner to start with the treatment of a disease like sycosis. It is only after considerable experience he should undertake cases of hypertrichosis, the after appearance of the skin being here especially a matter of the greatest moment. Since it occasionally happens that a single irradiation, even one which is by no means intense, may cause dermatitis, a brief trial-exposure should be given in every fresh case, 1 ) so that due allowance may be made for the special susceptibility of any par- ticular case. Bearing in mind the law that the intensity of an irradiation varies inversely as the square of the distance between the ray-source and the object, while the size of the area irradia- ated increases with the square of the distance, it will be necessary to increase the distance between the tube and the patient where large surfaces are under treatment; at the same time the ex- posure must be correspondingly lengthened. One must remem- ber that at the skin-surface which is nearest to the tube-wall (the part corresponding with the most brightly illuminated portion of the fluorescence screen) the effects are most pronounced. When the whole face is under treatment the cheeks should be exposed in turn and then the chin; one should not forget, how- ever, that by so doing, some regions may be twice exposed. The question of screening the healthy skin from the action of the rays must now be considered. Utina 2 ) recommended a zinc paste with the admixture of a body arresting the passage of X-rays, such as bismuth; Scholtz') tried a mercury plaster; Kaiser*) tried a funnel- shaped piece of lead sheeting, intending by this means to con- centrate the rays on the skin (forgetting, however, that they are not capable of refraction or reflection). Schiirmayer B ) recom- mended leaden screens which were "earthed" through a con- ducting wire. The author has found leaden masks the most effective. In place of the stiff, heavy and comparatively ex- ') Albers-Schonberg (Fortschr. IF, 4, t8i) and Scholtz (1. c.) advise this. J ) M i,r. f. prakl Dermatologie, [898, Vol. XXV] I L c. ') Wiener 1:1 in. Woch < No. 31. B ) 7.3- Vci amml. d. Naturf. u. Acrzte, Hamburg, 190] 260 RADIO-THERAPY pensive masks made by the plumber for this purpose, he now uses those which are made as follows : A piece is cut from a leaden sheet ^ mm. thick (Fig. 76). The measurements are ad = 42 cm., ae = 8 cm., kg = 16 cm., ab = ed = Q cm., bf = ch = 12 cm. The sheet has "billroth- battist" sewn to one side; at m and u two slits perforate it; through each of these a ribbon passes which is sewn to the lining. The mask is now ready for the upper part of the face. In case this mask has to be worn by several patients (e. g., in out- patient practice) they should be instructed to each bring a hand- kerchief to be placed beneath the mask. The mask may be roughly shaped to fit the face. Apertures should be cut in the mask corresponding to the diseased area. All parts of the body coming within the X-ray field which not do require exposure must be carefully protected from the rays by means of masks. Thus, if the chin is under treatment, not only the upper part of the face, but also the chest, requires protection, and where the angle of the jaw is the site of operations, the shoulder must be screened. In many cases it is a good plan to place the vacuum-tube within a lead-lined box, having an aperture at one side cor- responding to the diseased area. As a special protective measure, Kaiser 1 ) recommends the use of vacuum tubes made of red glass; Jutassy 2 ) again says he has never seen any bad effects accompanying the use of blue lead-oxide tubes. ') Wiener klin. Woch., 1901, No. 31. 2 ) Fortschr., Vol. II, Part V, p. 195. TREATMENT WITH X-RAYS 261 The operator's own safety must not be forgotten. One has known zealous radiographers who have, alter some hours' use of the fluorescent screen, developed severe dermatitis. It is probably cases like this which have led to excessive precautions being taken by some of those who busy themselves with X-ray therapy. I he author has known a conscientious operator who only worked with an armour of lead plate, a leaden helmet on his head; his appearance was scarcely calculated to soothe the patient. Undoubtedly the warnings and precautions have been exaggerated. The operator should remember that the tube only affects changes on a skin which is for some time exposed to its Held of action. He will avoid placing his own skin under these conditions. A brief manipulation of the apparatus, a brief examination of the mask, a change in the patient's position, etc., can be made repeatedly each day without affecting one's health in the least. For the last 6 years the author has been working daily from 6 to 7 hours in his Roentgen laboratory without ill effects; nor has he worn protective appliances of any kind to hinder him. § 31. Indications. We now come to the indications for the employment of Roentgen-therapy. Physiological experiments shew that Roentgen-radiation, like that with light and electricity, has a stimulating effect when administered in moderate amount, but a destructive action on certain tissue-elements (cells) when employed with greater intensity. We may assume that when acting beneficially the rays modify the process of nutrition in badly-healing ulcerative conditions and in paretic states ot cer- tain tissues, thereby promoting the healing of the former and the resumption of function in the latter (<•. g. } the hair papilla 1 in alopecia areata). It would appear by no means unlikely that the irritant effect of the irradiation, like (hat of certain chemical agents (silver nitrate, copper sulphate, camphor, etc.), stimu- 262 RADIO-THERAPY lates the function of the connective-tissue cells, thereby promot- ing scar-formation. Since this stimulating effect penetrates more deeply, it would appear applicable in cases where chemical agents, by reason of their more superficial action, are useless. The X-ray method is especially applicable for certain patho- logical conditions in which the lesions are widely spread; for others which are more circumscribed surgical treatment, treat- ment by drugs, or the "light-method," are preferable. In by far the greater number of cases the destructive action of X-rays is what is called for; this is especially so in affections which have their seat in cellular structures, such as the epidermis, the glands, and the hair follicles, or in which the essential fea- ture is an over-production of cellular elements, such as psoriasis and epithelioma. Clearly, however, both the destructive and restorative properties of Roentgen-radiation can often find their metier in one and the same disease; thus the healing of a lupus may be due as much to the stimulating effects of the rays, whereby hyperemia and improved nutrition are afforded and scar- formation assisted, as to the destructive action upon the dis- eased tissue. The following groups of diseases suitable for X-ray treat- ment may be classified from a purely empirical and histological standpoint : i. The so-called diseases of the hairs (including those of the hairy skin) . In this group we may include all those abnormal conditions for the cure of which epilation is the first desideratum, whether or not other effects of irradiation are called for (favus, sycosis, folliculitis barbae, blepharitis, dermatitis papillaris capillitii, trichotylosis, hypertrichosis, alopecia areata). 2. Ulceration processes in the skin. In this group we include not only simple, non-infected ulcerations, in which irradiation acts favourably by reason of its stimulating effects, but also those skin affections due to direct infection which so often end in ulceration. Here we utilise the destructive action of the rays upon the morbid tissues and so prevent further infection of surrounding tissues (lupus vulgaris, TREATMENT WITH X-RAYS 263 scrofulodermia, tuberculosis cutis, epithelioma, ulcus rodens, lepra, mycosis fungoides, atonic and varicose ulcers, etc.). 3. Acute and chronic exudative dermatitis ( inflammations) and granulation-formations. The explanation of the good effects obtained in diseases of this class is still obscure; perhaps it is to be found in the destructive action of the rays upon inflammatory products. Grouven and Scholtz have shewn that this is so in the case of psoriasis and lupus. It would seem not unlikely that the high-tension electricity already referred to (p. 162), as streaming from the tube, plays a considerable part. This group includes eczema, psoriasis, prurigo, lichen ruber, pemphigus, lupus erythematosus, acne vulgaris and rosacea, furunculosis. 4. Diseases which owe their origin to morbid changes in the blood-vessels. The histological changes in the blood-vessels which can be proved to follow irradiation explain the good results obtained with this class of disease (naevus flammeus). 5. Progressive disturbances of nutrition in the skin (ver- ruca?, naevi, spili, elephantiasis). /. Diseases of the Hair and Hairy Regions. Favus capillitii. Complete epilation of the whole scalp is an essential feature in the Roentgen treatment of this affection. I f the scalp be only partially denuded of hair, recrudescence of the disease is prac- tically certain, the fungus growing again from the hairy foci where it has been left. In order that the whole scalp may be exposed the tube should be first placed over the middle of the frontal region, next opposite the sides of the head (with the anti-cathode opposite the middle point ol a line between the ear and vertex), and finally opposite the centre of the occiput. The tube should be placed at some distance (25-30 cm.), so that as large a surface as possible may be irradiated, and each exposure should be from 6 to [O minutes. 264 RADIO-THERAPY As a rule, a somewhat intense irradiation is necessary for the cure of favus; this is probably due to the thick hairy coating of the diseased parts. (Hair does not materially prevent the penetration of X-rays; it is, however, a very bad conductor of electricity.) Before commencing operations, the hair should be cut to about the length of 2 cm. The usual course of events is, that after about 3 weeks (when hard tubes and weak currents have been used), the hair is found to be loosened on grasping it, or, on parting the hair, the skin is seen to be slightly reddened. Within the next 2 weeks the hair falls out in a circular patch. Any scutula in this region exfoliate, leaving superficial, pale-red, oozing excoriations behind, which very soon (in about 8 days) become cov- ered with skin. The part then presents a smooth, shining appearance (see Fig. 77), and about 6 or 8 weeks after the termination of irradiation becomes covered with lanugo; later on the scalp fully recovers its hair. In many cases the scalp remains permanently cured, and this result may be confidently expected if a relapse does not show itself within 10 weeks. Sometimes, however, a slight relapse necessitates a short supple- mentary treatment. Torok and Schein believe that relapses are not due to fungus being left behind in the hair follicles, but to fresh infection from without. Hence the advisability of treating the whole of the scalp as above recom- mended. As an extra safeguard against relapse, the following oint- ment may be used for the bare places on the scalp after reaction has subsided : Fig. yy. — Favus capillitii. Occiput, treated with X-Rays. TREATMENT WITH X-RAYS 265 Glycerin acid, carbolic . . . . . .2.5 Lanolin . . . . . . . . . 50 . o This is to be thoroughly rubbed night and morning into the scalp by the patient, the object being to get the carbolic acid (which, according to Calderone, 1 ) is the best destroyer of the fungus) well into the hair follicles. With this method very obstinate cases of favus may be cured in a few weeks' time. The author knows of several cases which have remained well since this treatment, which took place from 1 to 3 years ago. Should the carbolic treatment fail to prevent relapse, the Roentgen method must be repeated once or twice. Care must be taken, however, to avoid strong reactions; if the latter are frequently repeated the scalp will remain permanently bald. It will very often happen that old cases of favus which have been correctly and carefully treated by X-rays shew bald patches after healing. These are not due to irradiation, but are the effects of the disease itself. The beneficial effects of this treatment in the case of favus do not depend upon any parasiticidal properties of the rays themselves. We shall see later that the rays possess practically no qualities of this kind, and the fungus on the fallen hairs is not found to have in any way suffered in vitality. The good apparently consists in keeping large areas of the scalp bald for a considerable time; in this way much vantage ground for the fungus is eliminated with a great part of the iungus itself, and diseased hairs are removed which would otherwise retard the healing process. Then there is the stimulative effect of the irradiation to be considered, which improves the nutrition of the hair follicles; also a peculiar action oi the rays in causing degeneration of the cell elements among which the fungus pro- liferates, and so indirectly acting inimically on the latter. Lp to the present time no minute histological investigation in this line have been published. The favourable results obtained by this method ol treating favus, which was first introduced by the ') Giornals Italian, delle malall. vciut.. 1. Fasc. [899. 266 RADIO-THERAPY author 1 ) (and published later in connection with Schifj), have been confirmed by Ziemssen, 2 ) Neu- mann,') Albers-Schonberg*) Hahn, 7 ') Grouven, 6 ) Lion,') Norman Walker, 6 ) Sclwltz,'') and Spiegler, 10 ) Gaston and Nicolou, 11 ) Boczar and Bukofsky. Spiegler states emphatically that the method radically cures favus in a shorter time than any other known method, and is, in fact, the best possible means for treating the disease. Sycosis vulgaris and Folliculitis barbae. The mode of application of the Roentgen treatment for this class of affection must be guided by circumstances, such as the character of the sycosis and other conditions to be considered later. If we are dealing with an acutely suppurating process, tending to excoriation, it is better to give but few sittings (4 to 6) of 8-10 mintues' duration each, using a hard tube at a distance of 15 cm. In such cases even this brief treatment suffices to determine very evident results, the skin becoming drier, the pustules drying up without fresh pustular formation, the infiltration absorbing, and the itching, pain, and tension gradually lessening; all this happens without the loss of hair. The appearance of these signs and symptoms, together with a darker reddening of the skin, should be an indication for sus- pending the treatment. Should there be a relapse after a few weeks, the process may have to be repeated once or even several times. More powerful, but more radical, effects are obtained ') Freund, Wiener med. Woch., 1897, No. 19, Wiener dermatol. Ge- sellsch.. May 10, 1899. Fortschr., Vol. III. \. 109. ") Aerztl. Verein in Miinchen, June 8. 1898. 3 ) K. k. Gesellsch. d. Aerzte, 19 Oct. 1900. 4 ) Aerztl. Verein in Hamburg, 18. Oct. 1898, and Fortschr. Ill, Part IV, p. 160. 5 ) Aerztl. Verein in Hamburg, 19 Nov. 1900. 6 ) Fortschr.. IV. Part V, p. 183. 7 ) VII Dermatol. Gesellsch.. Breslau, 1901. s ) Lancet, 1900, January, p. 27. 9 ) Arch. f. Derm. u. Syph. Vol. LIX, Part III. 10 ) Wiener Klin. Woch.. 1900. p. 1094. ") Soc. de dermatolog. et de Syph., July 3, 1902. TREATMENT WITH X-RAYS 267 by epilation, which is produced by stronger irradiations (see below, also Figs. 78 and 79). In the treatment of this kind of skin-affection (folliculitis barbs) by means of X-rays, it sometimes happens that the skin reacts violently after compara- tively few (3 to 5) and weak irradiations; the reaction partakes rather of the nature of an exacerbation of the sycotic process than of an ordinary Roentgen-dermatitis. Numerous fresh pustules appear, which often run together; the whole skin becomes tense and exceedingly painful. Often deep-seated abscesses are formed, where Fig. 78. Fig. 79. the pus is collected sub-cutaneously in considerable quan- tities. Since the skin is already highly intumescent, so that the addition of Roentgen irradiation with its effects might even induce sloughing, the author in such cases suspends the treatment, applying appropriate dressings until the acute inflammation has subsided, after which the sittings may be cautiously recommenced. The sycosis again may manifest itself in the shape of small, red, infiltrated, superficially scaling nodules. These occupy the site of the follicles, being pierced by the hairs. In this variety of the disease (acne pilaris, Besnier, ulerythema sycosiforme, folliculitis barbae), it is advisable, if the patient can conveniently remain beardless for some time, to continue the treatment to the stage of epilation. Since a reaction is soon obtained in these cases, on account of the pre-existing inflammation, the skin 268 RADIO-THERAPY should not be exposed for more than 14 days with hard tubes. After this period, as a ride, the commencement of reaction is indicated by increased tension in the skin, with smoothening of its surface and a deep-red appearance. Loosening of the hairs soon follows. In order that we may be in a position to recognise the impor- tant sign of loosening of the hair, the patient must, at the out- set, be told not to shave or otherwise interfere with the beard; nor should the treatment be undertaken before the hair has reached such a length that it can be grasped by the finger-tips. It often happens, however, that the treatment cannot be pushed to the stage of epilation, many patients being obliged for social reasons to retain the beard. In such cases it is advisa- ble (as with cases of the first kind) to proceed more gently, exposing the skin only until the pustular and nodular formation ceases, repeating the process after three weeks' interval until no further lesions manifest themselves. It is by no means clear to what we are to attribute the favourable action of Roentgen-radiation in this disease. The observation that epilation of the hairs in the affected region is a better procedure than shaving permits of the assump- tion that good results are due not so much to the better pene- tration of medicaments after epilation, as to the actual removal by this procedure of an agent which maintains the follicular inflammation; just as gauze-strips introduced within an abscess- cavity prevent the latter from healing, although freely granu- lating, so the presence of a dead hair may conceivably interfere with the healing of a follicle whose walls are in a state of inflam- mation. The author assumed, therefore, that keeping the skin hairless for some time would have a beneficial effect on the process, and on this ground recommended the use of X-rays in the treatment of sycosis and favus. 1 ) Kaposi' 1 ) was of the opinion, however, on being shewn a case of this kind by Schiff and the author, that sometimes a 1 ) Wiener med. Woch., 1897, No. 19 — "Light Treatment," etc. — Compte. rend, du XII Cong, internat. de medicine, Moscow, 1897, Dermatolog. Section, p. 414. ') Wiener dermatolog. Gesellsch., May 10, 1899. TREATMENT WITH X-RAYS 269 sycosis is dependent on the irritation resulting from certain anomalies in the hair-growth (such as the presence of several hairs in one follicle, or a want of proportion between the diame- ter of the hair and the follicular lumen), and that reappear- ance of the hairs would be associated with relapse of the disease. It must, of course, be admitted that relapse is common in cases of sycosis. Still Kaposi's view is hardly justified, for if in these cases sycosis were actually provoked by the anomalies referred to above (follicles with several hairs, or hairs of too large a size), the first visible signs of new hairs would inevitably be accompanied by traces of the disease. This is, however, not the case. In all these cases the hairs rapidly grow again, and in normal fashion. The skin appears healthy, and remains so for some time. Then, after the patient has apparently had a healthy beard for a while, there comes a recurrence one day of his sycosis. This can be speedily removed in 4 or 5 sittings, without having to push the treatment to the stage of epilation. According to Kaposi, a radical cure of sycosis associated with anomalous growths of the hair is not possible by means of Roentgen treatment. This view is not correct, however. Of 17 cases of sycosis treated by the author up to November, 1901, 5 cases were thoroughly cured by the first course of sittings; in 5 cases, 1; in three cases, 2, and in 1 case 3 supplementary sittings were required for a permanent cure. Of the remaining 3 cases, some are still under treatment, the rest not having put in an appearance since the first sitting. These results shew that sycosis is certainly amenable to treatment by irra- diation. Gassmann and Schenkel 1 ) report a case so treated which had remained well a year later. Albers- Schonb erg and Halm, 2 ) Grouven*) Spiegler,*) Lion*) and Sclwltz, ) G. H. Lancashire?) Gaston and ') Fortschritte auf dem Geb. d. Roentgenstr., Vol. II, p. i. ■) [bid. Vol. Ill, p. 160; Aerztl. Verein in Hamburg, 19 Nov. 1900. 3 ) Nicderrh. Gesellsch. f. Natur und Heilkunde zu Bonn, Feb. 2, 1900. *) Wiener derm. Gesellsch., Nov. [4, 1900. B ) VII Cong. d. deutsch dermato! G ellsch., Breslau, 1901. e ) Archiv. f. Dermatolog. u. Syph., Vol. LIX, Part III. ^ ') Brit. Med. Journal, May 31, 1902. 270 RADIO-THERAPY Nicolou x ) also report the radical cure of obstinate cases. From these reports we may conclude that a radical cure of sycosis may be effected in a comparatively short time, very often in a single series of sittings. Moreover, in the majority of cases, there is no need for bringing about Roentgen-dermatitis or permanent loss of hair, as has been suggested by two writers on the subject. The prospect of cure by this method, which was first recom- mended and used by the author himself, is therefore quite good. The treatment may be combined, if desired, with the use of drugs. In that case a 15-30% sulphur-oil may be used, after all inflammatory signs of reaction have subsided. The relapses which undoubtedly occur from time to time after the employment of radio-therapy in this disease are urged sometimes as an argument against the method. But, after all, the repetition of the sittings after six weeks or so, followed perhaps by yet another course of sittings later on, is no great hardship to the patient. The inconvenience is one that is amply compensated for by the patient's feeling that he is no longer a conspicuous object for pity amongst his fellows. One must bear in mind what the ordinary treatment of the disease commonly entails, viz. : constant treatment for a very long period, daily shavings and epilation of the tender skin, unsightly dressings which may bar the patient from society. The fact that he may, after a painless treatment by X-rays which inconveniences him but little and lasts perhaps three weeks, be made once more presentable is surely an argument in favour of radio-therapy. Recently Ehrmann 2 ) has shewn that the disease called by him "sycosis scleroticans," but which is more generally known by Kaposi's title of "dermatitis papillaris capillitii," can only be cured by Roentgen-treatment or electrolysis. The author treated such a case in which the disease was accompanied by nodular glandular infiltrations the size of a walnut. After 7 sittings the hair became 1 ) L. c. 2 ) Wiener med. Woch., 1901, Nos. 30, 31. TREATMENT WITH X-RAYS 271 loosened, and the nodules decreased in size. A second course of treatment acted still more energetically. The technique is the same as for ordinary sycosis. Hyphogenic Sycosis (Trichophytosis). Grouven, 1 ) H. Zechmeister 2 ) and Lion 1 ) report good results with this disease. Zechmeister obtained a radical cure in one case after a single course of 21 sittings, the exposures lasting from 5 to 15 minutes each and the tube-distance being from 25 to 15 cm. He used hard tubes, and noted the spontaneous disappearance of a fluctuating tumour, the size of a hazel-nut, which had existed within the zone of disease. Bruno Chaves 3 ) recommended the treatment for herpes tonsurans. /. Pollitzer informed the writer that he obtained good results also with this affection. Blepharitis. The author had repeatedly observed that patients who were under the Roentgen-treatment for sycosis barbae, eczema faciei, acne rosacea, lupus vulgaris of the face, were incidentally soon cured of a co-existing blepharitis. He published the first case of this kind in conjunction with E. Schijf ; this was a case com- plicating a chronic eczema of the beard. Since that time he has treated 3 cases of uncomplicated blepharitis. As a rule the diseased region reacted after 4-9 weak irra- diations of the closed eye, using hard tubes. Response to the treatment was quickly obtained, whether the disease was of the ulcerating or scaly type. Crusts became detached, the colour of the part became lighter, excoriations skinned over, and the skin became once more healthy in appearance. All this hap- pened without the eyelashes falling, and no after-treatment by drugs was necessary. The accompanying conjunctival catarrh improved rapidly after the cure of the blepharitis. ■) L. c. ' J ) Monatsch. f. prakt. Dermatologie, Vol XXXII, No. 7. ) Giorn. Italiano delle Mai. Ven. e della Pelle, Fasc. III. 1900. .-. 272 RADIO-THERAPY Trichotylosis (Trichorrhexis nodosa). The author has used Roentgen-treatment in a case of this peculiar disease, the origin of which is as yet unknown. This was a remarkably obstinate instance of the affection, which had for years withstood other methods of treatment. The patient, whose moustache presented the charac- teristic appearance of this disease, had twelve sittings in September, 1901. The apparatus comprised a 25 cm. coil, worked from a supply-current of 6-8 amperes and no volts; hard tubes were used, the sittings occupied 7-10 minutes each, and the tube-distance was 10 cm. Slight erythema and partial falling of the hair ensued. Unfortunately, about this time the treatment had to be interrupted. After 6 weeks' time the hairs "began to grow again in a normal manner. At the present time (April, 1902), the patient has a normal moustache, the hairs of which average 2-24 cm. in length and shew no abnormality when examined microscopically. (Later note: Some trifling relapse is noted at the places from whence the hair had not previously fallen under expos- ure. But the new growth of hair appears quite healthy six months after the treatment. The patient is recom- mended further and more energetic treatment with the rays. ) Alopecia Areata. R. Kienbock *) treated a man, ast. 26, who had for over 3 years suffered from severe alopecia areata of the whole head, by the Roentgen method, giving six sittings of 20 minutes each with a tube-distance of 20 cm. He exposed the frontal region only. The small lanugo hairs soon fell out over the irradiated area, and were succeeded two months later by a strong growth of dark and normal hair. The rest of the scalp, which had not been treated, retained its diseased condition. Kienbock con- l ) K. k. Gesellsch. d. Aerzte in Wien, Nov. 2, 1900. TREATMENT WITH X-RAYS 273 eluded that the irradiation, with its consequent epilation, had determined the fresh growth of normal hair. G. Holzknecht 1 ) soon after this reported another case in which, after 5 sittings of 10 minutes each with a 20 cm. tube- distance, the same result was obtained. In this case, however, the epilation was not complete, a ring of thick black hairs being left surrounding each plaque. The plaques themselves became reddened 3 weeks after the irradiation, whilst the healthy por- tion of the scalp (in which reaction had shewn itself after 8 days) remained pale. New hair first grew on the plaques, which soon became covered with soft, thick black hairs; this occurred before the healthy portion of the scalp (which had been denuded by the rays) recovered its hair. In these cases fresh hair grew, as is usual after Roentgen- epilation, two months after the last exposure. In two more cases similar results were achieved. 2 ) Holzkneclit recommends two methods of treating alopecia areata : ( 1 ) in which only the plaques themselves are irradiated, together with a ring 1 cm. wide surrounding them where the disease is presumably latent (the rest of the skin is protected by lead masks; (2) in which the whole scalp is exposed, including both healthy and diseased areas. The above-mentioned two cases of alopecia areata shewed unmistakably that Roentgen-radiation caused the growth of fresh hair. Do we possess in this method a specific for the affection ? The author treated in this manner a boy, aet. 12, who had alopecia areata capitis. After 8 sittings of 10 minutes each, with a hard tube, lanugo appeared in all the bare places, one plaque indeed shewing a fresh growth of black hair.') In this case there was no pre- liminary falling of the hair. Improvement, however, was not maintained when the treatment was continued. ') K. k. Gesellsch. d. Aerzte in Wien, 7 Dec. 1900. Wiener klin. Rund- schau, 1901. Nos. 41 and 7.3. Versamml. d. Naturf. u. Aerzte, Hamburg, 1901. Fortschr. a. d. Geb. d. I\.. Vol. V, X". [, p. 62. 2 ) Wiener dermatolog. Gesellsch., Feb. 20, 1901. 3 ) K. k. Gesellsch. <1 Aerzte, Dec. 7, 1900. 274 RADIO-THERAPY J. Neumann 1 ) rightly insists that in these cases we must bear in mind the possibility of a spontaneous cure. In connec- tion with this point w T e may recall the fact that alopecia areata which has involved the entire scalp, in the case of elderly people, is generally incurable, whereas healing is the rule with younger people. The discreet type of the affection again usually heals of itself in due time. Few data are to hand of this particular branch of X-ray- therapy, nevertheless it is clear that it has been by no means universally successful. Holzknecht 2 ) found some of his cases to be absolutely refractory, and Kienbock 3 ) himself reports to the same effect. The author has had the same experience in two instances, and has learned from private communications received from several Viennese dermatologists that they also failed in several cases. We shall probably, therefore, have to abandon the hope of curing universal alopecia by the X-ray method, since it often fails to improve even the less severe forms of this malady. Kienbock attempts to explain the beneficial effects of Roentgen-radiation in alopecia areata, when these do occur, by ascribing some parasiticidal qualities to the rays. According to this writer, moreover, it is equally reasonable to expect good results if the disease be regarded as atrophoneurosis. With regard to the first point, it has not yet been demonstrated that all cases of alopecia areata are of microbic origin. Then again, X-rays cannot be accepted as possessing any microbicidal proper- ties at all. Even supposing them to be so endowed, the irradia- tion would have to be so vigorously maintained for a long time, in order to destroy the organisms, that serious injury to the skin could hardly be avoided. Finally, no experimental proof has as yet been forthcoming of the destruction of Sabonraud's micro- organisms in this manner. *) K. k. Gesellsch. d. Acrzte in Wien, Nov. 2, 1900. 2 ) Wiener kiln. Rundschau, 1901, No. 41. 3 ) Verhandlungen d. deutschen dermatolog. Gesellsch., VII Congress. P- 447- TREATMENT WITH X-RAYS 275 The theory advanced by several writers, including Schiff* ) Ehrmann, 2 ) Holzknecht 3 ) and the author,') would appear much more tenable, viz. : that we have here mainly an effect of mechanical irritation. It has often been observed that a few short exposures do not cause any falling of the hair, but rather some slight irrita- tion which may lead to thicker growth. The effect is quite analogous to that produced by certain chemical agents (tr. aconite, veratria, cantharides) , which are also employed as stimulants to the scalp. Probably, however, the effect of Roentgen-radiation (and also, according to Finsen, photo- therapy) is more penetrative, and therefore more likely to reach the structures concerned with hair-growth than is the case with these chemical agents, whose effect is more confined to the sur- face of the skin. We know that under certain circumstances alo- pecia areata may be cured also by other physical irritants. Thus Ehrmann shewed this with faradisation. If this view be cor- rect, the X-ray method should on theoretical grounds possess a certain therapeutic value in this affection. Undoubtedly it does, under certain conditions, stimulate the process of hair-growth, though it is an open question if the origin of this stimulus is to be found in the X-rays themselves or in the high-tension electricity flowing off the tube. In any event, to obtain this effect it is not necessary (as the author's experiments prove) to push the irradiation in the first instance to the stage of epilation. The property which Roentgen-radiation possesses of stimu- lating hair-growth is by no means so reliable as its action as a depilatory. It is interesting, however, as Kienbock remarks, to note that identically the same remedy may be employed to pro- duce diametrically opposite results. Holzknecht tried the method in the treatment of alopecia pityroides, but without any definite success. *) IV Intern, dermatolog. Cong., Paris, [900. 2 ) Wicnc-r med. Club, 30 |;inu:irv. [901. ') Sitziingsb. d. kais, Akad. d. Wis en ch in Wien, Mathem.-natur. c!., July [2, tool, Vol. 'IX. Pari III. p. 646. 276 RADIO-THERAPY Hypertrichosis. The methods of treating this skin affection are in the main those already indicated in general Roentgen-therapy. Almost every operator has his own technical-modifications, which he believes to be the best. The first essential is to become thor- oughly acquainted with the capacity of one's apparatus; it is only after that that one may safely introduce niceties of detail. The author himself uses hard tubes showing greenish fluo- rescence in a non-darkened room. He employs a 30 cm. coil and currents of 2 or 3 amperes and 110 volts, and a tube- distance (skin to glass) of 15 cm. If the cheeks and chin are to be exposed, a mask is used which covers the upper part of the face and extends to the edge of the lower lip. The chin is irradiated with the patient's head stretched far back, and at the same time care must be taken to protect the chest with a leaden mask. If the upper lip is to be exposed, a mask should be used covering the entire face, having an aperture coinciding with the part treated. Treatment should not be commenced before the hairs are long enough to be grasped, and the patient must be told never to pull out the hairs herself. The first signs of skin-reaction are usually seen after 20-25 sittings; these signs have already been considered at length (p. 255). The other methods of irradia- tion were also described in detail (pp. 250, 257, 258) and need not here be repeated. The author has not observed any differ- ences with regard to the reaction of blondes and brunettes. Occasionally fine lanugo falls more readily than the thicker medullated hairs; the reverse is, however, far more frequently the case. The later course of the reaction is as follows : After a few days, during which the earlier signs of reaction increase in intensity, the hair begins to fall out in thick tufts when lightly grasped, or it is seen on the towel after the patient's toilet. The hair-roots are thin and atrophied (see the "Physiology of Roentgen-radiation"), the skin is smooth and white, and the patient often feels a slight burning and sensation of tension. These signs disappear in a few days (5 to 8), including the sometimes marked pigmentation (which is especially seen in the . TREATMENT WITH X-RAYS 277 case of brunettes), and the skin again appears quite normal. If no further treatment be adopted fine hairs again make their appearance in the course of 6-8 weeks; these grow gradually to their former size. 1 ) If, however, after 4-6 weeks (even before there are the slightest signs of relapse) a brief supplementary treatment be undertaken, the skin will preserve its good appear- ance for another 4 or 6 weeks, after which period the process must be repeated. In this way the treatment must be kept up for 12-18 months, after which time a permanent cure may be expected. The author has had already a large experience, which war- rants him in saying that the series of supplementary courses of treatment as indicated above turns the depilatory effect from a transient to a permanent one. He bases this opinion on the repeated examination of a number of patients since their final exposures to the tube, in whom not the slightest signs of relapse were evident. At the termination of the sittings the skin looks plump and well nourished, as described earlier (p. 251). After a few months, however, it alters somewhat in appearance, the change depending solely upon the extent to which the treatment was pushed. The final effect is most perfect in those cases in which, during the whole series of operations, the intensity of the irradiation was regulated to such a nicety that no very marked changes were visibly produced in the skin. In this event the skin appears quite normal, and more or less smooth according to the age of the patient. In the site of the follicles one finds either very fine whitish points, which disappear after a time, or (in places which have been less exposed to the tube), exceedingly small white lanugo-like hairs; the latter do not increase in size and are prac- tically unnoticeable. Jutassy and K. Minich found on microscopic exami- nation the following conditions in a rabbit's skin which ') If the initial course of treatment was mure energetic relapse will take place much later — after three or four months. 278 RADIO-THERAPY had been epilated by X-rays. 1 ) The stratum malpighii presents a straight line bordering the cutis; only here and there can a hair-follicle be seen. These follicles pene- trate to various depths; the major part are found in the superficial layer of the cutis. They possess no lumen; in place of the hairs we find atrophied epidermic cells or their remains. Some of the follicles penetrate to a deeper layer of the cutis; in these thin, black hair-rests are to be seen, which are shrunken from the papilla. The papilla pili looks atrophied, and consists of small, light-coloured degenerated cells. The hair-groups which characterise the normal skin are absent, nor can their follicles be discovered. In place of the latter one finds richly-cellular connective tissue. Pigment granules are found here and there in the deeper layers of the cutis; in this region, too, the blood-vessels are found widely dilated and filled with blood-cells; there are, however, no thrombi. No abnormalities can be found in the larger nerves. The main feature is the atrophy of the follicles and the hair-papillae. If during the course of treatment the signs have been more severe — marked intumescence and erythema, or perhaps slight excoriation — one finds changes in other parts besides the follicles. The sites of the latter are marked by small scar-like depressions, and the whole of the irradiated skin appears thinner and more wrinkled than is natural. The wrinkles may not be noticeable while the facial muscles are at rest, but they become quite evident when the patient talks or laughs. 2 ) In other cases, particularly with brunettes, the skin remains darker than usual for some months; in course of time this excessive pigmentation disappears. In one case, that of a fair- haired girl who had been under treatment intermittently for 15 months for hypertrichosis of the forearms, and in whom somewhat marked erythema (without excoriation) had thrice arisen, a reddish-brown spotted discolouration remained after ') Orvosi Hetilap, 1898, 21-23. z ) According to Ehrmann, the wrinkling results from atrophy of small handles of connective tissue in the skin. TREATMENT WITH X-RAYS 279 treatment which disappeared very slowly. The elephantiasis- or sclerodermia-like thickening of the skin, described as an after- effect of Roentgen-radiation by many writers (Balzer and Mon- seaux, Salomon, Barthelt my, Behrend, Hallopeau and Gadeau), has not as yet been seen by the author. He has, however, seen cases treated by others which during their course had developed excoriations and ulcers. The scars were marked by extensive telangiectases which considerably impaired their appearance, the scars themselves being smooth and otherwise not very dis- figuring. Another result of too intense and too frequent expos- ure was described by ./. C. Johnston. l ) A medical man, who for four or five years had been working with X-rays, observed the back of both his hands to be going red, dry, slightly scaly and somewhat itching. About 20 small tumours developed, varying in size from a pin-head to half an inch in diameter, and forming hard, shining, horny elevations which were depressed in the centre and surrounded by a reddish areola. On microscopic exami- nation, these proved to be epithelial accumulations. The epidermis was considerably thickened throughout; moreover there were large masses of epithelial cells lying in trabecular, and small clusters between the con- nective-tissue fibres. Johnston regarded the condition as one of those keratoses which, like leucoplakia oris or verruca seborrheica, are considered to be often the fore- runners of carcinoma. Reviewing the advantages and disadvantages of this treat- ment for hypertrichosis, we find we have here one of the most reliable remedies within the reach of the medical man, inasmuch as its depilatory effect is certain. We must note that it causes all the hairs — the lanugo-hairs as well as the thicker ones — to fall; that large areas of the skin can be treated at a time; that though a relatively long time is required for permanent cure the actual sittings occupy but a brief period, so that the patience and endurance of patient and operator are not too severely '; Philadelphia Medical Journal, Feb. i. 1902. 280 RADIO-THERAPY tried. It must be borne in mind, moreover, that by proceeding on the right lines in the first instance and giving supplementary sittings as they are required, the epilation which is first pro- duced may be made permanent. We possess in the Roentgen- treatment an absolutely painless method of epilation, a method which enables us to dispense with drugs, dressings, manipula- tions on the part of the patient. It is, morever, one which does not attract attention or compel the patient to interrupt her usual avocations or social intercourse. We find also that the treatment has a definitely limited dura- tion; it matters not whether a small area of skin or the whole face has to be treated. At the same time it must be remem- bered that under certain circumstances changes in the skin occur which cannot be considered as advantageous to the complexion. It is possible that, with increased experience and ability, we may be able to avoid this contingency with certainty; nevertheless at the present stage of our knowledge the possibility of this con- tingency is one which must be put to the patient before com- mencing treatment: she must be asked whether she prefers her hirsute appearance to some facial wrinkles which may develop after treatment. Where the hairy places are small and circumscribed, the author, in common with Ehrmann and Schiff, would unhesitat- ingly advise electrolysis. Under any circumstances it would seem advisable to avoid visible reaction as far as possible. Considering the numerous undoubtedly successful results which not only the author and Schiff, but many Austrian, German, English, American, Hungarian and Swedish writers report (Grumnach, 1 ) Levy-Dorn, 2 ) Grouven, 3 ) Hahnf) Benedikt, 5 ) Sjogren and Seder- holm /•) Sharpe, 7 ) Dumstrey, 8 ) Neville Wood?) Deutsche med. Wochenschr., 1899, 37. Eulenburg's "Real-Encyclopadie," Article "Roentgenstrahlen." Niederrh. Gesellsch. f. Natur- u. Heilk, zu Bonn, Feb. 12, 1900. Aerztl. Verein in Hamburg, Nov. 19, 1900. Wiener med. Wochenschr., Nov. 19, 1900. Fortschr., Vol. IV, p. 163. Archives of the Roentgen-rays, Jan. 1901. Schmidt's Jahrbiicher, Vol. CCLVI. 9 ) The Lancet, Jan. 27, 1900. TREATMENT WITH X-RAYS 281 James Startin, 1 ) Kienbock, 2 ) Jutassy, 8 ) Havas*) Ullmann, 5 ) Pusey, G ) G. 11. Lancashire;)) — results some of which have been demonstrated and acknowl- edged at many congresses of leading dermatologists — the objections raised by Oudin and Barthelemy 8 ) against the Roentgen-treatment of hypertrichosis seem hardly justified. These writers are apparently of the opinion that internal organs may be injured by the process. Probably the "visceral accidents" they speak of, and which they ascribe to some influence on the sym- pathetic system, are to be explained by the hysterical character of so large a proportion of the class of women who would resort for this treatment to the Paris hos- pitals. Under certain circumstances the depilatory effect of the Roentgen-rays may be used for other purposes. Its application in this respect for sycosis, etc., has already been mentioned. Gocht") reports the case of a patient who had been operated upon for lymphadenoma of the neck. The edges of the wound became folded over, and owing to the irritation caused by the hairs healing was impossible. Epilation by Roentgen-rays resulted in per- fect healing of the wound. 2. Ulcerations and skin-affections leading to ulceration. Lupus vulgaris. The radio-therapy of lupus has received the greatest atten- tion and study by dermatologists. A really certain and reliable remedy for this most serious and obstinate disease has long been The Lancet. March 3, 1900, and Nov. if>, 1901. Wiener med. Club, Feb. 6, 1900. L. c. Festchr. f. Prof. Kaposi. K. k. Gesellsch. d. Aerzte in Wien, Oct. 26, 1000. The Journal of the American Medical Association, Sept. 28, IOOI. Brit. Med. Journal, May 31, 1002. La Radiographic, 1000, No. 39. Fortschr., Vol I. Pari 1. p. 17 2 8 2 RADIO- THERAP Y a desideratum; the affection is one which has been treated for decades past with no altogether satisfactory results. It must still be left an open question whether in Roentgen-radiation we have attained what has been so long wished for — a specific for lupus — and if the treatment will supplant all other methods. That lupus vulgaris can be cured by X-rays is beyond dis- pute; it still remains, however, to be proved that the process is easier of adoption and quicker to achieve success than other methods. The author is of opinion that the advantage of the Roentgen method is to be found: (i) in its being a bloodless process; (2) in its excellent cosmetic results (see Figs. 80 and 81). As regards the time required for the treatment, this is much the same as that required for the older methods or for Finsen's light-treatment. Just as in the Roentgen-treatment of hypertrichosis we have the choice of two schools. The one deprecates the production of dermatitis, regarding this as not only superfluous but as actually injurious and retarding the cure (Schiff, Freund, Albers-Schonberg, Hahn, Grouven, Kiimmel) . On the other hand, the opposite school recommends the deliberate excitation of powerful reactions, believing that in this way a scar may be obtained of good appearance and free from relapse for a con- siderable period (Lion, Scholiz) . The technique of the rival methods has already been described in this work. Suffice it to note here that by one method (with hard tubes and considerable tube-distance) a com- paratively large number of sittings is required, whereas with the other method (soft tubes and shorter tube-distance) a smaller number of sittings has the effect of producing very strong reactions. The usual course of events where the first method is adopted is as follows : the first signs of reaction in the lesions shew them- selves in the form of an alteration in their colour. They become hyper£emic, and visible nodules become dark-red; at the same time the morbid tissue swells. Later on the visible nodules break down and often necrose entirely away, leaving small, sharp-cut ulcers in their site. The whole site of the disease may be deeply indurated, and neighboring glands enlarged. The TREATMENT WITH X-RAYS 28' ulcers soon heal, leaving small scars. These scars for the first few weeks may present a perfectly sound and healthy appear- ance, the general intumescence and tension of the parts having not as yet suhsided. The tuherculin-test applied at this stage, however, proves cure to he incomplete (Neisser, Lion, Scholiz), and after a time, when the swelling has suhsided and the tissues have again become lax, more deeply-seated nodules become evi- Fig. 80. Fig. 81. Fig. 80. — Before treatment. FlG. 81. — After one year's intermittent treatment with X-rays. dent. After a few weeks, therefore, the treatment requires to be repeated again and again, until all traces of disease have finally disappeared. This in a case receiving no auxiliary treat- ment may take a year or more. It is worth noting that after a fairly prolonged treat- ment with X-rays lupus nodules often become visible 284 RADIO-THERAPY in regions which had hitherto been considered healthy. The rays would appear to have an elective action on the lesions — a peculiarity which was demonstrated by the physicist E. P. Thompson to exist in the case of many substances exposed to X-rays. The other method has for its object the destruction of the disease "en masse;" it may be regarded, though not altogether correctly, as a cauterisation of the whole lesion by means of Roentgen-radiation. The method is certainly more radical, and the duration of the actual treatment is very short. Never- theless, it is very questionable if the patient gains any advantage even in this direction. In place of his disease, he is now pro- vided with an ulcer which is exceedingly slow in healing and is, moreover, excessively painful; thus he is deprived of what should be the chief advantage of radio-therapy, viz. : its pain- lessness. Scholtz has shown the histological changes to be simi- lar whichever method be employed — molecular destruction of the morbid cell-growth, reactive inflammation and replacement of the lupus tissue by connective tissue. But the whole course of reaction is much milder with the first method, the patient is spared pain, and the proceeding is more conservative of healthy tissue; whereas with the more drastic method the whole tissue, healthy and diseased, within the zone of irradiation becomes necrosed and has to be replaced by scar-tissue. As has been pointed out earlier, the milder method requires more skill in its practice. Comparing the X-ray treatment of lupus with Finsen's method, it must be noted that according to reports published up to the present time the latter shews a larger percentage of radical cures. In connection with this point it may be observed that up to now Finsen's method has had the advantage of being carried out in well-appointed public institutions, on a properly regulated system. Thanks to the courtesy of Hofrath Prof. ./. Neumann, the author has now the opportunity of treating hospital cases also; he hopes in due course to be able to supply reliable data therefrom. Nevertheless the author must again remark that by the aid TREATMENT WITH X-RAYS 285 of the Roentgen-treatment he has succeeded in a great number of cases (sometimes, it is true, with the additional help of chemical applications) in obtaining radical cures of lupus. The scars have been of excellent appearance, moreover. He would advise those who contemplate the practice of radio-therapy, but whose resources are limited, to purchase an X-ray apparatus. Public institutions and private individuals who can afford the outlay should certainly possess Finsen's apparatus as well. In case the Roentgen-treatment of lupus be decided upon, one should undoubtedly employ the milder method of its appli- cation where large areas of disease are concerned. Smaller and more circumscribed lesions may be destroyed, too, in this way, due care being taken to protect the surrounding healthy parts with leaden masks. In these cases, however, the author's own predilection is in favour of radical excision and suture or Thiersch's method of transplantation. G. H. Lancashire 1 ) recommends the X-ray treatment of lupus where ( 1 ) the disease is too widespread for Finsen's treatment; (2) where there is much ulceration; (3) where unsightly scars add to the existing disfigurement; (4) where the mucous membranes are involved. /. Neumann 2 ) believes it to be the treatment "par excel- lence" for "lupus tumidus et exfoliativus" of the face, also for the hypertrophic forms involving the skin and sometimes the fascia and muscles, which have hitherto been considered incurable. Lupus ulcerations of a sluggish character assume quite another appearance after a careful series of irradiations; healthy granulations spring up and cicatrisation begins. Lupus of the mucous membranes is also favourably influenced. The first sign of reaction in these cases is increased secretion; thus a patient with nasal lesions presents the symptoms of nasal catarrh. Cavities of this kind may be irradiated through a leaden tube or speculum, the skin round the orifice being care- fully protected by a leaden mask. ') British Med. Journal. May 31. 1002. 2 ) K. k. Gesellsch. d. Acr/.u in \Yi< n, Oct. 26. 1900. 286 RADIO-THERAPY Himmel 1 ) found the following histological appearances in a section of a lupus nodule which had been subjected to the rays : The epithelium, which formed a thin narrow border to an apparently homogeneous mass, was perforated by small aper- tures, the size of which did not exceed the diameter of a cell- nucleus. Nowhere could the exact outlines of the individual epithelial cells be made out. The corium appeared shrunken. The individual bundles of connective tissue were packed closely together, thickened, and translucent. Elastic fibres could not be recognised. In stained specimens the cells of the connective tissue appeared shrunken; they took the stain badly. The lupus growth itself appeared greatly changed. The giant-cells were small ; they were seen as small, shrunken homogeneous bodies in which the nuclei were but faintly indicated; the epithelioid cells were four or five times smaller than usual, had lost their normal shape, were homogeneous, and their nuclei did not stain. The lymphoid cells had become transformed also into small shapeless bodies. The outlines of individual cells could often not be distinguished, they being so closely pressed together. The general microscopic appearance of the sections suggested a slow necrotic process going on in the lupus nodule, the epithe- lium, and part of the corium. Hueter 2 ) found that the tuber- cular tissue gradually underwent a fibrous transformation. A remarkable feature was to be found in the large number of giant-cells present. These were often situated eccentrically or close to the periphery of the nodule; many nodules seemed to consist almost entirely of giant-cells. The zone of leucocytes bordering the tubercular foci was very narrow or entirely absent. The nodules were closely encircled by bands of thick connective tissue, rich in nuclei. The line of demarcation between the morbid growth and this connective tissue was sharply pro- nounced. No tubercle bacilli were seen. ') Archiv. f. Dermatologie und Syph., Vol. L, p. 335. 2 ) Quoted by Halm and Albers-Schonberg, Miinchener med. Wochen- schr, 1900, Nos. 9-1 1. TREATMENT WITH X-RAYS 287 Dr. Grouven, whose investigations in this Held are most valuable, reports as follows 1 ) : "When examining with low powers, we are struck by the abundance of connective tissue which encapsules the several tubercular foci in the form of thick bundles of fibre, penetrating more or less freely the interior of the foci themselves ( Fig. 82 ) , and thus forming a closely woven network enveloping the residuum of the morbid growth. The spindle-cells, which are Fig. 82. — From C. Grouven, "Histological changes in lupus tissue after Roentgen treatment." Fortschr. a. d. Geb. d. Roentgenstr., Vol V, Part 3. p. 186. Fig. 83. — A giant-cell enclosed by new-formed connective tissue, highly mag- nified. From C. Grouven, 1. c, p. 187. present in great numbers (Fig. 83), suggest the active prolifera- tion of connective tissue. Under higher powers the epithelioid and lymphoid cells are seen to be greatly degenerated; this degeneration is shewn by the poor staining-properties of the nuclei, disorganisation of the nuclei, and vacuolisation changes in the cell-protoplasm. The general changes arc analogous to those described by Gassmann as occurring in the vessel-walls of Roentgen-ulcers." *) Niedcrrh. Ges. f. Nat. u. Hcilw., Bonn, June 17. 1001. Fortschr. a. d G. d. Roentg. Vol. V, Part 1. 288 RADIO-THERAPY Doutrelepont describes the process of healing of lupus under Roentgen-treatment as follows : "The first effect of irradiation is the production of hyper- emia ; this leads to increased migration of leucocytes from the vessels. Just as in the tuberculin-reaction the infiltration of leu- cocytes begins at the border of the diseased focus ; it, however, penetrates the latter also, there to transform itself probably into spindle-cells and fibrous connective tissue. The morbid cells themselves degenerate; thus we get a gradual absorption of the diseased tissue and its replacement by cicatricial tissue." According to Scholtz, 1 ) the primary effect is not hyper- emia, leucocyte infiltration, and fresh formation of connective tissue, the secondary one being destruction of lupus nodules. He believes that the reverse holds good: under the action of Roentgen-radiation we have, in the case of lupus, first a degen- erative process in the cell-elements, especially in the giant- and epithelioid-cells of the morbid lesions themselves; this is followed by inflammatory reaction. Scholtz believes the healing of lupus is mainly brought about by this inflammatory process, that in conse- quence of the degeneration in the morbid cells the inflammatory reaction is directly concentrated upon the diseased foci, and that we have, therefore, to deal with a selective effect of irradiation in this instance. Neisser 2 ) compares the effect of Roentgen-radiation with the tuberculin-reaction. In the former, however, the process is a slower one, and is attended by passive hyperemia. By this the cicatricial encapsulation, and, under certain conditions, the absorption and destruction of the tubercular foci is effected. "Especially in the case of Roentgen-dermatitis one can see," says this author/ 5 ) "that the old view with regard to inflamma- tory irritation is wrong, and that Weigert was correct in advanc- ing the doctrine that in all these processes we have always to deal with primary tissue-lesions, which are followed by inflam- matory reaction." What we see in the most marked forms of *) Archiv. f. Dermatol, u. Syph., Vol. LIX, Part 3. 2 ) Ebstcin-Schwalbc's Handbuch der prakt. Med., Vol. Ill (Skin Diseases). 3 ) Quoted by Scholtz, p. 242. TREATMENT WITH X-RAYS 289 Roentgen-necrosis takes place most probably also in those milder alterations in which actual destruction does not become visible under the microscope. Many writers speak of good results with this treatment. The first report in this field came from Kiimmel (26th Congr. d. deutsch. chirurg. Gesellschaft, 1897). The author, in conjunction with Schif, treated two cases on which he reported at the 12th Internat. Med. Congress, held in Mos- cow, and which Schif mentioned at the Naturforscherversamm- lung, Braunschweig, 1897. Further reports came from Gocht') and Albers-Schonbcrg 2 ) followed by Sonnenburg, 3 ) Neisser, 4 ) v. Ziemssen*) Gassmann and Schenkel,*) Sten- beck, 1 ) Ch. Schmid;) Grunmach?) Sharper) Newman? 1 ) Hall-Edzvards, 12 ) Sholefield, v ') Rona; 4 ) Jutassy, 15 ) Grou- ven 1 *) J. Neumann''') Himmel 1 *) Lion, 19 ) Schell, 20 ) Sjorgen cif Sederholm 21 ) Clark and Smith, 22 ) Pusey, 2i ) Geyser, 2 *) a> B ') Fortschr. I, i, 15. 2 ) Ibid. I, 2 and 3; II, 1, 23; Miinchener Med. Woch., 1900, 9-11. s ) Freie Vereinig. d. Chirurg., Berlins, Jan. 10, 1898. 4 ) Schles. Gesellsch. f. vaterl. Cultur, May 20, 1898. 5 ) Aerztl. Ver. Miinchen, June 8, 1898. °) Fortschr., II, 4, 1. ') Hygiea, Vol. LXI, p. 568. 8 ) Fortschr., Ill, 1, 1. 9 ) Deutsche med. Woch., 1899, No. 37. 10 ) The Roentgen Society of London, Nov. 6, 1899. Archives of the Roentgen Rays, Jan. 1901. 11 ) The Roentgen Soc, London, Nov. 6, 1899. 12 ) Fdinburgh Medical Journal, March, 1900. 13 ) Brit. Med. Journal, May 5. 1900. 14 ) Konigl. Gesellsch. d. Aerzte, Budapest, Nov. 9, 1899. ») L. c. M ) L. c. ") K. k. Gesellsch. d. Aerzte, Oct. 26, 1900. u ) Archiv. f. Dermatol, u. Syph., Vol. L, p. 335. M ) L. c. 20 ) Archiv. d'electr. medic, experiment et clinic, 1900, No. 96. 21 ) Fortschr.. IV, 5. 1 |m 2: ) Buffalo Med. Journal, Jan., 1901. ") The Journal of the American Medical Association, Dec. 8, 1900, and Sept. 28, tox)] 2l ) Aerztegi ell ch., New York, January, 1901. 2 9 o RADIO-THERAPY Jones, 1 ) Knox, 2 ) Lapinski, 3 ) Kirmisson, 4 ) Norman Walker, 5 ) Jadassohn,') Fan Dort, 7 ) Thurnwald, 8 ) Jeney, 9 ) Dn Castel and Foveau de Courmelles 10 ) J. de Nobele, 11 ) Stenbeck, 12 ) Holland,™) P. R. Egau 1 ') G. H. Lancashire, 1 *) G. H. Rad- man, u) ) J. C. Squance, 17 ) P. A. Morrow 1 *) and others. Most of these writers agree that Roentgen-treatment acts beneficially in the case of lupus, but that the duration of the treatment is a very long one, and that it is advisable to combine this method with others, such as cauterisation, scraping, etc. Grouven and Aronstam 19 ) reported similar good results in the case of scrofulodermia. Ivar Bagge 20 ) cured tuberculous ulcerations which had appeared on the chest in the site of old cauterisation-scars in an elderly man by means of X-rays. The rays were only directed on the chest, but this writer reports that at the same time some ulcerations existing on the back of the patient also healed. Sjogren and Sederholm treated 5 cases which they consid- ered to be of the nature of tuberculides with very successful results. (According to their reports, these cases seemed to par- take somewhat of the nature of perniones, or to suggest lupus erythematosus.) After 15-58 sittings the swelling and infiltra- I ) Philadelphia Med. Journal, Jan. 6, 1900. ' ) Journal of the American Med. Association, Nov. 10, 1900. 3 ) Gazette lekarska, Vol. XIX. 4 ) Soc. de Chirurgie, Paris, 1898, 2, 11. s ) Lancet, January, 1900. 6 ) Encyclop. d. Haut- und Geschlechtskrankheiten, 1900. 7 ) Tijdschr. v. Geneesk, 1900, No. 18. s ) K. k. Gesellsch. d. Aerzte, Oct. 26, 1900. °) Wissensch. Verein d. Militaraerzte der Garnison, Wien, Jan. 26, 1901. 10 ) Annales d'electrobiologie, 1898, Nov. 15. II ) Ibid. Vol. Ill, p. 236. 12 ) Quoted by Mocllcr, Der Einfluss des Lichtes, etc., Bibliothek. med., p. 121. ") Archives of the Roentgen Rays, May, 1901. ") American Medicine, Nov. 16, 1900. 13 ) Brit. Med. Journal, May 31, 1902, p. 1329. 10 ) Lancet, Nov. 16, 1901. 1T ) Ibid. 18 ) New York Dermatological Society, March 25, 1902. 10 ) Journal of Tuberculosis, Oct. 1901. 20 ) Fortschr. auf. d. Geb. d. Roentgenstr., Ill, 6, p. 218. TREATMENT WITH X-RAYS 291 tion receded and the irritation disappeared. In some cases there was slight atrophy of the skin left afterwards. Epithelioma, Ulcus rodens. In his able monograph "On the Influence of Light upon the Skin," with which we shall deal more closely in the next section, Magnus Moeller mentions a case of epithelioma of the face, treated by Sjogren, in which Roentgen-radiation had a marvellously good effect. The illustration bears out this impression. Irradiation with hard tubes was employed; the current-strength was 2.5-3 amperes, and the tube-distance 15 cm., the duration of each exposure being 10 minutes. After 15 sittings the scabs became detached and the ulceration com- menced to heal. In the course of two months the ulceration had entirely healed; there was at no time any marked reaction, and the skin retained an almost normal appearance. Later on, however, an acute dermatitis set in on the eyelid which led to ectropion of the lower lid. Altogether 100 exposures were given. Sequeira x ) reported four cases of ulcus rodens, the diagno- sis of w T hich had been microscopically confirmed. In these Roentgen-radiation had given excellent results. In a later pub- lication -) the same writer reported 12 cases of the same dis- ease and perforating ulcer treated by X-rays. live of these cases were cured, but of their permanency the writer could not at that time speak. In a third report (British Medical Associa- tion, Section of Dermatology, Manchester, 1902), Sequeira stated that he had indeed observed relapses after X-ray treat- ment, but that these were in turn entirely removed by further treatment. Out of 80 cases of rodent ulcer 34 were cured. He believed that those cases were unsuitable for the treatment in which bone or cartilage are involved; he found the hard- growing border of the disease resisted the treatment for a lony time. ') Roentgen Society of London. Jan. 3, 1901. 2 ) Treatment. March, 1901, No. 1. 292 RADIO-THERAPY Th. Stenbeck 1 ) treated 2 cases of epithelioma by X-rays, exposures being given daily for several months. Reaction set in after 8 days. On pressure fairly long yellowish plugs could be squeezed from the diseased area. The cases healed com- pletely and without relapse. In Stenbeck' s opinion the irradia- tion acts electively. In 4 later cases Sjogren ~) observed after 25-33 sittings absorption of induration, removal of scabs, healing of ulcers, and disappearance of subjective phenomena, such as pricking- sensations and tenderness. The skin afterwards looked soft and smooth and a shade darker in all these cases. The treat- ment was carefully carried out, reaction being avoided as far as possible. Stenbeck and Bolleau published in the July number of the Archives d'electricite medicale 5 other cases of malignant dis- ease treated in this way. In a report published in the 73rd Naturforscherversamm- lung,' 1 ) Sjogren advised the deliberate induction of energetic reaction so that necrosis and sloughing of the morbid tissue might be effected. He states that the result of this procedure is to leave a clean open wound which heals with a clear atrophic scar. Of the cases thus treated by him several had remained free from relapse up to the time of writing (| to 1 year). Johnson and Merill 4 ) observed in 5 cases of epithelioma that Roentgen-radiation diminished suppuration and, after about 50 sittings, brought about healing almost without any visible scar. Both operators used soft tubes, and endeavoured to produce "Roentgen-burns" (sic). Chamberlain 5 ) obtained very favourable results in 13 cases of carcinoma of the skin by means of hard tubes at 4-6 inches distance, 6 minutes expos- ures, and sittings held daily, or later twice a week. This author *) Congr. internat. d'Electrologie et de Radiologic medicales, Paris, 1900. Annales d'electrob., Sept., Oct., 1900. 2 ) Fortschr., IV, 4. p. 166. ") Fortschr., V, No. t, p. 38. . , ■*) Philadelphia Medical Journal, 1900, No. 8. °) Journal of Electro-therapeutics, New York, May, 1901. TREATMENT IF ITU X-RAYS 293 recommends for X-ray treatment those cases in which there are as yet no signs of glandular involvement. Other good results in cases of carcinoma were reported by Smith, 1 ) Williams, 2 ) Pusey, 3 ) G. B. Ferguson;) J. B. Levack, 5 ) I. F. Rinehart/) Walker, 7 ) Morgan;) Pugh, 9 ) Morton, 1 ") Taylor, 11 ) Williams, 12 ) and Schiff 13 ). Pusey observes that he employed the method recommended by the author and Schiff (hard tubes). G. H. Lancashire describes the course of events in a case of ulcus rodens treated by Roentgen-rays as follows: In the first place the hard border of the growth becomes softened, the neighbourhood becomes erythematous; the wax-like appearance of the ulcer-base gives way to a darker red, its smoothness disappears and granulations shew on the surface, which grow apace. In course of time the base of the ulcer becomes level with the surrounding skin, and may even reach a higher level. Gradually new epithelium spreads over the ulcer from its borders. On the whole, from the comparatively little experience so far gained, it may be said that Roentgen-radiation is an effective remedy in malignant affections of the skin which have not already involved the lymphatic glands, a remedy which removes the disease at any rate for a considerable time, and gives excel- lent cosmetic results. As regards the question of the intensity of irradiation which should be applied, the remarks already made on this subject when dealing with lupus will apply here with equal force. Several writers {Sjogren, Chamberlain, 2 i s a t 10 [902. 12 Philadelphia Medical Journal, Dec. i, 1900. Boston M. & S. Journal. Jan. 17 and April 4. 1001. The Journal of the American Medical Association, Sept. 28, 1901. Brit. Med. Journal, Feb. 1, 1902. Scot. Journal, Feb., 1902. Philadelphia Med. Journal. Feb. 1. 1902. Liverpool Med. Inst., April 17, i'J02. Ibid. Feb. 13, 1902. Brit. Med. Journal, April 12, [902. Med. News, April 5. 1902. Brit. Med. Journal, May 3, 1902. and Brit. Med. Assoc, Manchester, Ibid. K. 1,. Gesellschaft der Aerzte in Wien, Feb. 21, 1902. 294 RADIO-THERAPY Pusey, Schiff) have recorded that they have obtained good results with the milder method — the use of hard tubes. For several weeks preceding the publication of his work the author, in conjunction with Prof. Ehrmann, had been treat- ing a case of carcinomatous ulceration of the soft palate. This was in a patient 60 years of age, and the diagnosis had been confirmed by means of the microscope. The ulcer was the size of a thaler and 1 cm. in depth. Its borders were hard, the base coarsely granulated and readily bleeding. There was con- siderable pain. The method of treatment was as follows: The patient held in his mouth a tube lined with lead-foil, one end of which was placed over the ulcer. The face was pro- tected by a leaden mask. A hard tube was placed opposite the external aperture of the tube, and exposures given for ten min- utes daily. After the seventh exposure the borders of the ulcer felt considerably softer, and its size had decreased centripetally to that of a kreuzer; there was no visible reaction. Moreover the pains had been relieved and the swelling of the lymphatic glands had been strikingly diminished. Scholtz 1 ) found by microscopic examination of Roentgen- ised-carcinomata that the malignant cells degenerated and were finally destroyed just as in the case of normal epithelium. One specimen shewed abundant signs of commencing mitosis. Mycosis fungoides, Lepra, Sarcoma of the Skin. Scholtz describes 3 cases of mycosis fungoides in which an energetic treatment by Roentgen-rays was followed by super- ficial necrotic changes leading to complete disappearance of the morbid lesions, including both fully developed tumours and pre-mycotic foci. Norman Walker and H. G. Brooke have also reported good results in the case of the same affection 2 ). One case of sarcoma of the skin was also favourably influenced. In two cases of lepra, however, Scholtz achieved no success; de la Camp's experience was similar ;t ) . J ) L. c. 2 ) Brit. Med. Assoc, Manchester, July 30, 1902. 3 ) Fortschritte, Vol. IV. TREATMENT WITH X-RAYS 295 Scholtz examined histologically the effect on the lepra lesions by Roentgen-radiation. He found the morbid infiltration rather less in the regions treated, while the bacilli, which were abundantly present, were slightly more granular in appearance than elsewhere. They were, however, readily stained, and had certainly not diminished in numbers. Irradiation had therefore produced practically no effect on the pathogenic micro-organ- isms. Chronic ulcerations of various kinds. Many reports have been published which shew that chronic ulcers of various kinds which had proved partially or com- pletely refractory to other methods of treatment healed readily under X-rays. Thus Sjogren and Sederholm x ) described four cases of ulceration (their exact nature was not indicated) in which 17 to 38 exposures of 10 minutes each brought about healing. Weak currents were employed. Colleville 2 ) treated varicose ulcers in this way, and Sequeira 3 ) some cases of perforating ulcer. Both obtained successful results. Further experience in this branch of Roentgen-therapy is much to be desired. J. Acute and chronic exit dative Derma litis, and granulation- formations. Hahn and AlbersSchbnberg*) found that Roentgen- radiation in the case of chronic and acute eczema resulted in diminution of the discharge, drying of the skin, relief of itch- ing, and removal of crusts and scales after comparatively few exposures 2 ). Many other writers confirmed these observations (Grunmach : ) v. Ziemssen,') Jutassy," 1 ) Sharpe, 8 ) Sjogren ') Fortschritte, Vol. IV. No. 4. p. 162. : ) L'Union med. du Nord-Est, Aug. 30, [897. *) Medical Record, moi. ') Fortschritte, Vol. II. No. 1. pp. [6-24. °) Deutsche med. Wochenschr.. iSgo. \'<>. 37. ') Congr. f. Innere Medicin, Wiesbaden, [898. ") Fortschritte, Vol. Ill, No. 3, p. n8. '1 Roentgen Society of London, Nov. 6, [899. 296 RADIO-THERAPY and Sederholm, 1 ) Payne, 2 ) Scholtz, 3 ) Schiff 4 ) and others). All these writers stated that a course of 6-20 sittings consider- ably relieved the trouble. Sjogren and Sederholm noted espe- cially good results in cases associated with lichenification and exudation. The author's own experience in this field is not very large. Up to the present time he has seen no reason to abandon the well-tried treatment of eczema, as taught by the Viennese school, in favour of Roentgen-therapy. He believes that no new form of treatment deserves recognition unless it proves effective when other methods have failed, or unless it does bet- ter than what has been done before. Nevertheless, he has tried the Roentgen-treatment in some cases of eczema by way of experiment, and can quite confirm the opinions of Hahn and Albers-Schonberg. In these experiments the author adopted his usual technique, using hard tubes at a good tube-distance, and suspending operations at the first signs of reaction. The effect was at first to produce diffuse reddening, slight intumescence and signs of desquamation. In two cases the results were not permanent, the disease afterwards appearing again. In a case of eczema, with tylosis of the palm, the treatment proved ineffective. Roentgen-treatment for Psoriasis was adopted with more or less success by Albers-Schonberg*) Grunmach*) v. Ziemssen, 7 ) Rubinstein*) Sharpe*) Payne, 10 ) Fortschritte, Vol. IV, No. 5, p. 175. Roentgen Society of London, Nov. 6, 1899. L. c. Dermatologen-Congress, Breslau, 1901. Fortschritte, Vol. II, No. 4, p. 141. L. c. Aerzte Verein Miinchen, June 8, 1898. Berliner med. Gesellsch., Nov. 8, 1899. L. c. L. c. TREATMENT WITH X-RAYS 297 Grouven, 1 ) Hahti, 2 ) Sjogren and Sederholm, 3 ) and Scholtz 4 ) . They found that after the first 4 or 6 exposures the scaly plaques fell off without leaving the bright-red points character- istic of psoriasis (TIalin, Albers-Schonberg) . Large plaques must be exposed at a considerable tube-distance. Exposures are given daily for the first two or three times, then every alternate day, and finally every third day (Scholtz) . The author himself recommends treating the disease, when it involves a large sur- face of the body, with the tube at 30 cm. distance, giving expos- ures of 10-12 minutes each; small plaques can be treated at a shorter tube-distance and with correspondingly short exposures. The usual course of events is as follows: Should there be any very red plaques present they become lighter in colour after three or four sittings, yellow-brown pig- mentation collects round their borders; this gradually becomes darker, reaching finally a brown-black shade. The scales fall, hyperemia disappears, and the pigmentation spreads still further. The latter, however, soon disappears. Scholtz' s experi- ence agreed with the foregoing in most cases. Sometimes the results were lasting; in other cases relapses occurred. Other observers, on the other hand, report relapse to be the rule and state that it often actually occurs during the treatment. Scholtz recommends an auxiliary treatment by the ordinary methods on the termination of reaction and desquamation. Microscopical examination of psoriasis-lesions after exposure to X-rays were made by Scholtz. He found scarcely more than the ordinary appearances seen in the disease itself. The prickle-cell and granular layers were deeper than normal, and slight infiltrations were still to be noted on the papillary body and round the sub- papillary vessels. The epithelial cells shewed the same changes which are found in normal skin exposed to X-rays. Peculiar pigmentations were visible in the papillary body and in the rete. According to Scholtz, ') L. c. J ) Fortschritte, Vol. IV, No. 5, p. 90; Vol. V, No. 1, p. .<<>. ') L. c. <) L. c. 298 RADIO-THERAPY the situation of this pigment is not intercellular, but rather in the cell-walls and their protoplasmic sub- stances. Prurigo. Scholtz treated this affection also to X-rays by way of experi- ment, but without conspicuous success. On the other hand this observer, also Sjogren and Sederholm, obtained decidedly bene- ficial results in cases of pruritus ani and vulvw after very few exposures (6 Sjogren and Sederholm) . From the few accounts to hand, unfortunately, the benefit does not appear to be lasting. Scholtz obtained a temporary improvement in cases of pemphigus foliaceus. In a case of lichen ruber planus he obtained striking success ; the papules were absorbed, the process being accompanied by desquamation and pigmentation. The relief of pruritus in general by means of Roentgen- treatment is quite comparable to that obtained by d'arsonvalisa- tion. It should be borne in mind that the presence of the high- tension electricity accumulated on the surface of a Roentgen-tube in action is quite sufficient in itself to explain the relief afforded in the cases of pruritus. Lupus erythematosus. In 1898 E. Schif treated a female suffering from this affection by means of X-rays. The disease took the common form of "butterfly-patch" on the face, and for purposes of comparison the left side only of the lesion was irradiated. Schif observed 1 ) that the exposed region became of a dark- red colour; scales became detached, and the border of the patch became levelled. Here and there spots varying in size from a pin-head to a linseed became conspicuous by reason of their intense red colouring. In course of time the Infiltration within the exposed area entirely disappeared, the skin became perfectly smooth, white, and level. The sight of the original plaque was surrounded by a thin ring of pigment. The further course of events in 1 ) Wiener med. Presse, i8qq, No. 2. TREATMENT WITH X-RAYS 299 this case was somewhat remarkable, as described in a report published a year later by the author in conjunction with Schiff 1 ). Some little time after apparent healing fresh foci of disease appeared round the original site in the shape of prominent reddish lesions, scaling, and with plugged fol- licles. The hair fell from the left temporal region, this part having come within the X-ray cone. In the course of the next few weeks the secondary lesions disappeared, leaving the skin white and smooth. The alopecia, how- ever , persisted. The appearance of permanent alopecia after a single course of irradiation without any marked reaction is quite unique. The author can only explain this circumstance by the supposition that an outbreak of lupus erythematosus must have been determined in the temple itself, since this disease, as is well known, usually leads to permanent loss of hair when affecting the scalp. There were distinct evidences, as has been said, of fresh disease in the immediate neighbourhood of the site of the original disease. These were probably determined by the irradiations. We know that other forms of irri- tants, such as caustics (Kaposi), will often provoke fresh eruptions of lupus erythematosus. In the treatment of this case extreme caution was employed; any marked reaction was avoided by the use of hard tubes. Sjogren 2 ) proceeds on different lines in his Roentgen-treat- ment of lupus erythematosus. His object is to provoke a strong reaction (redness, swelling, exudation, and scab formation). He states that after this reaction has subsided the crusts fall, leaving an atrophied light-red skin which shows no traces of follicular apertures. Scholtz adopts the same pro- cedure. The author, in company with ScliijJ and many others ') Beitrage zur Dermatologie und Syphilis. Festschrift fur Hofrath Neumann, 1900. ') I., c. 300 RADIO-THERAPY (Jutassy, 1 ) Hahn,'-) I. Neumann,') Grouven*) Llaberia, 5 ) Lion, a ) Scholtz, 7 ) [Foods, 8 ) Taylor,'') ), has found that though often enough satisfactory results have been obtained in the first instance, treatment has constantly to be resumed on account of ever-recurring relapses. By very prolonged treat- ment in many cases a permanent cure may be attained. The scars are then smooth, very white, and level with the surround- ing skin. It must be admitted, however, that many cases are made worse by the treatment (Neumann, P. S. Abraham) . Acne vulgaris, rosacea Furunculosis. Gautier and Pokitonoff 10 ) reported in 1892 upon 17 cases of acne vulgaris and rosacea, which they had cured after daily exposures of $-6 minutes each. They used currents of 4 amperes and 18-20 volts, and a tube-distance of 30 cm. After the sixth sitting the disease began to diminish, the skin became paler, dilated vessels became less evident, and healthy skin appeared amongst the pustules and papules. K. Ullmann's 1X ) experience in a case of obstinate acne of the back was as follows: After 10-15 sittings the skin became diffusely reddened and the papules swollen; the latter, however, did not suppurate, but became absorbed, whilst the overlying skin exfoliated. The disease disappeared completely after 50 sittings, leaving well-marked pigmentation behind. Hahn 12 ) and Jutassy 1S ) also obtained successful results in the case of both of these affections. *) Fortschritte, Vol. Ill, No. 3, p. 119. 2 ) Ibid. IV, 2, 86. 3 ) K. k. Gesellsch. d. Aerzte, Nov. 14, 1900. 4 ) L. c. 6 ) Fortschr., V, 1, 56. ") Dermatolog. Congr., Breslau, 1901. T ) L. c. 8 ) The American Journal of Med. Sc., Dec., 1901. •) L. c. 10 ) Compt. rend, du XII. Congr. internat. de Medecine Moscow, Vol. IV, pp. 382-386. 11 ) Wiener dermatol. Gesellsch., Nov. 28, 1900. w ) Fortschr., Vol. IV, No. 2, p. 96; Vol. V, No. 1, p. 39. 13 ) L. c. TREATMENT JUT 11 X-RAYS 301 The author's own experience includes 1 case of rosacea and 2 cases of acne vulgaris. In these distinct improvement was brought about after a rather long period of treatment with weak irradiations. Small red spots persisted for some time in place of the papules; these spots afterwards became pigmented. In one case of acne a relapse occurred a few months later. The other cases were only recently discharged, so that nothing can be said as to the permanency of their cure. In a case of chronic lurunculosis of the neck the patient was relieved of the trouble for a considerable time by irradiation pushed to the stage of epilation. Torbk and Schein explain the successful action of Roentgen-rays m affections of this class, on one hand, by their parasiticidal qualities (?), and on the other hand, by their influence on the sebaceous glands, in which, as in the sweat glands, the secretion is dimin- ished 1 ). In the author's opinion the desquamation which so often results from irradiation is the most important factor. ^. Noevus flam mens. J nt assy 2 ) claims to have cured a case of this kind after inducing an X-ray dermatitis. He says that irradiation pro- duces contraction, thrombosis, and obliteration of the vessels. In the Breslau-clinic, however, the results were less successful (Lion, Scholtz) . In conclusion we may mention that Sorel and Soret claim to have cured a case of elephantiasis-like induration of the hand, of rapid onset, after 3 sittings of 10-25 minutes each 1 ). Sjogren and Sederholm cured a case of verruca?; and finally, other operators (Gochi and Scholtz) cured naevi spili, and Turok and Schein urticaria pigmentosa by means of Roentgen- radiation. '. L c. 1 ') Fori 1 In- , Vol. TT. No. 5, p. 197. ) La Nbrmandie Medicate, Feb., 1898. 3 o2 RADIO- THERAPY The Treatment of Internal Diseases by X-Rays. No account of the therapeutic uses of X-rays would be com- plete without some reference to the facts which warrant the employment of this method in the treatment of certain internal disorders. Several able and impartial writers have already furnished us with noteworthy data upon this subject. Thus Foigt 1 ) mentions a case of pharyngeal carcinoma in a man, aet. 89, in which the pain was relieved. Gocht'-) describes 2 cases of inoperable mammary carcinoma in which daily irradiation soon relieved the excruciating neuralgic pains, without, however, affecting the appearance of the growth in any way. Johnson and Merill") described similar results. The author himself learned from a private communication which he received from an eminent surgeon in Vienna that a woman suffering from metastic carcinomatous growths in the peritoneum was relieved of intense pain by the X-ray method; the malignant process itself was, however, uninfluenced. Clark states that in a case of ulcerated carcinoma of the breast he has seen distinct diminution in the size of the tumour and of the auxiliary glands after about 30 sittings of 15 minutes each 4 ). Despeignes G ) relates the case of an old man who suffered from cancer of the stomach, in whom "considerable improvement" took place after 80 sittings held twice daily for 4-^ hour. P. H . Eifkman G ) claims that he has cured a case of carcinoma of the breast, and we learn from Dr. Wcldor of New York 7 ) that John G. Oilman of Chicago has cured 50 cases of cancer by means of X-rays. Quenisset and Seguy report that they obtained improvement in a case of recurring and metastatic sarcoma 8 ). C. Beck treated a recurring sarcoma of the lower 1 ) Aerztl. Verein, Hamburg, Feb. 3, 1896. 2 ) Fortschr., Vol. I, No. 1. 3 ) Philadelphia Med. Journal, No. 8, 1900. 4 ) Brit. Med. Journal, No. 8, 1901. B ) Lyon Med., Dec. 20, 1896. e ) Krebs und Roentgenstr., Harlem, 1902. 7 ) Revue des Revues cit. "Wissen f. Alle," 1902, No. 1, p. 14. 8 ) Quoted by Foveau de Courmelles, Ann. de medecine et Chirurgie infantile, Vol. V, No. 5, p. 164. TREA TMEN T 11 7 Til X-RAYS 303 part of the thigh in a man, aet. 36, by exposure given 2-3 times a week for 10-45 minutes, lie accomplished a "cure" which lasted for 9 weeks (sic) x ). The writer was induced by a Viennese practitioner to treat an inoperable chondrosarcoma of the left parotid gland in a man xt. 70. Treatment was given daily for 20 days, using hard tubes at a distance of 15 cm., for 6-8 minutes. Results were entirely nega- tive. A similar case treated by a colleague proved equally unsuccessful. Another property of Roentgen-radiation which has already been referred to, viz., its analgesic effect, suggested its employ- ment in painful affections generally. Stembo ~) succeeded in relieving 21 out of 28 cases of neuralgia, giving from 3 to 10 sittings of about 5 minutes each. The author has himself proved experimentally that analgesic properties of X-rays arc not to be ascribed to suggestion-effects, since with the current reversed no improvement can be obtained. The true explanation is to be found, he believes, in the electrical stimulation of the peripheral sensory nerves, which inhibits the functions of deeper-lying nerves and so relieves the neuralgia. The author succeeded in the case of an old man who suffered from a trigeminal neuralgia, which was scarcely relieved even with morphia, in bringing about marked improvement after 11 sittings; there was no visible reaction in this case. In a second case irradiation proved unsuccessful. Grunmach "') employed Roentgen-therapy with varying suc- cess in cases of neuralgia of the face, occiput, and intercostal nerves, and in articular and muscular rheumatism. Southgate Leigh ') reported before the Seabord Medical Society the case of a patient who had been shot in the upper part of the thigh, who complained of pain in the knee-joint. The pain disappeared ') Munchener med. Woch., [901, No. 32. 2 ) D. Therapie d. Gegenw., [900, X" 6 ") Deutsche med. Woch., 1899, No. ,tf- 4 ) The American X-ray Journal, Vol. IV. April. [899. 30 4 RADIO-THERAPY lifter an exposure lasting 4 hours. In another case irradiation is said to have removed colic due to biliary calculi. Rheumatic and tuberculous joint-aftections are said to have been improved by Roentgen-radiation. Sokolow treated acute and chronic rheumatism in children's joints by covering the diseased parts with woollen blankets and exposing them for 10-20 minutes at a tube-distance of 50-60 cm. He states that after 1-4 sittings the pains disappeared, the swelling perceptibly diminished, and the mobility of the limb improved *). According to SoutJigatc Leigh, a tubercular elbow-joint was completely cured by 2-hour exposures, administered two or three times a week. Kirmisson states 2 ) that he much improved a tubercular wrist-joint affection, in a girl of 14, in 65 sittings lasting 10 minutes each. Similar reports come from Bazy, Lancaster, Sainton 3 ) and Escherich 4 ) . Even pulmonary tuberculosis and acute inflammation within the chest are stated to have been cured by some authors (according to Rendu and du Castel?) by Roentgen-treatment; Bergonie and Mqngour, 6 ) Sinapius, 7 ) Chanteloube, Descamps and Rouillies, 8 ) Destot and Dubard °) . Ansset and Bedard 10 ) report on a case of chronic tubercular peritonitis. After 50 sit- tings given daily for \ hour, employing powerful tubes at a distance of 20-23 cm., the ascites disappeared, likewise the hard irregular masses which had previously been felt through the abdominal walls, and the general condition of the patient improved. Two years later these writers reported a similar case. In conclusion we may mention that Paulin Mery and ') Wratsch, 1897. No. 46. 2 ) Soc. de Chirurgie, Feb. 2, 1898. 3 ) Quoted by Bergonie, La sem. med., 1898, p. 349. ") Revue mensuelle des maladies de l'enfance, May, 1898. 6 ) Soc. med. des Hopitaux, Jan. 15. 1897. fi ) Acad, de medecine, July, 1897. 7 ) Die Heilung der Lungentuberculose durch Roentgenbestrahlung, Leip- zig. 1897. 8 ) Arch, d'electric. med., May 15, 1897. •) Gazette des Hopitaux, Aug. 13, 1898. 10 ) Echo med. du Nord, 1898, No. 461. TREATMENT WITH X-RAYS 305 Cdmpenon ] ) are said to have hastened the union of a fractured bone, and A. de Lancastre 2 ) to have cured a case of suppurat- ing osteo-periostitis by means of Roentgen-radiation. The author has but little to contribute with regard to this particular department of Roentgen-therapy; he has seen practically no physiological or therapeutic effect which could be ascribed to the influence of the rays upon internal organs. Nevertheless he is not pre- pared to deny the possibility of such an effect existing; he believes that Kienbbck :t ) goes too far when he says that X-rays can only produce deep-lying changes when an ulcer is first formed. There may be rays of another kind from the tube which influence tissues other than the skin. § 32. Physiological Effects of X-Rays. Soon after the publication of Roentgen's discovery it became known that his rays have a definite influence upon the proto- plasm of living tissues. Investigations were duly made, with the following results : The chief objects of enquiry were as follows: 1. The influence of Roentgen-rays upon the higher organ- isms, upon certain regions and their functions. 2. The histological changes in the cells. 3. The influence of the rays upon bacteria. 4. Their action upon the plasmodial activity of various low forms of life. As regards 1, there is little to be added to what has been already stated in the previous section. Capranica*) observed that moles exposed to Roentgen-rays are excited for several hours afterwards, but that no alteration could be noted in the amount of carbonic acid they excreted. ') Quoted by Foveau de Courmelles, Ann. de tned. el Chirurg., cgoi, No. 5. P- i r >4- 2 ) Rcvi ta portugueza de medic, e. cirurgia praticos, Nov., \^>j. *) W'r. med. Pre e, coi 1. X". 19 ' ) Prometheus, Woch< n 1 In . 1896, p. H7- 306 RADIO-THERAPY On the other hand, Tar khan oft x ) states that frogs whose cerebra have been exposed to the rays sustain a loss of reflex- sensibility. After replacing the creatures in water their skin remains very dark-coloured, and only regains its lighter hue after several hours. Gaston Seguy and F. Quenisset 2 ) noted that after they themselves had been exposed to the rays for a long time they suffered from violent and irregular cardiac palpitation. A female patient also who had been under treatment complained of the same trouble, coupled with a feeling of oppression. Sabrazes and Riviere 3 ) carefully examined the heart's action in cold-blooded animals (frogs) after Roentgen-radiation. They could observe no change in cardiac rhythm even after pro- longed exposures. Destot*) watched the pulse while the hand was being irra- diated by a vacuum-tube worked from a static apparatus, and afterwards from a coil. The exposure on each occasion lasted one hour, the tube-distance being 5 cm. A pulse-tracing was taken by a Marey sphygmograph. The static machine caused the disappearance of the dicrotic wave after 10 minutes; the whole curve became higher, but the rate of pulsation was not affected. When the coil was used to work the tube the pulse shewed at first a higher tension. This, however, soon fell, and was succeeded by arhythmia and intermittent pulsation. In both cases the radiation was of like intenstiy. Destot concludes that the cause of the physiological disturbances observed in Roentgen-radiation is to be found in the effect upon the sensory nerves; these affect the spinal cord, and, in a reflex manner, the vascular system. L. Lecercle*) irradiated the shaven posterior regions of rabbits, and observed the temperature of the skin and rectum both before and after the experiment. (The time of exposure is not stated.) The first effect was a fall in the temperature; ') Gaz. Botkin, 32. 2 ) Compt. rend, de l'Acad. de Sc, Vol. CXXIV, p. 790. 3 ) Ibid. p. 981. 4 ) Compt. rend., Vol. CXXIV, p. n 15. ') Compt. rend. Acad., Vol. CXXV, p. 234. TREA TMEN T II 7 Til X-RA YS 307 this was soon followed by a rise to above normal. The same observer found *) that the animal's skin parted with more heat after irradiation, and this phenomenon was maintained for a considerable time. In a later publication Lecercle 2 ) states that the function of perspiration in rabbits becomes temporarily impaired by exposure to the rays. In yet another series of experiments it was shewn that exposure on 3 successive days caused increased excretion of phosphates in the urine, which change was maintained for a couple of days. Several writers argued from certain clinical phenomena (headache, insomnia, difficulty in micturition, menstruation, etc.), which appeared occasionally after irradiation, that the rays had some influence upon internal organs. Thus Oudin, Barthelemy and Darter 3 ) observed that irradiation with too powerful a current, or with certain other kinds of defective technique, resulted in gastro-intestinal disturbances, palpita- tation, etc. In a later publication 4 ) these authors described "visceral complications" as occurring after radio-therapy in cases where there were no actual signs of gastric-disorder. They refer these phenomena to a disturbance of the sympathetic system. (They would seem to overlook the fact that in emotional people these occurrences not uncommonly result from any kind of psychic disturbance.) Amongst the many thousand Roentgen opera- tions which the author has conducted for the past six years he has, however, met with no such case of "visceral complication." The trembling and disturbances of sensation which Oudin men- tions as occurring on the hands of those who work with X-rays are not to be explained in this way. The trembling may, oi course, be due to very different causes; the sensory disorders may result from the dermatitis which careless operators often contract. Walsh 5 ) also describes complication similar to those men- x ) Compt. rend. Acad., Vol. C.WXV. p. 583. 2 ) Compt. rend., 1896, Vol. II. p. 362. 1 Monal ch. f. prakt. Dermatologie, Vol. 25, No. 29. 4 ) La Radiographic, igoo, Vol. IV. No. 39. i Bril Med Journal, [897, p. [905. 3 o8 RADIO-THERAPY tioned by Oudin and Barthelemy. He has seen effects like those of sunstroke, also gastric disturbances. Rodet and Berthin *) after exposing animals to intense irra- diation produced dermatitis, paralysis, and convulsions followed by death. They found at the autopsy meningomyelitis (thick- ening and adhesions of the meninges, congestion of the spinal cord, cell-hyperplasia and small haemorrhages), which was evi- dently not due to sepsis; bacteriological examination of the blood, peritoneal fluid, and spinal cord giving negative results. Scholtz found on making enquiries into the effect of irradia- tion upon internal organs that even intense exposure, such as leads to necrosis of the tissues, causes no evident signs of mis- chief along the gastro-intestinal tract. Young animals, whose anterior fontanelles had not yet closed, died sometimes with paralytic symptoms, and sometimes without any definite symp- toms at all, after their crania had been exposed to the rays. Several other observers state that small animals, such as guinea- pigs, suffer from paralysis after irradiation of the occipital region ; sometimes sudden death ensues. Considering the thin- ness of the skin and bones in these cases, one can readily under- stand the possibility of the rays penetrating to the central nerv- ous organs and so producing dangerous or fatal lesions. It is known that high-tension electricity has an unfavourable influ- ence upon small animals. (See the author's experiments, pp. 121, 145. J 74-) Intense irradiation of a rabbit's eye has produced necrosis in the neighbourhood of the eyeball, but no important changes in the eye itself. Investigators have for some time been concerned with the question as to whether Roentgen-rays are visible, or whether they exert any effect upon the retina or other structures of the eye. Several observers have assumed that the retina is sensitive to Roentgen-rays. Thus Axenfeld 2 ) came to this conclusion after some experiments he made upon arthropedes. He placed the animals in a box made of half wood and half lead, and 1 ) Gazette des Hopitaux, May 7, 1898. 2 ) Centralbl. f. Physiologie, X. No. 6, p. 147 and No. 15, p. 436. TREA TMEN T Jf 7 Til X-RA YS 309 exposed this box to the rays; the animals all moved to the wooden portion. Blinded animals did not act in this manner. Brandes x ) made an experiment to see if aphakic persons are sensitive to the rays. A girl, both of whose lenses had been removed, received an impression of light from a Crookes tube which had been previously covered with a dark cloth. Brandes also believed he received a visual impression from Roentgen-rays after covering both his eyes with leaden masks; he believed that the rays gained entrance round the masks (which were shaped like spectacles), though they did not appear to traverse a central aperture which had been made in the masks themselves 2 ) . This observation was disputed later by Radiguet and Guichand, 3 ) also by Darieix*). Chalpuecky found that only apertures above 4 mm. allowed the passage of perceptible rays. The rays, moreover, were only effective in the periphery of the visual field; the central part of the lens would appear to be opaque to them, and this probably explains why radiograms of the lens give shadows almost as dense as those of the whole eye- ball. G. Bardet, 5 ) to some extent, confirms Brandes' experience; he believes that any one within the zone of action of a vacuum- tube receives an impression of light. For this, however, it is essential that the room be absolutely dark and that there be no colours on the walls, since many colours fluoresce on exposure to X-rays. Bardet finds that the eye placed a few centimetres in front of a covered vacuum-tube in action receives just such a feeble impression of light as is produced by moving a lighted candle before the closed lids. When the apparatus stops work- ing this impression disappears, and the same happens if a screen of iron, copper, or lead be interposed. A glass screen, however, diminishes the effect but little, an aluminium screen not at all. If the tube be turned on its axis through 180 , so that the cathode-rays strike the side of the tube which is furthest from ') Sitzungsh. d. Preuss. Akad. d. Wiss. iSg6, p. S47- ') Quoted by Gebhardt, Die Heilkrafl des Lichtes, Leipzig, 1898, p. 278. *) Acad. d. Medec. Nov. t6, [897. *) Quoted by G. Bardet. § ) Compt. rend, de 1'Acad. de Sc, Vol. CXXIV. p. 1388. 3 io RADIO-THERAPY the eye, no light impression is received, showing that the "elec- tric field" can have no share in this phenomenon. Foveau de Courmelles x ) examined 204 blind children. He found that only 9 of these received any impression of light from X-rays. It has long been known that electric currents and discharges applied to the eye cause a sensation of light. Purkinje 2 ) produced this sensation by the electric stimu- lation of the retina and optic nerves. G. E. Miiller 3 ) found that a constant electric cur- rent sent through the retina in an afferent direction pro- duces on "closing" a light blue-violet sensation; applied in the reverse direction, however, there is a sensation of dark yellowish green. On opening the circuit, the reverse takes place. Darier 4 ) found that in cases of amblyopia, without nerve-lesion, a sensation of light is induced by very feeble currents; where, however, there is atrophy of the optic nerve far stronger currents are required. D'Arsonval 5 ) shewed that the eye receives a quite similar impression of light when brought into an electro- magnetic field produced by an alternating current of 42 periods. (Recently Berthold Beer e ) has published observations to the same effect.) D'Arsonval empha- sises the fact that a magnetic field acts like other physio- logical irritants, not by virtue of its intensity alone but by its alternations. In variance with the above testimony, which speaks for some influence upon the eye by Roentgen-radiation, the experi- ments of Fitchs, Krcidls 7 ) and Gatti s ) would seem to indicate x ) Compt. rend, de l'Acad. de Sc, Vol. CXXVI, p. 919. 2 ) Briicke, Vorlesungen iiber Physiologic Vol. II, p. 919. 3 ) Zeitschr. f. Psychologie und Physiologie der Sinnesorgane, Vol. XIV. P- 329- . 4 ) Bull, de la soc. franc;., d'ophtha., 83, quoted by Nagcl, Jahresubersicnt. 1884. p. 242. 5 ) Compt. rend, de l'Acad. de Sc., Vol. CXXIV, p. 1389- ') K. k. Ges. d. Aerzte, Wien, Jan. 17, 1902. 7 ) Centralbl. f. Physiologie. X, No. 9, p. 249. ') Annal. di Ottalm., XXVI, p. 344- TREA TMEN T If 'I TH X-RA YS 3 1 1 no sensibility for the rays on the part of the retina. These observers found that no change takes place in the appearance of the visual purple on exposure to the rays; the latter, more- over, have no effect upon the pigment-epithelium. On the other hand, changes do occur in the anterior parts of the eyeball ; these, however, are quite analogous to the changes in irradiated skin. The author called attention some time ago to the mild attacks of conjunctivitis which are liable to occur in patients whose eyes are not suitably protected. Himmel 1 ) mentions the case of a patient who developed symptoms of photophobia after Roentgen-treatment for a patch of lupus on the forehead; this Himmel refers to irritation of the optic nerve. The author has pointed out in a previous communication 2 ) that troubles of this kind can generally be avoided merely by the patient closing his eyes during the sitting. It would seem, therefore that the Roentgen-rays themselves cannot be held altogether responsible for the conjunctivitis, etc., since they freely penetrate the thin tissue of the eyelids. On the other hand, were high-tension electricity the cause of the trouble, it can readily be understood that by closing the eyelids this electricity would be conveyed to other parts of the body and so easily earthed. Again, the author has frequently seen conjunctivitis make its appearance, although the eyes have been covered by leaden masks. Oitdin looks upon accidents of this kind as effects of the X-rays upon the general organism ("accidents generaux"). Chalitpecky's experiments") shewed that inflammation of the conjunctiva, when the rays are directed straight upon the eyeball, may involve, by extension, the anterior chamber and its vicinity. This observer irradiated a rabbit's eye for 24 hours and found the following progressive changes: Inflammation of the eyelids, falling of the eyelashes, conjunctivitis, and irregu- larities in the cornea; the latter became greyish-white, and, like the conjunctiva, covered with false membrane. R. B. If'ihl 4 ) saw a case in which panophthalmitis supervened upon excessive ', L. c. ") Wiener tned. Presse, 1S99. No. 31. ! ) Centralbl. t. prakt. Augenheilk., Aug., Sept., p. 267, ') Brili-li Med. Assoc, Manchester, July 30, 1902. 3 i2 RADIO-THERAPY exposure to X-rays, necessitating enucleation. Chalupecky believes that these effects upon the eyeball are common both to X-rays and ultra-violet rays. As a matter of fact, we find in the literature of this subject morbid processes quite similar to the above which are ascribed to the action of intense white light. The effect of Roentgen-radiation upon living skin, and the clinical and histological changes produced therein, will be more fully dealt with later; we have already discussed some of these changes when describing the method of treatment. Here we will only refer in a general way to the physiological peculiari- ties which characterise the Roentgen-reaction. These, which must always be borne in mind during the practice of Roentgen- therapy, are : i. The cumulative effect of irradiation. Although the immediate effect of each exposure may be but insignificant, the sum of these effects goes on accumulating, so that in the end Ave may get a sudden and unexpected reaction. The more intense the exposures, the sooner do the naked-eye changes become evident. The intensity and time of appearance of the reaction, therefore, afford a criterion as to the character of the irradiation (see Introduction, p. 5) ; they also give some indica- tion of the course the reaction itself will probably run. The author believes he was the first to point out the cumulative action of X-rays (Wiener med. Wochenschr., 1897, No. 10), though most writers give Forster the credit. Kie t nbock and Scholtz first indicated the important part played by the intensity of the irra- diation in determining the time of appearance of the reaction. 2. The peculiar character and course of the changes brought about by irradiation (reaction, dermatitis). 3. The changes first affect the cells of the skin; from this the peculiar effect on the hairs arises. 4. A skin treated by Roentgen-radiation is for a long time afterwards prone to again react after comparatively weak exposures. Reports upon the influence of Roentgen-rays on bacteria are somewhat conflicting. Whereas many observers deny the rays TREATMENT WITH X-RAYS 313 any bactericidal action whatever (Beck and Schultz, 1 ) Beaure- gard and Guichard, 2 ) Bert on,') S. Brim ton Blaikief) Blaise and Sambuc, 6 ) Grunmach*) Minck, 1 ) Pott, s ) Sabrazes and Riviere;) Sormani, 10 ) Wittlin, 11 ) M. JVolf 12 ) and others), others again found them to possess distinct bactericidal properties (Bonomo and Gros,™) Fiorentini and Luraschi, 14 ) Frantzius, 1 '") Lortet and Genoud, 1 '') Miihsam,™) Rieder, 18 ) Holzkneclit and Spieler 1:i ) ) . We can only quote a few of the experiments dealing with the question of the influence of Roentgen-irradia- tion upon bacteria. F. Berlioz (Compt. rend. Acad. d. Sc, 1896, Vol. II, p. 109) irradiated bouillon-cultures of diph- theria bacilli for 16, 32, and 64 hours. Guinearpigs were innoculated afterwards with these cultures, and it was found that the bacilli had not in the least lost in virulence. This result agrees with JVade's (Brit. Med. Journal, February, 1896) and Minck's experience. Pott 20 ) inoculated 25 test-tubes containing glycerin- agar-pepton with tubercle bacilli. The tubes were kept for 1 month at a temperature of 37 ° C. By this time Zeitschr. f. Hyg., 1896, p. 490. Soc. de biolog., July 27, 1897. La sem. med., 1896, p. 283. The Lancet, 1898, 11, p. 1425. Soc. de biolog., July 10, 1897. Quoted by Bergmann. Miinchener med. Woch., 1896, No. 5 ; 1S98, No. 9. The Lancet, Nov. 20, 1897. Acad, de Science, May 3. 1897. Quoted by Mbller. Centralbl. f. Bakt., 2, p. 676. Berlin med. Gesellsch., March 2, 1898. Giorn. med., June, 1897. Revue internat. d'electrotherapie, Feb., March, 1897, p. ^^,\. Centralbl. f. Bakt., March 5. 1897. Compt. rend.. March 30, [I Chirurgenverein, Berlin, Jan. io, iNoX. Miinchener med. Woch., 1898, No. 4. 25. Wiener mi d. Club, Jan. 30, [901. The Lancet, Nov. 20, 1897. 3H RADIO-THERAPY characteristic and pure colonies had developed. Of these 25 tubes 8 were retained for control purposes and 17 were exposed to the rays. (It had already been determined that the glass-tubes themselves offered but slight resistance to the passage of X-rays. ) Means were taken to secure an equal exposure for all the tubes by placing them on a revolving stand, above which the Crookes tube was fixed. Photographs were taken from time to time to make quite sure that the Roentgen tube was emitting X-rays. The 17 tubes were exposed daily for 3 months, and in such a way that always the same 2 tubes were placed out of reach of the rays after I, 1, 2, 4, 6, 8, and 10 hours respectively, while the last three tubes were exposed for 1 1 hours each day. At the end of the experiment it was found that the cultures had been entirely unaffected by this treatment; they differed in no way from each other, or from the cultures in the 8 control-tubes. This experiment conclusively proves that Roentgen-rays possess no influence upon tubercle bacilli, and that a Roentgen- cure of tuberculosis (if, indeed, such has been actually effected) must be due to other causes. /. Sabrazes and P. Riviere 1 ) exposed cultures of the bacillus prodigiosus in a case covered over with black paper for 20 days, giving daily irradiations of 1 hour. Absolutely no effect was produced on the organisms. In a second experiment a small opening was made in the abdominal wall of a frog by means of a cautery. Into this aperture a capillary tube, which had been previ- ously drawn through a culture of bacilli, was inserted. After an irradiation lasting several hours, the tube was withdrawn and its contents examined. The results were entirely negative; no increase in the number of white blood-corpuscles or change in the process of phagocy- tosis, as compared with non-exposed control animals, was discoverable. ] ) Compt. rend', dc l'Acad. de Sc, Vol. CXXIV, p. 979- TREATMENT WITH X-RAYS 315 H. Rieder 1 ) exposed cultures of the micro-organ- isms of cholera, anthrax, typhus, diphtheria, also pus- cocci and bacteria coli. The cultures were covered by leaden plates, in the centre of which a large square aperture had been made. He found that after 48 min- utes the colonies coinciding with the aperture perished, whereas the covered colonies continued to thrive. In these experiments Rieder used a 30 cm. coil, the primary current being interrupted 300 times per minute; dis- tance of anti-cathode from the object, 10 cm., time of exposure, 1-3 hours. In some cases the aperture in the leaden plate was covered with black paper. In order to ensure a sufficiently prolonged action of the most intense rays, a second interrupter in the form of a metronome was introduced into the circuit; this was self- acting and adjustable. It seemed unlikely that the bac- tericidal effect was due in any way to a chemical change in the nutritive medium brought about by heat-rays or fluorescent light from the vacuum-tube; there still remained, however, the possibility of effects caused by the electrical discharges from the tube. In order to eliminate this possible factor, Rieder employed a tin-foil screen to carry away the electricity. It was found that this procedure scarcely affected the bactericidal process. Moreover, on suitable arrangements being made to eliminate the X-rays themselves no bactericidal action could be secured. Finally, any action on the part of ozone was proved impossible. Rieder also claims to have proved by experiment that the production of Roentgen-dermatitis also is solely due to X-rays themselves 2 ) . By still more recent experi- ments, Rieder :i ) claims to have confirmed his earlier deductions. L. Lortet and Genoitd 4 ) also enquired into the ') Munchener med. Woch., 1898, No. 4, pp. [01-104 2 ) Munchener med. Woch., June 21, [898. ") [bid. March 1 1. [90 i 4 ) Compt. rend, de I'Acad. de Sc, [896, Vol. I. p. 1511. 3 i6 RADIO-THERAPY influence of Roentgen-radiation upon micro-organisms. They were of the opinion that even thin-walled glass test-tubes offer considerable resistance to the passage of X-rays; consequently they irradiated animals inoculated with micro-organisms (tubercle bacilli) . These animals were exposed daily to the tube for at least one hour April 25th to June 1 8th) . Three animals which had been treated in this way shewed no signs of tuberculosis, whereas other animals employed for control purposes (inoculated, but not irradiated) shewed abscesses and rapid emaciation. As the result of these experiments, followed by microscopic investigation, Lortet and Genoud concluded that Roentgen-radiation had modi- fied the effects of inoculation. Fiorentini and Luraschi 1 ) confirmed this opinion. R. Miihsam 2 ) inoculated guinea-pigs with tubercu- losis and irradiated 12 of them for one hour daily, another 1 2 being kept for control purposes. Results shewed that general tuberculosis was not prevented by irradiation; there was merely some weakening effect on local tuberculosis. Scholtz 3 ) exposed well-developed plate cultures of typhus, cholera, pyocyaneus and trichophyton germs to soft tubes for 1 to 4 hours with entirely negative results. He believes that X-rays have no serious bactericidal effect. He was unable to obtain positive results more- over in the case of animals inoculated with tuberculosis. The author made the following experiments bear- ing upon this question : A GitndelacJis vacuum-tube was employed, having a leaden screen fixed on it at the junction of the tube-neck with the globe. By this arrangement (Fig. 84) X-rays were excluded from the region of the tube-neck. Two plate cultures of staphylococcus pyogenes aureus on agar were placed, one at a distance of 1 cm. ') L. c. 2 ) Deutsche med. Woch., 1898, No. 45. 3 ) L. c. TREA TMEN T Wl TH X-RA YS 3 1 7 below the globe K (A), and one (R) at a distance of ^ cm. below the narrow end (H) of the Roentgen-tube. Below A a photographic plate P r was placed, wrapped in black paper, and with its film uppermost. Between A and P r a leaden letter A x was placed. A leaden letter Bi was also placed between B and a second photographic plate P 2 . Plate A x was covered in addition by a thick, aluminium screen Al, which was connected with the earth. After 5 minutes' working of the tube the photo- graphic plates were developed. On plate P t was to be seen a well-marked white image of the lettej A %1 ; the other plate P., shewed a very faint image of the letter B x and the plate as a whole was almost entirely white. 1^3* Fig. 84. Fresh photographic plates were treated in precisely the same way and developed after 5 minutes; the results were the same as before. Fresh photographs were taken at intervals during the half hour the plate cultures were exposed. The negatives always proved that X-rays were freely passing through the culture A and the aluminium screen covering it, whereas through B only rays in small amount were penetrating. On the other hand, B was throughout accessible to the silent discharges of high- tension electricity from the tube-surface, while A was protected from electrical discharges by means of the aluminium screen. The "earthing" wires (Abl) from the latter ran to a cleft between the ceiling and the wall of 3 i8 RADIO-THERAPY the room. The Roentgen-tube became very hot during the experiment. After half an hour both plates were covered and placed in the incubator. If now the electri- cal discharges and not the X-rays formed the»bacteri- cidal factor in Roentgen-radiation, it was expected that culture B would appear destroyed and culture A unharmed. The reverse, however, proved to be the case. A had a sterile patch in the centre, whereas B was uniformly grown over with colonies. This experiment seemed to indicate that the Roent- gen-rays themselves have bactericidal properties. On carefully considering the conditions of this experiment, however, the author began to doubt if A had after all been efficiently protected from electrical discharges; the earthing of the aluminium plate was possibly defective. Again, it seemed very likely that the electric discharges striking B were less powerful than those proceeding from the curve of the sphere towards A, so that B might have been insufficiently exposed. In order to eliminate these objections the next vacuum-tube experimented with was one made by the Voltohmgesellschaft of Munich. This possessed two spheres of almost equal size; the cathode-rays were produced in one sphere and projected from the anti- cathode in an opposite direction from the other sphere. In this experiment earthing was secured by connection with the water-pipes. The leaden screen was fixed on the narrow neck of the tube between the spheres. Two diffused cultures of staphylococcus pyogenes aureus on agar in Petri-dishes were used. Dish A was covered by a lid filled with paraffin wax and placed beneath the sphere K x . Dish B was left uncovered and placed beneath K... Each dish was i cm. distant from the tube; the earthing in connection with both dishes is shewn in the diagram Abl. Photographic plates and leaden letters were placed below the dishes as in the preceding experiment, and over A an earthed aluminium screen A I was arranged as before (Fig. 85). TREATMENT WITH X-RAYS 3i9 The above arrangements precluded any possibility of dish A being struck by electric discharges; on the other hand X-rays were allowed to penetrate freely, as the photographs shewed. Dish B received, however, no X-rays at all, the photographic plate P 2 shewing no darkening on development. This dish, however, received practically the same amount of electric discharge from the sphere K s as was evolved from sphere A\. Exposures of one hour were given. Dish B was then covered and both dishes were placed in the incubator. On the following day it was seen that dish A shewed an abundant and uniform growth of colonies. Dish B Mi Fig. 85. Abi shewed a sterile patch in the centre the size of a kreutzer. The dishes were left in the incubator for 2 days more and then photographed. The experiment was repeated five times; each time the same result was obtained, even when longer expos- ures were given 1 ) . ') Kienbock and Holzknecht urged against this experiment that the ex- posure was too brief. Quite recent experiments by Grunmach (1. c.), Scholtz (1. a), Zeit (Boston Med. and Surg. Journal, Nov. inoi), Asch- kinass and Caspari (I. c. ), however, quite confirm the author's experience. Even assuming that longer exposure with soft tubes would have demon- strated the bactericidal effect of X-rays, it must be borne in mind that no such exposures could be taken advantage of in actual practice, since they would inevitably produce severe X-ray dermatitis. 3 2 ° RADIO-THERAPY From these experiments it becomes evident that the bacteri- cidal action of X-rays — presuming such to exist — is very slight compared with that of the electrical discharges given off by the vacuum-tube. It may, indeed, be regarded as practically a negligible quantity. For the purpose of studying the more delicate intracellular processes which result from the irradiation of living matter, causing visible changes and the impairment of protoplasmic function, one turns from complicated higher organisms to the phenomena of plant-life, to germinating seeds and plant-cells, where one can readily observe the protoplasmic circulation. Or one may employ the cells of protozoa, whose usual course of existence is comparatively well understood (so that any depart- ure from the normal can be at once recognised) as the objects of this elementary physiological enquiry. According to Maldiney and Thouvenin, 1 ) seeds of con- volvulus arvensis, lepidium sativum, and panicium miliaceum, after one hour's exposure to Roentgen-rays, germinate sooner than others kept unexposed for control purposes. According to Lopriore, 2 ) Roentgen-rays have an accel- erating effect upon the protoplasmic circulation in vallisneria spiralis. If after \ hour's exposure the rays be withdrawn nor- mal conditions again obtain amongst the cells. After i hour's exposure harmful effects can be noticed: the protoplasm assumes a yellowish colour, becomes granular and vacuolised. After 2 hours' exposure the protoplasm ceases to circulate, and the chlorophyll bodies begin to lose their colour. Lopriore also examined the germination of the pollen of genista and darling- tonia coronillaefolia under the influence of X-rays. He found the process became suspended. After the experiment germina- tion began again, the pollen germs having absorbed water freely during the exposure. F. Schaudinn 3 ) examined the effect of irradiation upon *) Compt. rend, de l'Acad. de Sc, Feb. 14, 1898. *) Azione dei raggi sul protoplasma della cellula vegetale vivente in : Nuova Rassegna. Catania, 1897. *) Ueber den Einfluss der Roentgenstrahlen auf Protozoen Pflilger's Archiv. f. d. ges. Physiologie, p. 29. TREATMENT WITH X-RAYS 321 separate animal cells, using cultures of protozoa in open glass receptacles for this purpose. One culture was always reserved for control purposes, being covered with a lead plate. The vacuum-tube, covered with a black cloth, was placed 20 cm. above the cultures, and the exposure occupied 14 hours. Schaudinn found that under these conditions amoebia prin- ceps Ehrberg at first shewed signs of increased activity. After 5 or 6 hours this, however, generally diminished; after 10 hours the cells became clumped together in globules and remained stationary. After the experiment many of the cells died. The rays had an unfavourable influence after 4 hours upon "amoeba lucida Gruber" and "pelomyxa palustris Greef." Trichospha^rium sieboldi Schneider did not react at all to the rays. On the flagellates (chilomonas paramaccium Ehrberg, etc.) irradiation had a harmful effect. Spirostomum ambiguum Ehrberg (infusoria) was also exposed to the rays; after 4 or 5 hours activity was diminished, after 6 hours the infusoria died. Schaudinn argued from his experiments that Protozoa varied much in their powers of resisting Roentgen-rays, Many kinds did not appear to respond to the irritation in the least, others reacted slightly, and others again very markedly. The condition of the plasma seemed to bear a certain relationship to the capacity for reaction. Those which reacted quickly possessed a loosely-lying plasma, and contained more fluid than those which were only affected slightly or not at all. Recently //. Joseph and S. Prowazck 1 ) have published a series of interesting investigations on the influence of Roentgen- radiation upon living protoplasm. They found in the case of bryopsis plumosa (alga?) that a 1 5 minutes' exposure distinctly slowed the protoplasmic circula- tion ; also that the plasma did not appear so freely at the sites of artificially produced lesions. The chlorophyll granules became spindle-shaped and arranged in rows, or sometimes in star-shaped conglomerations. Some time after the irradiation conditions became normal again. These results are somewhat *) Zcitschr, f. allg. Physiologie, Vol. I, Part II, 1902, 322 RADIO-THERAPY remarkable, in view of the fact that Lopriore found in the cells of vallisneria spiralis an acceleration of the protoplasmic circu- lation after a half-hour's exposure. When infusoria (paramsecium caudatum and volvox) or daphniae were placed in a tube filled with water, one half of which was covered with lead-sheeting, the animalcule collected after 10-15 minutes in the portion where they were protected from the X-rays. In order to exclude the possibility of white light having some share in this phenomenon the half of the tube not covered with lead was enveloped in a cloth. The result was, however, the same. Joseph and Prowazek describe many other experiments upon low forms of animal life. Hard or soft tubes gave like results. All these experiments go to show that when administered to a certain degree Roentgen-rays have a stimulating and vivifying action, while beyond this limit they begin to be injurious. These deductions agree entirely with clinical experience. It is known that weak irradiations stimulate the granulation of atonic ulcers, the proliferation of pigment, and the function of hair-papillae. The latter fact explains why patients undergoing Roentgen- radiation for hypertrichosis are left with a stronger growth of hair if for any reason they are obliged to suspend treatment at an early stage. These facts (including the circumstance that irradiated tissues have for some time afterwards a tendency to react after comparatively mild exposures) are similar to those observed after irradiation by light. Axetifeld, Joseph, and Prowazek' s observations have shown that Roentgen-radiation stimulates cell-movement. We can, therefore, assume that the effect of Roentgen-rays, like other irritants, is to ( 1 ) stimulate, (2) act injuriously, (3) promote activity (movement). § 33. The Active Agent in Roentgen-therapy. A vacuum-tube in action emits various kinds of rays, and gives rise to various physical phenomena. Every enquiry under- taken for the purpose of determining that precise factor to which alone the changes wrought on the living organism are due must first take cognisance of the several effects produced on the tissues TREATMENT WITH X-RAYS 323 by the very different physical agents which go to make up the sum of these phenomena. On the surface of and within a vacuum-tube, in action, we find: 1. Heat; 2. Ozone; 3. Cathode-rays; 4. Ultra-violet rays; 5. Rays composed of material particles; 6. Roentgen-rays; 7. Spark- and brush-discharges from the high-tension elec- tricity accumulated on the surface of the tube; 8. Electric or electro-dynamic waves; 9. Rays of unknown character. With a knowledge of these facts, the author in 1896 made the experiments described on page 230. In these, by suitable arrangements, he absolutely excluded the action of other physi- cal agencies and was able to ascribe a definite influence to the Roentgen-rays themselves. He stated in effect that it is to the Roentgen-rays alone that we must look for the cause of the changes in the skin l ) The possibility of heat, ozone, or ultra- violet rays having anything whatever to do with his results was precluded by the condition of his experiments. The assumption that other factors are accountable for the tissue-changes is, moreover, disapproved by other circum- stances. Tesla's ozone theory 2 ) could not explain the deep-lying tissue-changes which Gilchrist ) and Kaposi 4 ) had observed taking place in the nerves, nerve-sheaths, periosteum and bones of the extremities, and which //'. Reid ) had seen in the back of a patient whose chest had alone been exposed to the rays ''). Still less comprehensible by this theory is that fundamental 1 ) Wiener med. Woch., 1897, No. 10. ') Public Opinion. Vol. XXI. No. 24, quoted by Gilchrist. ") Johns Hopkins Hosp. Bulletin, February, [897. 4 ) K. k. Ges. d. Aerzte in Wien, Oct. 27, 1899. ') Brit Med. Journal, [896, Vol. II. '; Quoted by Mdller. 3 2 4 RADIO-THERAPY peculiarity of Roentgen-radiation — its cumulative action. It is a widely known fact that the changes in the skin after Roentgen- radiation do not immediately follow on the exposure, but appear many days later. Even then they are announced by alteration in the deeper structures of the skin (shewn by falling of the hair, pigment changes, subjective symptoms, etc.), while the surface of the skin itself often remains throughout unaltered in appearance and function. Bowles, 1 ) Stenbeck,' 2 ) and Elliot 3 ) ascribed the changes in the skin to the action of ultra-violet rays coming from the Roentgen-tube. There can be no question that ultra-violet rays are contained to some extent in the phosphorescent light excited by the cathode-rays on the tube-wall. But we must not forget that those ultra-violet rays have their origin within the tube; in order to be effective they must, therefore, first penetrate the glass wall of that tube. Now ordinary glass absorbs these rays to a great extent; only certain kinds (crown-glass and light phosphate-crown-glass) permit their passage to any degree 4 ). It is, therefore, very questionable if many ultra-violet rays reach the outside of the tube at all. Even were this the case, the author's investigations (p. 231) and the observations of M. M oiler'') would seem to exclude the possibility of their exerting any real action in Roentgen-radiation. Moller observed that a woman who was being treated by X-rays for lupus of the face shewed signs of reaction also (pigmentation, etc.) on the chest, which was covered by a red bodice and a black dress. Moller believes that this phenome- non, which the author also has repeatedly observed, completely disproves the assumption that ultra-violet rays have anything to do with the reaction, since they would certainly have been absorbed in this case by the woman's clothing 6 ). a ) The British Journal of Dermatology, July, 1897. ■) Quoted by Moller. '') Journal of Cutaneous and Gen.-Urin. Dis., Feb. 1897. 4 ) For the properties of different kinds of glass, see Edcr & Valenta, Denkschr. d. math.-natur. classe der K. akademie d. Wiss., May 4, 1894. ') Einrluss des Lichtes auf die Haut. Bibliotheca Medica. Stuttgart, 1900. ") Thomson (Boston Med. & Surg. Journal. Dec. 3, 1896) describes an experiment which also disproves the effect of ultra-violet rays. TREATMENT WITH X-RAYS 325 The author's experiments with regard to the possible action of the phosphorescent light gave negative results. The idea of any real effect proceeding from the heat-rays ol the vacuum- tube may be dismissed as improbable. The heat evolved, espe- cially with the slow rate of interruption of the primary current usual in Roentgen-therapy, can be readily proved to be so insig- nificant that it can have no real physiological effect. This idea is further confirmed by the author's experiment with the alumin- ium screen (p. 231 ) . These three factors, therefore — ozone, ultra-violet rays, and heat-rays — can obviously have nothing to do with the physi- ological effects of Roentgen-radiation. There is, perhaps, more to be said for the remaining factors above mentioned, though there are many objections to be urged against nearly all of these. Against the cathode-ray theory of Gilchrist, 1 ) Ames, 2 ) and Foveau de Courmelles, 3 ) it may be urged that though cathode-rays have the power of penetrating very thin layers of aluminium, as Hertz showed, their progress is arrested by even thin layers of other bodies, such as glass. Consequently the glass wall of the vacuum-tube would prevent most, if not all, of these rays from reaching the exterior of the tube 4 ). A very interesting theory has been propounded that the skin-changes are due to a direct bombardment with material particles emanating from the electrode. Crookes 5 ) believed that when the discharges from a Ruhmkorf coil are passed through a vacuum-tube, small particles are driven off from the cathode. These are either particles of the gas within the tube or are particles of the cathode- itself; they may, again, be electrolytic elements of the gas-molecule. It is a matter of common knowledge that the region of a tube opposite the cathode becomes blackened after prolonged use. This blacken- ing is due to a deposit of material particles driven off the elec- 1 ) L. c. 2 ) Quoted by Gilchrist. 3 ) Congr. f. Ncurolog., Brussels, [897. *) Gractz, Die Elcktricit.it. Stuttgart, [898, p. 272. 6 ) Quoted by Grade. 326 RADIO-THERAPY trode. But against this theory of material particles it must be urged, ( i ) that it has not yet been proved that the particles penetrate the tube-wall and so arrive at the skin; (2) that no evidence has been as yet forthcoming of the presence of this foreign matter in the skin. Gilchrist examined a specimen of skin after exposure to X-rays, the pigmentation in which was so pronounced that the idea was suggested of there being possi- bly an invasion of aluminium particles in the tissue. Neverthe- less under the microscope no trace of metallic or other foreign bodies could be discovered. Abel made chemical investigations with the same results. Tesla, who supports the theory of bom- bardment by material particles (1. c), gives the comforting assurance that it would take at least a century before a sufficient quantity of the foreign matter collected would seriously threaten the health of the person undergoing irradiation. Any possible action on the part of the tension-electricity accumulated on the surface of the Roentgen-tube (such as was suggested by Destot, 1 ) Balthasard, 2 ) Jankau, 3 ) Foveau de Courmelles*) Apostoli, 5 ) Lester Lenard, 6 ) and the author 7 ), seemed excluded by the above-mentioned experiment; the alum- inium screen undoubtedly conveyed all the electricity to the ground; moreover, W. Reid's 8 ) observation seemed also to negative the electrical theory. Reid's observation, confirmed later by Kummel and Revillet, ) shewed that changes occurred not only in the area of skin directly exposed to the rays, but also in a corresponding area of skin on the opposite side of the body, where the rays emerge. This circumstance seemed also to speak against any electric-wave hypothesis; moreover, any theory of this kind could not explain the negative results of the author's experiment with the reversed current (p. 231). Quoted by M oiler. Soc. de biologie, July 17, 1897. Photogr. Monatsh. f. Med., 1896, No. 6. Soc. de biologie, July 17, 1897. Internat. med. congr., Moscow, 1897. The American X-ray Journal, 1898, No. 5. Vortr. in der Gesellsch. d. Aerzte in Wien, Jan. 15, 1897. British Med. Journal, 1898, Vol. II. Quoted by Mbller. TREATMENT WITH X-RAYS 327 The author's theory that the X-rays themselves are the active factor of Roentgen-therapy was held also by Gocht,' 1 ) kiim- mel, 2 ) Rieder*) Albers-Schonberg*) and others. Against even this view, however, came the following obser- vation : The author treated a woman for hypertrichosis; during the whole course of treatment very hard tubes only were employed, so that at no time could the least trace of fluores- cence be seen on the screen. Plainly there were practically no X-rays evolved from the tube. Nevertheless, after a certain time, the hair began to fall. Struck by this fact, the author treated a similar case with the current reversed throughout. Thus the experiment he made in 1896 was repeated, with the exception that in this instance (no result being evident by the twelfth day, as was usual with the ordinary arrangement of current) the exposure was prolonged for 8 or 10 days. By this time the hair began to fall. A repetition of this experiment with a third patient yielded the same result. Obviously, there- fore, the Roentgen-rays cannot be the sole cause of the changes in the skin. This view was confirmed by Woyzekowski's^) experiments on rabbits. In every case where the X-rays alone were employed, electricity and light being excluded as far as possi- ble, no injurious effects were to be seen; when, however, the X-rays were used in conjunction with the other varieties of radiation emanating from the tube, physiological effects fol- lowed in from 3-12 hours. A further striking fact, which could be noted at any sitting, seemed also to point to electrical energy as bearing some casual -elationship to the physiological effects. When the apparatus is in action the patient and the objects surrounding him become so charged with electricity that sparks can be drawn with the knuckles from any part of his body. The patient has often ') Fortschr. a. d. Geb. d. Roentgenstr., Vol. I, No. i. 2 ) Quoted by Gocht. ') Mtinchener med. Woch., 1897, No. 10. *) [bid. 1000, Nos. 9, 10, 11. B ) Quoted by Zarubin, Monatsh. f. prakt. Derm., 1899, Vol. XXVIII, No. 10. 328 RADIO-THERAPY the sensation of being in a light current of air ("electric wind") ; his hairs are attracted towards the tube. Next came detailed acounts from d'Arsonval and Oudin of the therapeutic employment oiTesla's high-frequency currents 1 ) . On comparing the effects of these currents with those of Roentgen-radiation, the author was at once struck by many points of resemblance between the two. Might not spark-discharges from the coil in the case of Roentgen-radiation also play an important part in the physiological action? Since the experiment with the alumin- ium screen argued against any direct spark-effect, it seemed natural to conclude that the electric vibrations due to the spark- discharges were accountable for the physiological effects, and that the intensity of the latter varied with the physical qualities of the electric vibrations. This idea, however, to which the author gave expression at a meeting of the Wiener dermatologischen Gesellschaft, May ioth, 1899,") appeared somewhat at variance with the fact that not only the leaden masks in common use, but even masks of cardboard 3 ) or ordinary paper, 4 ) were sufficient for pro- tective purposes. Since electric waves penetrate all bodies, with the exception of metals, and, moreover, since they are trans- mitted in all directions from the sparking-path (just as waves of light are propagated in all directions from the point of origin), their effect would not be confined to the region directly opposite their source, and still less would their progress be arrested by a sheet of paper. Further, doubts arose whether electric vibrations really emanate from a Roentgen-tube. According' to /. Tuma, 5 ) most probably no electro-magnetic waves arise in this way. In the endeavour to throw light on this perplexing problem, 1 ) Annales d'electrobiologie, d'electrotherapie et d'electrodiagnostie, Jan. IS, 1898. 2 ) Wiener med. Presse, 1899, No. 31, and Wiener klin. Woch., 1899, No. 39. 3 ) Hahn and Albers-S 'chonberg, Miinchener med. Woch., March 13, 1900. *) Stcnbcck, quoted by M oiler. B ) Quoted in the author's work "Die physiolog. Wirkungen der Polent- ladungcn hoch-gespannter Inductionsstrome." Sitzungsb. d. Akad. der Wiss. in Wien, Math.-naturw. CI., Vol. CIX, Section III, p. 594. TREATMENT WITH X-RAYS 329 the identity of the active agent in Roentgen-therapy, the author felt bound to reconsider the question of the spark-discharges. Two considerations in particular influenced him in this direction. The first was the question as to whether in his first experiment the aluminium screen had actually "earthed" all the discharges; it seemed at least within the bounds of possibility that more vig- orous sparks should have penetrated the screen. He remem- bered, moreover, that from the kind of tube he was at that time employing (a small vacuum-tube from Stiitzerbach) , often powerful sparks struck the screen, and that on the correspond- ing area of skin the necrosis made its appearance later. Again, it seemed not impossible that the vacuolisation degeneration discovered by Gassmann in the cells of the intima of the vessel- walls, in cases of Roentgen-ulceration, might be traced to the effects of direct spark-discharges. It seemed essential, therefore, to study the physiological effects of spark-discharges pure and simple — hence the experi- ments described on page 1 2 1 and onwards. Thus the fact was established that direct spark-discharges from a Ruhmkorff's apparatus have a similar influence on the skin and on bacteria to that which has been ascribed to Roentgen-radiation. This led one to the conclusion that electric discharges constitute the essential factor in Roentgen-therapy. Recently, however, Stralter, 1 ) Kienbock, 2 ) and Scholtz 3 ) have described a series of experiments tending to show that X-rays themselves possess a physiological action. These investi- gators shew that irradiation by means of soft tubes, which evolve X-rays copiously, brings about reaction in the same individuals much earlier than irradiation with hard tubes, which give a comparatively small output of X-rays. Kienbock urged the fact that the skin reaction only appears on the area exposed to the X-rays, and that by fixing a leaden screen between the tube and the surface of the skin a white patch (corresponding to the screen)' is produced, surrounded ') Deutsche med. Wochenschr., August, i<>, p. 546. 2 ) Wiener klin. Wochenschr., [900, No. 50. >) L. c. 330 RADIO-THERAPY by a zone of erythema. The effect on the skin is weakened according as other bodies are interposed between the tube and the body. The same investigator arranged a tube in such a way that the mirror of the anti-cathode lay at right angles to the surface of the skin. Thereby only that portion of skin underlying the fluorescent half of the tube was subjected to X-rays; behind the mirror the tube was dark, and from here but few X-rays struck the skin. Reaction only appeared in the first-mentioned area of skin; the border of this reactive zone coincided with the plane of the anti-cathode mirror. There are several objections to be raised against these experiments. In the first place, it is well known that under certain conditions even hard tubes bring about reaction far earlier than was anticipated. Again, it is quite clear that leaden plates not only intercept X-rays, but also spark-discharges. Finally, it must be men- tioned that the high-tension electricity is not evenly dis- tributed over the surface of the tube, as we are given to suppose, but has certain peculiarities in this respect. E. Riecke 1 ) examined the distribution of free elec- tricity on the surface of a Crookes tube, actuated by an induction-apparatus, by dusting the tube with a mixture of red lead and powdered sulphur. Peculiarly shaped figures appeared on the tube-surface; a ring was seen opposite the cathode, sharply outlined by yellow pow- der. The ring was situated somewhere about the bor- der of the brightly fluorescing part of the tube-wall. Within the ring alone red spots were seen; these were composed of positively-electrified red-lead powder. The distribution of the red powder was uneven, probably on account of the uneven condition of the cathode- surface. Metal wires and plates placed within the tube in the path of the cathode-rays caused shadows to appear on the tube-wall; these shadows were also indicated by the disposition of the powder. The shadows were *) Wiedcm. Ann., Vol. LXIX, 1899, p. 788. TREATMENT WITH X-RAYS 331 sharply outlined by streaks of red powder; the shadows themselves were either free from powder or covered in the middle with powdered sulphur. The author's own experiments confirmed those of Rieckc. He observed a striking arrangement of the yel- low powder in the form of broad rings opposite the poles of the tube. Moreover, in the brightly fluorescing portion of the tube placed opposite to the skin the accumulation of free electricity was especially marked. The following experiment seems convincing: Scholtz ^) irradiated a circular patch of skin, the size of one's palm, on a hog's back. The exposure was continued for y± hour, and the patch was divided into 5 segments; 4 of these segments were covered with lead, glass, aluminium and paper respectively, while the fifth was left uncovered. After 30 days the hairs loosened in the uncovered and paper-covered segments; later on, when the same phenomenon began to shew itself also in the aluminium-covered segment, the first-mentioned segments shewed a superficial necrosis. In the glass- and lead- covered regions absolutely no changes were visible. In a later experiment, Scholtz shewed that mercurial plaster also forms an effective screen against irradiation. In order to demonstrate that the alteration in the tube- vacuum, which occurs during every irradiation, has an impor- tant bearing on the physiological effect, Scholtz 2 ) exposed the left flank of a rabbit to a small "hard" tube, which became "soft" after 5 or 6 minutes' use; after that the tube was brought to bear on the right flank. After four irradiations in this man- ner an alopecia appeared on the right side, while on the left there was only a slight fall of hair. In order to decide whether Roentgen-rays are effective after they have actually penetrated the tissues, Scholtz exposed cer- tain regions on the backs and throats of rabbits and pigs over which he had fastened the animals' ears. The irradiation was vigorous, and inflammatory reactions were induced not only on ') Arch. f. Derm, und Syph., Vol. MX. Part I. 2 ) L. c. 332 RADIO-THERAPY both sides of the ears, but also on the parts beneath the ears. According to Scholtz, the muscles, cartilages, and bones are not affected; necrosis in these structures is generally secondary only to inflammation of the skin. Scholtz believes that Roentgen-rays exert their effects in the first instance upon the skin. These skin-effects, moreover, do not only occur where the rays enter the body, but may, after the penetration of thin layers of muscle and cartilage, occur at the site of exit. At the same time comparatively thin layers of tissue, which only show faint grey shadows on the fluorescent screen, considerably weaken the effect of the rays. Scholiz summarises as follows : i. The greater the output of X-rays from the tube, the greater the effect on the skin. On this ground, according to Scholtz, the therapeutic use of soft tubes is advisable. He recommends varying the intensity of treatment by alterations in the strength of current, the tube- distance, and the duration of exposure. 2. The less a given substance allows Roentgen-rays to trav- erse it, the more does it restrain effective rays from reaching the skin. Bodies, such as an aluminium screen, which throw only feeble shadows on the fluorescent screen, hold back, neverthe- less, a relatively large part of the effective rays. In other words, it is just the weakly-penetrating rays which are especially active on the skin. From the foregoing experiments it becomes evident that of all the physical factors emanating from an X-ray tube only the Roentgen-rays themselves and the discharges of high-tension electricity from the tube-surface can be considered responsible for the physiological effects. Both these agents appear simul- taneously while the tube is working, both have demonstrably similar effects, and these effects supplement and accentuate each other. The latter hypothesis appears borne out by the following experiment : A severe case of hypertrichosis of both cheeks and the chin was treated by the author as follows: The right TREATMENT WITH X-RAYS 333 cheek was exposed for the first 20 minutes to the "quiet" discharges from the special electrode, which has been described earlier. Afterwards the same cheek, was treated with Roentgen-rays for 1 5 minutes, the tube- distance being 15 cm. The tube was a very soft one, and could be touched without one receiving any perceptible electric discharge. The left cheek, was simply exposed to the same Roentgen-tube for 1 5 minutes at the same tube-distance. It would be approximately correct, Fig. 86. therefore, to say that the right cheek received X-rays plus electric discharges, the left cheek X-rays alone. The experiment was continued daily in this manner, and after the sixth day the right cheek shewed distinct signs of reaction, the hairs fell, well-marked erythema, etc., followed. The left cheek shewed as vet no signs of change; this region was, therefore, exposed S times further. After this, slight erythema and pigmentation shewed themselves, and a week later the hairs began to 334 RADIO-THERAPY fall. The reaction, however, on this side throughout ran a milder course than on the right. The experiment was repeated many times with the same result. Reac- tion and epilation always followed in a few days after treatment with high-tension electricity and X-rays, and the reaction was always most evident in those places which had been bombarded most vigorously by the dis- charges (Fig. 86). These regions appeared intensely red. The rest of the skin shewed the usual slight pig- mentation and erythema of commencing reaction. The combination of both methods also in cases of lupus ulcerations determined an earlier reaction and hastened the healing process. As regards the quality of tubes, it is certain that in most cases soft tubes are more powerful and act sooner than hard tubes. At the same time the rays emanating from hard tubes (including the electric discharges) appear to penetrate more deeply than those from soft tubes. Holzknecht's opinion is that any deeper action on the part of X-rays is impossible, since the physiologically active rays are absorbed by the skin, and only those rays which are inactive are allowed to penetrate. Against this we need only refer to the fact that animals which have been exposed for a considerable time to Roentgen-radiation show dermatitis on both sides of the body. In conclusion, we may discuss the mechanism of the physio- logical process. The action of electric discharges has been already explained (p. 159). With regard to the X-rays, the assumption that we have here to deal with a pronounced local action is opposed by the so-called tropho-neurotic theory of Oudin and Barthelemy *) . These authorities look upon the reaction as a reflex process arising from the central nervous sysrem through stimulation of the cuticular nerves. This theory may be abandoned in view of the local macro- and microscopical changes already described as occurring in irradiated tissues, bear- ') Monatsh, f. prakt. Dermatologie, Vol. XXV, 1897, p. 417. TREATMENT WITH X-RAYS 335 ing in mind, moreover, that there is complete absence of any symptoms on the part of the brain and spinal cord, or of any proof of peripheral nerve lesions 1 ). The action of X-rays is doubtless purely local, but as to its precise character there is still much to be learned. Kienbock believes in a chemical action, leading to disturbances of meta- bolism by which the cells of the tissue are led to react in the form of Roentgen-dermatitis. The action, however, cannot be purely chemical, for most enquiries shew that X-rays have remarkably weak chemical properties 2 ). The action of X-rays on a photographic plate must not be taken as a proof of the direct chemical effect of the rays on bromide of silver. Eder and Valenta have shewn that X-rays act on silver bromide gelatine, but not on collodion plates; this sufficiently proves that the photographic action of the rays is a highly complicated process, which does not consist merely in the reduction of bromide of silver. The author believes that through the destruction of tissue- elements certain products arise whose absorption leads to consti- tutional symptoms. This would explain the appearance of fever at the commencement of severe Roentgen-dermatitis, before any excoriation or ulcer affords the opportunity for local infection. Jankau") believed that electrolytic analysis of the cells takes place from irradiation, whereby the tissues are chemi- cally affected and inflammation is provoked. Kaposi 4 ) advanced the theory that Roentgen-rays affect the vascular system in the deeper layers of the skin similarly to sun- light, so that first an active and then a passive hyperemia results, which slowly extends to the more superficial vessels. It is well known that during the phenomenon of osmosis a slight potential-difference arises on both sides of the diaphragm through which the passage of the liquid particles takes place. H. Bordier*) affirms that under certain experimental condi- *) Jutassy, 1. c. *) ./. v. Hemptinne, Zeitschr. f.physik. Chemie, Vol. XXI, 3, p. 493- 3 ) Intermit, photog. Monatsschr. f. Medicin, Vol. V, No. i. 4 ) K. k. Ges. d. \rr/i, in Wien, Jan, 15. 1.897. °) Acad, dc Sc. Compt. rend., Vol CXXVI, p 595- 336 RADIO-THERAPY tions Roentgen-radiation retards the process of osmosis. An aluminium plate connected with the earth and introduced between the Roentgen-tube and the osmometer in no way inter- feres with this retarding process. Consequently Bordier ascribes the retarding influence to the X-rays themselves. Bor- dier explains this effect by the disturbing influence of X-rays on the electro-capillary phenomenon taking place in the membrane during osmosis. Since many vital processes in the cell depend upon the proper performance of this function of osmosis, Bordier believes that in the retardation of the latter is to be found the cause of many biological and therapeutic effects. The author believes that the pathological changes in irra- diated tissue may be explained by the disturbance of a pre- existing electrical equilibrium in the several tissue molecules by the X-rays, which possess the property of discharging electri- cally-laden bodies. B. Walter 1 ) also shares in this view. It seems, moreover, not impossible 2 ) that X-rays induce fluorescence in those tissue-elements capable of this phenome- non, and that this process brings about chemical changes, espe- cially in the cells. In this respect those tissues which contain earthy matter would appear to possess some affinity to the bromide of silver-gelatine, while other tissues, which have no fluorescence capacity, remain unharmed by the rays. Quite recently, Goldstein, arguing from the supposi- tion that where Roentgen-rays impinge upon material bodies ultra-violet light of very short wave-length is produced, ascribed to this ultra-violet light the cause of the biological effects produced in the deeper layers of the skin by Roentgen-radiation :! ) . According to this view, it is difficult to see why the rays should exert their influence mainly on the skin. They penetrate the whole body, and would, therefore, cause the production of J ) Fortschr. a. d. Geb. d. Roentgenstrahlen, Vol. I, No. 6, p. 242. 2 ) The author communicated this view to a meeting of the Vienna Medical Club, Jan. 30, 1901. 8 ) Sitzungsbericht d. k. preuss.Akad. d. Wissenschaften. quoted by Hols- knecht, Die Photochem. Grundlagen, etc. Fortschr. a. d. Geb. d. Roentgenstr., Vol V, TREATMENT WITH X-RAYS 337 ultra-violet light in the internal organs (the heart, liver, etc., where they are also absorbed) and so bring about changes there, which certainly is not the case. This difficulty does not arise with the author's hypoth- esis, for it is well known that the animal tissues do not all possess in the same degree the capacity for fluores- cence. § 34. Roentgen-ray Dermatitis. 1 The pathological changes in the skin which go by the name of "X-ray dermatitis" present the following clinical appearances: At first we have the milder signs of reaction already referred to : turgescence of the skin, pigment changes, pale- red erythema, loosening of hairs, and subjective phenomena (itching, burning, feeling of tension). Where the action is stronger the hairs begin to fall in from 3 to 14 days after the last exposure; first the thicker, and then the lanugo-hairs (seldom otherwise). The redness gradually becomes intensified, more and more cyanotic; while a small area of the skin (where the irradiation has been the strongest) soon shows superficial excoriation. The latter, which is accompanied by severe pain (see p. 251), and often fever, rapidly spreads centrifugally. Many authors affirm that Roentgen-dermatitis runs a painless course. The author cannot substantiate this from the cases which have come under his notice. 7 hesc were accompanied by considerable pain, especially when the raw surfaces were exposed to the air. In the case of naevus pigmentosus pilaris, which was mentioned earlier in this work, and which was the occasion of the first experiment in Roentgen-therapy, the pain was at first trifling. Later on, however, when ulceration shewed itself, the pain became at times very severe, espe- cially at night. The author has only seen pustular and bullous formations ') The li-t of Reports on X ray Dermatitis is a very large one. The reader is referred to Magnus Mailer's book. 338 RADIO-THERAPY in the above-cited case, though these are described as constant by several authors {Ehrmann, Kienbock, and others) . The excoriations have a yellow-red, smooth, wax-like appearance; they secrete a quantity of thin pus, and are covered by a peculiar (fatty-fibrinous) coating, which is with difficulty removed (this coating does not give a fibrin-reaction: Lion) ; at their border are seen circular or oblong islands of epithelium which may have bridge-like processes extending to the healthy skin in the neighbourhood. After very powerful irradiation a whitish patch (the "Roentgen-slough") differentiates itself in the middle of the excoriation. This becomes gradually darker and finally separates. The more powerful the irradiation, the sooner these phenomena shew themselves. Repair sets in as follows: The slighter signs of reaction which are the result of very weak irradiation soon disappear. Erythema and pigmentation are the first to go; often enough no traces of these are left after three days. Intumescence of the skin persists longer, and to this must be ascribed the excellent appearance of the integument in the earlier period after the suspension of treatment. Weeks or months later, when the skin has returned absolutely to the normal, one may be able to recognise slight wrinkles and atro- phic spots — shewing that the irradiation had been a little stronger than was perhaps thought at the time, and that it had consequently left certain permanent changes behind it. Where, however, the strength of the irradiation has been correctly gauged and administered, the excessive glossiness, elasticity, and smoothness of the exposed region disappear, leaving a skin which looks thoroughly healthy and normal. Six to eight weeks after the commencement of reaction new hairs begin to shew themselves in the smooth and hitherto hair- less skin; these hairs soon grow to the ordinary size. It is only after long and intermittent treatment that the hairs remain in a rudimentary condition, being white and small, with superficially- lying roots, so that they can easily be pulled out. Where very pronounced erythema (with or without excoria- tion) has been induced, this condition lasts for several days; after this time we find a drying up of the normal secretions, TREATMENT WITH X-RAYS 339 thickening of the cuticle, and marked pigmentation. Then, when the swelling has subsided, the skin exfoliates very freely. In more severe types of Roentgen dermatitis, with definite ulceration, the well-pronounced inflammatory phenomena are accompanied by pain and occasionally febrile symptoms for 6-8 weeks. After this time the after-effects of the X-rays seem to be completed (note that hair begins to grow again at the expiration of 6 to 8 weeks also). The X-ray ulcer has intensely red, sharp-cut borders, and heals but slowly towards the centre. The ulcer-secretions have a tendency to dry and form large rupia-like crusts adhering closely to the base of the ulcer; on removing these crusts one sees the characteristic, profusely-discharging Roentgen-ulcer; pain gives way later to a feeling of intense itching. When the ulcer is finally healed (and this may take a year or more in very severe cases), the scar is smooth, flat, and of good appearance, or it may be sclerodermatous or atrophic. Sometimes telan- giectases appear in the scar, either in the form of thick branch- ing vessels or as a reddish "marbling." An ulcer healed in this manner is liable to again break down and take a still longer time in healing. Besides this acute fulminating form of Roent- gen-dermatitis, however, we meet with another and milder form. The latter is seen after prolonged irradiation with weak tubes (hard tubes), a long tube-distance, and short exposures. The dermatitis then runs a milder course; the visible signs of reac- tion are less pronounced than in the preceding form. They have more the appearance of a chronic eczema, such as is seen in laundrywomen — the skin is swollen, dry, boardlike, thickly scaling, and in places excoriated or ulcerated. One often sees, moreover, an atrophic, cigarette-paper-like change in the skin and nails. Sensibility is of course disturbed in these cases where the hands arc affected. Cases of this kind, the so-called "chronic radio-dermatitis," may lead to the same cicatricial or atrophic conditions as the acute form. The author finds himself unable to agree with Oudin's dic- tum that Roentgen-ulcers have some tendency to become the seat of secondary infection. Antiseptic dressings would in any case negative possibilities of this kind. Still many writers appear to 34 o RADIO-THERAPY have discovered numerous bacteria in their histological examina- tions of the ulcers. As before mentioned, Roentgen-irradiation of the hands often brings about changes in the nails. These become dry, fissured, thickened and distorted; the ridges are deepened or become thinner, atrophic, and disappear where the action has been very strong. Numerous reports are to hand concerning the histological changes in the tissues after irradiation. Darier 1 ) noted an extension of the prickle and horn-cell layers, partly due to general hyperplasia of the rete, but more particularly to increase in the number of prickle and horn cells themselves ; further, a thickening of the epidermis, great increase of keratohyalin, and degeneration and atrophy of the hair- follicles, hairs, and glands of the skin. Vnna 2 ) found slight increase of the nuclei of the papillae and round the blood-vessels, and copious pigmentation in the upper layers of the cutis, whereas the pigment in the epidermis was not increased. The collagenous layers of the cutis appeared much thickened, swollen and pressed together, so that the inter- vening lymph-spaces were scarcely visible. They shewed, more- over, a peculiar staining reaction, becoming basophilic. The protoplasmic elements, especially the epithelium of the sweat- glands, appeared compressed and very small. The elastic bundles were not seen by ordinary methods of staining, and sec- tions shewed them to have a great tendency to separate from each other and fall away in small fragments. In Kibbe's case 8 ) the stratum lucidum was wanting, and keratohyalin, highly coloured, was found in the neighbourhood of the follicles. The cutis was richly cellular, and marked by vascular dilation. Gilchrist 4 ) found the horn-layer thickened, copious brown pigmentation in the rete, and dilated vessels in the corium. Jutassy's investigations have already been quoted (p. 277). ') Monatschr. f. prakt. Dermatol., Vol. XXV, 1897, No. 9. 2 ) Deutsche Medicinalzeitung, March 18, 1898. *) New York Med. Journal, Jan. 16, 1897. ') Johns Hopkins Hosp. Bulletin, Feb., 1897. TREA TMEN T // 7 TH X-RA YS 341 Gassmann' 1 ) found the following histological appearances in a small piece of blackened tissue taken from the base of a deep Roentgen-ulcer: The specimen was not necrotic in the ordinary sense, but consisted of different properly characterised and well-staining elements. The main portion was formed of collagenous bundles (white connective-tissue fibres), normal in appearance, and staining readily; their nuclei also stained well with ordinary methods. In places were seen degeneration-forms of peculiar appearance which took the nuclear stain. Between the nuclei, leucocytes and mast-cells were copiously distributed. Elastic bundles were readily shewn with orcein or by Weigert's method. Microscopic examination of another ulcer 2 ) shewed new- formed granulation-tissue which was in part skinned over; the lesion could in no wise be distinguished from other types of ulcer. The vessels of the cutis and sub-cuticular region shewed remarkable pathological changes in a Roentgen-ulcer 2 months old; there were seen enlargement and vacuole-degeneration of the intima, loosening of the elastica, vacuolisation and atrophy of the muscularis. The walls of many vessels were changed into a swollen mass and completely obliterated. The intima, which was thickened and possessed many swollen endothelial cells, was in places raised from the underlying layer, so that here and there round spaces were evident in this region. The greater part of the lumen of the vessel was occupied by this twisted, reticular, and vacuole-containing intima. Long bladder-like nuclei with nucleoli were visible, especially near the lumen, which could be readily recognised as endothelial nuclei. The vacuoles were either apparently quite empty or filled with a finely-bundled material ; here and there, moreover, a nucleus was seen. Only the larger vessels shewed the remains of a much unravelled, unequally thick, and often broken elastica. The muscularis often presented a honeycombed appearance, ') Fortschritte, Vol. II. II. 4. 2 ) Ibid. Vol. II. II. 6. 342 RADIO-THERAPY the brown-coloured, smooth, cross-cut muscle fibres with their well-stained normal nuclei being separated from one another by many vacuoles. The muscle-bundles themselves appeared atrophied. (These changes are very similar to those shewn in Fig. 59.) This vacuolisation degeneration affected both arteries and veins, but was not equally marked throughout the section. The fact that within a vacuole one often found a cell, a muscle-fibre, or a nucleus, made it not improbable, in Gassmann' 's opinion, that these spaces occupied the site of pre-existing cells. One might suppose that round the cell an exudation had collected which compressed the cell and so made it atrophy. Besides these vascular changes, Gassmann x ) also observed degeneration of the sub-cutaneous connective tissue, with abnor- mal staining reactions. Lion 2 ) found in his sections changes in the vessel-walls cor- responding to those described by Gassmann; he found also vacuolisation in all the layers of the epidermis and cutis; the cell-elements appeared swollen and perforated. He also found copious haemorrhages. Scholtz found the following changes in the skin of a hog's back; he excised the specimen for examination 7 days after one hour's irradiation: "The horn-layer, raised somewhat, contains here and there several nucleated cells. The granular layer is merely indicated; in places it is quite atrophied. The prickle-cell layer is much diminished, and the prickle-cells themselves are greately altered. The latter are swollen, their contour badly defined, their shape in the palisade-layer broader. The protoplasm is diffusely stained with haemotoxylin, the nucleus is only faintly stained, and the chromatin is seen in small conglomerations and in frag- ments. The nuclei are in great part swollen, and often indented and vacuolised. Vacuoles are found in the protoplasm, espe- cially in that adjacent to the nuclei. In nearly every microscopic field are to be seen cells with |) L. c. 2 ) VII Congr. d. deutschen dermatol. Gesellsch., Breslau, 1901. TREATMENT WITH X-RAYS 343 two or even three amitotic nuclei. Mitosis, on the other hand, is not seen, or at least only the commencement of it. All these signs of degeneration obtain from the palisade-layer to the horn-layer; near the surface the contour of the cells is scarcely more evident and their protoplasm has become almost a homogeneous mass; the nuclei are in great part only faintly indicated. The cell-changes in the hair root sheaths are quite similar; the loosening and falling of the hair can be readily explained by this cell-degeneration. I he corium is somewhat (Edematous; the connective tissue is less easily strained, somewhat swollen and homogeneous. Unna's "basophile" reaction is not obtainable with this tissue. The elastic fibres are preserved. The connective tissue cells have distinct, more or less diffusely stained protoplasm, are swollen and often peculiarly shaped. The cells of the sweat-glands shew similar mild degenerative changes, proliferating in places and projecting into the lumen of the ducts. Tn the media and intima of the larger vessels also are seen mild forms of cellular degen- eration, quite similar to that of the other cells. The cells of the intima are swollen, pressing towards the lumen; in places they are manifestly proliferating, becoming loosened and tend- ing to mingle with the blood-stream. In sections taken from a more powerfully irradiated skin the cellular degeneration was more pronounced, extending to the nucleus as well as to the body of the cell; besides this the signs of inflammatory reaction were seen: marked vascular dilatation, serous effusion into the tissues, conglomeration of leucocytes, and free migration of white blood-corpuscles. Where a high degree of cell-degeneration is attained from strong irradiation the leu- cocytes collect in masses round the dying cells and so aid in their complete destruction. Moreover, many "highly-charged" mast-cells are visible. The cells of the intima and media of the blood-vessels shew changes similar to those described by Gassmann. Round the hairs, where the rete extends towards the cutis as the root-sheath, quite similar degenerative processes are found among the cell-elements, also inflammatory signs. By these 344 RADIO-THERAPY means the coverings of the hair are completely destroyed, masses of leucocytes taking their place. In the severest grades of reaction microscopic examination reveals the appearance of a "Roentgen-slough." The rete mal- phigii and the horn-layer are completely wanting; in their place is seen a zone of thickly accumulated and mostly well-formed polynuclear leucocytes. The pus-cells are copious, and are sur- Fig. 87. — (a) Degenerated swollen connective-tissue cells — "vacuolised con- nective tissue." (b) Connective-tissue cells still more altered — giant-cell forms. (From W. Scholtz "Ueber den Einfluss der Roentgenstrahlen auf die Haut in gesundem und krankem Zustande." Archiv f. Dermatol, u. Syph, Vol. LIX, Part III.) rounded by fine thread-like masses. These could be shewn by JVeigert's method of staining to form in places a fine network between the pus-cells. Over this zone of leucocytes lies a thin layer composed of broken-up pus corpuscles, nuclear remains, detritus, and largely of masses of bacilli and cocci. Towards the cutis the zone of leucocytes either presents a sharply-defined border, or is seen penetrating the connective TREATMENT WITH X-RAYS 345 tissue. The papillary body has its outline comparatively well preserved for the greater part, or is at least recognisable. The connective tissue is soaked with serous exudation, swollen, in parts loosened into small bundles. The elastic network is pre- served; on the other hand, the connective-tissue cells shew marked degeneration: the protoplasm is swollen, diffusely stained by hasmotoxylin, containing one and often several blad- der-like nuclei of peculiar shape. The small vessels are much dilated, gorged with blood, and surrounded by leucocytes. In the zone of leucocytes and in the cutis haemorrhages are seen of varying size. In the case of severe Roentgen-ulcers the vessels of the cutis and sub-cutis are in places completely obliterated, the connective tissue vacuolised throughout, the connective-tissue cells forming a kind of giant-cell. (See Fig. 87.)" Scholtz studied the process of healing of superficial Roent- gen-ulcers in several specimens taken from the human skin. 'The infiltration in the corium diminishes; the connective- tissue cells and their nuclei become normal again, and where the papillary body has been destroyed it becomes replaced by fine, well-staining connective-tissue fibres which lie parallel to the surface of the skin. The epithelium slowly spreads from the borders of the ulcer and soon sends processes towards the still somewhat (Edematous connective tissue, or covers over the papillary bodies which may be still retained. In the latter event complete restoration of the normal configuration of the skin is effected, in which only the destroyed follicles are wanting. Not only does the connective tissue in the healed area remain for some time soft and wanting in strength, but the epithelial cells also shew signs of marked disturbance for a while. The rete remains (Edematous for some time, the prickle- cells swollen, the nuclei bloated and badly-staining, the prickle, and especially the granular layer, is often much widened, and the keratohyalin collected in lumps and particles in the cells. In the horn-layer are found nucleated cells in which the horning process is incomplete. Moreover, in cases where the reaction has not reached the stage or excoriation or ulceration, but merely a well-marked dermatitis has shown itself, several weeks after 346 RADIO-THERAPY the irradiation has been discontinued and all inflammatory phe- nomena have disappeared similar enlargement and changes in the prickle-cell and granular layers are evident. It is quite comprehensible that under these conditions the newly formed Roentgen-scar and powerfully irradiated areas of skin should be very sensitive to caustic applications or to fresh exposure to the tube. Weak dressings of pyrogallol oint- ment may readily cause fresh ulceration of the whole, and these new ulcers may be very slow in healing." The destruction of the cell-elements and especially of the connective-tissue cells is probably the cause of the tedious repair of Roentgen-ulcers, since, as is well known, scar-formation pro- ceeds from the connective-tissue cells. The above-described histological changes afford a ready explanation of the falling of the hair after Roentgen-radiation. The rays soon take effect on the prickle-cell layer and bring about degenerative changes in its cell-elements; it naturally fol- lows that the cells of the hair-sheaths, in which the cells of the rete form the outer layer in the depth of the cutis, are soon affected, and may be completely destroyed. This only happens where a certain degree of intensity in the irradiation has been attained, whether by one single powerful exposure or by the accumulated effects of several weaker exposures; moreover, it may occur without the rest of the tissues being especially affected. Salomon 1 ) described pronounced changes in the elastic fibres in a case of lupus treated by X-rays. These fibres were quite normal in the deeper layers of the cutis; more superficially, however, "innumerable small, very fine fibrils were seen, which could be demonstrated by the Unna-Tanzer or Weigert methods. These were slightly twisted, often wavy, and some- times lay parallel to the surface, sometimes vertically. They increased in numbers towards the surface and reached to the small-celled infiltration below the epidermis, without actually coming into contact with the epidermis itself. The same appear- ance was manifest in the thickened adventitia of the blood- ') Archiv. f. Dermat. u. Syph., Vol. LX, Part II. TREATMENT WITH X-RAYS 347 vessels, but here the fibres lay always parallel to the vessel- wall." Clearly these were very young elastic fibres. Zehmann l ) examined hairs which had been caused to fall by Roentgen-radiation. In most hairs the portion of the shaft nearest to the hair-root was considerably thinner, and instead of the usual bulbous appearance seen in the root itself was a thin, pointed remnant. In other cases, where the hair-shaft retained its usual calibre, in place of the bulb a stumpy, conical end was seen. Often the bulb shewed a slight swelling at the lower end. In a few cases hairs were found having well- marked bulbs with a peculiar brush-like condition. In view of the three first-named conditions, Zehmann considers that we have to deal in these cases with a rapidly developing atrophy of the hair-root, reminding one in some ways of the condition obtaining in alopecia areata. The prognosis of Roentgen-dermatitis depends upon the following factors : the intensity of the irradiation, the extent and depth of the pathological changes, the locality affected. The sooner a powerful reaction makes its appearance, the more severely does it run its course, and the worse are the prospects of early cure. As a rule, dermatitis and ulceration shew a ten- dency towards improvement after about two months, by which time in ordinary cases the after-effects of the irradiation have exhausted themselves, and fresh hairs begin to make their appearance. Of course the rapidity of healing depends largely upon the size of the ulcer. The extent of the scarring, telan- giectasis, etc., which may follow, depend, moreover, upon the intensity of the dermatitis and the extent to which the tissues have been transformed. These after-conditions, therefore, are controlled by earlier factors — the intensity of the treatment and the reaction. The appearance of a white patch on a larger, red, shallow excoriation is a bad prognostic sign; this indicates later ulceration. Ulcers lying over superficial bony prominences (the chin, vertebral spines, etc.) are especially obstinate. The treatment of these affections is not so ineffective as is generally supposed. In the mildest case, marked only by sub- x ) Freund. Wiener med. Wochenschr.. [897, No. 10. 34 8 RADIO-THERAPY jective symptoms, the application of a dusting powder is quite sufficient. If erythema or excoriation be present, tepid dress- ings of boracic lotion, a 15% boracic lanolin, or diachylon oint- ment, are useful. Oudin recommends peroxide of hydrogen dressings. Cold applications of liquor Burowii, which are so often recommended, are directly harmful. The author repeatedly observed in several cases of hyper- trichosis under treatment by X-rays during a cold winter sea- son that when the patients reached the stage of reaction the skin, under the influence of the extreme cold, became darkly cyanotic, so that the patients and their friends became not a little alarmed. This discolouration, and a strong burning sensation which accompanied it, disappeared in a few days. Perhaps the con- dition is to be referred to the relaxing effect of the cold upon the blood-vessels. The application of warmth to the affected regions is always acceptable to the patient, whether in the form of hot fomenta- tions, poultices, or otherwise. The author recently treated, in conjunction with Prof. Ehrmann, two cases of deep Roentgen- ulceration which had resulted from exposure to soft tubes by a Viennese practitioner; radiant heat from a powerful incan- descent lamp (100 candle power) was employed, with daily half-hour sittings. This not only relieved the subjective symp- toms, such as intense itching, but rapidly healed the sores. The good results attained in these two cases would appear to speak well for the method 1 ). Very obstinate ulcerations should be thoroughly and deeply excised and a plastic operation after- wards performed. Apostoli and Oudin have seen good results from the employ- ment of spark-discharges. The pigmentation left after irradiation disappears as a rule spontaneously in a short time. Torok and Schcin hasten its departure by the shaling action of naphthol ointment. J ) The author heard afterwards that Bar had achieved good results in the treatment of Roentgen-ulcers with red light. Referred to by Oudin at the II Congr. intcrnat. d'filectrologie et de Radiologic, 1 Sept. 1902. IV. BECQUEREL-RAYS. BECQUEREL-RAYS. §35. This is the name given to a physical phenomenon, strikingly similar in its effects to the X-rays, which was discov- ered by H. Becquerel in 1896. Whilst, however, the X-rays can only be produced by the aid of rather complicated appara- tus, in which electrical processes take place, the Becquerel-rays require no physical instrument at all. They are emitted by certain chemical elements procured usually from uranium pitch- blend, and, so far as is at present known, no external action on the substances is required to bring about their emission. Neither directly nor indirectly is any electrical apparatus needed for the production of these rays, and the radiation, for some reason still unexplained, goes on, undiminished, without any assignable external cause. Becquerel found that not only uranium salts, but also metal- lic uranium possesses radio-activity. Mme. Slodkowska Curie proved that when the bismuth is eliminated from natural uranium pitch-blend, traces are found of a substance which gives out Becquerel-rays of great intensity. This substance M. and Mme. Curie called polonium. A second radio-active constitu- ent of pitch-blend is found combined with barium; this is called radium. Debierne discovered yet another substance with radio- active properties in pitch-blend; this he called actinium. Thorium, too, and its combinations have been found to be radio- active. A f anas jew and Crookes discovered that all minerals containing radium and thorium are more or less radio-active, even when extremely minute quantities of these elements are present. According to Elster, many, indeed, perhaps ally bodies present on the surface of the earth emit Becquerel-rays. The radiation of polonium, of the radio-active lead discovered by K. A. Hofmann and E. Strauss, and of other radio-active substances, falls off markedly in course of time, but sulphate of lead is said to regain the power under the influence of cathode- 352 RADIO-THERAPY rays; the elementary nature of these substances is a matter of doubt, and it is surmised that they owe their activity to induced radiation or to incorporated traces of radium or actinium, which permanently retain their activity. Becquerel, for instance, found that a non-active body brought near to an active body and exposed for some days to irradiation from the latter, itself becomes for some time radio-active. Elster and Geitel have lately proved that in the atmosphere too, particularly where (as in enclosed spaces) it is seldom renewed, some radio-active substance is present, which diffuses electricity in the atmosphere. It is exceedingly difficult to procure these radio- active preparations. Herr Giesel told the author that from 800 grammes of raw material he gained only 0.3 gram of radio-active substance. Hence these prep- arations are very costly. Von Lengyel lately suc- ceeded in obtaining synthetically radio-active substances (sulphate, chloride and carbonate of barium). A distinctive mark of radio-active salts is their self-lumi- nosity. They phosphoresce unintermittenly, without any preced- ing illumination, by means of their own rays, which proceed from the depths of their own substance. Giesel found this quality specially marked in active bromide of barium, freed from water. The luminosity of radio-active substances dis- appears when they are warmed and re-appears as they become cold. Becquerel-rays blacken a photographic plate; like the cathode-rays (Becqnerel, Goldstein) , they produce certain after- effects of colour on rock-salt, chloride of potassium and fluorite; and, like the X-rays, they colour glass violet {Villari, Berthe- lot) . M. and Mme. Curie, Berthelot and Becqnerel found other chemical effects of Becquerel-rays. Thus, they impart ozone to the air, and darken barium platino-cyanide, and, in presence of oxalic acid, reduce corrosive sublimate to calomel. Further points of similarity between the cathode-, Becquerel-, and X-rays were proved. Thus, P. Bary found that all the chemi- cal compounds which are made luminous by the X-rays become 'phosphorescent also through the others. According to Him- B ECQ UEREL-RA YS 353 stedt, both kinds of rays lessen the resistance of selenium-cell; the property of ozonizing the air, too, is common to both cathode- and Becquerel-rays. The best known peculiarity of these rays is their power of passing through dark opaque bodies (metals, too, with the exception of lead), and then acting on a photographic plate or a fluorescent screen. Becquerel-rays, however, differentiate less than the Roentgen-rays. A metal object enclosed in an opaque covering is recognisable on the luminous screen and on the photographic plate, but not so the bones of the hand. With suitable experimental conditions the Becquerel-rays have a similar electric action to the short-waved light rays; thus they impart a certain electrical conductivity to gas permeated by them x ) . Geitel holds that air in a normal condition has some slight conductivity, which is raised by the merest trace of a radio-active substance. When radio-active substances have been kept in any room the walls for a long time after radiate radium rays (induced radiation) and ionize the air, so that, for experiments on the normal conductivity of the air, it is necessary to work in places where it is certain that no radio-active substances have been stored. The rays of radio-active substances are capable of discharg- ing a charged electroscope; the brush and spark-discharge of an induction-apparatus between a sphere (as anode) and a disc (as cathode) is converted into a glow-discharge. Becquerel- rays possess this peculiarity to such an extraordinary degree that it may be used to prove the presence of very feeble rays, and of the rays of those bodies which preserve their radio-activ- ity for a short time only. Under the influence of Becquerel- rays the delaying of the process of spark-discharge (discovered by Jaumann) is suspended Giesel, v. Schweidler, and St. Meyer regarded the detec- tivity of these rays in the magnetic field as a negative-electricity l ) According to St. Meyer and E, v. Schweidler, the conductivity of the air irradiated by Becquerel rays i diminished by the presence of a magnetic field. 354 RADIO-THERAPY movement. This behaviour in the magnetic field points to the deflectible rays carrying with them negative electrical dis- charges. In the electrostatic field, too, as is seen from Bec- querel's and Dorn's experiments, they are movable. It has been concluded from this behaviour, and from other qualities in har- mony with it, 1 ) that the rays proceeding from the radio-active substances are physically identical with cathode-rays, and that they owe their origin to the emanation from the radio-active bodies of very minute particles. The rays proceeding from radio-active bodies are not homo- geneous, but are of several kinds, quite distinct in character, which vary in their power of penetration (JV alter) , in their behaviour in the magnetic field {P. and S. Curie, Becquerel, Villard, Giesel, St. Meyer, and others) , and in their physiological action on the eye and the skin {Aschkinass, and the writer). It has been shown that besides the rays which undergo distinct deflec- tion in the magnetic field and have great penetrating power, whose co-efficient of absorption diminishes as the thickness of layer increases, radium, uranium, and Giesel's polonium emit other rays very similar to the X-rays. These rays, like X-rays, are not affected by a magnetic field, and have far less pene- trating power than those in the first group; their co-efficient of absorption increases with the thickness of the layer. Dorn dis- covered the remarkable circumstance that rays not magnetically deflectible are converted almost wholly into magnetically deflec- tible rays by passing through paper, and partially so by passing through aluminium. The wave-length of the Becquerel-rays has not yet been determined; it is surmised that it is far less than that of the Roentgen-rays (calculated at 0.0014 micron). Their velocity has been calculated by Kaufmann at about 250,000 km. per second. This is not very different from the velocity of light (310,000 km.), and that of cathode-rays (280,000 km.) 2 ). 1 ) For instance, they evoke, like cathode-rays, the thermo-luminosity of fluorspar, which previous heating has destroyed. 2 ) Many of the facts given here are taken from Dr. /. Elster's compre- hensive references in Dr. /. M. Eder's Jahrbiicher fur Photographie u. Re- produktionstechnik (for 1900, 1901, 1902), to which the reader is referred for fuller information. BECQUEREL-RAYS 355 § 36. As has been already mentioned, certain biological effects of Becquerel-rays have become known to us. We are acquainted mainly with their influence on the skin and the eye, and on bacteria. According to Henri Becquerel, the germinating power of seeds is destroyed by prolonged irradiation. Two Italian investigators were the first to report an action of the rays of radio-active substances on micro-organisms. Pacinotti and Porcelli 1 ) found that various germs could be killed within 3 to 24 hours by the rays emitted by a freshly obtained powder of metallic uranium, which had been exposed to sunlight and then cooled down to a temperature of 44-55 degrees in a receptacle from which the air was excluded. The microscope, it was averred, showed distinct changes in these germs, which could only be ascribed to chemical action on their protoplasm. Experiments were made in this way on staphylococci and streptococci, proteus, and cholera germs, also on the bacilli of tuberculosis, diphtheria, and typhus. Five ccm. of a very poi- sonous broth culture of streptococcus were injected under the skin of both ears of a rabbit, and one ear was exposed to the action of the uranium rays. No inflammation at all resulted in the irradiated ear, whilst in the other ear the local affection took its ordinary course. The present writer in the beginning of 1900 made some experiments with a view to testing the possible bactericidal power of Becquerel-rays 2 ). In his investigations he used the salts of metallic uranium, not uranium itself. M. and Mme. Curie had observed :i ) that both natural pitch-blend and the bismuth and barium compounds obtained from it are considera- bly more active than metallic uranium itself. Of the two sub- stances (radium and polonium), three preparations of radium were at the author's disposal. The first was a few grains of the original preparation of M. and Mme. Curie of Paris, which l ) Gazetta degli Ospcdali, ref. to in Wiener mcd. Blatter, 1899, No. I, P- 15- ') Die physiologischen Wirkungen der l'nlentladungen, etc., 1. c. *) Compt. rend., 189K, CXXVII, pp. 175, 1215. 35 6 RADIO-THERAPY Dr. St. Meyer of Vienna most kindly lent him for purposes of experiment. The two other radio-active substances A and B came from the laboratory de Haen at List, near Hanover, where they had been prepared according to the directions of Herr A. de Haen. A differs from B in being self-luminous to a greater degree; B, on the other hand, stimulates fluorescence in the barium-platinum-cyanide screen much more than A does. Sev- eral grains of both A and B, thanks to the kindness of Hofrath Prof. Dr. /. M. Eder, director of the Imperial Graphischen Lehr-u-Versuchsanstalt, were procured and set aside for experi- ment. In the first place Dr. St. Meyer established the fact that both A and B had the same electric qualities as the Citric preparation. As the substances are extremely hygroscopic and lose something of their strength on contact with the air, each of the three preparations was first wrapped in a small covering of parchment paper, and this again enclosed in an envelope of fairly thick aluminium foil, any gaps being closed with a cement impervious to air and moisture. These covers of paper and aluminium apparently offered no obstacle to the passage of the rays, as could be easily seen from tests with the barium-platinum- cyanide screen. They were marked on the outside A, B and C. On the agar plates {a, b and c) diffused cultures of staphylococcus pyogenes aureus were made; on the cen- tre of each dish a piece of sterilized paper was spread, and on these again the substances A, B and C were laid. They were left, each on its respective dish, for 3 hours, and at the end of that time both they and the papers were removed and the dishes put in the incubator. After 24 hours all three cultures showed a quite even growth, without any interruption of luxuriantly develop- ing colonies. The experiment was repeated, with the modification that the irradiation was left to work for 3 days instead of 3 hours. The result was again a wholly negative one. The subject of the next experiment was a micro-organism of less resisting power, viz., the typhus bacillus. The experiment was arranged like the preceding one. BECQUEREL-RAYS 357 In this case, too, even after 3 days' action of the rays on the cultures, there was not the slightest evidence of any influence on the growth. These experiments, undertaken for the purpose of showing any possibly existing power of the Becquerel rays to kill bacteria, already developed and capable of life, were carried on by the author in precisely similar fashion to the methods he adopted in his experiments on spark-discharges. These experiments too yielded a negative result, and justify us in the conclusion that Becquerel-rays of the quality and inten- sity available for enquiry are not in any way capable of checking the development and life of bacteria. With regard to the action of Becquerel-rays on the skin, observed by Giesel, M. and Mine. Curie, and others, when the preparations were used under other experimental conditions, the author surmised 1 ) that radium preparations emit various classes of rays, of which some are more biologically active than others. This surmise is confirmed by the result of experiments reported by Aschkinass and Caspari. These writers made experiments on the bactericidal properties of Becquerel-rays with a very powerfully radio-active preparation of barium- radium-bromide, investigating first the action of the nonabsorb- able rays which had passed through aluminium foil. Results were absolutely negative; the bacteria developed under the action of these rays just as they did without irradia- tion. But when the absorbable Becquerel-rays were examined, the result was positive; the easily absorbable rays checked the development of the bacteria on an agar plate, the organism growing luxuriantly in the part on which no rays fell. Asch- kinass and Caspari proved by special control experiments that bacterial development was checked, not by the air changed (ionized) by the Becquerel-rays, nor by the bromine freed from the bromide, but solely by the easily absorbable rays falling on the bacteria. Where these rays had to pass through a thicker ') Naturforscherversammlung, Hamburg, [901. 358 RADIO-THERAPY stratum of air before they reached the agar plate no effect was seen; the effective rays had been absorbed by the air *). Strebel, too, reported 2 ) experiments with positive results; according to him bactericidal action is sometimes present, some- times not. Quite lately the author was again in a position to make some experiments, with a radium preparation made by Herr Saubermann of Berlin. This time he did not use an aluminium covering, but enclosed the prepa- ration in parchment paper only; in spite of this the result was negative, after the bacteria culture had been' exposed as close as possible to the rays for 3 days. This preparation too, therefore, emitted rays too weak to act on the bacteria. The writer, simultaneously with these experiments on bac- teria, made the first experimental investigation of the action of Becquerel-rays on the skin. The 3 aluminium envelopes were enclosed side by side in a gutta-percha paper, and this was made adhesive with chloroform and applied to the outer aspect of the upper arm. The whole was bound closely to the arm with a bandage. For 3 days the little packet was left on the same spot. At the end of this time it was removed, when the skin did indeed show some redness, but so slight that it seemed to the author more probable that this had come from the rubbing and the irritation of the gutta-percha paper than from any action of the rays. Groitven too made experiments on himself with a radio- active preparation. This was bound on the arm for 12 and 36 hours; after 6 weeks there was still no sign of reaction 3 ). On the other hand, IFalkhoff*) observed an action of the Becquerel-rays on the human skin exactly corresponding to that of the X-rays, x ) PHiiger's Arch. f. Physiologic 1901, Vol. LXXXVI, pp. 603 ff. z ) 73- Versammlung der Naturforscher und Aerzte in Hamburg. s ) Versamml. der Naturforscher und Aerzte in Hamburg. 4 ) Phot. Rundschau, XIV, p. 189. BECQUEREL-RJYS 359 On February 19th, 1901, Dr. Giesel told the author: "JJ'alkhoff laid on his arm for 20 minutes on two occasions 0.2 grm. of a preparation of mine in a double celluloid capsule. After 14 days the skin became violently intlamed. The spot was still reddish brown after six months, and is even yet distinguishable. By mistake I applied to myself for two hours 0.3 grm. of a more powerfully active preparation. At first there was only faint redness, but after 2 to 3 weeks violent dermatitis set in, followed by blistering and destruction of the epidermis as after a burn. At this time the exactly circumscribed spot looked so bad that I put myself under medical treatment (Dr. Slant hal) , fearing that the destruction of tissue might extend deeper. Two or three days after that the place began to heal, and in two days more the skin had formed all over it; only a rough- ness was left for some time. The place now, after about three months, is faintly indicated by the absence of hairs. "I was the first to find that radium reacts also on the living plant leaf after contact for a few hours; the chlorophyll disappears after some days, and months later the spot is still recognisable by the autumnal- yellow colouring of the whole leaf and the brownish spots on the surface. "Even the best preparations have absolutely no effect on bacteria, as Walkhof has proved in the Munich Physiological Institute. "To-day a medical man, who wanted to experiment on the eye with one of my preparations, assured me that he had not been able to observe the slightest bac- tericidal properties on the part of radio-active bodies." Dr. A. Sternthal, who had treated Dr. Giesel for this der- matitis, reported at the Breslau Congress of Dermatologists ' ) that in the site of the inflammation a smooth, white, somewhat depressed scar was to be seen, with more colour round its bor- ') Verhandlungsbericht, p. 480. 360 RADIO-THERAPY ders. The spot was absolutely hairless, whilst hairs grew all round about it on the arm. M. P. Curie made several interesting experiments, based on those of Giesel on himself, with a preparation the activity of which was about 9,000 times as powerful, as that of uranium. Curie gave the author the following particulars of the experiments: August 1st, 1901. "I allowed the preparation to act on my arm for 10 hours. It was separated from the skin by a thin layer of gutta-percha, and held firmly in place by a bandage, for it is necessary that the substances should be very close to the skin and be only separated from it by very thin media. The action under; such experimental conditions was more powerful than I desired, for even now, 4 months after the irradiation, the wound is not yet healed. "Stronger preparations — and we possess some 1,000,000 times more powerful than uranium — act from a distance and through glass, and an exposure of 10 minutes suffices to produce inflammation of the skin. The reaction sometimes does not show itself until 19 and even 30 days after irradiation/' Becquerel put into a glass tube 1 cm. long and 3 mm. in diameter a few decigrams of radium-barium chloride, which has considerable radio-activity, surpassing that of metallic uranium about 800,000 times. The glass tube was hermetically closed, wrapped in paper, and put in a little cardboard box. On the 3rd and 4th of April this box was repeatedly put into the pockefof the waist- coat worn by the experimenter. The latter kept it in his pocket for perhaps 6 hours in all. On the 13th of April he noticed that the rays, which had traversed the glass tube, the wrapping paper, the cardboard of the box and the clothes, had produced on the skin of the body a red oblong patch, 6 cm. long and 4 cm. broad. On the 24th of April the skin peeled, and the most severely affected part began to suppurate and discharge fragments of necrotic tissue. The wound did not heal BECQUEREL-RAYS 361 until 49 days after the rays had acted. Thirty-four days after the experiment dermatitis of a less violent nature showed itself also in a second part, corresponding to the other end of the waistcoat pocket, to which the glass tube had probably got shifted for a time. Mme. Curie, who had carried a few centigrams of the same radio-active substance in a glass tube from one place to another, had similar inflammation on her hand, though the glass tube was enclosed in a case (which had very- thin sides). P. Curie and Becquerel further report 1 ) that in the course of their experiments, beside the above- mentioned lesions, they suffered from peeling of the skin of the hands, and at the tips of the lingers, with which they had carried the little tubes, from very painful spots, which caused trouble for some time. Aschkinass notes 2 ) the interesting fact that the power of the Becquerel-rays is not lessened when the preparations are allowed to act on the skin packed in aluminium capsules. Giesel discovered") that the Becquerel-rays act on the eye. If a radium preparation is wrapped in light-proof paper and brought in the dark near to the closed eye an intense sensation of light is felt. This is strongest when the preparation is laid on the lid, but it is still very clearly perceptible when the hand is interposed or the preparation brought near the temporal region. According to Giesel, this phenomenon is probably due to some phosphorescence in the interior of the eye. Giesel's results have been substantiated by numerous other investigators also. M. Mater 4 ') reported radium rays as not acting on the normal eye, but this theory is contradicted by the observations of all the other investigators. F. Himstedt and JV. A. Nagel have subjected to closer examination Giesel's discovery of the light-sensation produced ') Acad, dc Sc, June 13th, iqoi. 2 ) 7?>- Versammlung deutscher Naturforschcr und Aerzte in I [arnburp:. a ) Physik. Zeitschr., 1899, No. 3, p. 43. 4 ) Bleiblatter, etc., 24, 1900, p. U44- 362 RADIO-THERAPY on the eye by Becquerel-rays 1 ) . They confirm his experience only in the case of an eye adapted to the dark, just as Roentgen-rays and ultra-violet light can only be perceived by a completely rested eye. It was not possible to determine whether the Becquerel-rays act directly on the light-perceiving organs of the retina, rods or cones, as they produce fluorescence (which acts as a diffused light source on the eye) in the transparent media of the eye, the lens and the vitreous humour. Himstedt and Nagel proved a stimulative action of ultra-violet and Roent- gen-rays on the frog's eye. F. Himstedt reports that it is surprising how quickly the eye tires of this sensation of light. If two perfectly similar little bags of light-proof paper are prepared, the one filled with radium, the other with a corresponding quantity of sand, and if these are placed alternately on the eyes, it is impossible, after about 30 repetitions of the experiment, for any one to tell on which eye the radium and on which the sand is placed. Blind persons who have lost their sight through opacity of the cornea or of the lens, have, as might be expected, a sensa- tion of light under the action of the Becquerel-rays. Grunmach noticed phenomena of irritation in the retina when working with radium. For some hours after he felt a glimmering sensation in his eye. Dr. Javal~) together with M. Curie made several experi- ments on blind persons with a very powerful radium salt; this was enclosed in a glass tube, which again was kept in an opaque box of cardboard. The two blind persons first examined saw nothing; the radium gave them no sensation of light. One of them had lost his sight through atrophy of the visual nerves, the other through glaucoma. J aval and Curie pursued their investigations further in the Blind Institute in Paris. One blind person, a boy who had lost his sight through displacement of the retina, had still some slight capacity for receiving light impressions. Under the influence of the rays from the radium his whole field of vision was lighted up, and again, even when *) Physik. Zcitschr., 1901, II. Jahrg. p. 362. 2 ) Physikal. Zcitschr., tqoo, I, p. 476. BECO UEREL-RA YS 3 63 he covered his eye with both hands, he perceived light. From this experiment Dr. J aval draws the conclusion that if it were possible to restore the transparency of the cornea the boy might recover his sight to a great extent. Little is known as yet as to other physiological action of Becquerel-rays. E. Aschkinass and JF. Caspari 1 ) were unable even after several hours' exposure to Roentgen- and Becquerel-rays to dis- cover that they had any effect on the consumption of oxygen by muscle preparations made from frogs. § 37. H. Strebel made therapeutic experiments with radium substances in lupus. According to his reports, 1 ') reaction took place in so far that the nodules became distinctly paler and the tissues softer. On another occasion he reports 3 ) having pro- duced an ulcer in a lupus patient. Danlos and Block cured two cases of lupus erythematosus by the application for 24 to 63 hours of two preparations with an activity of 5,000 and 5,200 respectively 4 ). Further, Dan- los treated ) four cases of lupus vulgaris with two radium preparations with an activity of 2,500 and 19,000. The period of application varied from 24 to 36 hours. The treatment answered excellently. The scars were smooth, soft and super- ficial. With weaker preparations too (activity of 1,000 to 1,800) Danlos gained, as he reports, favourable results for the time, but recurrence soon took place. Danlos considers the stronger preparations to be the more suitable for therapeutic use, as the weaker ones have to be applied for a very long time before they produce any effect, and this inevitably causes ulcera- tion. Such complications may, he believes, be avoided by using the stronger preparations, which require less time. According to Danlos, the course of radium reaction is as follows: The first redness shows itself, then after 6 to 20 days ') 73. Versammlung d. Naturforschcr u. Aerzte in Hamburg, 1901. 2 ) VII Congress of the German Dermatological Soc, Brcslau, Transac- tions, p. 488. 3 ) 73. Versammlung d. Naturforscher 11. Aerzte, Hamburg, 1901. 4 ) Soc. d. dermatolog. et d. syph., Nov. 7U1, 1901. 5 ) Ibid. July 3rd, 1902. 364 RADIO-THERAPY the epidermis becomes whitish, macerated, and peels off. Often a bulla appears, which bursts and leaves an ulcer. The ulcer discharges freely, and is deeper or more superficial and more or less painful according to the intensity of the ray's action. The pains, as in Roentgen-dermatitis, are often more pro- nounced by night. Danlos recommends radium in lupus vul- garis and erythematosus, hypertrichosis, superficial malignant disease and nasvus. Hallopeau and Gadaud 1 ) treated lupus verrucosus of the hand with radium. The preparation had an activity of 19,000. It was applied from 72 to 120 hours. After this there was a change of colour, and in 15 days an ulcer appeared with yellow- ish base and regular borders; the ulcer was the seat of shooting pains. At the same time the hand became very stiff. Other parts which were only exposed for 24 hours appeared markedly improved. Oudin proposed that in order to allow only the X-rays from radium preparations to act the substance should be encased in aluminium, which absorbs cathode-rays better than X-rays. He believes he has proved by experiments on guinea-pigs that vari- ous parts of the body react differently to radium rays. From the little that we know as yet of the biological action of the Becquerel-rays we may assume that they are in this respect very similar to the Roentgen-rays. Like the latter, they produce on the skin — earlier or later, according to the intensity of the irradiation — a kind of dermatitis, which besides other peculiari- ties (epilation) is specially marked by its slow course and the sluggish character of the lesions induced. Their action, too, on the eye is analogous to that of the Roentgen-rays. With regard to the bactericidal action of the rays of radio-active substances opinions are still divided. It would seem that only one special kind of rays is effective (i. c, those easily absorbed), and that only under special conditions and when very powerful prepara- tions are used. We require further experience before we can determine how far these rays are of practical therapeutic value. For the pres- *) Soc. d. dermatolog. et d. syph., Nov. 7th, 1901. BECQUEREL-RAYS 365 ent they possess only scientific interest, partly because ol the difficulty of making radio-active preparations and their enor- mous price, but partly also because few preparations are actinic to the same extent, and it is hence impossible to give directions for the strength and duration of treatment which shall be uni- versally applicable. V. TREATMENT WITH HEAT AND LIGHT RAYS. (PHOTOTHERAPY.) TREATMENT WITH HEAT AND LIGHT RAYS. (PHOTOTHERAPY.) I. Elements of Photophysics. §38. Light is the agency which renders bodies visible. There are two hypotheses concerning its nature. Newton held that luminous bodies emit a very fine matter, which produces in the eye the sensation of light. This hypothesis is called the emis- sion theory. According to the wave or undulation theory, formu- lated by Huyghens at the end of the 17th century, light consists in an undulatory movement of ether, an exceedingly elastic, im- ponderable medium which pervades the whole universe, pene- trating even between the molecules of material bodies. Waves proceeding from the source of light reach the eye and irritate the visual nerves of the retina, thereby producing in the brain the sensation of light. This theory enables us to explain readily most optical phenomena. To Thomas Young we owe the fundamental discovery that the law of interference is applicable to light as well as sound. He applied the wave-theory successfully to explain the colours 1 ) Text-books and references: /. M. Edcr, Ausfuhrl, Handbuch der Photographic, Halle, 1891. — /. M. Eder, Jahrbiicher f. Photographie und Reproductionsverf. 1. bis. 16 Jahrg., Halle a. S. — II. M. Vogcl, Handbuch der Photographie, Berlin, 1894. — Muller-Pouillet, Lehrbuch der Physik, Vol. II, 1. — //. Kayscr, Lehrbuch d. Physik, Stuttgart, 1900. — /•'. Kbrner, Lehr- buch d. Physik, Vienna, 1897. — E. Riecke, Lehrb. d. Experimentalphysik, Leipzig, 1896. — F. Frankenhduser, Das Licht als Kraft, Berlin, 1902. — Niels R. Finscn, Ueber die Anwcndung von conccntrirtcn Lichtstrahlen in der Medicin, Leipzig, 1899. — Finsett, Die Bedeutung der chem. Strahlen des Lichtes. Leipzig, 1899. — Magnus Moeller, Der Einfluss des Lichtes auf die Haut, Biblioth. med., Stuttgart, igoo. — Gebhard, Die Heilkraft des Lichtes, Leipzig, 1898. — 0. Lassar, Ueber die neueren Methoden der Lupusbehand- lung, Zeitschr. diatet. 11. physikal. Therapie, 1900-01, Vol. IV. II. 1. — //. Strebel, Die Verwendung des Lichtes in der Therapie, Munich, 1902. — /. Raum, Der gegenwartig Stand un erer Kentnisse ueber den Einfluss des Lichtes etc.. Zeitschr. f. Hygiene, Vol. VI. p. 312 etc. — //. Rieder, Hand buch d. physikal. u. diatet. Therapie, Part I, Vol. II. 37 o RADIO-THERAPY on certain kinds of thin plates and ridged surfaces. All his experiments in interference were explicable on the assumption that light is a wave-movement; the idea that light consists of flying particles explained nothing. Young discovered also the difference between light waves and sound waves, viz. : that in sound waves the air vibrates in the direction of propagation (longitudinal air-vibrations), whereas in light waves the ether particles move vertically to the direction of propagation (trans- verse ether-vibrations). Just as there are high and low notes, so there are varying rates of ether-vibration. Violet light, for instance, makes nearly twice as many vibrations as red. The waves of red light are therefore nearly twice as long as the waves of violet light, for in the atmospheric ether all are propagated with equal velocity. The vibrations of ether particles may proceed along straight lines vertical to the ray of light, and in so doing may either lie all on one plane throughout the ray — this is rectilinear polarisa- tion — or they may move in turn in all directions, as in the case of ordinary light. When the vibrations proceed along circular or elliptic courses, circular or elliptic polarisation takes place. The surface of a luminous, like that of a resonant, body may produce waves of varying size; hence daylight or composite light — like complexity of sound — consists of light of all possi- ble colours and directions of polarisation. The simplest light is that which shews only one colour, or which consists of waves of equal length and is polarised in straight lines. Of late a theory has been brought forward which is founded largely on the work of Maxwell and Hertz and on our gradu- ally increasing knowledge of the correlation of electricity, mag- netism, and light. This theory regards ether-movements as the common cause of all three classes of phenomena. Scientists have inclined lately more and more to the assumption that luminosity is brought about not by the movements of atoms themselves, but by the movements with and upon them of their electrical charges, electrons. § 39. Bodies which are in themselves sources of light, i. e., which become visible through their own power, are called self- luminous bodies. PHOTOTHERAPY 371 Amongst terrestrial bodies those which glow and burn are self-luminous. As long as they are at a fairly low temperature (less than 400 ) they send out rays of great wave-length (heat-rays) ; with increase of temperature the wave- length lessens. The heating power of light-rays lessens in the spectrum towards the violet end. As the tem- perature becomes higher, the constant movement of the molecules composing the bodies becomes more violent. The atoms of which the molecules again consist begin to vibrate when the latter collide, and the vibration is communicated to the ether surrounding the atoms. As the molecular movement grows in intensity the clashing of the molecules becomes more violent, and thereby quicker vibrations of the atoms and the ether are induced. Again there are in nature (in the vegetable, animal and mineral kingdoms) bodies which are self-luminous in the dark. Amongst self-luminous bodies we must in the first place include the sun and the fixed stars; of terrestrial substances there are, firstly, those which glow by reason of their high temperature (hot or molten metals, glow- ing carbon in illuminating gas, in electric lamps, etc.) ; secondly, luminous organisms (e. g. t those on rotten wood, fireflies, the infusoria which produce marine phosphorescence, certain jelly-fish, etc.). The source of light in the latter class is as yet by no means accounted for. Non-luminous bodies may be classified as transparent, trans- lucent, and opaque, according as they allow more or less free passage to the ether waves striking them, or as they absorb them entirely. There are no absolutely transparent bodies. Thick layers of even the most transparent bodies appear slightly col- oured, a sign that part of the white light falling on them has been absorbed. The space through which light passes is called (whether it contain solid matter or not) the medium. A very small luminous body or a very small luminous surface is called a "point" of light. 372 RADIO-THERAPY §40. A straight line along which light is propogated is called a ray of light. Objects may be discerned through straight tubes, not through curved ones. Light is propagated in straight lines in all directions. The extension of light in straight lines may be observed where sun rays fall into a dusty room. The formation of shadows, too, is only explicable on the hypothesis of the recti- linear extension of light. 1. The term "light ray" must be conceived of as a purely geometric definition, as the straight connecting line which we imagine as drawn from a point of light to some illuminated point. A light ray has no physical existence at all. A number of light rays are called a bundle of rays. The phenomenon of the reception of light by one point from another luminous point in the same medium, in spite of the breaking of the straight connecting line between the two points by an opaque body, is called "deflection of light." The velocity of propagation of light was first estimated by astronomical means. It may be taken as being 299,300 kilom. a second. §41. If light is thrown on a sheet of paper from, say, a candle flame, the paper is illuminated less brightly in proportion as it is removed further from the source of light; or, the dis- tance from the source of light remaining the same, as the angle of inclination at which the light rays strike the paper becomes less. Light rays being projected along straight lines, it follows that the light effect spreads over spherical surfaces, of con- stantly increasing diameter, the superficial area being propor- tional to the squares of the diameters; hence the intensity of illumination of a given surface by rays striking it perpendicularly diminishes in proportion to the square of its increasing distance from the source of light. The strength of light varies inversely as the square of the distance. If the distance be doubled, the strength of the light is dimin- ished to one- fourth; if the distance be increased threefold, the strength of light is one-ninth, and so on. Thus, if the distance PHOTOTHERAPY 373 be multiplied by four, the strength of the source of light must be multiplied by sixteen in order to gain an equally powerful illumination. A surface is illuminated most powerfully when the effective light rays strike it at right angles. If the illumination is oblique, fewer rays fall on the same plane; some of the rays, too, are longer, and hence feebler in light as they strike the plane. Whilst therefore the brightness of a self-luminous body depends on the intensity of the light in each single point and on the size of the illuminating plane, the brightness of illumi- nated bodies depends further on their distance from the source of light and on their position in relation to it. The strength of illumination of a plane surface by parallel light rays is proportional to the cosine of the angle of incidence of the rays. The brightness of a body, i. e., the amount of light which it reflects, is further dependent on its colour and its albedo. The albedo of a body is that numerical value which gives the proportion of white light falling on a body compared with that which is reflected from it. § 42. It is not possible, by the eye alone, to estimate with even approximate accuracy the relative brightness of two illuminating planes, or of the various points (e. g., in a gas flame) where the intensity varies. The aid of photometers has therefore to be called in; these make it possible to estimate with certainty the relative intensity of two illuminating bodies. The strength of light is denoted in normal candle-power. In Austria and Germany the normal paraffin candle (N K) (20 millimetres in diameter and. with a flame 50 millimetres in height) was formerly often used in denoting the intensity of a light source. It is generally known as the German unit. In the last few years the more exact H efner-Alteneck normal lamp, burning amyl-acetate, has been more and more used as the light-unit. In England the light unit is a certain sperm candle (stand- ard candle), in France a certain oil lamp (bee carcel). The unit of measurement for the illuminating power of an illumi- nated plane is the metre candle ( 1 M. K.), i. e., the illuminating 374 RADIO-THERAPY power produced by i normal candle at a distance of i metre, where the light rays strike perpendicularly. Photometers serve to measure the optical intensity of a source of light, i. e. } to com- pare its strength with that of a normal candle. In Rumford's shadow-photometer two shadows of an opaque stick are cast on a white plane, the one by the source of light to be measured (L), the other by the normal candle (/) ; one source of light remaining at the same distance (J), the other is moved on (up to D) until the two shadows appear equally dark. Then L :l = D 2 :d 2 . L=(»\.L ©" In L. Weber's photometer light is thrown on 2 opa- lescent glasses, on one from a constant flame, on the other from first one and then the other source of light. A completely reflecting prism brings the images of the glasses side by side. By regulating the distances equality of brightness is produced. The principle of Bunsen's grease spot photometer is that a grease spot on a piece of white paper appears dark when light is thrown on it from a source of light in front, and light when it is lighted up from behind. If light is thrown on the paper from the back and the front at once, the grease spot will look alternately dark and light, according as the back or the front light is the stronger. If the one light is kept stationery and the other brought nearer or further, a point will soon be found at which the grease spot will vanish, i. e., become invisible, because it will then look as bright as the surrounding paper. Here, as in the case of the Rumford photometer, the equation holds good : L: I — D 2 : d 2 . These photometers can only determine the intensity of the effect of the light on our eye. But this is essentially different from the intensity of the chemical effect of the light. No direct PHOTOTHERAPY 375 conclusion can therefore be drawn with regard to the chemical effect of various sources of light from their brightness as determined by the photometer. For testing the chemical inten- sity of a source of light recourse is had to photographic photo- meters or actinometers (/. c, sensitometers) , which are based on the chemical action of light on substances sensitive to its effect. Sensitiveness of various substances (e. g., silver salts) to the chemically effective rays varies according to their colour sensitiveness. The photometer of Bunsen and Roscoe is based on the fact that chlorine and hydrogen combine to form hydrochloric acid, slowly in diffused and explosively in direct sunlight. The amount of hydrochloric acid which is formed in a given time and dissolves in the water serves as a measure of comparison for the various sources of light. The Eder photometer is based on the decomposition of a mixture of bi-chloride of mercury with neutral ammonium oxalate. The intensity of the effective light is estimated according to the amount of sub-chloride of mercury precipitated. Eder proved experimentally that about 90% of the precipitate of chloride of mercury was the work of the ultra-violet rays, only 10% being pre- cipitated by the rest of the spectrum. Further, there are actinometers made from sensi- tised papers. These arc constructed on one or other of two principles. Either exposure is made until the paper assumes a certain normal colour (photometers on Run- sen's and Roscoe' s principle), or exposure is made with a scale of regularly diminishing strength of light (as, e. g., with superimposed strips of transparent paper), and observations are taken of the progress of the photo- graphic effect ') . A. Larsen with his chloride of silver paper photo- meter measures the blackening of the paper as the light passes through. l ) /. .1/. Eder, Kv fiihrl. Handbuch d. Photogr., I. t, p. 352. 376 RADIO-THERAPY While photometry by means of the ordinary photo- graphic papers is used to measure the intensity of the blue-violet and ultra-violet rays alone, it is possible, by adding certain colouring matter to the bromide of silver, to render the normal papers sensitive to other classes of rays. This was shown by Andresen with rhodamin paper, which is sensitive to yellow light; the bromide of silver indeed still remains very sensitive to blue- violet, but this is counteracted by the use of yellow filters (auramin) . A. Win gen 's is a normal colour photometer con- structed on the same principle. /. M. Eder proved the colour-sensitiveness of Andresen s rhodamin-bromide of silver paper, and of rhodamin-chloride of silver and other papers by a series of experiments, from which it appeared that such photometer papers are affected by different zones- of the spectrum, according as they are exposed to a more or less strong light. When shutting out (by yellow light filters) the blue and violet rays, which become effective with longer exposures, it is neces- sary to take into account the concentration and quality of the filtering colour 1 ). Electric photometers are based either on a peculiar property of selenium, which is a better conductor of electricity in the light than in the dark, or on the elec- tric currents resulting from the chemical action of light on chloride of silver plates. A. Larsen constructed an actinoscope for ultra-violet rays, based on the fact that ultra-violet rays are favour- able to the formation of electric sparks. The spark of a Ruhmkorf coil jumps across a longer spark-gap if the negative electrode be irradiated by ultra-violet rays. The mechanical effects of light and its power of producing phosphorescence have been utilised in the construction of photo- metric apparatus (radiometers, Warnecke's phosphorescence- photometer), but such apparatus have been but little used in practice. l ) Wiener klin. Wochenschr., 1902, No. 29. PHOTOTHERAPY 377 § 43. The theory of the reflection of light is called katoptrics. I f a light ray falls on an opaque body the light is thereby pre- vented from passing along a straight line in the same direction. In such a case part of the light is thrown back or reflected. If the reflecting surface is smooth the resulting effect on the light is termed reflection; if the surface is more or less rough dispersion or diffusion results. Mirrors may be plane, or they may have curved surfaces. If the curve is outwards the mirror is convex; if the mirror is like part of a sphere, polished on the inside, it is concave. The angle at which a light ray falls on a mirror is called the angle of incidence; the angle at which the ray is reflected from the mirror is called the angle of re/lection. The angle of reflection of light is equal to the angle of incidence. Light rays falling on a concave mirror, spherically curved, so as to pass through the centre of the sphere of which the mir- ror forms a part, are called axis rays. The spherical centre of the mirror surface is called the centre of curvature, and the straight line passing through this point and the curve-centre of the mirror itself is the optical axis of the mirror. An axis ray is reflected directly back. Rays parallel to the axis of the concave mirror (e. g., the sun rays, coming from an infinite distance) are reflected in stick a manner that all pass through the burning-point or focus. The focus is therefore the gathering-point of all the rays that strike the mirror parallel with the axis. The focus of a concave mirror lies on the main axis, mid-nay betzveen the mirror centre and the sphere centre. As the source of light approaches the mirror, so that its rays are no longer parallel to each other, the focus recedes further and further, even to infinity, when the source of light is in the focus. The reflected rays are then parallel. They become divergent when the source of light is brought between the focus and the surface of the mirror. Important practical use has been made of this power of li< r hr dispersion for li^ht-projectors. Mangin in his 37 8 RADIO-THERAPY apparatus uses spherical concave mirrors, consisting of weak concavo-convex lenses with a silver coating. Scluickert's glass parabolic mirrors, being in one piece, have the advantage over Mangin's of being free from chromatic and spherical aberrations (see 52), and of absorbing little light; further, they allow of the choice of a suitable focal distance. An arc-light is used. The carbons lie horizontally; the crater- formation on the positive carbon thus produced enables the source of light to be more fully utilised at a medium focal distance from the mirror. The laws governing the origin of the various images cast by mirrors will not be treated of here, as they have no bearing on our present subject. § 44. The theory of light refraction is termed dioptrics. We have seen above that opaque bodies do not allow of the rectilinear extension of light, but reflect it. The direction of light rays is altered further by transparent bodies, i. e., by those which allow a large part of the light to pass through. An oblique ray, passing from one transparent body into another which transmits light at a different rate changes its direction, i. e., is refracted. Refraction is governed by the following laws : 1. The incident and the refracted rays are on opposite sides of the axis of incidence and lie in one plane — the plane of inci- dence. 2. The quotient of the sine of the angle of incidence and the sine of the angle of refraction equals the ratio of the velocity of light in the two media, and is called the quotient of refrac- tion, or "refraction" index. Rays impinging at right angles on the dividing surface of two transparent bodies are not refracted. The refraction index depends on the rate of vibration of the light ray, i. c., its colours. The refraction of light by means of polished glasses is fre- quently turned to practical account. Glasses with polished spherical convex surfaces are called lenses, or convex lenses; they are thicker in the middle than at the edges. Glasses which are PHOTOTHERAPY 379 hollowed out or concave (hence thicker at the edges than at the centre) are called hollow or concave lenses. The optical axis of a lens is the straight line passing through the curve centre of its two surfaces, or — if one surface be plane — through the one curve centre, falling perpendicularly on the plane surface. Rays striking a concave lens parallel with the axis are dispersed after refraction. The axial rays passing through the centre of the lens are not refracted. Objects looked at through a concave lens appear smaller and nearer. Sun rays passing through a lens convex on both sides are so refracted as to converge as one point of light at a certain dis- tance from the lens. A piece of paper held at this converging point, the focus, becomes heated and finally burns. The convex lens acts as a burning glass. Light rays impinging on a convex lens parallel with the axis are so refracted as all to pass through the focus. The distance of the focus from the centre of the lens is called the focal distance. Rays passing through the focus and impinging on a convex lens are, after refraction, parallel with the axis of the lens. The axial rays pass through without refraction. All objects within the focal distance appear, when seen through a convex lens, larger and more distant. The image of an object outside the focal distance appears reversed. The effect of a lens depends on its diameter and its curve, as well as on the refracting power of its substance. § 45. Parallel rays striking a large spherical concave mirror, or a spherical lens close to the edge, do not converge in one focus after reflection, but spread over a wider zone, whose axis is the focal line proper. The effect of this spherical aberration is to blur the image. It happens especially with thick lenses, and is due to the disturbing influence of the prisms of which one may imagine a lens composed. Lenses are further subject to chromatic aberration. They break up white light into its component parts, as does a prism. I Ience if a bundle of rays is thrown on a convex lens parallel to the optical axis, the violet rays, being refracted at a sharper angle, intersect each other 380 RADIO-THERAPY again behind the lens at a shorter distance from it than the other rays; the red rays intersect at the greatest distance. At whatever point the image is caught, only one colour is sharp; the others are all blurred. Parabolic mirrors, on account of the geometrical properties of the parabola, have no focal plane, but only one single con- verging point for all parallel rays. Hence parabolic mirrors are used in preference to concave as light projectors. § 46. In most cases we have to deal with both reflection and refraction of light; that is to say, the whole of the impinging light is not reflected, but part of it finds its way into the second medium. In other words, reflection is associated with loss of light. The amount of loss depends on the nature of the media and the direction of the rays. Part of the refracted light, again, does not pass through the second medium, but is used up in it, being converted into other forms of energy (heat, chemical energy, etc.). Photometric measurements prove that the sum of the strength of the light reflected by a body and that of the light passing through it is less than that of the impinging light rays. This phenomenon is termed light absorption. An absolutely transparent (diaphanous) body would absorb no light at all, but such a body is as non-existent as an absolutely opaque (adiaphanous) one, which would reflect all the light (total reflection excluded). Even gold and other metals are transparent if sufficiently thin. A whole class of bodies (e. g., coloured glasses) absorbs only certain light colours; another (fluorescent bodies) changes the colour of the impinging light. Transparent bodies become translucent by the incorpora- tion of foreign particles, from which the light is diffusely reflected. Opalescent glass, blood, milk, etc., are examples of such media. According to the law of the conservation of energy, the force of absorbed light is not lost, but is converted into other forms of energy of equal value. A change takes place in the condi- tion of the light-absorbing substance, and, on the other hand, those rays which are absorbed are the only effective ones. Hence PHOTOTHERAPY 381 light which has passed through a substance and left behind in it some of its component parts is sensibly weakened. § 47. A light ray passing through a prism is diverted from its original direction and resolved into its component colours. A colour series {spectrum) appears of red, orange, yellow, green, blue, violet; the red appearing least, and the violet most divergent. The yellow and orange of the sun spectrum are about twice as bright as the green, 30 times as bright as the blue and the red, and nearly 200 times as bright as the violet. The colours in the spectrum are neither of equal size nor sharply defined; they merge insensibly one into the other. White light then is composite. Dispersion is the resolving of a composite light into its component coloured parts; each of these, in the case of white light, is simple or homogeneous. By means of a lens the colours of the spectrum may be reunited into white light. Colours of bodies are not identical with the colours of the spectrum, being dependent on the light striking them. A body absorbs certain coloured components of the light and reflects or permits the passage of the rest. It is in the one case opaquely, in the other, transparently, coloured. The colours of bodies have thus no actual existence, but are mere products of light. A transparent body is transparently colourless if it allows all the parts of the impinging light to pass through equally; it is, e. g., transparently blue if it absorbs all but the blue rays. In a blue solution of copper sulphate the red and yellow rays chiefly are absorbed ; the green and violet ones are allowed to pass, but less freely than the blue; hence the blue colour. Yellow colouring solutions allow of the free passage of the yellow rays, and less freely the red and the green ; they absorb the blue and violet entirely. An opaque body is white when it reflects strongly and equally all the component parts of white light, and black when it absorbs them. It is interesting to note that colourless bodies which are equally transparent to light rays may vary very much in the degree in which they suffer the so-called 382 RADIO-THERAPY chemical rays to pass. For instance, "double-spath- soda" absorbs chemical rays less than crown glass and flint glass; rock-crystal and rock-salt absorb them least of all. Red light penetrates bodies far .more readily than blue. If lamp-light, which has been passed through a thick sheet of paper, is subjected to spectrum analysis, it will be found that nearly all the blue light has been absorbed and that only the red and yellow remain. With a thicker absorbing layer, red alone passes through. The same holds good of gases and vapours, e. g., the atmos- phere (as may be seen from the red colour of stars, and especially also of the sun, as they near the horizon). The sharper the angle at which the light is refracted, the more readily will it be absorbed. According to the wave theory of light, each of the colours making up sunlight has its own rate of vibration. Red has the lowest rate (about 400 billion vibrations per second) ; the vibra- tion rate increases with the other colours of the spectrum accord- ingly as they approach the violet end, while violet itself has the highest rate of vibration (about 800 billions per second). A ray of white sunlight thus comprises vibrations ranging from 400 to 800 billions per second. The various light-waves of a composite light ray are dif- fracted variously in a prism. The red light, having the lowest rate of vibration, is least diffracted, or retarded; the violet, having the highest rate of vibration, suffers most diffraction and retardation. Hence the varying refractive indices of the differ- ent rays of the spectrum. The cause of this retardation of the smaller light-waves was for a long time not understood, and that it could not explain this phenomenon was felt to be a flaw in the wave theory. Cauchy lent fresh support to the theory by establishing the connection between'the velocity and the length of a wave, when- ever the molecules of a body are in such a position that the dis- tance between them bears a distinct relation to the wave-length. Different colours have different wave-lengths, decreasing in the spectrum from red to violet. PHOTOTHERAPY 383 Hence the colour rays towards the violet end of the spec- trum are known as rays of lesser wave-length, or more highly refrangible rays; those towards the red end as rays of longer wave-length, or less highly refrangible rays. Various methods, which we will not enter upon here, have been used to gauge the wave-length of the different kinds of light. Fraunhofer first determined the length of the visible rays, Cornu, Esselbach, and Eisenlohr that of the ultra-violet, Abney f that of the ultra-red spectrum. To Angstroem we owe the more accurate measurements, and his unit {A E) is now used to denote wave-lengths: AE = mm. 10,000,000 Light of shorter wave-length has a correspondingly shorter duration of vibration, but a higher rate. The density of the ether particles amongst the molecules is greater in solid and fluid bodies than in gases; hence, light of shorter wave-length, on passing from the air, is more slowly propagated in solids and fluids than light of greater wave- length. Hence, too, it is more highly refracted. The solar spectrum has at either end of its apparent limits further rays; beyond the red, the so-called infra-red or ultra-red rays of greater wave-lengths and lesser rates of vibration (less than 400 billions) ; and beyond the violet, the so-called ultra- violet, of shorter wave-length and higher (more than 800 bil- lions) rates of vibration. The principle that a light ray is refracted more highly in proportion to the shortness of its wave-length applies also to the invisible ultra-red and ultra-violet rays. Spectroscopes are used for the closer examination of the spectrum. The white light emitted by glowing solid and fluid bodies gives an unbroken spectrum. If, however, sodium chloride is vaporized in the flame of a Bunsen burner, only two bright yellow lines appear as the spec- trum of the sodium vapour. Lithium vapour gives a red and yellow line, as do also salts of barium, calcium and strontium. Every metal when vaporized 384 RADIO-THERAPY shows its own special line in the spectrum; hence the presence of certain lines in the spectrum of a flame points conclusively to the presence of the corresponding body in the flame. (Spec- trum Analysis.) Gases, too, give such spectra when examined in Geissler tubes and illuminated by an electric current. If the light o{ a bright flame be passed through sodium vapour, the spectrum will show two dark lines at the spot where sodium vapour alone would give two bright yellow ones. Fol- lowing Kirchhoff, we call this phenomenon "reversal of the spectrum." If the light be passed through a coloured glass plate, or a glass vessel filled with a coloured solution, the lines of the colours which have been absorbed on the passage of the light through the coloured body vanish from the spectrum, and parts of the spectrum appear dark ; thus we have an absorption spectrum. This filtering or decomposing of white light has long been turned to practical account in various graphic crafts. In a self-luminous body, emitting only light of one colour, i. e., of one wave-length, the particles all vibrate at the same rate. Vibrations of the same length striking the body set the particles in motion, like a body resounding in unison with another body giving out the same tone. The energy which makes the particles vibrate lessens the energy of the impinging ether vibrations, and weakens the light as it passes through; but the vibrating body at the same time gains in energy. This energy, however, is now radiated in all directions, not only in that of the impinging vibrations, where it is less than before. This is the explanation of Kirchhoff' 's law: that a body, which, when glowing, emits only light of a given wave-length, absorbs an impinging light ray of the same wave-length. If it emits light of varying wave-length, it for the same reason absorbs all corresponding light rays. The ratio between the emissive and the absorptive powers for rays of a like wave- length is, as Kirchhoff has proved, the same for all bodies at the same temperature. (Eisenlohr.) What becomes of the light that has been absorbed? I. Absorbed light is usually transformed into heat. The PHOTOTHERAPY 385 impinging visible rays are then emitted by the heated body as dark heat rays of greater wave-length. Conversely a body played on by dark heat rays may be heated till it shines. (Tyndall terms this calorescence.) 2. Absorbed light often causes the immediate emission of new light rays of a different colour (this is fluorescence) . In such cases the bodies are, as it were, self-luminous throughout the period of their illumination; the colour of the light they emit is different both from that of the impinging light and from that peculiar to the body itself. The colours of bodies are caused by reflected rays, fluorescent colours by absorbed rays. 3. Absorbed light may also cause a more or less continuous emission of new light rays of different colours. This phenome- non, known as phosphorescence, is seen in sulphide of calcium, sulphide of strontium, etc *) . 4. The light may produce chemical effects, notably de- composition. Photography is based on such effects. 5. Electric phenomena may in many cases be caused by the impinging ether vibrations. 6. The light may, under certain conditions, produce mechanical results. (Crookes' radiometer.) Emission spectra may be unbroken, in lines, or in bands; absorption spectra show only lines or bands. One end only of 1 ) Becquerel proved with the aid of the phosphoroscope that all solid fluorescent bodies are also phosphorescent, if only for a very short time. Hence he concluded that fluorescence and phosphorescence are in their essence the rame, the difference lying merely in their duration. Fluorescence is chiefly caused by light of short wave-length ; the waves in fluorescent light may be longer, but are never shorter, than those in the exciting light. Luminescence, according to /:'. Wiedemann, is luminosity produced by external causes without any corresponding rise of temperature. He distin- guishes several kinds, according to the exciting cause: K 1 iiim; Cause. Irradiation Electric discharge ( Ihemical processes Slight heating Friction Crystallization Name. Photo luminescence Electro a Chrmico tt Thermo it Tribo a Crystal (( 3 86 RADIO-THERAPY the spectrum may be absorbed (e. g., alum absorbs ultra-red, glass ultra-violet), or both. Fraunhofer observed innumerable fine black lines (known after him as "Fraunhofer lines") in the solar spectrum; some of the most important of these are shown in Fig. 88. They were named by him after the letters of the alphabet. Kirchhof explained their appearance by assuming that there are certain gases present in the gaseous envelope of the sun which would, if not interfered with, produce bright lines where dark pnes are shown in the spectrum; that is to say, that the light irradiated from the white-hot sun suffers on its course loss of certain shades of colour through absorption. Accordingly Infra fRed Red Yellow Green Blue Violet Ultra-violet A B C D E F Fig. G H H' I M O R 5. — Solar Spectrum. S T U the solar spectrum is an absorption spectrum, and the Fraun- hofer lines will show which gases are contained in the sphere of light. Spectrum analysis, by enabling us to examine the chemical composition of distant bodies, especially of the heavenly bodies, has led to most important results. Further, by its intense sensitiveness to the slightest trace of an element, it has led to the discovery of a whole range of new elements. The careful measurements of Kirchhof, Thalen, Huggin, Dewar, Abney, Eder, Valenta, Exner, Kayser, etc., have determined the wave-length of the light emit- ted by various elements. Thus: Na shows a bright yellow double line, the so-called D line. ( A = 5896.16 and 5890.19). Li shows red lines (6708 and 6104). Ba emits green light; its main lines are: 6497, 6142, 5828, 5536, etc. Lines A to H in the spectrum are the most readily recog- nisable. The eye is most sensitive to the light between D and PHO TO THERAPY 387 E, that is, part of the yellow; from that point towards either end the light is less and less visible, until the red rays beyond A and the ultra-violet beyond H are hardly distinguishable. Our visual organs then are limited in range, like our organs of hearing (we cannot hear sound waves of less than 1 mm.). D' Arsonval thus explains the insensibility to his currents. It does not, therefore, follow that the light rays of either greater or less wave-length have less intensity of vibration. As a matter of fact, as Herschel showed, the heat of sun rays increases towards the red and goes on increasing in the dark space beyond. § 48. By the aid of an intensely sensitive instrument (the bolometer, based on the principle that a wire offers increased electric resistance with increase of temperature) which regis- ters heat-differences to the millionth part of a Celsius degree, Langley discovered a heat spectrum, almost 20 times as long as the visible spectrum, extending beyond the red. In this heat spectrum there are about 700 "lines of cold" (reminding one of the Fraunhofer dark lines), where the bolometer marks no heat. The wave-length of the heat rays that have been examined ranges from 0.7^ to 5.2 /i (/* = two mm). The heat spectrum, as examined by the bolometer, shows a constant change of temperature, at longer and shorter intervals. The spectrum shows lines corresponding to the sudden fall and rise of the temperature; the broader bands of lower tempera- ture may be regarded as absorption bands. Langley's further investigations, at a height of 4,000 metres on Mount Whitney, proved that a great deal of heat is absorbed by the atmosphere; he was able at the same time to determine the amount of solar heat reaching our atmosphere. This amount is so great that, if the rays struck vertically, it would thaw in one minute an ice crust of nearly 3 centimetres. The thickness of the atmospheiv which the sun's rays have to penetrate varies at different times of the day (it is much less at noon than at sunset) ; hence the spectra vary correspondingly. Rays of short wave-length suiter most absorption. At noon the heat maximum is at orange, in the evening towards red. The 3 88 RADIO-THERAPY character of the heat spectrum varies also at different seasons of the year. Further investigation of the heat spectrum may, in Lang- ley's opinion, have important results for meteorology. Both the quality (i. c, the rate of vibration of emitted rays) and the intensity of heat radiation from bodies are dependent on their temperature, their chemical nature, and the character of their surface. Of the heat rays striking a body part are reflected, part penetrate the body. A diathermanous body is one which allows the penetrating rays to pass through; an athermanous body is one which absorbs them wholly or in part. Since glass does not allow of the passage of rays of long / Ultra-red Red Orange Yellow Green Blue Indigo Violet Ultra-Violet Fig. 89. — From A. Lainer's Lectures on photograph, opt., Vienna, 1890, p. 107. wave-length, /'. e., of heat rays, prisms of rock-salt or fluorspar must be used in these investigations. § 49. Rays in the almost invisible part of the spectrum from H to R act chemically on many light-sensitive preparations. Bromide of silver is affected at F, iodide of silver at G. On the whole, chemical action is strongest at H, and lessens in either direction. (On Fig. 89, line a, b, c gives the curve of thermal action, line d, e, f, g the curve of the chemical action; line h, i, k gives the light curve, with its maximum at yellow.) This is true only of the solar spectrum; the spectrum of each light source varies. The spectrum of Drumond's limelight and that of the electric arc-light extend much further towards the ultra-violet end than the solar spectrum, because of the great absorption by the atmosphere of the short-waved sun rays. PHOTOTHERAPY 389 (The amount of ultra-red rays in sunlight depends on the amount of vapour and carbonic acid in the atmosphere.) Still more ultra-violet is shown in the spectrum of the sparks of an induction-coil; most of all in the spectra of aluminium, cobalt, iron or Edcr's alloy (lead, zinc, cadmium). These are line spectra, showing innumerable lines, especially in the ultra-violet. The spectrum of iron, c. g. t has about 5000 lines. Amongst the media which have been so far examined, rock-crystal, white fluorspar, and calkspar have no appre- ciable absorptive power for ultra-violet; rock-salt, ice, alkali-sulphates, -carbonates, -arseniates, and -borates, alkaline earths, soluble compounds of fluorides, chlorides and bromides of the alkalies and alum have very little. Ultra-violet rays pass without appreciable diminution through the flame of a candle and through pure hydrogen (Schumann) . Organic acids and their compounds, and especially many benzol derivations (Hartley) , have great absorp- tive power. Glass, mica, gypsum, gelatine, and many animal and vegetable liquids absorb ultra-violet largely (dc Chardonnet) 1 (thus, £. g., watery vapour absorbs all waves of less length than 307 pp) . Fluid albumen (/'. e., a 12% solution) absorbs, according to G. P. Dross- bach, all waves of less than 320 pp, and, when much diluted, all of less than 300 pp. A 1% solution of pep- ton-gelatin is permeable in the same degree as an equiva- lent solution of albumen. Heavy flint glass and all kinds of dense lead-contain- ing glass are most absorbent, crown glass and baryt- flint-glass less so. Cornu proved that a quartz prism gives a solar spectrum stretching beyond R in the ultra-violet; a calk- spar prism gives the spectrum to beyond / } , light flint- glass towards l\ r in the ultra-violet, whilst heavy flint glass stops short of even all the visible violet. ') Compt. rend., 1881, Vol. XDIII, p. 406. 2 ) Deutsche med. Wbch., November 21, kjoi. 39 o RADIO-THERAPY . Schumann's experiments showed that a glass plate 0.125 mm. in thickness absorbs a third of the extreme ultra-violet rays of the magnesium spark (more than A =2 7 v). 1 ) Ultra-violet rays are refracted, i. c, gatherea, by quartz, rock-salt, or fluorspar lenses. Ultra-violet rays, like the short-waved rays of the visible spectrum, can produce fluorescence. Cathode- and Becqucrel- rays make the air light-conductive and convert its oxygen into ozone, and ultra-violet rays of short wave-length ( , X= 0.00014 — 0.00019 mm.) have the same effect. Herz found that irradiation with ultra-violet light does away with the oscillatory character of the discharge from an apparatus emitting electric waves. We may imagine the layer of gas between the two ends of the conductor as becoming conductive through the splitting up of the electrically neutral molecules by the impinging corpuscles 2 ). Following up this discovery, Hall- wachs found that negatively charged metal surfaces are discharged by ultra-violet rays. Lenard 3 ) discov- ered that the negatively charged "corpuscles" of a metal surface irradiated by ultra-violet light oscillate so vio- lently in sympathy that they are thrown off from the surface at a great rate, showing all the characteristics of the ordinary cathode-rays produced by an electric discharge. The negative electric charge of a body is, thus, under the influence of ultra-violet rays, transmuted into cathode-rays, which pass off into space, at, however, 1 a noticeably lower rate than light rays. Side by side with the normal dispersion of light there is, exceptionally, an abnormal dispersion, when the *) /. M. Eder's Ausfuehr. Handb. d. Photog., I, 1, pp. 213, 283. ') See Lampa, Ueber Stromunterbrechung mit besonderer Beriicksich- tigung des Wehncltsch.cn Unterbrechers, Sitzungsber. d. Kaiserl. Akademie d. Wissensch., Vienna, 1901. 3 ) Annalen d. Physik, 1900, Vol. Ill, p. 298. — Drudc's Ann., Vol. 1, 1900, p. 486. — Sitzungsber. d. Kaiserl. Akad. d. Wissensch., math.-naturw., CI, October 19, 1899. PHOTOTHERAPY 391 sequence of colours and lines in the spectrum is wholly different from that of normal dispersion. When a fuchsin alcoholic solution is used, as the prism violet is least diffracted, then red, then yellow, green and blue- green are quite absorbed. The position, too, of the spectrum lines may be changed. Humphreys and Mohler found that when the source of light burns under pressure the lines are always shifted slightly towards the red. Further, P. Zeemann discovered that when the light source is brought under strong magnetic influence the spectrum lines show peculiar changes; according to the point of view, they appear either doubled or trebled, with fixed ratios of polarisation. § 50. The term interference of light is applied to the phe- nomena resulting from the mutual effect of light-waves meeting each other. The interfering waves strengthen or weaken each other in proportion to the variance in their rate of progression. Hence with homogeneous light a series of alternate light and dark bands, with white light, a series of spectra, is obtained. The colours of thin plates, due to interference, enable us to calculate the wave-length of the light used. § 51. Deflection or diffraction of light results when light is passed through a narrow aperture or past a thin rod; the light is then transmitted slightly on one side, thereby giving rise to interference phenomena. If homogeneous light be used a bright band of the same colour as the light will be seen, with alternate bright and dark bands on either side. If white light be used, a white band will appear, with colour bands to right and left of it. A grating is a series of narrow parallel apertures, made either with line wires stretched at equal distances across (wire grating), or by scratching parallel lines on a soot-blackened glass plate, or on an ordinary glass plate with a diamond (glass grating), ll white light, admitted through an aperture, is passed through a grating, and the image is projected on a screen, brilliant spectra 392 RADIO-THERAPY are seen on either side of the white centre, the direct image of the aperture. In the spectrum nearest to the centre the colours are clear, and the red, yellow, green, and blue bands are of approximately equal breadth. The first spectrum is the clearest and brightest, the second is broader, the following ones are blurred. The same phenomena are observed when the light is reflected from a scratched surface. The reflection gratings most in use now are metal mirrors with very numerous fine scratch-marks (700 to the millimetre) . The metal is polished and concave, so as to serve at the same time as a mirror, giving back the images of the aperture without a lens. These are concave gratings. The diffraction spectrum obtained from this apparatus has not only the advantage of being uninfluenced by absorption (an important point in investigations of ultra-violet, which is so much absorbed by glass prisms), but it has also the further advantage over the refraction spectrum of giving a deflection of the rays proportional to their wave-length. The refraction spectrum gives a quite disproportionate deflection of the more refrangible rays, so that the blue end is much broader than the red. The identity of heat rays and ether vibrations is proved by the observation or similar interference phenomena in the visible and in the ultra-red (/. e., heat) and the ultra-violet rays. § 52. Electro-magnetic vibrations of any wave-length are capable of affecting chemical processes. K. Schaum 1 ) showed that under the influence of electro-magnetic vibrations: 1. Processes are accelerated which go on in the dark also (crystallisation, formation of HCl from H 2 + CI,) . 2. Processes are brought about which require light (de- composition of silver halogenide into silver and sub-haloid) ; many of these are reversed again in the dark (phototropy) . ! ) Sitzgsber. d. Gesellsch. z. Befocrderg. d. Naturwissensch. zu Marburg, No. 9, July, 1901. PHOTOTHERAPY 393 Processes influenced or caused by light may be due to either exothermal (/'. c, heat-producing) or endothermal (/. e. } heat- absorbing) reaction. It was formerly held that the red end of the spectrum had special thermal properties; the centre, where yellow, orange and green seem brightest to the eye, especially optical; and the vio- let especially chemical. It is a fact that violet, blue, and even green light has a pre- ponderating effect on all preparations used in photography, and these rays are called (following JFollaston) the chemically effective or actinic rays. Yet recent investigations have proved that no colour is abso- lutely ineffective chemically; the outermost red and even ultra- red affects silver salts; indeed, red light affects many substances more powerfully than violet. Again, according to recent investigations, heat is no peculiar characteristic of the less refrangible red and ultra-red rays, but is distributed over all parts of the spectrum. Thus all the light rays of the spectrum may be chemically effective and be absorbed by sensitive preparations. These chemical effects are as follows: 1. Under certain conditions light produces molecular changes, resulting in allotropic modifications, or isomeric com- binations. Thus, yellow phosphorus is transformed by heat or light into red. 2. Light has the power of setting up processes of chemical combination. Equal volumes of chlorine and hydrogen will not combine in the dark, but will combine explosively in the light to form HCl. Light very often favours oxidation (cf. bleaching, the fading of many-coloured materials in light). 3. Light causes chemical decomposition. The most notable instance of this is with chlorophyll, the green colouring matter in plants. In sunlight chlorophyll decomposes the carbonic-acid gas of the air, absorbing the carbon, which plants need for growth, and giving nut again the oxygen needed in the air. 394 RADIO-THERAPY This action of chlorophyll takes place only in the light, and depends on absorption, mainly of the red rays, as is shown by the absorption spectrum. Photographic processes are of the same nature, depending mostly on the reduction of metallic salts, usually haloid com- pounds of silver. Each of the spectrum colours has both an oxidising and a reducing effect; but red light affects metallic compounds for the most part by oxidation, violet light by reduction. Organic compounds are usually most powerfully oxidised by violet light, and pigments by the special light which they absorb. Photographic preparations (AgBr, AgCl, etc.) are decomposed not only by the light they absorb of themselves, but also by the light they absorb by reason of the admixture of cer- tain substances (optical sensitisers) . These substances (chemical sensitisers) favour decomposi- tion by light by binding chemically the constituents (bromine, iodine, oxygen, etc.) eliminated by light. Artificial light-sources, being very unequal in actinic rays, do not affect the photographic plate in proportion to their visible optical strength. According to Eders table, e. g., both the mag- nesium and the electric arc-light have more than 20 times as much actinic effect as lamplight of apparent brilliancy. The effect of the coloured rays depends on the intensity and the nature of the light and its duration, and on the nature and molecular condition of the illuminated body. Each wave- length (/'. e., color) has its own chemical effect. No ray is effective unless it is absorbed. The course of photochemical reaction may be influenced by rise of temperature, pressure, and electricity. Physiological Effects of Light. § S3- By the "physiological effects of light" are usually understood : 1. Its physical effect on matter, on the elementary particles of which the tissues are composed. Such physical and chemical processes are various, and may reveal themselves as optical, PHOTOTHERAPY 395 chemical and heat effects. We know that light may produce fluorescence, phosphorescence, electric phenomena and other physical processes. 2. Its effect on the vital functions. Under the influence of light living tissues may pass from a state of passivity to one of activity, and change of form, of energy, of matter may be induced. In this sense, light works like other physiological irri- tants, under certain conditions awakening and strengthening ele- mentary forms of life, under others weakening or annihilating them. These two main effects of light stand in causal relation to each other. According to Loeb, 1 ) light is not merely an irritant in the physiological sense: it actually infuses the organism with energy. This energy is transmuted into other forms, for the most part of a chemical nature; morphological differences, even chemical, require an organ. In general the physiological effects of light are great in proportion to the intensity and duration of the energy at work. In many cases, however, the shorter the process, the more pow- erful is the effect of intense light. Analogies to this may be found in the effect of sudden fluctuations of temperature or of electric currents. The Effect of Light on Plants 2 ). § 54. Plants, more than any other living organism, need light. Without it they cannot take from the air the indispensa- ble carbonic acid, nor, by means of chlorophyll, assimilate it, giving out the freed oxygen and retaining the carbon in new combinations, such as sugar, gum, starch, cellulose, albumen' 1 ). There are two theories as to the way light works. Most ') PAUger's Archiv, [896, Vol. I. XIII. I From C. Mueller and //. Potoni, Botanik, Berlin, 1893, p. 260. 8 ) It can he chemically proved thai the amounl of carbonic acid taken from the air by leaves in sunlight is precisely the same as the amount of oxygen given off. Without sunlight leaves add to the amount of CO* in the air. 396 RADIO-THERAPY physiologists assume a direct photochemical effect on the chlorophyll, an effect dependent on the intensity and the quality of the light. For each plant there is a certain degree of light intensity most helpful to its assimilative process; certain plants (shade- loving plants, marine algae growing at a great depth) flourish best in a dim light, others (light-loving plants) prefer sunny places. The quality of the light needed for the "chlorophyll func- tion" coincides with that demanded for certain physical and chemical processes. The photochemical effect of light is usually ascribed to the indigo and violet rays (i. e., the more refrangi- ble and short-waved rays). In the decomposition of carbonic acid by chlorophyll, it is just the red and yellow rays (/'. e., the less refrangible) which are effective. The chlorophyll pigment can only be found in light; plants and plant-parts grown in the dark have no chlorophyll, but are pale yellow in colour (etiolation) . But artificial light sources, such as the flame of candles, gas, oil lamps and the ray of the electric arc-light, may take the place of sunlight here; they all have the yellow rays needed for chlorophyll. The quantity of light need not be large. Wiesner proved that sprouting plants will grow dark green in a light which barely suffices for the reading of large print. The chlorophyll-producing property of light was deter- mined by means of Peletier's bell-jars, vessels filled with col- oured solutions to allow the passage of the desired rays alone. Pringsheim's theory of chlorophyll is opposed to the more widelyaccepted viewof direct photochemical effect. He holds that the chlorophyll pigment, by absorbing the blue, violet and ultra- violet rays, without being itself decomposed, acts as a kind of light screen, lessening the degree of respiration (/'. c, the oxida- tion connected with the elimination of C0 2 ) and increasing pro- portionally the assimilative processes, especially the collecting of carbon and giving off of oxygen, going on within the plasma of the chlorophyll body. There are always changes of energy corresponding with the PHOTOTHERAPY 397 changes of matter brought about in plants by light ') ; they are often more noticeable than the changes of matter. Trans- formation of energy in plants shows itself in movement, of which two great groups may be distinguished, growth-movement and irritability-movement. In the latter are comprised all the proc- esses in which a change of position of the irritated part is brought about by any physical reaction. Light is needed for many growth phenomena, but not for all. It is unnecessary for germination, for the growth of roots and many blossoms, as well as for the flourishing of many endo- phytic (living in the body of plants) and endozoic (living in the body of animals) living parasites. In general light has a retarding effect on growth, both as regards rate and extent (this holds good also of organs which are above ground) . This explains the varying rate of growth at different hours of the day, a rate which is not for a time immediately influenced by artificial exclusion of light. The growth of stems and leaves is on the whole least towards evening, most towards or in the morning. Van Tieghem ~) showed that all light rays except the red and ultra-red retard and lessen the growth of plants, and that the effect is most pronounced in the rays that are most refracted in the spectrum. This phenomenon may be, conditionally, regarded as a paralysing effect of the more refrangible rays. According to Flammarion, 3 ) the colour, too, of flowers is influ- enced by different light rays, so that, e. g. t very various shades of the lilac may be obtained under variously coloured light. But the effect is greatest on the scent. Thus, strawberries grown under red glass had a wonderful aroma, and crassula flowers, which are nearly scentless in ordinary sunlight, emitted a deli- cate fragrance, like that of bananas, under the influence of red light. J ) Augustus Waller proved thai lighl develops electro-motive energy in the assimilating leaf, more by the brighl red rays, especially those absorbed by the chlorophyll, than by the heal rays. (Compt. rend, de la soc. de biolog.. 1900. I.I I. p. I",; 1 2 ) Traite de Botanique, Pari . [889. 8 ) Gcbhard, Die Heilkrafl I ! I'- 44- 398 RADIO-THERAPY The way in which light affects extent of growth is shown most clearly by the fact that plants grown in the dark have abnormally long internodes and leaf stems, but no leaf surface. All green leaf surfaces are furthered in their growth by light through the effect of light on the assimilation of carbonic acid. We must carefully distinguish between the heat effect and the chemical effect of light (thermal and photo-chemical effect) . Amongst specific growth movements due to light may be noted certain forms of nutation and heliotropism. In so far as light in these cases acts as the stimulus, these movements may also be regarded as irritation phenomena. Nutation is the term applied to the automatic movements made once or repeatedly within a certain given period by certain growing parts of a plant. A special class of these periodic nutation-movements are the sleep-movements (nyctitropic nutations) made by the green leaves of certain plants towards sundown. In the daytime the leaflets are spread open in such a position that the light rays impinge vertically; at night they close up and fold themselves either upwards or downwards, according to their kind, against the common stem.. Heliotropism is the faculty possessed by many parts of plants of turning towards or away from the direction of the strongest light. Stems and leaf stalks are usually positively heliotropic, i. e., they grow towards the light source in the direction of the light rays. Roots and rhizomes are almost all negatively heliotropic, i. e., they turn away from the light source. Green leaf surfaces show transverse or dia-heliotropism, i. e., they turn themselves at right angles to the direction of the light. Parts of plants removed from their normal position make curved heliotropic movements. Heliotropic properties are dependent on the degree of brightness of the light. In a very glaring light organs usually PHOTOTHERAPY 399 positively heliotropic may become negatively so. Heliotropic curvature is conditioned by the direction of the incident light. We may regard as movements of irritability purely many of those locomotor movements which light frequently induces in plants. Many unprotected plasmic bodies, such as the swarm spores of many algae, are capable of independent movement by means of waving cilia. The direction of the movement depends partly on temperature-effects and partly on the action of the incident light. Light is the cause of change of place with the microscopic inhabitants of the ocean, ponds and lakes, as with the larger animals; they are attracted by it, and in sunlight rise from the depths to the surface. Very often they are present there in such large numbers that the water loses its natural clearness, transparency, and colourlessness, and appears dull-green, bluish, brown, or red. This phenomenon is termed the "flowering of the water." The rising of the water plants to the surface is due, in part, however, to their lessened specific gravity through the production of oxygen, and, amongst the threads of the algae, or in the higher forms, in the air passages or cavities. Those reproductive cells of the algae (swarm spores, zoospores) , which, like the infusoria, are capable of independent movement by means of waving cilia, show heliotropic movement, i. e., they move as far as possible in a straight line towards the source of light. A few kinds are negatively heliotropic and are repelled by light. The movements of swarm spores are connected with a turning on the longitudinal axis of their body; whether to right or left depends again on the light rays. The more quickly vibrating blue rays alone influence the direction of the move- ment (heliotropic action) ; red rays, like darkness, do not affect it at all. The creeping or amoeboid movements of the plasmodia of myxomycetes, as of flowers of tan, are dependent on light; these bodies are negatively heliotropic, working themselves slowly along on their base, away from the bright spots into the shade. On this plasma-movement are possibly dependent the move- 4 oo RADIO-THERAPY ments of chlorophyll bodies, which bear some relation to the greater or less intensity of the light. Portions of the green leaves of phanerogams, mosses and the prothallia of ferns which have been kept continuously in deep shade, assume a darker shade on account of slow changes of position in the chlorophyll corpuscles in the protoplasm. These corpuscles under the influence of light, especially of the short-waved rays, collect mainly in the cell-surfaces turned towards the surface of the leaf; in the dark they collect mainly along the side-walls of the cells, at right angles to the cell- surface. It is uncertain whether we have here a direct influence of light on the protoplasm, or an indirect, induced possibly by primary change in the chlorophyll corpuscles. Borodin distinguished between day-position and night-posi- tion. Stahl divides the position of the (for the most part) flat chlorophyll corpuscles with regard to light incidence into "sur- face-position" and "profile-position." In all cases the position of chlorophyll corpuscles is governed by the following general rule : With a medium degree of brightness the chlorophyll cor- puscles turn so as to present the broadest possible surface to the light rays. With a minimum of brightness (i. e. } dark- ness) and a maximum of brightness {e. g., direct sunlight) they turn their narrow edge, i. e., the least possible surface, to the light. Locomotor movement is the property of the chlorophyll bodies in all assimilating tissues. Corresponding to the general rule for locomotor movement is the form-change of chlorophyll corpuscles, depending on degree of brightness. They are flattest in the most favour- able light. They are capable of contraction. Hence a green plant may take on a lighter or darker green shade accord- ing to the degree of light (just as a chameleon changes its colour) . The protoplasmic current in plant-cells seems under ordinary conditions to be independent of light, though it is conditioned, as may be proved, by temperature, the amount of water con- tained, or presence of oxygen, and is frequently only recognis- PHOTOTHERAPY 401 able under the microscope after being accelerated by a mechani- cal stimulus. According to our present knowledge, the current in the cells goes on unhindered by the exclusion of light. But E. Josing ') proved that under changed external conditions the protoplasmic current may after all be radically influenced by light. These changed external conditions he brought about in two ways: first, by subjecting objects with freely flowing protoplasms to the effect of weak solutions of ether or chloroform ; and, secondly, by withdrawing, by the aid of suitable agents, the car- bonic acid from the surrounding air. Under such external con- ditions the protoplasmic current ceased to flow when the light was excluded, and resumed its course on its re-admission. Pringsheim 2 ) was the first to furnish data as to the injuri- ous effect of light on plants. Klemm agreed with him in find- ing no changes specially characteristic of these effects. Rigidity, formation of nodes, concretion of plasma, granulations (espe- cially in the cell-nucleus) occur, but without being specially marked and characteristic. The disorganisation caused by illumination differs from "death by heat" in that no such intensive corporeal movements are ever produced as in the case of sudden change of temperature. For the rest "light intensity raised to its maximum tends directly towards precipitation in the plasma and towards its rigidity." Vacuolisation does not occur; contraction occurs only in the case of death supervening. 2. The Effect of Light on Bacteria. § 55. In 1877 Downes and Blunt :: ) first drew attention to the fact that diffused, and, still more direct, sunlight has the power of killing putrefaction bacteria, that the heat rays play no part here, and that the blue, violet and ultra-violet rays take the ') Jahrb. d. wi sensch. Botanik, [901, Vol. XXVI. '-') Jahrb. f. wissensch. Botanik, Vol. XII, p. 288. (Ref. Schmaus and Albrecht in Lubarsch-Ostertag's Ergebn. A. allgem. Pathologie, 1899 I ') Proceedings of the Royal Societj of London, Dec. 6, [877, Vol. XXVI. p. 488, and Dec. 101I1. [878, Vol. XXVIII, p. 199 4 o2 RADIO-THERAPY most active share in the effect, though the red and orange rays are not wholly inactive. They showed that the effect is the same whether the bacteria be damp or thoroughly dried; further, that the presence of oxygen is necessary, and that the manner in which the light works in these experiments is not to be sought in a modification of the nutritive basis. They took into account also the possibility that the products of metabolism in the bacteria may be influenced by light. These data, disputed at first by Tyndall, 1 ) were soon confirmed on all sides, and a large number of fresh facts were added to our knowledge of the subject. Whilst Downes and Blunt made their experiments with any bacterial mixture of decomposing liquids to hand, the later investigators used pure cultures. Later on, too, physical conditions were taken more into account, and the arrangements for the experiments made more exact by the use of light sources of varying intensity, and of light filters. The fact that light has a very great power of destroying bacteria has now been established. This has been deduced from the experiments of Fatigati, 2 ) Arloing, 3 ) Duclaux*) Liibbert;') Janowski, ) Santori, 7 ) Raspe, 8 ) Geissler?) Kotliar, 10 ) Dan- drieu, 11 ) Chmiliewsky, 12 ) Gaillard, 13 ) Marshall Ward, 1 ') Ledoud-Ledard, 15 ) Pansini, 16 ) d'Arsonval and Charrin, 17 ) *) Nature, Sept. 15th, 1881, Vol. XXIV, p. 466. 2 ) Compt. rend., 1879, Vol. LXXXIX, p. 959- 3 ) Ibid. Vol. C, p. 378, and Vol. CI, p. 5"- 4 ) Ibid. 1885. 5 ) Ref. in Raum, Zeitschr. f. Hyg., Vol. VI. e ) Centralbl. f. Bakteriologie, Vol. VIII, p. 167. 7 ) Boll, della Accad. med. d'igiene, Roma, Vol. XVI, p. 386. 8 ) Einfluss des Sonnenlichtes auf Mikroben. Dissertation, Schwerin, 189 1. 9 ) Centralbl. f. Bakt, Vol. XI, p. 161. 10 ) Ibid. Vol. XII, p. 836. a ) Annales d'Hygiene, 1888, p. 448. M ) Wratsch, 1892, No. 20. 13 ) These de Lyon, p. 396. 14 ) Proceedings of the Royal Soc. of London, Vol. LII, p. 393, and Vol. LIII, p. 23. 15 ) Arch, de medec. exp. etc., Ser. 1, Vol. V, p. 779- 10 ) Riv. d'igiene, 1889. ") Arch, de physiologie norm, et patholog., Vol. VI, p. 335. PRO TO THERAPY 403 Roux 1 ) Billings and Peekham,-) Kruse,*) Koch*) Beck and Sclutltz, 7 ') Dieudonne *) Buchner, 7 ) v. Es march*) Giunti;) Martinaud, 10 ) Momont, 11 ) Wittlin, 12 ) Richard- son, 13 ) Schickhardt 14 ) and Ruhematin 15 ). Most pathogenic bacteria are injured in their development and growth or are annihilated by light. This was proved by Ward and Bie in the case also of moulds and yeast-cells. The various kinds of bacteria are differently affected {Axel L. Larsen "') ) whilst, e. g., the bacilli of typhus, diphtheria, plague and splenic fever have comparatively little resisting power, tubercle bacilli and staphylococci offer greater resistance. Some kinds are, indeed, said to be directly favoured in their growth by light; this was observed in bacterium photometricum (Engelmann) , in certain yeast and mould fungi (Gaillard), and in a coccus cultivated from faeces by Schenk 1T ) . Different degrees of resistance are offered by the spores and by the bacilli of splenic fever. The former were killed by Arloing in 2 hours' direct sun-heat, whilst he needed 26-30 hours for the killing of the bacillus. A degree of illumination which is insufficient for the complete checking of development may yet in some cases prove harmful to the formation of pigment. But in the *) Ann. de l'instit. Pasteur, 1887. 2 ) Centralbl. f. Bakt.. Vol. XIX. p. 244. 3 ) Zeitschr. f. Hygiene, 1895. 322. *) Ueber bakteriologische Forschung, Berlin (Hirschwald), 1890. 1 Zeitschr. f. Hygiene, Vol. XXIII. c ) Arbeiten aus dem Kaiserl. Gesundheitsamte, Vol. IX. 7 ) Centralbl. f. Bakt., Vol. XI, p. 781, Vol. XII, p. 217. and Arch. f. Hygiene. Vol. XVII. B ) Zeitschr. f. Hygiene, Vol. XVI. 1 Stat. sper. agrar. ital. Vol. XVIII. I Compt. rend. Acad. d. Sc, Vol. CXIII. u ) Annales de l'instit. Pasteur, 1892. ") Wiener klin. Wochenschr., 1896. ! ) Transact, of the Chem. Soc, 1893. ") Friedreich's Blatter I gericht Med. 1893, p. 405. Zeitschr. f. dial, und phys. Therapie, Vol. IV. " 1 Mittheilungen aus Finsen's med. Lichtinstitut, I. p. 89. ") Koch's Jahresb. ueber die Fortschr. in der Lehre von den Gahrun organismen, 1893, p. 53. 4 o 4 RADIO- THERAPY case of other bacteria again, as, e. g., micrococcus ochro- leucus, light is a necessary condition for this. Side by side with the checking of the development of bacteria, illumi- nation causes a lessening of the virulence of these micro- organisms. A raising of the temperature makes the bacteria die more quickly (Geissler, Bang), but that is not necessary to the process. Direct sunlight has a more powerful action than diffused daylight, but it is weaker than simple or concentrated arc-light. Arc-light with metal electrodes (Bang) and the light of the electric spark (Strebel) have a far stronger bacteri- cidal action. Dieudonne observed that bacteria were killed in half an hour by direct sunlight, in 6 hours by diffused daylight, in 8 hours by electric arc-light of 900 normal candle-power, and after 1 1 hours by the electric incandescent light. The bacteri- cidal action of sunlight naturally varies with its intensity at different seasons of the year. Amongst the different spectrum rays the red and the green are neutral, or even, according to some observers, favourable to the growth of bacteria; the more refrangible blue, violet and ultra-violet rays, on the other hand, have distinct bactericidal properties. As to how the light acts, we assume ( 1 ) that it acts directly on the plasma of the bacteria themselves; (2) that it is at the same time, by producing photochemical change, indi- rectly injurious to the nutritive basis. Kruse found that by subjecting sterile nutritive bases to light complex chemical bodies (peptones) were formed, which checked development. Richardson proved that in fresh urine under the influence of direct illumination peroxide of hydrogen is formed, which is decomposed by the bacteria, the latter being killed by the liberated oxygen. Dieudonne showed that in water, too, through the action of the chemical light rays peroxide of hydro- gen is formed, most freely in the upper layers. This compound is strongly antiseptic. Under illumination, when oxygen was excluded, Dieudonne, and also Tizzoni and Cattani, 1 ) found *) Arch. f. exper. Pathologic und Pharmakologie, Vol. XXVIII, p. 59- PHOTOTHERAPY 405 the bactericidal action very largely diminished, which may be explained by the fact that peroxide of hydrogen could no longer be formed. The injurious action of light on bacteria, however, is not due alone to the fact that it renders the nutritive basis unsuited to their growth, but to the direct injury it inflicts on the pro- toplasm. Jl'ard and Kruse proved that dried spores away from all nutritive material are also killed by sunlight. The recent work of Finsen, 1 ) Bie, 2 ) S. Bang, 8 )*znd H. Strebel*) is interesting, not alone because it shows the more powerfully bactericidal action of light sources with preponderating short- waved rays (concentrated sunlight and arc-light, Finsen; arc- light with metal electrodes, Bang and Strebel; electric spark, StrebeT"), but also because in their ingenious experimental appli- *) Ueber die Anwendung der concentrirtcn chcmischen Lichtstrahlen in der Medicin, Leipzig, 1899. 2 ) Mittheilungen aus Finsai's med. Lichtinstitut. I. s ) Ibid. III. 4 ) Deutsche med. Wochenschr., 1901, No. 5-6. B ) G. O. Drossbach has been led by his experiments to differ from others; he is extremely sceptical as to the parasiticidal action of light, and regards it especially as impossible that bacteria can be affected by the ultra-violet rays at a distance of even ^ mm. below the surface of the skin. His experiments on the influence of chemical (ultra-violet) rays on the growth of bacteria yielded negative results. The inoculated nutritive gelatin was divided in two Petri-dishes which were exposed to iron arc-light (1000 Watt) at a distance of at most 10 cm. from the arc. the one directly, the other through glass, four times a day for two days (for 10 minutes at a time) — i. e., for 80 minutes altogether. The illumination had perforce to be intermittent, as the gelatine melted away when light was applied for a longer time at once. The colonies developed in the same way on both gelatine plates, the mould fungi on the third and the bacteria on the seventh most vigorously. In another case a gelatine plate was subjected to direct rays six times for so long a time as to melt the gelatine. After seven days the colonies had developed normally. Evidently then the effect in checking development is very slight, whether the rays pass through glass or through air only. Light waves shorter than those given by sunlight are hence of no value in this respect. If we take further into account the slight light strength (as measured by the bolometer) of tin- iron arc-light as compared with the carbon arc lighl or with sunlight, the first- named may be practically disregarded. In general, the microbicidal action of our artificial sources of light is much less than is often a sumed. Probably it docs not exist at all when the micro-organisms are in a really favourable nutritive soil. Pathogenic bacteria, which in anj jrow badly in our artificial culture media, may perhaps when in the latter be affected, It 4 o6 RADIO-THERAPY ances we have a guarantee for the utmost possible exactitude in estimating, on the one hand, the bactericidal energy of a source of light, and, on the other, the light-resisting powers of a micro-organism. It appeared that concentrated sunlight checked the growth of bacteria after one minute, and caused death in 5 to 7. Concentrated electric arc-light checks growth of bacteria after 4-5 minutes, and kills them in 15 to 20. Both the arc-light from metal electrodes and the electric spark kill micro-organisms after a few seconds (5 to 40). V . Bie, by his experiments, was able to prove exactly with which parts of the spectrum the bactericidal action of light is essentially connected, and how great is the difference between the action of the different parts. Bie made his experiments with the bacillus prodigio- sus and the light of an arc-lamp of 35 amperes and 44-46 volts (about 6,000 NK) ; the light was concen- trated by a Finsen apparatus and fell vertically on to the culture. As light filter he used vessels with piano- parallel glass walls, enclosing a layer of fluid 3 cm. in thickness. As absorbing media he used: 1. A fresh 1% sulphuric acid solution of quinine with a few drops of sulphuric acid, which allows the passage of all the rays but the ultra-violet; 2. A 5% solution of sulphate of nickel, which was similar in action; 3. A \\% solution of chromate of potassium, let- ting through red to green, inclusive; 4. A 1^% solution of bichromate of potassium, let- ting through red to yellow, inclusive; 5. A \% solution of fuchsin, letting through red alone. To determine the light of intensity, Bie compared the degree of blackening of spots produced during given periods of illumination on aristo paper. The outcome of these experiments was that all the spectrum therefore curative action has been proved, it can only be referred to the heat conditioned by light-absorption." (Deutsche med. Wochenschr. Nov. 21, 1901, No. 47.) PHOTOTHERAPY 407 rays (except the ultra-red, which were not examined), in an increasing ratio from red onwards, check bacterial development. The action increases with the ratio of refrangibility, and is espe- cially marked in the blue, violet, and ultra-violet spectrum. Red, orange, yellow and green rays also act injuriously on bacterial growth, but only after prolonged illumination. Pure red light even did not produce the faintest perceptible retarda- tion of growth until after an hour and a half's exposure. The experiments of SopJms Bang, Finsen's most competent colleague, are specially remarkable, the care with which they were conducted making them a model for all later investiga- tions of the kind. Ban? took into account all the conditions to be noted with regard to light-action, the strength of light used, the distance of the object from the ray-source, the kind of rays passing the fdters and the amount passing through, the percentage of light penetrating to the bacteria (taking into account the absorption and refraction of the light through the containing vessel and the culture medium). The experiments were conducted so as to ensure that the light-ray should meet with as few obstacles as possible on its passage from the light source to the object; the reflecting planes were as few and as simple, and the absorption and refraction as slight, as possible; an even temperature was maintained, and measures were adopted for varying the strength of the light according to the gradation desired. Bang used for these experiments an apparatus in which the bacteria culture was spread out for examina- tion in the thinnest possible layer, e. g. } as a suspended drop on a thin quartz plate. This quart/, plate is used as the lid of a "moist chamber," this chamber again is fixed in a box filled with water of an even temperature, kept constantly flowing by a paddle-wheel. The light is admitted through a quart/ window in the side of the box; its intensity and direction of incidence are exactly estimated. In this manner, Bang came to the conclusion that under the influence of light at a distance of 2S cm. from an electric arc light of 35 amperes and 50 volts, at an angle ol 45 to the axis 4oS RADIO-THERAPY of the carbon, after part of the heat rays have been kept back by a layer of water (25 mm. in thickness) between quartz plates, and at a temperature of 30°, a 3 hours' prodigiosus broth-culture in a pendant drop is sterilised in about one min- ute, a 10 to 15 hours' culture in 3 to 5 minutes. The light acts more quickly at 45° than at 30°, sterilising a 3 hours' culture in about half a minute!" Thus, then, the older the culture, the greater its power of resistance to light action; and further, with increase of tem- perature comes increase of bactericidal light-action. . The bactericidal effects of sunlight, according to Bucheur, Schickhardt, Dieudonne, Uffclmann, von Pettenkofer, Prans- mtz and others, probably plays an important part in nature in the "self-cleansing" of rivers. River water, contaminated by sewage, etc., after having flowed for some distance, becomes again, so far as bacteria are concerned, what it was before the introduction of the contaminating matter. No doubt, however, this is partly the result of the great dilution of the foul matter, the deposit of floating particles as sediment and the absorption or decomposition of substances by living creatures (plants or animals). Wittl'in showed that street dust is disinfected in a high degree by exposure to direct sunlight. Von Esmarch tested the bactericidal action of direct sunlight on germ-contain- ing clothes, bedclothes, etc., and found that the action is con- fined to the uppermost layers of the objects and does not pene- trate at all to the interior. It has also been maintained that the receptivity of an organ- ism to living bacteria and to bacterial poisons is lessened by exposure to light (Kondratjezv, 1 ) (Gebhard,-) (Jousset 3 ) ). According to Boeder*) however, who investigated this point minutely, this is open to question. Besides its action, in checking the development and growth of bacteria, we know further that light influences their move- *) Quoted by Dworctzky, Zeitschr. f. diaetetische u. phys. Therapie, Vol. V, bk. 3. 2 ) Die Heilkraft des Lichtes, Leipzig, 1898. s ) La Semaine medicale, 1900, 45. 4 ) Arbeiten aus dem kaiserl. Gesundheitsamts, 1900, Vol. XVII. bk. 1. PHOTOTHERAPY 4 o 9 ments. According to Winogradsky, 1 ) and Beijerinck, 2 ) sul- phur-bacteria and the chromogenic bacteria always collect at the lightest spot; they are thus positively phototaxic. J. The Effect of Light on Higher Organisms. {Animals, including Man.) § 56. In animals, as in plants, light exercises a stimulating 'nfluence on the functions of tissue-elements and organs; the :nergy infused into the body by light is transmuted into stimu- lus, quickening and heightening all the vital processes. As a stimulus, light either influences directly the protoplasm of the irradiated cells, or it brings about by indirect means (through the sense-organs and nerves) certain functions on the part of given organs. It has long been recognised as a fact that the development of many animals is dependent on light; without light develop- ment proceeds slowly or is suspended altogether. William Edwards*) observed that frog-spawn in an opaque glass died, whilst spawn in a transparent glass became duly developed. The development of tadpoles then proceeds more slowly in the dark. Schnetzler's 4 ) experiments proved that white light is more favourable than green to such development. E. Young 6 ) showed that violet light helps on the development of the embryo or rana, salmo and lymenea, whilst darkness or other parts of the spectrum hinder or disturb it. Beclard*) found that flies' eggs develop more quickly under blue and violet glass than under red, yellow, green or white. Guarinoni 7 ) believes his experiments to prove that violet light acts favourably on silk- ') Znr Morphologic und Physiologic dcr Schwefelbakterien. 2 ) Centralblatt f. Bakteriologie, Vol. XIV, p. 844. *) Dc l'influcncc des agents physiques Mir la vie, Paris, 1X24. *) Archives des sc. physiques el naturelles, 1874. Vol. LI. ') Compt. rend., Vol. LXXXVII. •) Compt. rend. 1858. 7 ) Quoted by Edcr, J. M., Ueber die chem. Wirkungen d. Farb. Lichtes, Vienna, 187';. 4 io RADIO-THERAPY worms. Godnew 1 ) noticed that maggots are much more quickly developed in pieces of meat exposed to the light than in meat kept in the dark. Loeb 2 ) made a study of the action of light on polypi and found that growth is not affected equally by all the rays, but that only the more refrangible (i. e., blue) rays fur- ther growth, whilst the red ones have the same effect as dark- ness. Light exercises a powerful influence also on the growth of the higher animals at a later stage. Poey 3 ) believes he has proved that sucking pigs and calves do better in violet light than in white ( ?) . Young rabbits do not get on at all in the dark. Every farmer knows that it is a universal rule that beasts flour- ish better in bright, sunny sheds than in dark ones. And the healthy development of young children, as is well known, depends in large measure on light. Not only the general growth, however, is affected by vary- ing supply of light, but also the development of individual organs and parts of organs. It is a well-known fact that a large number of pigment-containing cells are found in the light than the dark (ephelids). Berthgld*) and Finsen r °) have shown that epidermal growth (as of nails and hair) is favoured by light and hindered by darkness. Both patients and nurses in Finsen's clinic acquired a thicker growth of hair on those parts which were exposed repeatedly and for a long time to the powerful electric ray. It has been proved that with amphibia and fishes limbs that have been broken off grew again more rapidly in the light than in the dark. The stimulating effects of light on transformation of form and transformation of energy, especially on the phenomena of movement, have been proved by many interesting observations. The arrangement of the protoplasm of amoeboid cells [(amoeboe, rhizopods, infusoria) is noticeably changed by expos- ure for any length of time to light or darkness. The Plas- modia of asthalium, which in the dark have crawled to the sur- ') Kasan'sche Dissert., 1882. 2 ) Pflueger's Archiv, Vol. LXIII. 3 ) Compt. rend., 1871, Vol. LXXIII. ') Mueller's Archiv. f. Anatomie unci Physiologic 1850, p. 158. '" ) Mittheilgn. aus Finsen's med. Lichtinst., Vol. I, p. 118. PHOTOTHERAPY 411 face of the tan withdraw again to the depths in a bright light. In the light they develop short, compressed projections; in the dark long, thin, narrow processes. Here then light seems to act in the same way as artificial irritants. It is well known that change of light causes changes of form in the contractile pigment-cells, in the skin of many fishes, amphibia, and reptiles, thereby producing change of colour in the animals. Under a bright light, e. g., the black pigment- cells of the frog's skin, which in the dark have wide-spreading ramifications, contract gradually into little balls, making the skin appear lighter. Under sudden illumination pelomyxa pal- ustris contracts in a few seconds into a ball, after the granule- streaming has ceased. If the light is maintained, only weak, slow movements are again observable. When the darkness is dissipated, by the gradual coming on of daylight, there is no irritant effect (Engelmann *) . To Engelmann we owe also the discovery of bacterium photo-metricum, which is extraordinar- ily sensitive to light stimuli. So long as it is exposed to light, it propels itself swiftly about in the drop of water by the aid of the scourge-like thread which is found at the ends of each bac- terial body. When it is brought into the dark the movement of the thread gradually ceases and the bacterium remains motionless, to be stimulated again, however, to fresh movement under renewed light-action. By means of a spectrum apparatus Engelmann was able to fix on the orange and ultra-red rays, as the specially active factors in this bacterial movement 1 ). Light has also a very powerful influence, particularly in regard to the direction, on the ciliary movement of the green swarm- spores of the lower plants and flagellates. According to Uskoff, the ciliary movement of the epithelium of the oesophagus is equally swift in red and in violet light, but it is suspended if red light is substituted for previously acting violet. Even among the ciliary infusoria, which are not generally sensitive to light, isolated specimens arc found whose ciliarj ') Archiv. f. d. ges. Physiologie, XIX, p. 1, and Handbuch der Physi ologie, Vol 1. p. .37°- I /////, , ,■', Archiv., Vol. XXX. 4 i2 RADIO-THERAPY movements are stimulated by light. Verworn *) observed that pleuronema chrysalis, which when undisturbed lies motionless in the water, makes violent movements when suddenly exposed to light, but only after a period of latent irritation (one to two seconds), not at once when the light falls on it. Verworn proved that this leaping movement is not the result of possible heat-action of the light, but is due in largest measure to the action of the blue and violet rays. It is true the same effect can be produced with intense (con- centrated) heat-rays. Uskoff 2 ) made a study of the behaviour of the protoplasm of blood cells. The white corpuscles of frog's blood showed more and longer processes in red light than in violet; further they were in the former spread out, for the most part, in the form of hardly visible discs. According to Hermann?) on the other hand, leucocytes are not sensitive to light, whilst red cor- puscles show distinct changes of shape. Finsen observed 4 ) that the red corpuscles in tadpoles' blood changed shape under the influence of sunlight; they contracted and became rounder. According to Anerbach, light acts as a powerful inducer of contractions on the protoplasm of frog spawn. Finsen?) too, noticed in his experiments with frog-spawn and salamander germs, that light possesses in a high degree the power of induc- ing movements of the germ, and that this power is present to a quite special extent in the blue-violet rays. Daphnia pulex shows with increasing strength of light increased precision and swift- ness of motion. Red light is most favourable to the movements of amcebce. Both the violet rays and white light have an impeding effect. {Harrington and Learning.) Experiments on the influence of light rays on the move- ments of older animals have given similar results. *) Quoted from Verworn, Allgemein. Physiologie u. psycho-physiolog. Protistenstudien, Jena, 1889. 2 ) Central bl. f. d. med. Wissensch., 1879, No. 25. 3 ) Quoted in Strebcl, p. 6. 4 ) Ueber die Bedeutung d. chem. Strahlen, Leipzig, 1879. 4 ) Centralbl. f. d. Wissensch., 1870, No. 23. PHOTOTHERAPY 413 To this class belongs the action of light in directing the movements of the more highly organised animals; it is not always easy, however, to determine the extent of this because of the large part played also by the organs of sense and the nervous system. The experiments of Loch') and of Parker and Burnt tt -) have shown that, just as with plants, so also with many animals, light has an influence on the direction of their movements. Many sightless animals even show signs of helio- tropism. Light often exercises over animal, as well as vegetable organisms, the same kind of irresistibly compelling power that a magnet does on iron; they are forced to turn towards or away from the source of light. Thus a gnat is always attracted by an artificial light, in w r hose flame it will singe its wings and lose its life. Blind frogs always turn their heads towards the source of light and place themselves so that its rays may fall symmetrically on both sides of their bodies {Wwedensky 3 )). If put in a box, of which one-half is illuminated, the other dark, they will, according to Bert, 4 ) always try to get to the bright part. It is well known, however, that whilst some animals love the light and always make for sunlight, there are others which dread light and live in the dark. Many animals, e. g., ants and bees, are able to distinguish colour. Earwigs, wood-lice, carabidde (Finsen 6 )), even eye- less creatures, like the earthworm (Graber ) ), and blind ones, like the triton, are peculiarly sensitive to the short-waved ( blue, violet) rays of light, taking shelter in darkness or the longer- waved (red) rays. Other creatures again, e. g., butterflies, prefer the blue and violet rays. ') Dor Heliotropismus dor Tliierc. etc., Wurzburg, f8go 2 ) Wirkung auf Planarien, Amer. Journal of Physiol., IV, 8. p. 273. 5 ) Bull, de I'Acad. des Sc, a Petersbourg, 1879. *) Revue Scientif., [878, 42. 5 ) Ueber die Bedeutung der chem., Strahlen, Leipzig, p. 58. '» Sitzung«ber. der kaiserl. Vkad. der V h., Wien, math.- naturw., CI. 1883. \ -1 LXXXVII, Tart I, \>. 201. 414 RADIO-THERAPY Cohen and Strassburger proved that in general the short- waved rays have a stonger phototaxic effect than the long- waved, which, if not present in a too high degree of intensity, have the same action as complete darkness. The course of phototaxic phenomena, however, often depends on other circumstances. Light affects paramcecium bur- saria only when the supply of oxygen is insufficient; with suffi- cient oxygen the light stimulus is ineffective. With larva? of polygordius, phototaxic phenomena appear only if the temperature is raised at the same time. Many animals react chiefly to fluctuations in the intensity of the light. With reference to the action of light on given tissue-ele- ments, a close study has been made of its effect on muscles. We do not at present know that light has any influence on the movements of striped muscular fibre. Researches have been made into the action of light in stim- ulating unstriped muscular fibre by Fr. Arnold, Reinhardt, Budge, Brown-Sequard and Heinrich Mueller 1 ) and Steinach 2 ) . The incidence of light (without heat) causes the iris to contract in the extracted eye of amphibia or fishes, that is, independently of the central nerve-system, and this though the retina may have been removed and the eye extracted for a long time (16 days from an eel in winter!). Brown-Sequard regards this phenomenon as direct muscle- irritation by light. Harless, 3 ) with human corpses, too observed for a period of 30 hours after death distinct con- traction of the pupil of the eye exposed to light, as compared with that of the closed eye. De Parville (quoted by Buedingen) claims to have proved the red end of the spectrum to be nerve-irritating, and the reverse end (green, blue and violet) to be nerve-soothing. Buedingen, however, was unable to confirm this. Th. Buedingen, 4 ) in order to solve the question whether light *) Wiirzburger naturw. Zeitschr., 1861, II, p. 133. 2 ) PMigcr's Arch., Vol. LII. 8 ) Abhdlgn. d. bayr. Akad., 1848, V, p. 490. 4 ) Zeitschr. f. diaet. und physik. Therapie, Vol. VI, bk. 5, p. 272. PHOTOTHERAPY 415 acts on muscle directly, or through the motor nerves, on a nerve- muscle preparation, and further, whether reflex movements can be set up by irradiation of the skin, made experiments with ani- mals whose cerebrum had been removed and the nerve connec- tion between brain and spinal cord severed. These experiments showed that light, as applied in the form of sudden transition from darkness to a blue or red light in concentrated form, had no direct influence on the nerve-muscle preparations made from frogs, and further, that it was not able to modify contractions caused by other stimuli. Neither did the experiments, as to the possible influence of concentrated red and blue arc-light, on the reflex irritability of animals whose cerebra had been removed show the slightest trace of such action. Buedingen concludes that the reflex irritability of the spinal cord is not influenced by light rays falling on the skin. Besides the muscle-cells, there is a series of other cells which react to the stimulus of powerful light-irradiation. This is proved by the phenomena of erythema solare, dermatitis photo- electrica, xeroderma pigmentosum, hydro, and summer erup- tions, pellagra and the various pigment anomalies, due to the influence of light. Light produces obvious effects on the skin of the higher animals. According to Unna, 1 ) the skin becomes coarser and harder in parts exposed to the light, because under the influence of light protoplasm becomes reduced to keratine. Moeller 2 ) was able to prove, experimentally and microscopically (p. 432), that light sets up hyperplasia of the epidermis and an abnormal horning-process. The changes in the skin, known as erythema or eczema solare s. photoelectricum, consisting in the diffused production of redness, small blisters and pustules, which may in severe cases lead to leuco-sero-ftbrinous inflammation of the whole skin-covering, are regarded as disturbances of the circulation. We cannot for the present discuss the question whether these . phases of hyperemia and the conditions which they induce, l ) Monatsh. f. prakt. Dermatologie, [885, IV. p. 284. *) Der Einfluss des Lichtes auf die Haut. Biblioth. tned., Stuttgart, 1900, p. 18. 4 i 6 RADIO-THERAPY which arise also in other organs under strong light, e. g., the conjunctiva, the nose, gills (in proteus, Rusconi, 1 ) are to be regarded as due to action on the vascular nerves, or as being induced by primary injury (degeneration) of the tissue cells. It has certainly been proved, by various histological experiments (Ogncff, Moeller, Glebowssky) (see later) that light produces local pathological changes in the body-cells which are subjected to powerful rays. It is well known that it is often difficult to get workmen in factories where the work is carried on in strong arc-light, because of the injuries caused by light {Maklakozv) . The phenomena of this reaction on the skin are as follows: the skin becomes a bright to copper red, swells, and is burning and painful. These signs are masked in consequence of prolif- erative processes in the horny layer. After more powerful light action, larger or smaller blisters are formed, with ecchy- mosis, and even more or less deep-seated necrosis of the tissues. Very marked signs of ill-health may thus be produced. After a few days the skin becomes less red, and increasing pigmentation ensues; the swelling goes down, the blisters dry up, the epider- mis peels off, at first in larger flakes, as after scarlet- fever, and later in small scales. Makalkozv 2 ) and JFidmark 5 ) drew attention to an important fact, in connection with this reaction, viz., that the changes in the skin do not appear at once, imme* diately after the action of the light, being in this respect a con- trast to changes brought about by heat-rays, which are visible at once, but die away quickly. Light erythema, on the other hand, as well as the Roentgen reaction, appears only after being latent for a longer or shorter time; the period of its duration, in which it reaches its height, is prolonged in proportion to the intensity of the light action, and it dies away slowly with desquamation and absorption of pigment. Maklakozv tried to determine the period of latency after the J ) Cit. bei Raum, p. 338. 2 ) Archives d'ophthalmologie, 1889, Vol. IX, p. 97. 3 ) Hygiea, Festband, No. 3,, 1889. — Beitrage zur Ophthalmologic Leip- zig, 1881, p. 438. PHOTOTHERAPY 417 use of a powerful arc-light. The effect of an irradiation, last- ing only 15 seconds, was not seen till after 10 hours. A part of the skin, subjected to light action for one minute, showed dis- tinct circumscribed hyperesthesia after half an hour, redness . showing itself only after 2-/+ hours. Regions of the skin exposed to the light for 3} minutes became red in 11 minutes, and parts irradiated for 5^4 minutes showed erythema, after 3 minutes. These results were confirmed by Finsen 1 ) and Moel- ler'-) after accurate experimental research. If now we compare these facts, with the effects produced on the skin by heat-rays and Roentgen-rays, we may deduce the following laws as to the speed with which the reaction shows itself and the length of its duration : /. The duration of the period of latency is in inverse ratio to the wave-length of the active-rays; in like manner the effect lasts longer in proportion as the wave-length of the active rays becomes shorter. 2. The greater the intensity of the light, the earlier does reaction show itself and the longer does it last. If the intensity is less, reaction shows itself later and lasts for a shorter time. Finsen and Moeller proved by experiment a peculiarity of light reaction precisely corresponding to that observed by the author with Roentgen-ray reaction 3 ). Skin, which has been exposed to powerful influence from chemical (blue, ultra-violet) rays, retains for a long time (months and years after the first light-erythema has disappeared) a peculiar predisposition to react remarkably quickly (by reddening) to mechanical, chemi- cal and thermal stimuli- and also to internal influences (psychical stimulus, etc.) . The relation of the skin pigment to light is very interesting. We have above (p. 410) already referred to the part played by light, in causing colour-change in animals. There are in the skin of very many animals ( also in other organs, e. g., in the iris of amphibia and fishes) pigment-cells or chromato- 2 ) Mittheil. aus Finsen's tned. Lichtinst, [900, I. Leipzig, Vogel. 2 ) Der Einfluss'des Lichtes auf die 1 1. mi. Stuttgart. *) Cf. die physiolog. Wirkungen der Polentladungen, etc. Sitzungsber. d. kaiserl. Akad. d. Wissensch., math, naturw. CI., Bd. < IX, Abth. III. p. 644. 4 i 8 RADIO-THERAPY phores, the protoplasm of which, on being irritated by light, extends or withdraws processes, thereby distributing the pig- ment over a larger or smaller space. In many parts (e. g., the iris) these chromatophores may also be regarded as pigmented, unstriped muscle-fibres, or as cells to the periphery, of which muscle-fibres attach themselves, which react to light stimulus by contraction. Bruecke, who has made the closest study of colour-change, in the chameleon, showed that the movement of the chromato- phores is dependent on the central nervous-system. Darkness acts on the skin of this animal as a stimulus, whilst daylight, even sunshine, reduces the pigment-cells to a passive state. When these creatures are brought out into the sunlight they become dark (projecting the elongations of their pigment-cells to the surface of the body) ; when they are taken into the dark they become pale in colour (the creature drawing back the dark elongations of its pigment-cells, so that they are covered by the light-coloured pigment in the upper layers of the cuticle). It is clear, from the varying behaviour of chromato- phores under irritation (strychnine-poisoning, rubbing with turpentine, strokes of a magnetic electromotor) and under paralysation (by cutting through the main- nerves) that we are right in taking the condition in which the cells extend their processes as being the pas- sive condition of rest, and the condition in which they draw in the processes as the active condition of irrita- bility. The action of light on the skin is local; for according to Bruecke if a band of tin-foil is put round a chameleon and the creature placed in the sun, there will be a light-coloured strip under the tin-foil, whilst the rest of the body will be dark. Bruecke proved that this is really light action, and not the action of radiant heat. P. Bert 1 ) found that it is the blue constit- uents of light, and not the red and yellow, which affect the chromatophores and to which we must ascribe the effects dis- cussed. *) Hoppc-Scylcr, Physiol. Chemie, 1881, p. 25. PHOTOTHERAPY 419 As with the chameleon, so with other animals, it has been proved that the protoplasmic movement of the chromatophores caused by light takes place through the central nervous system. The experiments of Ehrmann, who observed in frogs the direct passage of nerve filaments into the pigment cells, make it prob- able that the chromatophores are connected with the central nerve organ. Turbots, which had had the sympathetic nerve cut through, became dark in that part of the body whose nerves had their origin behind the incision. Blinded fishes become dark in colour through the spreading out of the pigment cells. Bruecke surmises that there is a reflex action starting from the visual nerve, and that a stimulus of the optic nerve passes on to the central organ, a stimulus which causes the chromato- phores to contract; so that when this stimulus is wanting, they permanently cover a larger space 1 ). According to Wittich 2 ) and E. Du Bois-Reymond,*) the colour of frogs and the sheaf- fish is also dependent on light, these creatures being black in the dark and turning light-coloured again under the influence of light. Exner drew attention to the movements of pigment in the eyes of insects as a result of light. The behaviour of these creatures with regard to light becomes intelligible when we consider that pigment, as we shall see directly, is a natural protection against the action of light. Creatures avail themselves of this protection in proportion as the light-irritation becomes more or less unpleasant to them. We must distinguish this passing and occasional reaction of the chromatophores to light irritation from the more or less per- sisting pigmentation, observable in both men and animals in regions exposed to light. According to Ehrmann, where the sun's rays fall on a skin in which melanoblasts arc present (/'. c, cells which produce melanin, a melanotic brown pigment, l ) Oik, led from Bruecke, Vorles. ueber Physiologie, [885, Vol. I. Mueller's Archiv, [854. uch. zur Naturlehre des Menschen u, der Thiere, von Molc- scott, 1858, Bd. V. 4 2o RADIO-THERAPY formed, only by cells, not in the interspaces) melanin is developed there from the more abundant nutriment received, and under the stimulus to the cells of the light rays. Thence results the sepia-brown colouring of the skin, lasting some- times for years. There is a different reason for the deep but evanescent brown of the skin often to be seen, e. g., in tourists after a glacier excursion, as the remains of erythema solare s. photoelectricum after a single but intense exposure to light. In this case the strong light produces marked hyperemia of the skin; blood- plasm, in which haemoglobin is dissolved, finds its way out freely through the walls of the capillaries. In a short time the haemoglobin is deposited in the interstices of the tissues as golden-yellow hemosiderin, causing the brownish-yellow colour of the skin, which only disappears in a few weeks after this blood pigment has been reabsorbed. 1 ) The pigment may also be developed from the red corpuscles directly; they may pass by diapedesis out of the walls of the blood vessels and shrivel up into pigment corpuscles. As already observed, pigment is the skin's protective organ against light rays. One evidence of this is that races of men exposed always to strong insolation, are, like animals, darker in colour at those parts of the body exposed to the light. Wed- ding' 1 } observed the remarkable fact that cattle and sheep fed on buckwheat broke out in blisters, if they were light in colour or were exposed to sunlight. Beasts kept in the dark remained healthy. Parti-coloured beasts showed sickness only in the light parts, the dark parts remaining unchanged. Wedding smeared part of one cow with tar; the eruption appeared only on the untarred parts of the skin. Last summer the author came, by chance, on a cor- roborating instance. A dark-complexioned man, who had for many years had vitiligo patches on the body and face, after a long walk over the Grossglockner glacier, developed violent inflammation (erythema) in the *) S. Ehrmann, Wiener med. Wochenschr., 1901, No. 30. 2 ) Verhandhingen der Berliner Gesellschaft fiir Anthropologic, 1888, p. 57. PHOTOTHERAPY 421 neighbourhood of the white patches on the face, but in these regions alone. The rest of the skin was quite unaffected. Finsen proved, by a very interesting experiment, that acquired pigmentation may also have protective power against the injurious action of light rays. Finsen painted a ring round his arm with black paint and then exposed the arm for 3 hours to very strong sunlight, after which the paint was removed. The skin after a few hours seemed quite white and nor- mal, showing only some redness at the edges of the belt of paint. A few hours later violent erythema was developed in the exposed part, but in the painted belt the skin was white as before. The boundary line between the affected and the normal parts of the skin was extraordinarily sharp and showed precisely the same small irregularities as the edges of the black belt. After the erythema had passed off the skin was a good deal discoloured. Now Finsen again exposed the arm to sunlight, without blackening any part; the result was precisely the reverse, the white band was attacked by erythema, the neighbouring parts remained unchanged. Light erythema and light pigmentation are due to the ultra violet rays. Charcot 1 ) already surmised that it is the so-called chemical rays that produce erythema photoelectricum. Veiel?) too, showed as early as 1887 that the chemical rays of sunlight produce a peculiar affection of the skin, consisting in swelling of the face and a red eruption, like nettlerash. He recom- mended the wearing of a red veil to absorb the chemical rays, and this simple remedy acted very well. Unna*) too, and C. Berliner, 4 ) also JFolters'') pointed to the chemical (violet and ultra-violet) light-rays as the cause of erythema solare, of xero- derma pigmentosum, and of Hutchinson's summer-eruption, and ') Compt. rend. Soc. biolog., [859, p. 63. '*) Vierteljahresschr. f. Derm. u. Syph. Jalirp;.. 1SS7, p. 277. :; ) Monatsli. f. praktische Dermatologie, 1885, Vol. IV. p. 277. '> [bid. [890, Vol. XI, Nos. to, ti. 6 ) Erganzungsh. v.. Arch. f. Dermat. u. Syph., [892, p. 1X7. 422 RADIO-THERAPY recommended treatment with curucuma-yellow masks, veils or windows, to be used persistently for weeks and months. Bowles relates (Monatsh. f. pr. Dermatologie, 1894, Vol. XVIII, p. 16) that an officer in India, who suffered much from the sun, protected himself by having his clothes and sun helmet lined with yellow. Bouchard, Widmark, Hammer, Finsen, Moeller and Mak- lakow have all made direct experiments to test which part of the spectrum is really injurious. Bouchard 1 ) used coloured glasses and found violet to act more strongly than the rest. Widmark 2 ) investigated the cause of erythema photoelec- tricum. He used the light of a powerful electric arc lamp, concentrated firstly by a lens of rock crystal; secondly a glass plate was introduced between the irradiated object and the light- collecting apparatus, to absorb the ultra-violet rays. Further, for another series of experiments, in order to make parallel the diverging rays from the source of light and to cool them down, Widmark used a metal tube, closed at one end by a rock-crystal lens, at the other by a plain sheet of glass with a hole in it, into which a disc of rock-crystal was cemented. The interior of the tube was filled with water, kept constantly in circulation. Widmark' s experiments showed that it was the rays which had passed through the rock-crystal and in which ultra-violet predominated which produced erythema. The heat rays and bright rays played only a subordinate part. To distinguish the action of light rays from that of heat rays Hammer 3 ) used a gas lamp with an Argand burner and a ruby glass chimney. Thus the ultra-violet rays and all the light rays, except the red ones, were almost entirely excluded. The upper arm, on which one spot was marked off by adhesive plas- ter and brown paper, was then exposed and held at about to to 15 cm. distance from the flame. A fairly intense heat was felt. The experiment lasted an. hour and a half. After 25 minutes the skin showed distinct redness and was warm to the touch. At *) Compt. rend. Soc. Biolog., 1877. 2 ) Hygiea, 1889, Festband, No. 3. Verhandlungen d. biolog. Vereins in Stockholm, 1889, 20. — Skandin. Archiv. f. Physiologic 1889, 1. 3 ) Ueber den Einfluss des Lichtes auf die Haut, Stuttgart, 1891. PHOTOTHERAPY 423 the end of the experiment the skin was moderately reddened and showed a few lighter patches within the red part. Then white patches, during the next few hours, encroached more and more on the red, and in 24 hours the skin was again normal. It was further noted that the part covered by the plaster, but not that which was covered loosely by the brown paper, was of the same speckled red colour as the exposed skin. In an experiment in which two adjacent strips of skin were irradiated evenly by the electric light, but one of them further exposed to the light of a gas flame with a ruby glass chimney, there was at first more intense reddening of the latter strip and of the parts near it covered by plaster, but later on both the exposed strips showed a quite even degree of erythema. These experiments show quite clearly the difference between the action of heat and of the chemical ultra-violet rays on the, skin. Both produce redness, but with this great difference, viz., that redness of the skin, caused by heat, appears very quickly and disappears as quickly, unless the heat has been such as to make albumen fluid. Redness of the skin, caused by the ultra- violet rays, on the other hand, shows itself for the most part some hours later, is very persistent and is followed by desquama- tion and by pigmentation. In Maklakow's opinion, 1 ) the effect of an arc-light on the skin is not thermal, but chemical and very like that produced by insolation. Yellow and red light, which have no chemical rays, have also no effect on the skin. Less powerful sources of light produce no marked effect on the skin, but lead to discolouration, if applied for a long time continuously. Long exposures or very intense light set up necrotic changes : the skin becomes gangre- nous as a result of the chemical light action. Finsen 2 ) exposed certain parts of the skin to all the rays of the spectrum, other parts to certain rays only. For this purpose he fixed on his arm a rock-crystal disc and a row of variously coloured pieces of glass, and painted on the arm a few letters and stripes. All these articles and colours were so arranged on ' , !.. c. *) Mittheilungen aus Finseris med. Lichtinstitut, I, p. 9. 4 2 4 RADIO-THERAPY the arm that the skin surrounding each figure was exposed to the full influence of all the light rays; the arm was exposed for 10 minutes to the light of an 80 ampere lamp at a distance of 75 cm. The skin was slightly reddened at once; after 2 hours the redness had increased, after 4 hours it had increased still more, but only in the parts which had not been covered. After 12 hours in all the skin was quite dark red, hot and sensitive. Wherever the skin had been covered during the experiment with paint, it was now quite white and normal, standing out sharply against the red surroundings; the two letters were very clear, white on a red ground. Where the five pieces of glass had been there were five white streaks of the irregular shape of the glass, and the skin at these places was throughout quite normal. On the other hand, at the part where the rock-crystal had been the skin was quite the same colour, and quite as hot and sensitive as at the parts which had not been covered at all. Thus this experiment again showed that light erythema is caused by the ultra-violet rays. In a second experiment Finsen collected the arc-light through a quartz lens and held variously coloured bits of glass and also rock-crystals in front of it. At the same time means were taken to pass the light through a layer of cold water, and the irradiated spot was played on with a stream of cold water. Reaction of the skin resulted at the three spots where the light acted through rock-crystal, clear glass, and blue glass, but not the slightest reaction appeared with the other colours. From which we may infer that not only the ultra-violet, but also the visible chemical rays have the power of producing erythema photoelectricum. A question of great interest to determine is, how deep does the light, and especially the so-called chemically active rays, penetrate into the tissue? Since, as has been shown, a peculiar influence on the phenomena, appearing after insolation, has been ascribed to the ultra-violet rays in particular, it seemed to the author important to test how far the latter assumption is justified. Attention was directed not as to whether the ultra- violet rays did as a matter of fact produce the effects here dis- cussed, but as to whether these rays were capable of having any effect on those structures situated deep in the corium (capillary PHOTOTHERAPY 425 vessels, ends of nerves, chromatophores, etc.), from which various unhealthy conditions of the skin have their origin. The outermost ultra-violet rays, being for the most absorbable In- various transparent media, c. g. t glass, 1 ) it was a matter of interest to find out whether the opaque layers of epidermis pre- vent to any sensible extent the passage of these rays. The reply to this question has a further practical interest, at the pres- ent time, when, owing to the favourable results reported by Finsen on the light treatment of lupus, so much attention is being given to the irradiation of parasitic affections with so-called chemical rays. Quite recently, indeed, Strebel has been substituting for Finsen's treatment with electric arc-light irradiation with the ultra-violet light of the induction-spark, and he claims to have destroyed bacterial cultures far more quickly with this than with the arc-light. Under these circumstances it is specially important to determine the transparency of the epidermis for ultra-violet rays. For if the ultra-violet rays are indeed so powerful in their action, and if in practice they are actually able to bring their action to bear on the deeper-lying layers of the skin, i. e., if they are not intercepted by absorption in the surface tissues, then it would surely be well to use as little as possible the visible constituents of the spectrum, and to make use only of such sources of light as emit the greatest proportion of ultra-violet rays. In the author's experiments in this direction he wished, therefore, not merely to test whether the chemical and ultra- violet rays are able to penetrate to the lower layers of the skin, but to determine as exactly as possible which part of the ultra- violet spectrum has this peculiar penetrating power. It has long been known that animal tissues allow of the free passage of light, or at least of certain constituents of it, and before the discovery of Roentgen-rays this transparency of the tissues was largely taken advantage of to investigate the char- acter and seat of morbid changes within the human body. 1 his ') See the treatise by Eder and Valcnta, Die Spectren farbloser und ge» faerbter Glaeser. Denkschr. d. kais Ucad. d. Wissensch. Math.-naturw., CI, Vol. LXI. 426 RADIO-THERAPY transparency is present in various tissues in a varying degree; it depends not only on the density and chemical nature of the layer, but especially on its uniformity, as regards both matter and density. Most substances found in the human body are not equally transparent to all colours; they absorb the rays of one or several colours and allow passage to rays of the other colours. The transparency of the skin is shown by the simple experi- ment of holding the hand in front of a strong light, when the finger tips will show the red light through, or of looking at the sun with closed eyes, when a sensation of red light will be felt. The red colour shows that the red rays have penetrated the tis- sues. The commonly used test for hydrocele also shows in simple fashion that light penetrates the skin of the scrotum. Dessaignes 1 ) demonstrated the passage of light through the skin by making a diamond sparkle when the finger covering it was illuminated from above. A similar result followed # when the light had to find its way through a white or chamois leather. An experiment of Gadnefs 2 ) threw further light on the nature of the rays penetrating the skin. He filled small tubes with chloride of silver, sealed them hermetically, and then with the aid of a trochar, introduced them under the skin of dogs and cats. When the animals had been exposed for some time to the sunlight, the chloride of silver was found to be blackened, whilst with animals in captivity, which had been kept in the dark, it was unchanged. Finsen proved the passage of light through the skin by placing sensitised paper behind the lobe of the ear and irradiating the latter. The paper was blackened, and to a more marked extent when the blood was driven out of the skin by pressure. Darbois 3 ) showed that a piece of photo- graphic paper introduced into the mouth under the skin of the cheek between two watch glasses was blackened after one min- ute by light from the Finsen concentrator, directed on the out- side of the cheek. Gebhard 4 ) inbedded a hand so completely in plaster of Paris that only the back of the hand was exposed. J ) Quoted by Gebhard. 2 ) Quoted by Boubnoff, Arch. f. Hyg., Vol. X, p. 335. 2 ) P. Darbois, Traitement du lupus vulgaire. These dc Paris, 1901, p. 80. 4 ) Die Heilkraft des Lichtes, Leipzig, 1898, p. 131. PHOTOTHERAPY 427 A photographic plate had been placed in the hollow of the palm. Then the hand was exposed for 20 minutes to the light of an electric arc-lamp and afterwards (in the dark room) taken oft the plate and the latter developed. The plate was blackened, the contours of the hand and lingers being distinctly seen — a sign that light had passed through the hand. Similar experi- ments were made InBechterezv's laboratory by Sol uc/ki ' ) . Tubes filled with strips of silver-bromide-gelatine were inserted under the skin of dogs and the wound sewn up. Light was projected on the parts from an electrical projection-apparatus of 10 to 20 amperes current strength and 50-65 volts. After */> minute the bromide of silver was seen to be decomposed. When, on the other hand, the tubes were inserted deep down into the mus- cle substance of the glutei, the light had no effect. When the tubes were put behind the ear or inside the cheek of patients, decomposition soon set in ; in the former case after half a minute, in the latter after 2 minutes; when placed behind the fore-arm or in the fist the bromide of silver was unchanged after 15 minutes. With a current, then, of the above-mentioned strength, light only penetrates through the skin; with a stronger current, say of 25 amperes and 1 10 volts, it penetrates through the whole body, for under such conditions the sensitised gelatine-film was chemi- cally altered, even when it was placed on the opposite side of the body from the part exposed to the light. Thus Solucha placed it at the back of the neck when he exposed the front of the throat, or at the right side of the body when the light came from the left. Kime and Hortatler 2 ) proved that sun rays, too, may pass through the human thorax and still have sufficient power to produce an image on a photographic plate. Finsen ") passed concentrated sunlight through the ear ol a white rabbit on to a bacteria culture. After ; 1 hour he was able to observe distinct weakening or killing of the culture. Finsen also proved with the skeptroscope that a light ray ') Wissenschaftl. Sitz. d. Vereinig. d. Petersburger Klinik f. Nerven und Geisteskrankheiten, 24. Februar, [900, Wratsch, [900, Nr 28, p. 864. '■'1 Vllgi in. Photogr.-Ztg., i'ioi, p. i' ■ ') LJeber - G; '" ' ^^e^s-sS^"""* ^-^W0 Fig. 90. The interruption of continuity occurs in various places. With the human being it occurred approximately on the border line between the granular and the horny layers, but this by no means precludes the possibility that on other occasions (other skin and other degree of light intensity) the bullous exudation may arise differently. This would be analagous with the course, e. g. y of pemphigus, 1 ) where in some cases the blisters appear ') Jarisch, Zur Anatomie u. Pathogenese der Pemphigusblasen. Arch. f. Derm. u. Syph., 1898. Festschrift gewidmet F. J. Pick, Part II, p. ,341. PHOTOTHERAPY 435 between the cutis and the rete, in others between the granular and the horny layer. With more intense light thrombi are formed in the vessels of the cutis." In Moeller's case the contents of the blister con- sisted of a line reticulum, containing numerous red cor- puscles and isolated leucocytes. Everywhere close to the surface numerous light, round blisters are to be seen, with a more or less delicate covering membrane and a light centre (Fig. 91). In some of the horn-cells, loos- ened from the covering of the bulla, may be seen very distinctly through the swelling of the cells, a longish ■ Fig. 91. Fk;. 92. rod-shaped hole in the centre in place of the nucleus. In the remaining prickle-layer, too, which forms the base of the blister, cell changes occur, which vary from a sim- ple swelling to bullous degeneration (Fig 92). It was interesting to have confirmation ot the fact ol the deeply-penetrating action ol the ultra-violet rays, which was seen very beautifully in the rabbit's ear. For the disturbances were {when the light was very intense) very marked, also on the reverse side of the cartilage; nay, in consequence, no doubt, of the larger number ol vessels on that side, they were more noticeable there than on the directly illuminated side. 436 RADIO-THERAPY In a further series of experiments Mocller proved that heat radiation (50 to 55 °) acting together with intense ultra-violet irradiation, just the same as heat radiation alone, after the filter- ing away of the ultra-violet rays, when directed on the skin of the skull of rabbits, produced more or less intense cerebral dis- turbances, sometimes even sudden death. The autopsy showed the skin of the head, after intense irradiation of that nature, to be much swollen, and a bloody gelatinous exudation to be pres- ent in the subcutaneous tissue. The periosteum, the cranial bones, the dura were discoloured and covered with ecchymoses. The vessels of the brain surface were much dilated, and it showed numerous, in part confluent, ecchymoses. When, on the other hand, the heat rays were filtered off and the ultra-vio- let rays alone applied, no central disturbance was observable. These last experiments show that the action of the ultra-vio- let rays at any depth is relatively unimportant. No change of tissue was to be seen, even in the spongy subcutaneous tissue, this in direct contrast to the condition after irradiation by heat rays. Both heat rays and ultra-violet rays cause hyperaemia of the cutis, followed in the case of the latter rays by discoloura- tion and hyperplasia of the epidermis, especially of the horny layer, which prevents them from penetrating further into the tissues. No less important than the changes in the skin are those which light produces in the visual organs. Ogneff ^) asserts that prolonged action of an electric arc-light of high power, with preponderance of violet and ultra-violet rays, produces necrosis in the cells of the cornea in the case of rabbits, pigeons and frogs. In the cells of the cornea, necrosis is preceded by ami- totic nuclear changes (whilst with brief exposure mitosis results) . Of the other parts of the eye, the lens and the vitreous humour are not affected at all, the retina only slightly. Ogneff believed he guarded against any action of temperature in his experiments. Light, acting on the retina, bleaches (Kuehne 2 ) the red-col- ouring matter, "rhodopsin," proved by Boll to be present in the 1 > Pftueger's Arch., Vol. LXIII, p. 209. 2 ) Untersuch. a. d. physiol. Institut Heidelb., Vol. I, u. ff. PHOTOTHERAPY 437 outermost portion of the rods. It is extremely doubtful, how- ever, how far this affects the power of sight. By means of the local bleaching of the rhodopsin, images of light objects on a dark background (e. g., illuminated win- dows), may, as though by a photographic process, be obtained white on red in the eyes (previously kept in the dark) of either living or dead frogs and rabbits. (In the case of dead animals, the eyes are cut out.) These images may be fixed by means of alum ("optograms"). The pigment granules, when the eye is in the dark, i. c, in a state of rest, lie at the back of the pigment cells of the epithe- lium, nearest the nucleus; when light falls on the retina, the granules move forward into the ciliary processes, lying between the rods and cones, and the rods and cones themselves draw together and contract. {Boll, Angelucci, Engelmann, v. Gen- deren, Heger, Perpens and E. Fuchs. 1 )) A retina that has been kept in the dark changes its electrical condition when light suddenly falls upon it; the electric current which passes normally from the retina to the brain is made stronger (Holmgren) . The so-called photo-electrical variations may be here referred to : for the eye accustomed to darkness the maximum of stimu- lation is found in yellowish green close to the thallium line, whilst the eye adapted to the light reacts most to the yel- low D line of the spectrum (Himstcdt and Nagel -)) . Engelmann 3 ) proved that frogs, from whose eyes light was artificially excluded, reacted with contraction of the interior cones of the retina to irradiation of the skin of the back. This fact proves that the light stimulus reaches the brain by a centripetal course, and is able thence to induce motor phe- nomena. Buedingen has shown that this reflex action does not take place when the brain is removed, whence we may con- clude that this transformation of the stimulus takes place within the brain itself. According to the researches of Bence Jones, Dupre ami John Tyndall, the lens possesses the power of fluorescence in a ') Lehrb. d. Augenheilk, Leipzig und Wien, 1893. *) Physik. Zeitschr., rgoi, Jahrg II. p. 362. ») PAueger's Arch., 18X5. Vol. XXXV, p. 498. 438 RADIO-THERAPY high degree. "If I bring my eye into a violet ray, I notice a bluish-white glimmer filling the space in front of me. This glimmer comes from the fluorescent light produced in the eye itself. The crystalline hue of the eye, when looked at from without, lights up brightly at the same time 1 )." This peculiarity of the lens, which it shares in common with the vitreous body, may perhaps explain why Roentgen and Becquerel rays produce sensations of light with some persons. It is not, however, impossible that electric stimuli of the retina and the visual nerve may have something to do with it. Of great importance, in connection with the effects of light on the whole human and animal organism, is the influence which it exercises on the blood and the capillary system. We have already referred to the changes of form caused in the blood vessels by light. Blood absorbs light in a high degree and in quite a peculiar manner. This is shown by the characteristic absorption spec- tra in greenish-yellow (Hoppe-Seyler) and in blue-violet obtained by d'Arsonval") and the author''). Finsen 4 ) laid on one side of the lobe of an ear a piece of aristo-paper and directed a pencil of blue-violet rays on to the other side; after the lapse of 5 minutes under these conditions no result was visi- ble on paper. When, however, the lobe had been compressed between two glass plates, so as to appear white and bloodless, the paper turned black in 20 seconds. Whence we see that blood, to a considerable extent, prevents the chemical rays from penetrating the tissues. There is especially one constitutent of blood which uni- formly absorbs light, viz., haemoglobin. Oxyhemoglobin gives a different absorption spectrum from metha?moglobin. Quincke ) showed that haemoglobin gives off its oxygen more quickly in the light than in the dark (the oxyhasmoglobin band 1 ) Das Licht. Sechs Vorlesungen von John Tyndall. Braunschweig, 1895, p. 179. 2 ) Arch, dc Physiolog., XXII, 2, p. 340. 3 ) Cf. p. 430. 4 ) Ueber die Bedeutung der chem. Strahlen des Lichtes, Leipzig, p. 78. 6 ) Ptiucget's Archiv, 1894, Vol. LVII, p. 134. PHO TO THERAPY 439 in the spectrum vanishes), hence light increases the oxidising power of the blood and, correspondingly, the processes of oxida- tion in the human body. We must refer ultimately to the action of light on the capillary system, the pigmentation left after exposure to strong light, which comes (cf. p. 419) from the accumulation of hemosiderin in the interstices of the tissues. If this process is widespread, /'. c, if this giving off of blood-colouring matter, in consequence of the exposure of extensive parts of the body to strong light, takes place to a large extent, then it causes a cer- tain impoverishing of the blood in elements and blood-colouring matter, and the body may be stimulated to compensate for this. According to this theory (Lowenthal ') ), the influence of light on certain processes of metabolism is intelligible. Grafenber- ger 2 ) holds that the mass of haemoglobin contained in the red corpuscles is lessened in the dark; a diminution in the total quan- tity of blood results from prolonged stay in darkness. Marti*) too, by means of experiments with rats, established the fact that deprivation of light lessens the number of red blood corpuscles and to a less extent the amount of haemoglobin, whilst strong and continuous illumination stimulates the formation of erythro- cytes and also of haemoglobin 4 ). In accordance with the results of these researches are the facts that the women of the far north are much predisposed to amenorrhea, and are even said to be quite free from menstrua- tion during the long night of winter (Eulenburg*) ) whilst at the close of the Polar night the oxyhemoglobin bands in the ') Deutsche Medicinal zcitung, 1899. No. 72. 2 ) PHugcr's Archiv. 1892. Vol. LIII, p. 238. 3 ) Verh. d. Congr. f. innere Med., 1897. *) P. Borrisow, too (cf. Zeitschr. f. phys. u. diat. Ther., Vol. V. p. 237), was unable to prove any influence of either light or darkness cither on the number of the red or the white blood corpu cle . or on the formation <>t' haemoglobin. According t<> his experiments, the weighl of dogs kept in the light increased considerably, after an initial decline, whilst that of dogs left in darkness showed no increase; the former also possessed a better appetite. *) Quoted from Strebel, Die Verwendung des Lichtcs in dcr Therapie, p. 8. 44 o RADIO-THERAPY blood of such persons as were examined showed signs of exten- sion (Holmgren and Gyllenkreutz 1 )). Whether it is this direct action on the blood or stimulation of the nervous system which again reacts on other vital functions, stimulating them, the fact remains that under the influence of light the tissue-change in men and animals undergoes certain modifications. Several writers have cited interesting observa- tions which favour the second of the two theories. In the first place we must notice the important results obtained by Quincke, 2 ) who showed that various tissue-cells (blood, pus, muscle, kidneys, liver, etc.) absorb more oxygen in the light than in the dark. When these substances were mixed with subnitrate of bismuth, the latter was reduced, but only in the light. Severed muscles and nerves, so long as they are not quite dead, eliminate carbonic acid more freely in the light than in the dark (Moleschott and Fubini 3 ) ). From these researches we might then conclude that light influences the oxidation of the tissues. Various experimenters claim to have observed on many occasions that matter-change in living animals and men is thus influenced. When light is excluded, dogs, hens, pigeons and frogs elim- inate less carbonic acid than in the light (Moleschott, 4 ') Selmi and Piacenlini 5 ) ) ; the amount of carbonic acid given is in direct ratio to the intensity of the light (Moleschott) and is not dependent on the freer movement of animals in the light (Chassanotvitz °) ) . With frogs and toads the blue rays were most effective in increasing the amount of carbonic acid given off; with birds and a ) Quoted from Gebhard and Moeller. 2 ) L. c. 3 ) Untersuchungen zur Naturlehre des Menschen und der Thiere von Moleschott, 1881. Vol. XII, p. 266. -- Archivio di Bozzozero, 1879, Vol. Til No. 19, p. 23, quoted from Return. 4 ) Wiener mcd. Wochenschr., 1885, No. 4,3. c ) Rendi conti del Reale Instituto Lombard di sc. e. lettre, 1870, Vol. III. Ser. II, p. 51, ref. Allg. med. Centr. Ztg. 1872, p. 810. e ) Ueber d. Einfluss des Lichtes auf die Kohlensaureausscheidung im thiarischen Organismus. Inaug. -Dissert. Konigsberg, 1872. PHO TO THERAPY 44 1 rodents the red rays had most influence (Pott 1 )) . Van Peclf)io\m<\ that beetles (Brunchus pisi)take in more oxygen in the light than in the dark. Scharling, 3 ) Pettenkofer and Voitf) Fubini and Ronchi 5 ) proved that human beings give off less carbonic acid in the hours of the night than in the daytime, even with absolute rest. The two last-named writers confined their researches to a single limb (fore-arm and hand). Brown-Sequard, Pjluger and others hold, however, that the increase of carbonic acid elimination through light is only apparent, being occasioned by the movement and enlargement of the muscle with light causes. S. Godnew 6 ) found that persons and animals to whom day- light was accessible excreted more urine, urea, and chlorides than those who stayed long in the dark. 5. Daitsch 7 ) and B. Kogan 8 ) formed the following conclusions from their experiments : ( 1 ) Red light weakens the processes of both assimilation and dis-assimilation; (2) green light stands lower than white, in regard to the accumulation of nitrogen, as well as to quali- tative metamorphoses; destruction changes proceed more vigor- ously in green light; (3) yellow and violet light induce the max- imum of energy in all the vital processes, more complete meta- morphosis prevailing under the influence of violet light; (4) darkness causes a diminution in the exchange ol nitrogen in the body and, incidentally, a diminution in the daily amount of urine. ') Vcrglcichende Unters iiber Mengenverhalten d. ausgesch. Kohlensaure. Habilitationsschrift, Jena 1875. *) Amsterdamer Maandblaad voor natuurwet. 1879, p. 116. 3 ) Ann. de chim. et de pharm., 1843, S. 3, p. 488. 4 ) Bcricht dcr Miinchener Akademie, 10 November, 1866. 6 ) Arch, per la sc. med., 1876, Vol. I. ') Zur Lehre v. d. Einfluss d. Sonnenlichtes auf die Thiere. Kasansche I M I It., 1882. 7 ) Uebcr den Einfluss des weissen Lichtes und der verschiedenfarbigen Strahlen auf den Gasaustausch bei Warmblutern. Petersburger Dissert., [891. ") Ueber den Einfluss des wei sen (elektrischen) Lichtes u. der ver- schiedenfarbigen Strahlen auf die Stickstoffmetamorphose bei Thieren. I '( ter liurger Dissert.. [894. 442 RADIO-THERAPY According to Godnew, Gorbazewicz, 1 ) Hammond 2 ) and others, animals gain more weight in light than in darkness. The influence of light on metabolism may be either direct or indirect; it depends: i. On the influence of light on the blood and the circulation generally. (See p. 43 8.) 2. On the influence of light on the tissue elements them- selves (cf. p. 41 1 )• 3. On its stimulating effect on the nervous system, which produces increased action of the muscles and movement of the body (Loeb). 4. On the stimulating effect of light on the organs of sense (the eyes), inducing increased or reflex energy in the body func- tions. In connection with this dependence of the processes of mat- ter-change on the accessibility of the sensitive retina to light, Moleschott, Bechard, Selmi and Piacentini, Pott, Pfiiiger and v. Platten :! ) proved that under the influence of light, through stimulation of the retina, there was marked increase in the elim- ination of carbonic acid and absorption of oxygen. Experiments with animals, which have been deprived of not only eyes, but also even of brain and lungs, furnish proof that matter-change may be influenced by reflex action through the skin. It must, however, be stated, as opposed to the results given above, that papers have been published denying light has any influence at all on matter-change, or assuming only quite a dif- ferent kind from that shown in the experiments quoted. According to the observations of Graff enber gcr 4 ) and others {Bidder and Schmidt), the metabolism of carbon com- pounds is lessened in the dark, and more fat is formed and deposited. Hence, animals kept in the dark increase in weight (geese, for fattening, are kept in dark sheds). This retarda- *) Ucbcr den Einfluss der verschiedenenfarbigen Lichtstrahlen auf die Entwicklung u. das Wachsthum der Saugethiere. Petersburger Dissert., 1883. '"') The Sanitarian, 1873-74, Vol. I. s ) Arcb. f. d. ges. Physiol., 1875, XI, pp. 263, 272. 4 ) Pfluger's Arch., 1892, Vol. LIII. PHOTOTHERAPY 443 tion of matter-change in darkness enables starving animals to live much longer in the dark than in the light (Aducco 1 )). Bie '-') does not regard it in any way as proved that light influ- ences the amount of haemoglobin in the blood, or that it pro- motes the elimination of carbonic acid. Justus Gaule 3 ) claims to have proved that with frogs in winter time the fatty bodies lying next to the sexual organs dis- appear in the day time and are formed again at night, and this in the case of blinded frogs as well, which shows that light acts on the fatty bodies through the skin. It has been assumed by many that light influences the breathing, the temperature of the body and the pulse. Fere 4 ) found in one case that respiration was 19 to the minute in yellow light, 17 in green, and only 15 in red. Under the influence of red light the pulse becomes fuller and slower; in darkness it falls so greatly that the sphygmograph ceases to show oscillation. /. Go dnew*) -too, found that the number of heart beats and the rate of breathing increased noticeably whilst the animals on which he was experimenting were under illumination. Triwus 6 ) made researches under the guidance of W. v. Bechterew into the influence of coloured light on the pulse of healthy persons. Mosso's plethysmograph was mainly used in the measurements. The subjects were usually kept about two hours in the special coloured room of the clinical hospital. The plethysmograms were taken at the beginning and end of each experiment. In most cases the coloured light caused depres- sion of the pulse, i. e./\t became less rapid and less full. Violet is the most depressing colour, and red the least; the action of the other colours correspond with their place in the spectrum, with the exception of yellow, which had no effect, probably because the yellow plates let through nearly all the rest of the x ) Communicazone all' .Acad.
  • s ) which was to be used 'in vari- ous diseased conditions. The medical literature of the 19th century from that time on records a series of investigations which we must regard as the basis and forerunners of the mod- ern light treatment. In the first rank we must place the researches of the numerous bacteriologists, who have proved the parasiticidal action of light, and have determined to which part of the spectrum this is specially due. Then come the physio- logical works of Hammer, Widmark and others (mentioned on pp. 420, 422) on the different action on the skin of the red and the blue end of the spectrum, and Moleschott's on metastasis. We find in the beginnings of chromo-therapy in Ponza, Charpig- PHO TO THERAPY 449 non, Martin, Veiel, Unna, Berliner, Wolters, and of so-called negative light-therapy in Piorry, Picton, Black, Barlow and Waters. We see attempts to substitute electric light for sun- light {Lahmann) , to use concentrated light in the treatment of lupus ( Thayer, Otterbein, Mehl) . We find the methods of light- decomposition (heat and light filters), long used in physics and photo-chemistry, now turned to account in researches into the physiological action of light on the skin (JFidmark). Keloggs works on the effects of electric incandescent baths gave a pow- erful impetus to the study of light in its bearing on medicine, and mark an important stage in its development. None, however, has done such work for the furtherance of light-therapy as Finsen (from 1893 onwards). He first made careful experiments of his own, and tested thoroughly those of others, and then, having laid a sound theoretic basis, he con- structed the apparatus by which he was able to prove the use- fulness of light when applied in its most intense form to malignant growths, such as lupus. Finsen was in the happy position of being able to go on his way unhampered by external circumstances; help came to him from private individuals and from the State, and he was thus enabled to carry his plans to completion and in a comparatively short time to demonstrate forcibly to the medical world, by results with an enormous number of patients, the extraordinary value of the light treat- ment. We owe it no doubt to this circumstance that light- therapy has made such strides within a comparatively brief period. We may reasonably hope that the near future will clear up many a doubtful point and widen the range of photo-therapy; for many other workers are busy in the field. Bang, Strebel, Gorl, Foveau de Courmelle, Lorlet and Genoud have pub- lished interesting work on the possible simplifying of the appa- ratus and the strengthening of its effect; Moeller, Strebel, Glc- bowsky, the present writer, and others, are seeking by theoretic researches to solve certain important problems in light-therapy, and the practical results of light-trentment on most diverse dis- eased conditions are at the present day being studied with the greatest zeal. 450 RADIO-THERAPY Light may be used for therapeutic purposes either as natural or as artificial light; i. e., either without being decomposed and collected or as broken up into its component parts and concen- trated. (a) Treatment with Sunlight. § 58. The sun is our most natural source of light. Even in our latitudes on bright clear days it is the most powerful light source which we possess. This may be seen by the following scale (from Picker- ing 1 )) : Light-giving Power in the Several Parts of the Spectrum Total Light- Power expressed in Normal Candles C Red D Yellow C Blue White light Gas lamp Lime light Electric arc light. Magnesium light. Moonlight Sunlight 73 74 59 61 5° 87 45 100 100 100 100 100 100 100 10 j. 103 113 121 223 155 250 134 125 285 735 1,129 3 6 3 2,971 1 16 90 362 215 204 70,000 Unfortunately, as regards our use of this source of light, we are dependent not only on weather, but also on other cir- cumstances which affect chemical intensity as well as its optical brightness. As long ago as 1866, Roscoe and Baxendell, follow- ing Eder~) (from whose standard work we have taken these and the following data), proved that the chemical intensity of light does not by any means coincide with optical brightness. The chemical light-intensity of the sun's rays varies with the time of day and season of the year; that is to say, with the sun's height in the heavens. The maximum intensity is found when the sun is at its highest, i. e., at midday. In summer the chemical action both of the sun and of the blue light of the sky is distinctly more powerful than in winter; thus, for instance, at Vienna the 1 ) Ausfiihrl. Handbuch d. Photographie, Vol. I, pp. 320 ff. 2 ) From Edcr's Ausfiihrl. Handbuch d. Photographie, I, p. 355. PHOTOTHERAPY 45 1 intensity of the sunlight even at midday in December is only about as great as it is at six o'clock, either morning or evening, in June. The chemical intensity of light is weakened in spring. The optical intensity of sunlight is weakened by about one- fourth during its passage through the atmosphere. The chem- ically active rays lose very much more. Langley found that the following percentage of the various classes of rays passed the atmosphere 1 : Ultra-violet 39 per cent Violet 42 t( u Blue 48 U U Greenish blue 54 (( (( Yellow 63 (( u Red 70 u u Infra red 76 (( (t According to E. v. Oppolzer,-) the atmosphere absorbs about 20 per cent, of the optical rays and about 30 per cent, of the photographic rays. C. Masch ") proved that 57.5 per cent, of the sun rays acting on bromide of silver are lost by extinction in the atmosphere. The extent to which the air absorbs the light is thus con- siderable; it varies with the amount of vapour, carbonic acid and suspended dust present in the air, also with its movement and temperature. By the atmospheric movement, layers of varying density are formed, and the intensity of the light rises with the temperature. The chemical intensity of sunshine increases considerably as one rises into the higher regions of the air, i. e., as the atmos- pheric pressure becomes less; thus Simony found that the ultra- violet spectrum of sunlight extended much further towards the more strongly refrangible end on the summit of the Pic de Teyde on Teneriffe (3,500 metres high) than in the plain ') For further information see /. M. Vernier, Meteorolog. Optik, Vienna, 1902; also /. Wiesner, Studien iiber das photochem. Klima. Wiener Akad. 2 ) Sitzungsbericht d. K. Akad. d. Wissensch, 107, Part II, p. 1477, 1898. ") Schriften d. Naturw. Ver. f. Schleswig-Holstein, Vol. XII, H. 2. 45 2 RADIO-THERAPY below. There differences are, however, slight compared with those dependent on geographical latitude. Corresponding to the course of the sun, which up to the latitude of about 23 passes the zenith twice in the year, there are within these latitudes two maxima of light-stretch, in March and September at the equator, in April and August at lat. io°. At lat. 20° there is only one maximum, but that lasts from May to July. The nearer we approach to the higher latitudes the more sharply do we find the curve, which denotes the distribution of light during the year, rising towards the maximum in the summer months. The absolute amount of light given off by the sun to the earth in the course of a day is greatest at the equator and the lower latitudes; it lessens towards the higher latitudes. There is only one irregularity in this respect, i. e. t in the highest latitudes of all, where the sun does not set dur- ing the whole Arctic summer. (From D. Spitalcr 1 )). Holetschek estimates the chemical intensity of diffused day- light at mid-day in winter as one-half in the summer, as only one-quarter, of that of direct sunlight. In summer the morn- ing and evening direct sunlight has still about double the chem- ical intensity of diffused daylight, but in winter there is a very slight difference between the two. According to Roscoe and Baxendtll, the ratio of the chemical intensity of direct to that of diffused sunlight is not constant for a given height of the sun in different places, but varies with the transparency and other conditions of the atmosphere. Naturally, the chemical intensity of daylight is much influ- enced by the condition of the clouds, e. g., by the depth and density of the layers of cloud and the colouring, shape and posi- tion of the clouds relative to the sun. Mist and clouds lessen the chemical intensity far more than our subjective sensations of light would lead us to believe. Simple sunlight is used therapeutically in sun-baths and light- and air-baths. Single filtered components of the spectrum are ') Eder's Jahrb. f. Photogr., 1888. 2 Jahrg., p. 379. PHOTOTHERAPY 453 used in so-called chromo-therapy. In a concentrated form, either without being decomposed, or after abstraction of certain com- ponents (the heat rays), it is used in the treatment of skin diseases. Sun-Baths. § 59. Patients taking sun-baths *)are usually placed on rugs or mattresses, with the head raised and protected from the wind, in a verandah entirely open to the south. The head and eyes are protected from the direct rays by dark glasses and suitable shades. Sun-baths are taken in the height of summer between 10 a. m. and 5 p. m.; beginning with at least a quarter of an hour, the time is usually increased to three-quarters, seldom to more than an hour. During the bath the position is changed at intervals, so that the rays may fall on all parts of the body; the same position is maintained until violent perspiration breaks out on the exposed part, but not for longer, or too violent inflam- matory reaction might result. After, and possibly even during the sun-bath, a quick bath (of either the whole body or parts) at 72 to 82 ° is recom- mended. After this the patient is rubbed down and at the same time massaged, unless there are symptoms which make this not advisable. Many doctors order a dry pack of a quarter of an hour after the sun-bath. When the bathing is done the patient takes exercise. The sun-baths are sometimes taken every day, but usually only 2 or 3 times a week. Persons in health would find one a week sufficient. As direct effects of sun-baths, besides the erythemous reac- tion of the skin (in appearance like a scarlet-fever rash), leading to intense pigmentation and subsequent desquamation, may be mentioned profuse perspiration, rise in temperature to 40 C. in the case of sensitive persons, nervous disturbances, and with healthy persons a pleasant feeling of refreshment and comfort. ') For incandescent light baths, pee pp. 366 ff. 454 RADIO-THERAPY The appetite is improved, and the patient feels cheerful and often very sleepy. Sun-baths are said to be beneficial in disorders of nutrition (obesity, diabetes, gout), in scrofula, rickets, some diseases of the internal organs (asthma, heart-disease), anaemia, cachexy, nervous affections (neuralgia, neurasthenia, sciatica), affections of the skin and mucous membranes. The beneficial effects of sun-baths are due to their action in promoting perspiration (for the sweat eliminates harmful matter from the body), and also to the stimulation of meta- bolism and of the nervous system by light, and to the direct action of light on the blood. The violent prolonged hyper- emia of the skin induces a determination of blood from the internal organs to the surface of the body, and thereby the depletion of these organs. The bactericidal action of sunlight does not count for much here, as the ultra-violet rays (which are most effective in that respect) have little penetrating power. The blue and violet rays, however, penetrate more deeply, and their anti-bac- terial action is not to be disregarded. On the other hand, light promotes the general power of assimilation. The more vigorously this goes on, the greater, according to Liebermeister, will be the vital energy of the body and its power of resistance to everything injurious, especially to pathogenic micro-organisms. This, as well as the hyperemia induced in limbs exposed to irradiation for a long time (2 or 3 hours daily), may explain the cures reported by Cic- chansky, 1 ) Poncet, 2 ) Perdu and Blanc*) in cases of local tuber- culosis in joints and bones. As a substitute for sun-baths in the open air, Riedcr in the cold season orders sun-baths within doors — or electric arc-light baths. Light- and Air-Baths. § 60. In these baths the patients move about in the open air, vith little or no clothing, for a period of from 2 to 6 hours. To *) Gesellsch. d. Kinderartze, Moscow, March 7th, 1901. 2 ) Millioz, These de Lyon, 1899. 3 ) Revue intern, de I'eleetrotherapie, Jan., 1900, p. 157. PHOTOTHERAPY 455 keep themselves warm they do some manual work or gymnas- tics, or have massage. Light- and air-baths are taken morning and evening, with a sun-bath or hot-bath at midday. According to Rieder, the effective factors with these baths are the thermal stimulus, the increased activity of the skin through the radiation of heat, and the influence of light on metabolism. Light- and air-baths are used as a general tonic for bracing the nervous system, for treating obesity, in cases of congestion of internal organs, and to stimulate the action of the heart and kidneys. Their effects are similar to those of the "water-cure." Chro mo-Therapy. §61. Coloured, that is filtered, white sun-light in a non- concentrated state has been hitherto used in the treatment of infectious general diseases (small-pox, measles, scarlatina, erysipelas), nervous affections and a few skin diseases. General chromo-therapy is applied by keeping the patient continuously, for some time, in a room to which light is only admitted through suitably coloured glass (red or blue). Chromo-therapy is applied to local affections by wrapping the diseased part of the body closely in suitably coloured stuffs, which. serve as light-filters. Our experience so far leads to the conclusion that the treat- ment of localised skin affections with red diffused light leads to good results. According to Finsen, 1 ) chromo-therapy was first success- fully employed in the popular medical practice of past centuries. Thus in China, Japan and Roumania the face and hands of small-pox patients were swathed in red cloths, and graver symptoms thereby averted. The first experiment in chromo- therapy on a scientific basis was made in 1887 by Th. Veiel, who cured violent persistently recurring eczema solare in the case of a lady by ordering the use of red silk veils.-) ') I'dicr die Bedeutung der chem, Strahlen des Lichtes, etc. Leipzig, 1890. ') Vierteljahrschr. f. Derm, und Syph., 1897, i>. 11 1.3. 456 RADIO-THERAPY TVolters, 1 ) Unna 2 ) and Berliner 3 ) reported similarly good results in 1892. Instead of the red light niters, Unna and Berliner used yellow (coloured with curcuma) masks, veils and windows. Quite recently TV. TVinternitz*) has reported similar results in the case of affections not in any way traceable to light action. By covering up with red materials the parts of the body exposed to the sun, he has diminished chronic-hyper- asmia of the skin and improved and cured eczema ; and by the same means he has brought about distinct improvement in cases of chronic rheumatic affection of the joints, hands and feet. Acute exanthemata were first treated by chromo-therapy by Niels Finsen ) in July 1893. As long ago as 1832 Pieton*) observed that light had an unfavorable effect on the course of small-pox, and Piorry 7 ) came to the same conclusion in 1848. Communications to the same effect are frequent in medical liter- ature. Barlow s ) and Waters*) therefore excluded all light from their small-pox patients, and they found that this treatment resulted in the drying up of the pocks without suppu- ration or scars. Finsen noticed that persons recovered from small-pox have the deepest and most numerous scars on the face and hands, i. e., on those parts most exposed to light. Taking into account his own experiences and those of others, Finsen surmised that the so-called chemical rays, whose injurious effect on the skin had been proved, represent an etiological factor in the suppuration of the lesions. On this assumption he treated his small-pox patients, as Veiel had done before him in the case of eczema solare, with red light, i. e., he kept them in a room from which the chemical rays were excluded. This treatment, according 1 ) Erganzungsh. z. Arch. f. Derm. u. Syph., 1892, I, p. 187. 2 ) Monatsh. f. prakt. Derm., 1885, Vol. IV, p. 277. s ) Ibid. 1890, Vol. XI, Nos. 10 and 11. 4 ) 22. offentl. Vers. d. balneol. Gesellsch., Berlin, May 7-12, 1901. D ) L. c. 8 ) Arch. gen. de med., XXX, p. 406. T ) Traite de medecine pract, T. VII, p. 495. 8 ) The Lancet, 1871, p. 1. 9 ) Ibid. 1871, p. 151. PHOTOTHERAPY 457 to the reports of Lindholm, Swendsen, Feilberg, Strandgaard, Bencher t, Krohn, Mygind and others, 1 ) results in the total or partial suppression of suppuration and its concomitant fever, and the absence of scars. Such scars as are left are mostly only superficial, smooth, hyperasmic patches, which clear away later. There is no deep-spreading loss of substance, but at most shallow depressions. As severe ulcers of the skin are avoided there are for the most part no resultant serious general symptoms (Engel ~) ) . The results of this treatment in small-pox induced Chatin- iere, 3 ) Backmann*) and Th. Schiller 5 ) to try it recently in measles. Here, too, the treatment is said to have been most suc- cessful. The hyperpyrexia was lessened and the laryngeal and bronchial symptoms improved. In scarlet fever and erysipelas, too, according to E. Schouli, 6 ) Festner,') Schiller and Kruken- berg, s ) good results followed its adoption, the course of the illness being modified in duration and severity. The question here arises: Are we justified in calling this therapy chromo-therapy ? The name might suggest the thought that light of a certain colour has a healing action on these morbid processes. Such an assumption cannot, we think, be based on the data quoted in the preceding paragraphs. We have seen that it is not only the exclusion of the chemical light rays, that is, of one component of white light, which has good results (Feiel,Finsen) ; we know that darkness, that is the complete exclusion of light, may act in precisely the same way. This is proved both by the observations of Barlow and Waters, and by the fact that per- sons who have had small-pox are free from scars in the parts which have been covered up, i. e., kept in darkness during the 1 ) Quoted by Finsrn. 2 ) Therapie d. Gegenwart, iqoi, No. 3." ") La Presse medic, 1898, No. 75. *) Quoted by Bic, Mittheilungen aus Finsen's Lichtinst, IT, p. 150. s ) Ibid. •) Refer. Zeitschr. f. diat. u. phys. Th., Vol. Ill, p. 612. 7 ) Quoted by Bie, Bchandlung von Maseru u. Scharlach tnit Ausschl. d. sog. chem. Licbtstrablcn Mitth. a. Finsen's Lichtinst., II. p. [46. ") Munchen. med. Wochensclir., ryoi, April 1st. 458 RADIO-THERAPY illness. From this point of view we might regard Finsen's red- light treatment as a modification of Barlow's and Waters' dark- ness-treatment, a form of cure both easier to carry out and more pleasant for the patient. It would not be easy to keep a sick-room permanently and absolutely dark *) . But it does not follow that the red rays do not play a certain active part in this therapy. We have as yet made no study as to the action of these rays on morbid processes, and it does not seem improbable, when we remember the favourable influence of the allied heat rays, that they too should have beneficial action. This theory would be in accord with En gel's observa- tions; he tells us that the treatment of small-pox patients in a red room has no effect on the eruption in the mucous membrane of the upper air passage, i. e., on parts which are usually in darkness. Many observations point to the active part played by the less refrangible rays in the various physical phenomena. We know (Cf. p. 446) that on many substances they have a stronger chemical effect than the more refrangible rays. We have evidence, too, of a certain antagonism between the actions of these two classes of rays, of the neutralization, to some extent, by the red rays of certain effects of blue and violet rays. According to Eder, 2 ) Herschel, as long as 1830, 3 ) found that red rays have an opposite effect from blue ones on certain photographic papers. Fizeau and Foucault, 4 ) too, have described very precisely the so-called negative effect of certain light rays. Claudet ) in 1847 demonstrated that the red and yellow rays of the spectrum check the action of the others (especially blue rays on bromide, iodide, or chloride of silver), or reverse it, if it has already taken place. Later he found 6 ) that red and yellow light always have a negative or destructive effect on bromo-iodide or br.omo-chloride plates, but act on clean l ) In this sense we should have to look on the exclusion of light, which is insured by dressings, as a factor in the healing of wounds. "') Ausfiihrl. Handb. d. photogr., I, 1, p. 262. 3 ) Biblioth. Univ. de Geneve. New Series. Vol. XXIII, p. 185. 4 ) Compt. rend.. Vol. XXIII, p. 679. '') Philosoph. transact., 1847. Daguerreian Journ., 1851, Vol. I, p. 161. ') Philosoph. Magaz., Vol. XXXII, p. 199. PHOTOTHERAPY 459 iodide of silver plates sometimes negatively and sometimes the same way as blue. As regards the relative action of the single rays, according to Claudet, in order to reverse the action of white light that has acted for the time-unit 1, red light requires 50 units, orange 15, yellow 18. W aterhouse' s x ) investiga- tions showed that each part of the spectrum (from red up to violet) may neutralize a previous action of light on silver bromide. The importance for our present subject for this kind of action must not, it is evident from these instances, be disregarded. Yet further experiments with photographic preparations show that the opposed action of the red and the violet light is by no means proved, and that in fact the two ends of the spec- trum rather work in concert. The antagonism in the effect of red and violet rays on phos- phorescence is interesting and highly important as bearing on the present question ; we shall recur to it later on. Mental and nervous affections would seem to offer another field for chromo-therapy. Akopenko, 2 ) working in Bechterews laboratory, proved that the colour of the light unquestionably affects the duration of psychical processes, and that the various rays have, in this respect, various effects, according to their position in the spec- trum. The nearer we approach the heat rays of the spectrum the more invigorating and quickening become the effects of the colours. The mood of the person under observation is affected: in red light he feels brisk and cheerful, inclined to move and to act. Physical effects are produced; e. g., at the close of the sit- ting headache sometimes has disappeared. Yellow light has no special effect on the quickness of physical reaction and on the temperament, being in this respect like daylight. Rays of shorter wave-length have a depressing effect, so that, e. g., pro- longed stay in a room with green light, though at first pleasant, becomes later oppressive. Under the influence of green light ') Proceedings of the Royal Soc, London, XXIV, |>. 186. '-'» Quoted from Dworctzky's Refer. Zeitschr. f. diat. u. phys., Th., Vol. V, ,.. [6 460 RADIO-THERAPY psychical processes are retarded : mental quietude results, move- ment is checked, excitement allayed. This depressing effect is still greater in violet light. The mental attitude becomes mel- ancholy, dreamy; after some time headache is felt. The psychical processes are checked and become very slow, whilst the feeling of general depression becomes almost unbearable. The above coincides with Goethe's observations: He noted that red and yellow light was bracing, green and blue depressing. Baron Reichenbach's observa- tions were to the same effect. v. Jaksch, 1 ) too, emphasizes the soothing, soporific effect of blue light, and he consequently used blue lamp chimneys in his sick wards. On the other hand, G. Oleinikow 2 ) reports that patients seriously ill, when kept in the red room, suffered from delirium with frightful hallucinations, but these passed away at once on their being carried into a light room. According to Bine, Fere and Gilles de la Tourette, 3 ) red light strengthens the nerves. It was noticed in the photo- graphic plate factory of humlere Bros., in Lyons, that the work- men in the red rooms were singularly lively over their work, singing, arguing loudly, gesticulating vehemently. When the red panes were replaced by green they became much quieter. The author's own experience does not quite accord with this. He heard, on enquiry from many professional photographers, that they felt most depressed after spending any length of time in the dark room. Ponza 4 ) was the first to try the practical effect of chromo- therapy on mental disease. He noticed that persons affected with melancholia, after a short time (3 to 24 hours) in the red room, became cheerful and chatty and were ready to take food, whilst the blue room had a quieting effect on maniacs who had already required the straight-waistcoat. The editor of the Inventuo Medica, in Guatemala, is said to have observed the same 20 years before. J ) 20. Congr. f. innere Medicin, 1902. 2 ) Jeshenedelnik, 1900, No. 38. ') L'annee electr., 1901, p. 368. 4 ) Annates Medico-Psychologiques, 1876, Vol. XV, Ser. V. PHOTOTHERAPY 461 Up to now blue-diffused sunlight has been little used in photo-therapy. General Pleasanton claims to have effected complete cure in a case of contusion by thrice-repeated irradia- tion for half an hour 1 ). In many districts of the Bohmer- wald erysipelas is treated by packing the affected part with blue cloths and carefully keeping off white light. Probably the blue colour of the material that shuts off the light, though insisted on, is of no practical value. Concentrated Sunlight. $ 62. Concentrated sunlight is obtained by using convex lenses or concave mirrors. Long ago isolated cases of lupus were treated (by Thayer, Mehl and a layman mentioned by Otter- bcin,-)) by means of sunlight concentrated by a burning glass on the affected part, and good results were obtained. Suitable as this simple apparatus is for the intensifying of the light action proper, it has one failing which prevents its general prac- tical use in therapeutics; viz., with a simple convex lens not only the light, but also the heat rays, are gathered into focus, in which such a high temperature is generated that it is simply impossible to expose living mat- ter to it for any length ot time. In order to eliminate the heat rays Finsen availed himself of a method of filtering by means ot cold water; which had been often used by physicists, and Fic g3 _ (Concentrating apparatus also in physiological experiments for sunlight. — Finsen.) ') Chicago Times, quoted by Raum. : ) Quoted by Finsen. 462 RADIO-THERAPY (e. g., by Widmark) . His apparatus consists of a plano-convex hollow lens, 20 to 24 cm. in diameter, filled with cold water; this lens is mounted in a forked stand in such a manner that it can be moved in any direction on a vertical and horizontal axis, and can at the same time be raised and lowered (Fig- 93)- With this apparatus all the components of white sunlight are not" directed on the diseased spot, for the ultra-violet rays are much absorbed on their passage through the glass. The liquid used in the cold filter has also a great effect on the quality of the light passing through. Distilled water indeed absorbs very little, but the ultra-violet rays are sensibly weakened by the additions of methyl-blue or ammoniacal sulphate of copper which Finsen, who uses only the chemical rays, put in at first to filter away the less refrangible rays. If a blue filtering fluid of this kind (a solution of double sulphate of copper and ammonia), in a vessel (quartz) allowing the passage of ultra-violet, be intro- duced in front of the opening of the lattice spectroscope in the path of the light rays from the spark produced between electrodes of Eder alloy, and the spectrum be then photographed, the plate will show, when developed, that — with a layer of 5 per cent, solution of ammonia- copper sulphate, an opening of 0.1 mm. and an expos- ure of 3 minutes — the spectrum has been broken off at the air-line A = 3955. Thus a light filter of that kind, under these conditions, allows blue and violet light to pass, but practically no ultra-violet. The use of blue light filters has now been given up on account of their weakening of the light. Quartz, which, according to Stokes, lets more ultra-violet rays through than any other material, should really be used for this optical apparatus, in order to make it as pervious as possi- ble. (According to Hankel, St over, Eder and Valenta, ordi- nary glass absorbs very much ultra-violet, hard flint glass and all plumbiferous glass more than crown glass and baryta-flint.) But according to Finsen, glass does let through the relatively weak ultra-violet rays of sunlight, and in any case pieces of PHOTOTHERAPY 463 quartz of the required size would be hard to obtain, and appara- tus fitted up with quartz lenses would be very expensive. For the rest, the favourable results obtained by Finsen with his old apparatus (glass lens and blue light-filters) are proof that it is not so very important that the irradiation should be with pure ultra-violet rays. Ultra-violet rays of low intensity are absorbed by the surface layers of the skin, whilst if raised to higher intensity (e. g., by the Bang lamp) they soon produce violent inflammation. It would hence appear wiser in treating skin diseases (lupus) not to lay such great stress on the use of the rays of shortest wave-length, but rather to confine oneself to the rays of somewhat greater wave-length. The latter have more penetrating power (vide the blackening of photographic plates by sunlight that has passed through thick parts of the body) and at the same time they possess the desired chemical and therapeutic efficacy (cf. Finsen' s results) , though not to such an extreme extent as to injure healthy tissues before affecting the morbid growths. Concave mirrors serve to concentrate greater quantities of light than can be done with lenses. Strebel uses metal reflect- ors, 1 metre in diameter, with water-cooling arrangements in front of them. The method of treatment with concentrated light and its results in lupus vulgaris will be fully dealt with later, in con- nection with the arc-light treatment, which is based on the same principles. E. Nesnamow 1 ) made some interesting experi- ments with the cure of suppurating processes in the cornea by sunlight. He used a collecting lens similar to Finsen's. Five severe ulcers in the cornea were treated for 2 to 5 minutes daily with blue-violet sun- light, with excellent results. 6. Treatment with Artificial Sources of Eight. § 63. Sunlight is so little to be relied on that one is driven in l ) Westnik Ophthalmolnpii. igoi, Jan. and Feb. J cf. Dworetsky, Zeit- schr. f. diat. u. phys. Th., Vol. V, Part III. 464 RADIO-THERAPY photo-therapy to fall back mainly on artificial sources of light. Naturally the attempt is made to bring their intensity as nearly as possible up to that of sunlight, and to heighten as much as may be their illuminating power. Here we must distinguish clearly between the optical brightness of a light, which is a mat- ter of its physiological effect on the eye, and its chemical or pho- tographic illuminating power. Many a light which seems very bright to our eye has little or no effect on photographic plates and other light-sensitive preparations, whilst many pale-blue flames have considerable photo-chemical effect. The illuminat- ing power of the sun is 524 times that of magnesium, but it is only 5 times more powerful chemically. Burning magnesium has as powerful a chemical effect as the sun at io° altitude with no clouds about, i. e., if both light sources have the same appar- ent superficies. With the sun at 22. 4 , its chemical effect is 36 times that of magnesium (Bitnstn and Roscoe) . It is desirable for the various purposes of photo-therapy to have light-sources of considerable optical brightness and chemi- cal power. Most kinds of artificial light have very little brightness as compared with sunlight. There are, however, light sources which are extraordinarily powerful, chemically or photographically. Thus the light of burning magnesium is very rich in violet and ultra-violet rays {Schrotter, Bunsen, Roscoe) ; it is so powerfully actinic that in the fraction of a second 4 to 5 grammes of magnesium powder will develop chemical illuminating power equal to that of a million candles. In the same way there is very much violet and ultra-violet in both the electric arc-light and the light of sulphide of carbon burning in nitrous oxide gas (//. W. Vogel). These light sources are, as regards their chemical rays, superior to the Drumond lime light, which is very rich in yel- low and red rays {Becquerel) . The electric mercury light of the Way lamp 1 ) is very rich in blue, violet and ultra-violet rays, being more actinic than the electric light from carbon points (Monckhoven, Bullet, soc. franc., 1871, p. 210), but it gives hardly any red rays, differing ') In this a strong electric current is sent through a thin thread of free- falling mercury. PHOTOTHERAPY 465 from the light of the voltaic arc between carbon points; further, it is dangerous on account of the mercurial vapours given off. This light {Way's light) affects photographic bromide and iodide of silver plates almost as powerfully as sunlight, and decomposes iodine salts even more forcibly. The electric incandescent light from a carbon filament is yellower than the voltaic arc, and much less actinic. The light of burning zinc is rich in blue rays, but, as compared with magnesium, poor in violet. According to Eder, of all known artificial light sources, magnesium powder gives the most powerful chemical effect rela- tively with the shortest combustion 1 ) . Thanks to its richness in the more refrangible rays (blue, violet, ultra-violet), magnesium light is very actinic. Unfor- tunately, this light burns away with extraordinary rapidity, so that it is not possible to keep it continuously powerful, and, fur- ther, it gives off too much smoke to allow it to be used for a pro- longed period, as is for the most part necessary in photo- therapy. For this reason the electric arc and spark lights, which come next to magnesium light in chemical strength, are mainly employed for photo-therapeutic purposes. Of the other light sources, from which light is emitted by increasing heat- energy of the bodies, only the acetylene light in concentrated form has been so far used in photo-therapy. G. Colleville 2 ) reports that he has had good results with this in cases of slug- gish ulcers. The electric incandescent light is used successfully for all such methods of photo-therapeutic treatment as require mainly rays of greater wave-length. Treatment with Electric Incandescent Light. § 64. The electric incandescent light has a very similar spec- trum to that of petroleum ami gas incandescent light; it is poor in violet and blue rays and rich in yellow, red and green. Its chemical (photographic) efficacy is therefore slight, but this may, l ) Edcr's Ausfuhrl. Handb. d. Photogr., I. 1, pp. 455. 456, 457. *) Gaz. hebd. d. medec. Oct. 5, 1899 466 RADIO-THERAPY as well as its brightness, be materially increased by strengthen- ing the current, as is proved by the following table {Abney 1 )) : Number of Grove Illuminating Power Photographic Elements in Normal Candles Effect 12 0.132 immensurable 14 . 26 °-35 16 1. 17 1. 61 18 2-44 5-33 20 3-^4 12 .84 22 6.85 36-45 24 10.38 86.60 Increasing the strength of the electric current not only affects the optical brightness of the electric incandescent light, but also the amount of its blue and violet rays. Strong cur- rents, however, destroy the incandescent lamp very quickly. In general 380 incandescent lamps of normal power with- out reflectors have the same chemical effect as natural light at a distance of one metre from the object. When it is a question of producing intense chemical light rays (as in the treatment of lupus) the electric incandescent light is of little value, but it is exceedingly useful where longer-waved rays (heat rays, red light) are to be applied. The treatment with electric incandescent light is either gen- eral, in the shape of electric incandescent baths, 2 ) or local. The first apparatus for these baths was described by /. H. Kellog in 1894 3 ) and shown at the Chicago Exhibition. The first incandescent baths were introduced into Germany by the Chemist Gebhard; many improvements have since then been made in them. They are arranged sometimes for a sitting, sometimes for a recumbent position of the patient, but are always constructed on the same principle. Sometimes they have arrangements attached by means of which the arc-light and incandescent light can be brought to bear on the patient at once. ') From Eden's Ausfiihrl. Handb. d. Photogr., I, 1, p. 463. 2 ) For arc-light baths, cf. p. 383. 3 ) American Electrotherapeutic Association, Sept., 1894 PHOTOTHERAPY 467 Modern incandescent baths are made for connection with the street electric wires. They consist of octagonal boxes, sup- plied with panes of mirrors, opalescent glass plates, etc., and lifted with a door, fastening on the inside and outside, for the entrance of the patient, and with a movable lid above with a hole for the patient's neck. Along the inner walls 40 to 60 incan- descent lamps, each of 16 normal candle power, are arranged; these lamps can be put in or withdrawn from without, and if necessary from within, by means of several switches (in Ricdcrs apparatus arranged on one switch-board) in series, along ver- tical, horizontal or spiral lines. The lamps are protected by lattice work. A thermometer for measuring the inside temper- ature is fixed on the wall. Recently, too, a window has been put in the wall of the chamber, through which the pulse and the course of the perspiration may be observed. By means of other openings with roll-shutters light may be admitted from an arc- light reflector. It is as well to have an electric bell fixed inside the chamber. The patient is seated naked on a stool in the light box; light from without is completely shut off by a towel round the neck opening. A cold bandage, or ice-cap, is applied to the head. The temperature of a light-bath should not begin with more than no° to 122 F. ; only after the way the patient reacts has been carefully noted may the temperature be raised to 156 to 167 . The bath should last in all 25 to 30 minutes. It depends on the special case whether the box should be heated beforehand or not. Tn the case of an otherwise strong, healthy person, where powerful light-action (e. g., in producing perspiration) is desired, he may be put into a previously heated chamber. The sudden stimulus of the high temperature in such a case has great effect (similar to the stimulus of the switching on and off of the electric currents). But with weakly, ailing persons this plan must not be adopted; the air in the chamber must be heated gradually after the patient is in the hath. The temperature can be raised by adding to the number of lamps and increasing the strength of the current. During the bath the pulse of the patient must be constantly observed 468 RADIO-THERAPY and care must be taken for the admission of fresh air. After the light-bath follows a bath, douche, or wet pack. These baths should not be taken daily, but twice, or at most, three times a week. The action of the incandescent bath is mainly that of radi- ating heat. We are able by these means to apply heat to the deeper tissues; we have seen (p. 436) that the heat rays easily penetrate even bones {Moeller), and this it is which constitutes the value of this treatment. The conducted heat from water, vapour, Russian, Turkish, Irish baths, etc., confines its action to the surface of the body. Yet the light rays may perhaps, side by side with this action of radiant heat, have certain other effects. The light of these incandescent lamps is indeed poor in so-called chemical rays, and consists mainly of red, yellow and green rays. But, as has repeatedly been mentioned above, it is not impossible that red and yellow rays, too, may have certain biological and therapeu- tic effects. The most striking effect of this treatment is its action on the secretion of sweat. Whether this is produced by stimula- tion of the peripheral nerve-endings or by the raising of the patient's temperature by the radiant heat (Strebel) we cannot decide. In any case the accumulation of heat in the body is obviated through the profuse perspiration. Kellog *) observed that the amount of sweat excreted in the electric incandescent bath was twice as much for the same time as in the Turkish bath, whilst the average temperature in the electric light-bath was 8i° F., and in the Turkish bath 140 to 148 F. Generally, if all (50) the lamps of the apparatus are lighted, perspiration begins after 6 to 10 minutes at about 95 F. If the temperature in the chamber is raised to I40°-I58°, sweat to the amount of a litre and more may be excreted in a short time (a quarter to half an hour). Below and Anfrecht note the very interesting fact that in the perspiration of persons who years before had been treated by mercurial inunction traces of mercury were found. Katten- *) Fortschr. d. Hydrotherapie, Festschr., Wien, Leipzig, 1897. PHO TO THERAPY 469 bracker found 0.26 per cent, of sulphur in the sweat of a glass-blower. Further effects of incandescent light-bath on the circulation, respiration, metabolism and weight have been observed. It has been asserted that the action of the heart is unchanged or little affected in the incandescent light chamber. Facts do not bear this out. M. Roth ^observed that a pulse which had before the light- bath been steady at 72 beats, became rapidly quicker after 10 minutes in the chamber, giving 84 beats; after 15 minutes, 104; after 20 minutes, 132. At first it remained fairly steady, but later it grew thin, galloping and irregular. On the whole we may take it that with the temperature in the light-chamber at about 122 F. the pulse is quicker each minute by about 15 to 20 beats. Strasser 2 ) and Strebel 3 ) report to the same effect. These changes in the pulse, however, are often no longer so marked in succeeding baths. Increased blood-pressure, with its conse- quences (congestion, bleeding at the nose, etc.), has been observed as one of the immediate results of this treatment. In most cases, however, after copious perspiration, when the patient has stayed 20 to 25 minutes in the bath, the blood- pressure subsides again. Wintermtz 4 ) noticed in the case of anaemic persons an increase of haemoglobin and erythroctes after each light-bath. Respiration is powerfully affected by the bath. - The breath- ing- often becomes twice as rapid after a short stay (a quarter of an hour) in the chamber, and at the same time more shallow and superficial. The temperature of the patient is raised a little by about 2° F. Kellog found in the case of three persons under obser- vation, who had previously exhaled on the average 3.60 per cent, of carbonic acid in ten minutes, that the amount given off was by the incandescent bath increased in 5 minutes to 4.10 ') Wr. med. Wochenschr., 1899, No. [9. 2 ) Encyclop. Jahrb., [900. a ) L. c. , *) Blatter f. klin. Hydroth. X. Jahr., 1000, TT. 6, p. 144. 47 o RADIO-THERAPY per cent., in 20 minutes to 4.20 per cent., and in 30 minutes, 5.13 per cent. Light-baths seem, according to Roth's investigations on the urine and perspiration, to have no specially marked influence on organic decay in the body. But we may assume that the higher body temperature observable after every light-bath furthers the combustion of fat. The body-weight shows after each bath a more or less marked decrease, according to the amount of perspiration. If the patient satisfies the violent thirst usually but not always felt by drinking freely, the loss in weight is very soon made up; if, however, he has suitable diet, a comparatively short time suf- fices to bring down his weight considerably. Occasionally the light-bath brings on nervous symptoms, such as palpitation of the heart, difficulty in breathing, excitabil- ity or languor. After an ordinary light-bath the skin shows signs of simple though marked hyperemia. With the ordinary type of bath, if its temperature be not raised so as to scorch the skin, the hyperemia disappears very quickly (like all hyperemia brought about by radiant heat), without leaving behind any erythema or pigmentation. All we know as to the action of electric incandescent light- baths points to their use /';/ all our cases where copious perspira- tion is desired, with the least possible strain on the heart. The light-bath -is distinguished as a convenient and efficient source of heat by the fact that its temperature can be exactly regulated. It may safely be raised far higher than is possible in vapour, Turkish, Russian and Irish baths, because most patients, under like conditions, perspire sooner and at a lower temperature in the light-bath than in other baths, and have further only the body and not the head exposed to the heat. Further investiga- tions are necessary before we can determine how far we should take account of the deep-seated action of the penetrating long-waved light rays (red and yellow). Ordinary incan- descent light-baths, then, are suitable in cases of faulty assimila- tion (obesity, diabetes, gout), rheumatic affections of joints and muscles, nerve complaints (sciatica, neuralgia, neurasthenia, PHOTOTHERAPY 471 hysteria), anaemia and chlorosis, chronic poisoning (metallic poisoning, syphilis), chronic exudation and effusions, bronchial asthma and bronchitis, dropsy, ascitis and oedema after nephri- tis, hypertrophic and fatty heart, eye complaints (keratitis par- enchymatosa, iridocyclitis, choroiditis), and as a tonic and pro- phylactic against disease. According to Strcisser, 1 ) this treatment is especially suited to the hydraemic forms of corpulency, particularly the anaemic, pasty-looking type found in young people. For plethoric cor- pulent patients he prefers packs. According to Strebel, the tem- perature of the light-bath should never exceed 113 F. for this class of patients. Incandescent light-baths are usually regarded as not in them- selves sufficient treatment for diseases due to faulty assimilation. In combination with suitable diet and medicine they give, how- ever, effective help in cases where, owing to heart complications, other methods of inducing perspiration cannot be resorted to. For instance, they are said to be very efficacious in gouty com- plaints in the joints, arterio-sclerosis, etc. They are, however, not always advisable in all such cases; as Strebel remarks with truth, in gouty complaints a thorough transfusion of the tissues with fluid is desirable, and this wholesale process is checked by the great loss of water through perspiration. Strebel,-) there- fore, does not use baths producing perspiration in such cases, but much prefers protracted sun-baths or arc-light baths, in which light rays and not only heat rays come into play. The same holds good with rheumatic affections of the joints. In muscular rheumatism, however (lumbago, torticollis, etc.), incandescent light-baths are excellent. For the various forms of anaemia, incandescent light-baths are probably relatively less effective than sun-baths. The chemical rays in the latter cause lasting hyperemia and pigmen- tation, and thereby a removal oi blood corpuscles from their ordinary course, thus stimulating the system to replace the blood substance and simultaneously to carry on more vigorously the metabolic processes (Lowenthal, Strebel). We cannot here ') Blatter f. klin. Hydrother., rgoo, Nfos. 4, 5. 1> 94- -') I), in che Medicin. Zeitung, tgoi, Nos. 6-8. 472 RADIO-THERAPY enter into the question of whether the action of light here is helped by the stimulus to the marrow given by the red sun rays penetrating the bone {Strebel). Incandescent light-baths, producing only temporary hyper- emia of the skin and thereby only temporary depletion of the internal organs, are of less value in these cases where the latter effect is chiefly aimed at, as in cases of congestion of the internal organs or in the venasportas, difficulty of breathing, valvular heart disease, angina pectoris, etc. In all these cases sun-baths or arc-light baths are more suitable. On the other hand, in dropsy, caused by heart or kidney disease, incandescent light- baths are a great advance on all previous treatment; they do not, however, much affect the cause of the trouble. Writers are much divided as to the value of these baths in functional diseases of the nerves. Whilst, for instance, some cannot speak too strongly of their good effects in, e. g., neuras- thenia, their soothing influence on general irritability, sleepless- ness, singing in the ears, oppression and palpitation of the heart {Colombo, 1 ) ) others {Strebel) regard a patient suffering from neurasthenia as not a favourable subject for this treatment. It seems to be much the same with the incandescent light- bath treatment of these nervous conditions as with all the other methods of cure tried for them. One patient is benefited, another is not; much depends on the amount of confidence in the treatment possessed by the patient himself. Sometimes incandescent light-baths relieve or remove neu- ralgia and migraine {Strebel, Freund) , but by no means always; many cases are quite refractory to the method. It has been held by many 2 ) that these baths have a specific influence on tuberculosis, scrofula and other infectious diseases; here bactericidal action of light being assumed. As we have more than once stated, such an assumption is quite mistaken, for it is well known that incandescent lamps give out very few of the chemically active rays, which are more bac- tericidal in their action than other light rays, and such chemical 2 ) Revue de Therapie physique, 1901. 2 ) Ruhemann, Apery, Kattenbracker, Candler, Minin, Cleaves, Below, and others, quoted by Boeder. PHOTOTHERAPY 473 rays as are completely absorbed on their passage through the glass walls of the lamp and the tissues of the body. Obviously then, assuming the light source to be sufficiently rich in actinic rays and sufficiently powerful, we can only consider its bacteri- cidal action as having a very superficial effect. It may be urged that in the treatment of infectious diseases it is not the actinic rays which matter, but more penetrating long- waved yellow, red and heat rays. Experiments with bacteria cultures show that these rays have no specially pronounced bac- tericidal properties. These experiments, it is said again, need not be regarded as conclusive; for the rays, by penetrating the body, set up hyperemia in the infected organs, which acts as a curative. There is certainly something to be said for this theory, main- tained by Strebel amongst others. As a matter of fact, various observers have reported a favourable action of light on infected animals {Kondratiew, De Renzi, Kutschuk, Aufrecht 1 )) . Yet Boeder's-) experiments show no specific, and specially no specifically bactericidal effect of light rays on infected animals. Drigalsky 8 ) even observed that mice inoculated with splenic fever or other bacteria died more quickly in the light- bath than control-animals, even though they were kept only a short time in the bath. He holds that the very copious perspi- ration brought on by the heat rays weakens the resisting pow- ers of the body, and calls attention to the danger to many feeble patients, e. g., tuberculous persons, from such haphazard treatment. The whole question calls for more detailed investigation, but so far as our present knowledge goes, we may say that any favourable effect of light treatment on infective diseases of the internal organs must be explained by its indirect action in stim- ulating metabolism and the action of the heart, and in increasing phagocytosis and perspiration, etc. Incandescent light-baths are unsuitable in cases of extreme *) Quoted by Boeder. 2 ) Arl). aus dem Kaiserl. Gesundheitsamte, 1900. 3 ) Centralbl. f. Bakteriologie, Vol. XXV, II, Nos. 22, 23. 474 RADIO-THERAPY weakness and arteriosclerosis, for patients with organic heart disease and marked congestive symptoms, in phthisis with night sweats, in hemorrhagic cases (hemoptysis, haematemesis, apo- plexy), and in all cases where no perspiration results from the earlier baths (Rieder, Strebel). Partial light-baths are a convenient modification of the gen- eral incandescent light-bath. For them smaller boxes are used, with reflecting surfaces and incandescent lamps fixed to the sides, and with suitable openings for the insertion of a limb; or else one or more lamps are used, provided with a reflector (Trouve, Foveau de Coiirmelles, Laquer) . The apparatus (similar in principle to the above) which the author himself uses for partial light-baths 1 ) (treatment with radiant heat) consists of two incandescent lamps of ioo N. can- dle-power, each with its own cut-out switch, which are fixed in a parabolic metal reflector. The conducting wires are carried to a rheostat, the lever of which can be so adjusted as to regulate the brightness of the lamps. On its open side the reflector has slots for coloured glass filters or blinds. This apparatus may be either fixed to a stand, or it may be attached to other apparatus. In treating the extremities a drum-shaped box is used, an open- ing being cut out in its casing corresponding to the exact size of the reflector, which can be fitted in. The drum with its reflec- tor is placed on two supports and fixed with straps; in this posi- tion it can be turned so that the rays fall in turn on all parts of the limb under treatment. Asbestos netting is stretched inside the drum at some distance from the reflector to prevent the exposed limb from coming too near the lamps. Another apparatus for treating the trunk or single parts of it consists of a trough-shaped framework covered with thick heat-retaining material. Curtains of the same material with tapes cover the two ends. The trough has a rectangular open- ing at the top into which the reflector fits. Below this opening, but attached to two rollers on the outside of the trough, is a thick, close curtain of asbestos, consisting of two nets, one coarse and the other fine-meshed, put one above the other. By draw- 1 ) This was made by L. Schulmeister, Vienna, IX. PHOTOTHERAPY 475 ing the one or the other part of the curtain by means or the rollers the irradiation may be varied in strength. Both these apparatus are fitted with thermometers. The action of such partial light-baths is precisely similar to that ot the general incandescent light-baths, but in some respects the former are much superior. They are useful for the treatment of bed-ridden patients who cannot be moved to the larger bath. Then they are more suitable for many cases, because a far higher temperature can safely be used with them. A tempera- ture of* over 122° F. is unpleasant in the general bath, but with these apparatus, especially at a second and a third bath, temper- atures of 2 12° F. and more are borne without inconvenience. When parts only of the body are exposed to the rays, perspira- tion does not result except at a high temperature (from 194 F. to 221 F. ), but it is then usually very profuse. It is interesting to note that irradiation of the extremities raises the temperature of the whole body. The writer has made repeated observations on this point with patients under treatment for the joints of the hands and feet. Half or three- quarters of an hour after the treatment had begun, when the temperature inside the apparatus was about 176 F., the patients reported themselves as getting comfortably warm over the whole body. At the same time the face became a little flushed, and the temperature, on being again carefully taken, showed a rise of from 3 to io° F. The pulse showed on the whole no change; being rarely slightly accelerated. The respiration, too, was unaltered. The rising temperature may be explained by: 1, Heating of the body by heat passing from the apparatus into the tissues; 2, higher temperature of the limb, carried over the whole body by the heated blood; 3, sympathetic rise in temperature, through the nervous system. Considering the comparatively rapid rise in temperature and the size of the parts under treatment, together with their slight heat-conducting power, we may proba- bly disregard the first explanation. Which of the other two is the more effective we can hardly for the present determine; pos- sibly each has an equal share in the result. The method of this treatment is as follows: If a powerful 476 RADIO-THERAPY stimulus is to be administered to the affected limb, it is put into an apparatus heated beforehand to about 122 F. ; if, however, a longer irradiation be desired, the current is only turned on after the apparatus is applied to the patient. Various methods may be adopted to make prolonged application of the treatment bearable. The current may be weakened by means of the rheostat when the irradiation becomes unpleasant; or one or both lamps may be switched off for a longer or shorter time; or radiant heat is dispensed with altogether for a time and only the thermometric heat of the box utilised (this is done by simply placing a dry linen compress on that part where the heat is felt unpleasantly, to keep off the direct rays). By these means the treatment may be variously modified. As soon as the desired result, e. g., perspiration, is attained, treatment is suspended, the part is thoroughly rubbed down, and either active, passive and resistance movements or massage applied. One should not leave the affected limb in the apparatus after the heat has been turned off and allow it to cool down gradually. The author's experience has proved this procedure to be most harmful to the effect of the treatment. For the treatment of superficial skin affections, neuralgia, myalgia, etc., we use the simple radiant apparatus with or with- out coloured filters. We may take the appearance of marked hyperemia of the skin and possibly slight perspiration as indica- tions for suspending the treatment. The symptoms indicated for this treatment are precisely the same as those for the general incandescent light-baths. This method, however, may be said to be more universal in its appli- cation, inasmuch as it taxes the heart to a much less degree. We have attained excellent results with this method when sys- tematically carried out, both in relieving painful affections of the joints and muscles, and in quickening the re-absorption of serous exudations and effusions into the joints, and in the case of dropsical accumulations. Rheumatic pains are usually immediately relieved. Patients who could hardly stand before the treatment are able to walk without pain after it. But the effect is not lasting; the pains are felt again after one to three hours, and a complete cure is only effected when the treatment PHOTOTHERAPY 477 has been prolonged and combined with suitable medicinal and mechano-therapeutic measures. It is doubtful whether radiant heat can do much for neural- gia. Patients indeed, in many cases of trigennial neuralgia, sciatica, etc., professed that they felt relief, especially at times from treatment with rays filtered through blue glass. But in the case of other and unhappily of most patients, their suffering was not in the least alleviated by the treatment, and one cannot help thinking that in the successful cases something was due to the effect of suggestion. On the other hand, it appears that irradiation by powerful incandescent lamps has a strikingly good effect on superficial inflammation and suppuration. The author treated at times with the unfiltered light of an incandescent light apparatus, at other times using a red glass filter (spectroscopically examined) , several long-standing cases of acne vulgaris, 2 cases of ulcerat- ing Roentgen-dermatitis, which Prof. Ehrmann had passed over to him, 1 ) an ulcerating lupus, and a scrofulous abscess which had been left on the neck after ulceration of the lymphatic glands, and a syphilitic ulcer. The disease was checked or les- sened in all these cases except the last-named, which was untouched, and the scrofuloderma, which had finally to be treated surgically in spite of improvement at first, because of the ulceration of the neighbouring gland. In the other cases, the inflammatory induration round the acne nodules was les- sened, fewer pustules were formed, and the suppuration dimin- ished in the small abscesses, whilst healthy granulation and surface-healing were visibly furthered. The irradiation lasted each time at least half an hour, with the diseased part as close as possible to the light source. In these cases, of course, no other treatment was adopted, the sore places being simply dressed with vaseline after each sitting. It has been already observed that we are still waiting for a complete explanation of the good results of this treatment. The character of the light source being what it is, we cannot look to any action of chemical rays; we can only take into *) Ges. d. \< T/t< in Wien, Feb. 21st, 1902 478 RADIO-THERAPY account the rays of greater wave-length, which are produced fairly abundantly, and their power of penetrating the deeper layers of the skin. In this respect, remembering the well- known good effect of high temperatures on ulcerating processes we may probably assume that the heat rays are beneficial in this way; it may also be that the irritation of the deep-penetrating long-waved rays may stimulate healing and the formation of connective and scar-tissues, just as chemical irritants do when applied to sluggish ulcers 1 ) for the stimulation of granulation- tissue formation. The effect may perhaps be made more intense by substitut- ing for the ordinary incandescent lamps the Aner osmium lamps, which have a stronger illuminating power. The literature on this subject, especially the Rus- sian, describes a number of results which, even allowing for the enthusiasm of some of the writers, testify to the value of local treatment with electric incandescent light. Thus v. Stein,-) Gatschkowsky , 3 ) Mining) Makaive- jew, 5 ) Kessler, G ) Turner, 1 ) Upensky*) and others (all quoted by Dworelzky, ) ) speak of its good effect in cer- tain painful affections (lumbago, rheumatism, cephal- gia, odontalgia, pleurisy, pains in the chest after influenza, etc.). This treatment was valuable also in the case of exudations (rheumatism, pleurisy, peritonitis, gonorrhoeal inflammations) and in subcutaneous, sub- periosteal and retinal effusions of blood ( Tichomt- 1 ) Even in Finscn's arc-light treatment, in which recently no blue filters have been used, a curative action of the long-wave rays may be possible under certain circumstances. This is not especially the case when the compressing apparatus is not used ; the blood not being removed by pressure, the actinic short-waved rays are considerably checked in their passage into the tissues, while the long-waved rays pass through comparatively freely. ') Medizinskoje Obosrenie, 1890, Vol. XXXIII, p. 1156. 3 ) Russkaja Medizina, 1892. 4 ) Wratsch, 1899, Nos. 22, 38, 47; 1900, Nos. 11, 27. G ) Ibid. 1900, No. 8. °) Ibid. 1900, No. 14. 7 ) Ibid. 1900, No. 36. 8 ) Russky Mediz. Westnik, 1900, No. 19. ,J ) Zeitschr. f. diat. und phys. Therapie, Vol. V, p. 3. PHOTOTHERAPY 479 rozv 1 ) and as a healing factor in skin affections (ulcerations, eczema, lupus, lepra) and in venereal and syphilitic affections. Minin, Turner and others claim to have cured by irradiation from incandescent lamps (16 to <;o candle- power) not only local tuberculosis of the bone, but even general symptoms of tuberculosis (e. g., night sweats, etc.), tabes, scurvy, sickness. Kaiser,-) too, reported similar results. Possibly, however, one may be allowed a little scepticism as to these marvellous results, seeing that they are reported as being obtained with treatment for 10 to 15 minutes at a time, repeated every 2 to 3 days, one lamp only being used. The Electric A re-Light. § 65. The construction of arc-lamps is based on Davy's dis- covery, in 1 82 1, of the galvanic arc-light. If the pole of a pow- erful galvanic battery or a dynamo be connected with two car- bon rods, a current will be established at once on their contact. If now they are drawn apart to a distance of several millimetres from each other the current will not be broken, but a luminous arc will be formed between the carbon points, along which the current passes. At the same time, in consequence of the heat developed, the carbon points will become highly incandescent, hence their use for purposes of illumination. The arc of light is composed of gaseous carbon and of the vapours of metals retained in the carbon, as the spectrum of the arc shows. In lamps with alternating currents the carbons are consumed equally, and hence are approximately equal in brilliancy, giving off, therefore, a nearly equal amount of light on both sides (see Fig. 94) where the length of the radii bounded by the curved lines corresponds with the strength of light radiated in the given directions. In lamps with a continuous current the positive carbon glows more intensely than the negative car- ') Wratsch, 1900, No. 11. 2 ) K. k. Gescllschaft d. Aerate in Wien, Feb. 7. 1902. 48o RADIO-THERAPY bons, being consumed about twice as fast (for the resulting light radiation (see Fig. 95). The carbon rods in lamps used for lighting purposes must be kept at a constant distance from each other whilst the lamp is burning, in order that the light Fig. 94. Fig. 95. point may be kept at the same spot. Generally the carbon points, as they gradually burn away, are adjusted by automatic regulators. In electric arc-lamps the regulators are almost always worked by the magnetic action set up by the cur- rent of the lamp itself. Electric arc-lamps are known as main-current, shunt-wound and differential arc lamps, according to the winding of the coil in the regulator. Lamps with hand regulators are sometimes used in photo- therapy. The light-point is further maintained in an unchanged position by taking the rate of combustion of each of the carbon rods into account when selecting their size. For a con- tinuous current cored carbons are usually taken as the upper or positive ones, homogeneous carbons for the lower or negative ones. As the positive carbon is consumed about twice as quickly as the negative, if both carbons are to burn for the same time, the positive carbon must either be longer or, as is usual, of greater diameter. With an alternating current cored carbons are used both above and below, as they burn away nearly at the same rate. On the whole, thinner rods burn more steadily and give better light than thicker ones, but the latter are often chosen, and are used as thick as possible because of the longer time they last. The brightness of the electric light, of course, depends con- siderably on the strength of the current. The following table PHOTOTHERAPY 481 (after S. v. Gaisberg 1 ) ) gives the average illuminating power furnished by open lamps burning without open shades, with currents of different strength and suitable voltage. The table gives further the approximate right diameter of the carbon rods (for rods measuring together 400 to 500 mm., in length) if they are to burn fairly evenly. Continuous Current Alternating Current rength of 11 r rent el > Cored Homogeneous Carbons Average Illuminating Power thrown down - be > Lamps with Reflector, Cored Carbons Average Illuminating Power thrown down 55 u A hove Below Above Below Amp. Volt Mm. Mm. Hefner Candles Vc.lt Mm. Mm. Hefner Candles . 2 3 4 6 8 10 12 15 20 25 33 39 40 40 40 4i 42 -4 3 44 44 9 11 12 14 16 18 20 21 23 25 7 8 9 10 11 12 14 15 16 17 80 140 2IO 3/0 550 77" 1,000 1,400 2,050 2,8oo 28 29 29 30 30 31 32 32 7 8 9 10 1 1 13 15 16 *8 9 10 12 13 15 17 19 90 170 280 430 580 820 1 , 200 I,6oo The voltage given in the above table is deviated from in certain kinds of lamps for which a different material is taken for the carbon rods and a smaller light arc. Graetz assumes for his average that an arc-lamp with con- tinuous current gives light of about 100 normal candle-power for each ampere consumed. I^ilaz gives the following table") for various strength of current. (See next page.) The voltage necessary for establishing the arc is dependent, with both continuous and alternating current, on the length of the arc, the kind of carbon used, the strength of the current and (with alternating current only) the form of the curve. For con- tinuous current, with current strength of 6 to 14 amperes and ') Taschenbuch fur Monteure elektrischer Beleuchtungsanlagen, Miinchen, Leipzig. [901, p. 102. R. Ruhlmann, Grundziige der Gleichstromtecknik, Leipzig, 1901, p. 59- 482 RADIO-THERAPY Strength of Current in Amperes Average Spherical Strength of Light in Decimal Candles Consumption of Watts for an Average Spherical Decimal Candle 4 302 0.66 6 470 0. 64 8 650 . 62 IO 840 . 60 12 1,042 0.58 14 1,255 0.56 16 i,477 °-54 20 1,960 0.51 3° 3,36o °-45 length of arc, 2 to 4 mm. (the more usual numbers), the ter- minal voltage would be 40 to 50 volts l ) . The illuminating power of the lamp depends, the strength of current remaining the same, in large measure on the length of the light arc. If the distance between the carbon points is too great the light flickers, becomes unsteady, and often goes out with a loud noise. The length of arc must always be pro- portional to the strength of the current, the number of amperes which pass through the lamp. Gractz puts the right length of arc for lamps supplied with 5 to 6 amperes current at 1 to 2 mm., for 8 to 10 amperes at 3 mm., and for powerful lamps with 20 or more amperes strength at 4 to 5 mm. The arc-light may be examined through smoked glass, or super- imposed red and green glass. As is evident from Fig. 95, with a continuous current lamp the measurable strength of light varies very considerably according to the direction in which the light falls on the eye or the photometre. The greatest illuminating power is radiated at an angle of 40 to 6o° below the horizontal. In H. W . Vo gel's -) experiments with a Siemens' lamp, at a nearly horizontal position (i°, with a current of 8^4 to \) /. Herzog and C. P. Feldmann, Handh. d. elektr. Bclcuchtung. Berlin and Munchen, 1898. p. 17. 2 ) Das Licht im Dienste dcr Photographic, Berlin, 1894, p. 123. PHOTOTHERAPY 483 9 amperes and the use of nearly 1 horse-power), the light was 394 amyl candle-power; at 25^° below the horizontal $y 2 to 8^ amperes gave 1043.74 candle-power. Thus, if the illuminating power of an electric lamp of a certain strength of current be given, it is necessary to indicate also the direction of the radiation. Lamps with alternating current give approximately the same amount of light above and below. A reflector is usually placed immediately above the arc to utilise the light radiated upwards, and in this case the brightness of the alternating lamp is equal to that of a lamp with continuous current; as regards the actinic rays, however, there is considerable difference between the two lamps. Alternating lamps are seldom used with a less than 4 amperes current, because of their slight illuminating power. The brightness of the different parts of the spectrum varies quantitatively (cf. scale on p. 450) in the electric arc-light as in sunlight. This scale shows that the blue rays preponderate greatly over the red and yellow ones in electric light. Abney r ) showed that as the rotary movement of the dynamo-electric machine 2 ) increased in speed, not only does the light as a whole become brighter, but the intensity of the more highly refrangible rays is increased disproportionately to that of the less refrangible rays. This has been confirmed recently by Absolon Larsen's reports :; ) . After direct sunlight and magnesium light, no light is so effective chemically as an electric arc-light. The light of power- ful arc-lamps acts on photographic bromide or iodide of silver plates almost as powerfully as sunlight, and decomposes iodine salts even more energetically 4 ). The following figures of ') Eder's ausfiihrliches Handbuch, I. 1, p. 466. 2 ) On which the strength of current or electro-motor power depends— cf. p. <)<). ; ) Mittheilungen aus Finsen's med. Lichtinstitut, II, rgoi, p. ti8. '1 v. Leeds, Chem, News, \> I \i.li. p. 147. - Eder's Ilaiidlnich, Vol, I. p. 369. 484 RADIO-THERAPY Eder's 1 ) give its strength chemically as compared with that of sunlight. Photographs of drawings, taken for purposes of comparison, were exposed: 6 minutes in electric arc-light of 1,800 candle- power at a distance of half a metre, a white reflector being used; 2]/ 2 minutes in diffused daylight; 40 seconds in direct sunlight. Prof. Vogel gives another table with reference to the photo- graphing of paintings. He arranges the different kinds of light, as regards their efficiency for photographic purposes, as follows : 1. Sunlight is 8 to 14 times more powerful than diffused daylight with a clear sky; 2. Electric arc-light (6 lamps of 7,000 candle-power altogether, distance i l / 2 metres, with white reflector) is 4 times as powerful as daylight in November with a clear sky; 3. Then comes clear sky with white clouds; 4. Blue sky; 5. Dull sky (light often only one-tenth as powerful as white, cloudless sky) . We need hardly point out how fundamentally important for the various forms of phototherapy are these thorough photo- metric investigations of Eder, Vogel, and others. Starting from the assumption that the curative results of arc-light treatment are due mainly to the chemical, and par- ticularly to the ultra-violet, rays, attempts have recently been made to construct sources of light which should produce these rays in special abundance. This end was attained by taking as electrode-material, instead of carbon, metals and substances not readily fusible (lime, silicic acid, zircon, thorium, magnesium compounds). Finsen hollowed out the positive electrode and filled it with a mixture of graphite and calcined lime. Strebel, too, at the Dermatological Congress in Breslau in 1901, 2 ) showed useful apparatus for photo-therapeutic purposes. Great a ) Photogr. Mitth., Vol. XX, p. 39, quoted from Eder's Handbuch, p. 465. 2 ) According to Drossbach, Secchi used iron electrode arc-lamps as long ago as 1873. PHOTOTHERAPY 485 difficulty was found at first in using pure metals for electrodes, because the metal at the ends of the electrodes is apt to melt and drip, forming a sort of bridge between the electrodes and extinguishing the light. This difficulty was met by Soplnis Bang's iron-electrode lamp with water-cooling arrangement, 1 ) invented in 1901 (Fig. 96). This lamp is very handy and cheap, and requires only a weak j? £ current to produce a noticeable chemical effect. The principle t of its arrangement is that the conducting wires H H are car- ried to two electrode holders F F, fastened to the springs K K ; changeable thimble-shaped iron electrodes E E are screwed on to FF. The electrodes are hollow, and connected by thin -^Ty pipes G, running along the in- side of the tube that serves as handle, with the water appa- ratus. The lamp is lighted by pressing the button A to let the electrodes touch and then re- leasing the button at once. It is blown out like any ordinary lamp. By the screw R the dis- tance between the electrodes can be altered and the voltage kept sufficiently constant. I f the lamp burns with 8 amperes and 40 volts an iron electrode lasts on FlG - 96.— Iron-electrode lamp, by Dr. , c -1 S. Bang. (From Zeitschr., etc. 1 ) the average four to six hours. The lamp is provided with one of Finsen's quartz compression apparatus; this is fixed on the tube A B C D m such a way as to be easily removable, either for cleaning or for being exchanged ') According to Bang, 1/ . Siemens as far back as 1879 used metal electrodes cooled by water for arc-lamps. 486 RADIO-THERAPY for pressure apparatus of different shape and size. When using this apparatus, one has to bear in mind that if the water-cooling apparatus is not effective little drops of molten iron may form on the electrodes. These drops must be removed with a little Fig. 97. — Iron arc-lamp, by Rcinigcr, etc. wooden stick or they may fall down and damage the compressor or hurt the patient. The Kjeldsen arc-lamp "Dermo" is con- structed on the same lines. Andre and Broca, Chatin, too, use arc-lamps having a carbon with metal "core" for positive elec- trode. Reiniger, Gebbert cjf SchalVs iron arc-lamps (Figs. 97 and 98) have a convenient improvement on the Bang lamp. In aw Fig. 98. — Iron arc-lamp by Rcinigcr, Gcbbcrt & Schall. arrangement similar to Bang's, two light arcs are used, put one behind the other. This not only increases greatly the illumi- nating power of the apparatus but also works the lamp much more economically, for almost the entire energy of the total PHOTOTHERAPY 487 voltage of 1 10 volts is converted into two light arcs of 45 volts each, whilst in lamps with only one arc of 45 volts more than half the energy used is expended to. no purpose in overcoming resistance. The greater intensity of the light enables one to diminish the duration of the sitting. E. Rasch a ) lately described an arc-lamp in which oxides of the metallic earths, here called "electrolyte electrodes," are used as rods. To produce the arc these rods have to be made con- ductive by heating, which is done by means of an auxiliary arc between carbon electrodes, arranged close to the others. Arc- lamps of this kind are said to be highly efficacious, more so, according to the inventor, than any other arc-light; the light is white. The new arc-lamp of Bremer") is constructed on another plan. The poles contain a mixture of carbon and fluor-spar; it is not necessary to heat them. The usual arrangement of the rods one above the other is departed from in this lamp; they are arranged side by side at an angle with each other; the arc of light directed horizontally between the carbon points is turned downwards by the current, so that it spreads out like a fan. This lamp, too, is highly efficacious; its light looks yellow. W. Vedding's s ) experiments with two Bremer con- tinuous-current lamps, of 12 and 60 amperes, with 44 and 60 volts respectively, the positive carbons of which were made of a calcium compound, show that the smaller lamp had a maximum illuminating power of 6,400 candles, that the illuminating power was constant below the angles 45 ° to 90 to the horizontal, and only then decreased towards the horizontal to 1,000 candles. The scond powerful arc-lamp had 4 arc-lights arranged on the occasion of the measurement in two rows. This lamp gave its maximum of 83,000 candles below 37 . The experiment showed further that with this new lamp three times as much light was obtained as in other *) Elektrotcclin. Zeitschr., Feb. i .jili. [901. •) Elektrotechn. Zeitschr., April 4th, iyoi. ') Ibid. 1900, part 27. 488 RADIO-THERAPY arc-lamps with the same expenditure of energy. It shewed advantages over the older systems even when alternating currents were used. In both Rasch's and Bremer's lamp, no doubt, side by side with the effect of the glowing electrode tips, a considerable part is played by the gaseous metal compounds glowing in the arc. The noxious vapours given off by these lamps may probably stand in the way of their being used for photo-therapeutic purposes. The arc-light in a non-concentrated form is used for electric light-baths, in a concentrated form for the treatment of localised skin complaints. The Therapeutic Use of Non-concentrated Arc-light. § 66. Arc-light baths form a quite distinct class of electric light baths. Whilst in the incandescent light-baths the long-waved rays (heat rays, reddish yellow) come chiefly into play, in the arc-light baths the whole body is exposed mainly to the chemical light rays. The heating action of this light is quite subordinate here to its chemical action. Superior to them both is the natural bath in sunlight, where both the heat rays and the actinic rays act powerfully on the body. It is necessary, therefore, to take account of the special characteristics of the various light-baths when judging which symptoms point to any particular method. Arc-light baths are taken either in the open or in a chamber. Finsen 1 ) administers them in the open as follows: Two huge arc-lamps, of ioo amperes each, hang in the middle of a circu- lar room a few metres from the ground. Compartments are formed round the room by a number of radial partitions, and in them are inclined couches, turned towards the light, on which the patient lies naked. The temperature in these light-baths is so low that artificial heat has to be applied to keep the patient from feeling cold, and yet the chemical action on the skin is as powerful as in strong sunlight. They produce a pleasant, slightly prickly, and feebly warming sensation in the skin. Some persons after only ten minutes show distinct erythema, whilst \) Ueber d. Bedeutg. d. chem. Lichstr., p. 71. PHOTOTHERAPY 489 others are able to stay in the baths for hours without more than very slight erythema appearing. The arc-light "enclosed baths" of Kellog 1 ) are quad- rangular boxes in which the patient sits with his head outside, as in the incandescent light-baths. A powerful arc-lamp is fitted in each corner, capable of being turned both upwards and downwards, so that the rays can be directed on the patient in any position. Arrangements are made for the introduction of coloured glass filters to obtain at will either red light or blue light, according as the heat rays or chemical rays are to t~e excluded. Strebel 2 ) brings forward the well-founded objection to the use of arc-lamps for enclosed bath, that in order to produce a chemical effect about equal in'degree to that of diffused daylight they develop such tremendous heat in the box that the patient can only stay in the bath for a limited time, however good the ventilation may be. The use of reflectors to intensify the light has been the objection that burn-blisters are liable to be formed on those parts of the skin on which the concentrated cone of light and heat falls. Another drawback to this use of electric arc-light is the formation of noxious gaseous products (acetylene and other compounds of carbon and hydrogen), which are not only absorbed by the skin, but also, escaping at the neck opening, may penetrate the patient's air-passages (Strebel). From these considerations it is evident that the Finsen method is the more suitable for electric arc-light baths. The chemical effect of this arc-light treatment might be considerably heightened by the use of parabolic reflectors, which would reflect the otherwise wasted light which is radiated upwards. The irradiation thus utilized has considerably more actinic power than concentrated light, without the disadvantages we have mentioned. According to //. IP '. Vogel,*) a Schuckert reflector (in which not only the parabolic reflector but also a ') Blatter f. klin. Hydrotherapie, X. Jahrg., p. 14. 2 ) Die Verwendung des Lichtes in der Therapie, Munchen, i<)<>_>. p. 20. 3 ) //. W. Vogel, Das Licht im Dienste der Photographie, Berlin 1894, p. 123. 49 o RADIO-THERAPY system of cylindrical lenses are used, with the result that the reflected rays are even divergent) with 60 amperes strength of current produced a black photographic reproduction in 15 seconds, whilst daylight in November required iy 2 to 3 minutes ' ) . It is necessary with every kind of arc-light treatment to bear in mind the specifically physiological effect of the so-called chemical light rays (the peculiar and lasting irritation of the skin [Finsen, M oiler], the action on the blood [Finsen and others, cf. p. 412], also the as yet uncertain influence on the nervous system) and to judge accordingly the symptoms point- ing to its use. Arc-light baths are often combined with incandescent light by introducing incandescent lamps on the sides of the bathing box; by this means the effects of the two kinds of light are united in one apparatus. We have as yet no precise, full and suggestive accounts of the therapeutic results of this light-bath method, but we may assume that light by strengthening the organism and furthering the process of phagocytosis in the elimination of micro- organisms and toxins will give us a remedy against many dis- eases. Metal electrode lamps have been recommended for the treatment of circumscribed skin affections. They are used similarly to the light concentrating apparatus. Treatment with Concentrated Arc-light. § 67. The idea of using concentrated electric arc-light in the treatment of skin diseases was brought into practice by Niels Finsen. His apparatus in the first place makes the divergent rays from the arc parallel (just in the same way as did the appliance used by Widmark in his experiments) . These parallel a ) Strebel in his recent interesting work, "Die Verwendung des Lichtes in der Therapie" (Munchen, Seitz. u. Schauer, 1902), states that he has been led by the same conclusion of which Fovcau de Courmcllcs, the present writer, and many other colleagues, arrived quite independently, to use refracted arc- light in place of a sun-bath in his practice, and has done so with good results. PHOTOTHERAPY 491 rays Finsen collects again into a cone, the apex of which falls on the part of the skin to be treated (Fig. 99). In physical and medical laboratories precisely similar appa- ratus has long been in use which made the divergent rays from the electric arc first parallel and then again convergent, and filtered the heat rays through layers of water. Thus, in the \=a If s=> Fig. 99. — Finsen' s light apparatus. Vienna Institute for experimental pathology (Prof. Paltauf, and formerly Prof. Strieker), an apparatus constructed pre- cisely like Finsen s has been used for many years to project light. Finsen uses as his light source an arc-lamp of 80 amperes with continuous current only; he computes its light intensity at 40,000 candles. The voltage of powerful continuous current lamps of this kind is at the terminals of the lamp hardly more than half the voltage of the ordinary current in the street. If, therefore, the lamp were to be attached directly to a supply of no and more volts over 50% of the electric energy would be lost in the resistance coils 1 ). The setting up of two lamps of this kind, one behind the other, is in practice inadvisable on account of their unsteady action. Neither does the supply allow of such strong currents being taken from ') Naturally a supply of tins kind would, on account of the large amount of energy consumed, 1"' much dearer than a current of only the required voltage. 492 RADIO-THERAPY it, on account of the strain involved on single cables and the resulting fluctuations in voltage for other neighbouring consumers connected with the same street cable. For this reason, when such powerful arc-lamps are used with a street-voltage of more than 65 volts, a transformer has to be employed to transmute driving voltage of the electrical supply to the required lamp voltage, including the steadying resistance. Alternating current lamps of the same great in- tensity of light act unsteadily, and it is difficult to concentrate the light with them; hence for these pur- poses alternating current lamps are not used. The connecting apparatus (Fig. 99) consists of two metal cylinders telescoped one in the other, each containing two plano- convex lenses. The two parts of the apparatus may be sepa- rated by means of a rack-and-pinion movement. The various lenses are in Finsen's apparatus so proportioned as to size that lenses 1 and 2 have together a focal distance of 12 cm., lenses 3 and 4 together a focal distance of 10 cm. The two lenses, 1 and 2, nearest to the source of light col- lect the diverging rays of the arc-lamp into a bundle of parallel rays. Lenses 3 and 4 make these parallel rays converge on the surface to be irradiated. Between lenses 3 and 1 is a water chamber x ) for the purpose of absorbing the heat rays. As the water in this chamber becomes heated when the lamp is in use, means are taken to keep it constantly replaced by cool water. This is done by a system of tubes (one part bringing the cold, the other carrying off the heated water) in connection with the water supply. At first Ftnsen used glass lenses and distilled water, and fixed light filters consisting of glasses filled with a solution of sulphate of copper at the end of the aparatus turned towards the patient. Now, in order to lessen the risk of absorption for the ultra-violet rays, no colour filters are used, and instead of J ) According to Rcyn's suggestion, the water chamber is now fixed be- tween the lenses turned towards the lamp, so that they may be cooled and their constant cracking avoided (Quoted A. Hubcr. Der heutige Stand der Finscn-Thevapie, Wiener Med. Wochenschr., 1902, No. 20 ff.) PHOTOTHERAPY 493 the strongly absorbing glass lenses only quartz lenses. A con- siderable part, however, of the effective energy radiated from the arc of light is still lost on passing through the layer of undisturbed fluid, and the unavoidable use of several lenses weakens the force of the rays which are allowed to pass. Four of these collecting apparatus are usually arranged round the arc-lamp (Fig. ioo), which is either suspended from Fig. ioo. — Finsen's apparatus. the ceiling or mounted on a high iron stand. The spaces between the single concentrators are filled with asbestos plates, so that the operator and the attendants may not be inconvenienced by the strong light. By means of this arrangement four patients can be treated at once and the expensive light be fully utilised. The light from this concentrating apparatus not being even yet sufficiently cool to be borne without discomfort for any length of time on the skin, Finsen hit upon a very useful plan. A compressor, consisting of two quartz discs fixed in a brass ring, is pressed on the irradiated spot; through this apparatus a constant circulation of cold water is maintained by means of 494 RADIO-THERAPY a suitable system of tubing 1 ). This arrangement does away with what is left of the heat, and by the continuous pressure on the irradiated skin it serves the further important purpose of making the skin anaemic. This, as Finsen has shown (cf. p. 426), enables the actinic rays to penetrate far more deeply. This pressure apparatus is fixed to the patient's body with bandages, or may more conveniently be held on with the hand. Benrmann drives the blood out of the irradiated parts by applications of adrenalin (1:1000), which constricts the ves- sels 2 ). But the author's experiments go to show that adrenalin only acts thus when first applied; the effect soon lessens. As has been said, Finsen replaced by quartz lenses the glass ones, by which ultra-violet is so strongly absorbed. But that had the further disadvantage of necessitating the use of lenses of small diameter (7-8 cm.) only, for quartz lenses of greater diameter are hard to get and very costly. The light from the voltaic arc, however, can be utilised to a comparatively slight extent with small lenses. In this respect metal reflectors act better. Fovean de Conrmelles, Trouve 3 ) Kime*) J. G. Muller, 5 ) Strebel and others, therefore, proposed to have appa- ratus with mirrors instead of lenses. Strebel described the con- struction of a concentration apparatus in which the rays are concentrated by metal mirrors of magnalia, an alloy of alumin- ium and magnesium. These mirrors, according to V . Schu- mann*) reflect not only the visible spectrum but also the ultra- violet rays satisfactorily. The light falls on four magnalia concave mirrors 7 ) mounted in a metal frame at an angle of 1 ) In the accompanying figure the water-supply of the compressor is rep- resented, for simplification of the drawing, as coming from the cooling water of the concentrating apparatus. In practice, however, each of the two appa- ratus has its own two pipes to the water-supply. 2 ) Soc. de dermatologie et de syph., July 3rd, 1902. J ) See below. *) -Medical Record, Oct. 13th, 1900. ") VII. Dermat. Congr., Breslau, 1901. °) /.. Mach and V. Schumann, Ein neues Spiegelmetall. Sitzungsber. d. kais. Akad. d. Wissensch., Math.-naturw. CI., 1899. 7 ) Other metals too might be suitable for such reflectors, e. g., steel and the Brandcs-Siluhicmann alloy (41% Cu + s6% Ni + 24% Sn -+- 8% Fe PHOTOTHERAPY 495 45° round the arc-light. They project their light through a cooling apparatus fitted with piano-parallel plates or suitably curved lenses. To protect the polish of the mirror from the destructive effect of the ozone, sometimes provision is made for a stream of water to run over the mirror-surface, 1 ) or the metal is cooled from the back (Fig. 101). The author is not aware if such apparatus has actually been made, or how it acts in Dractice. Fig. ioi. — Strcbcl's Light Apparatus. According to a fundamental law of optics (cf. p. 372), the intensity of light varies inversely with the square of the distance* Hence we should expect to heighten the effect of + 1% Sb), the latter of which, according to Glatzel (Physik. Zeitschr., 1900, Vol. II, p. 176). takes a very good polish and resists the action of the air. Both are very well adapted for photographic purposes. Silver mirrors reflect 92% of the visible spectrum, the Brandes-Schunetnatm alloy only 50%; hut the latter reflects ultra-violet more than other metal ') Which probably, however, destroy the ultra-violet. 496 RADIO-THERAPY irradiation by bringing the source of fight as close as possible to the object to be irradiated. ( The law holds good, indeed, only for non-concentrated light; with concentrated light the distance is not of such great importance.) This law is observed by the metal electrode lamps already described, as well as by the apparatus designed by Foveau de Courmelles and Lortet and Genoud. Being designed with due heed to this principle, these apparatus have the advantage of not requiring so extraordinarily powerful a source of light, or so strong a current, as Finsen's concentrating apparatus; and, further, the absorbing media are in 1 WJ Figs. 102, 103. — Apparatus by Trouve-F oveau de Courmelles. them reduced proportionately in size. Consequently the action with these apparatus is very intense, and* the time of exposure can be considerably diminished. , Foveau de Courmelles and Tronve's apparatus consists of a parabolic mirror, in the focus of which is the arc-light of a lamp of 10 to 12 amperes (Figs. 102 and 103). Suitable filters are fixed at the opening of the reflector, according as light rays or heat rays or both are desired. The heat filter consists of two PHOTOTHERAPY 497 quartz discs, 2 to 8 mm. apart, between which a layer of cold water circulates. These two discs may be of various shapes and sizes, and are applied directly on the part to be irradiated, act- ing as a pressure apparatus at the same time ' ) . At a meeting of the Soc. Franc, de Dermatolog. et Syph. on May 1st, 1902, Du Cast el reported that he had found this apparatus to act admirably in the treatment of lupus. Du Castel gained strikingly good results with the Foveau-Trouve apparatus in the case of two patients, giving 65 and 40 one-hour sittings respectively, with a current of 6 amperes. He believes that the length of treatment each time is an essential factor in the cure, and never now has a sitting of less than an hour. With Lortet and Genoud's apparatus, Fig. 104 (LTnde- pendance medicale, March 27th, 1901), a constant arc-light Fig. 104. — Apparatus by Lortet and Genoud. is produced between two carbon points which form so great an angle that the crater of the positive carbon radiates the greater part of the light in the shape of a cone, whose axis passes through the centre of the opening (). This opening *) According to Foveau de Courmelles (Bulletin office de la Soc. med. des Practiciens, n Ann.. Jinn- 15, [901, No 6), G. Trouvi has from [893 used parabolic mirroi b trengthen the therapeutic action of light. 49 8 RADIO-THERAPY forms the centre of a curved metal light-screen D D, between the double walls of which cold water is kept constantly cir- culating. A small mirror M prevents any light from being radiated backwards, so that almost all falls in front. A system of screws and slides enables the arc to be regulated and advanced more or less near to the opening. When the apparatus is working the carbons are brought to within i or 2 cm. of the opening. In front of this is a chamber consisting of two rock crystal discs set in a metal ring; in this chamber a stream of water circulates. This chamber constitutes the compressor. Experience shows that the arc-light may be approached to within 3 to 4 cm. of the chamber without the latter being heated. The heat rays in this apparatus are well absorbed. The size of the part irradiated may be as much as 6 cm. The lamp is said to require not more than 10 to 12 amperes. The time of illumination for therapeutic purposes is given as 10 to 15 minutes x ) . The most important use of all these apparatus is for Finsen's treatment of lupus vulgaris. This is applied as fol- lows: Each patient has his own attendant whose business it is to direct the light constantly on the diseased spot. The patient lies on a suitable couch with his head raised, or sits in an arm- chair with a head-rest. (The patient would hardly be able to keep immovable for a long time, say two hours, in a sitting position.) His eyes are protected by a cloth, the attendant's by darkened glasses. Any scabs or crusts there may be are removed, having been previously softened, with forceps, and the part is washed with a weak antiseptic solution (3% boracic) and dried. Now the light cone is directed on to the site of disease, and care is taken that the axis of the light cone is perpendicular to the area illuminated; the part to be treated is not placed directly at the focus, but a little in front of it so that not one point but a small circle is illuminated. This, *) Fovcau de Courmcllcs, however, asserts (L'annee electr., 1902, p. 354) that with this apparatus a supply current of 20 to 25 amp. and sittings of one-quarter to half an hour proved necessary. The unshaded light, too, in the apparatus might be troublesome to the operator. PHOTOTHERAPY 499 moreover, helps to prevent the skin from being heated. A circular area having a diameter of 2 cm. may be treated at one sitting. The surrounding parts are covered with wadding or yellow paper. Now a suitably shaped compressor 1 ) is placed on the diseased spot and held there firmly with equable pressure. The duration of the sitting varies according to the quality and intensity of the light used. Finsen recommends a two hours' exposure with his concentrator and a lamp of 30 amperes; with lamps of 80 amperes the time may be cut down to an hour, or an hour and a quarter. With these powerful lamps, Finsen, after only 13 to 20 minutes' continuous illumination, effected a definite cure of lupus nodules the size of peas. The designers of the newer kinds of apparatus (Foveau, Lortet, Bang, Strebel) give the necessary time of exposure for their instruments, on account of the greater light intensity — that is, the greater proportion of ultra-violet rays — as 10 to 20 minutes. The treatment con- sists of one sitting a day, except in cases where the morbid growth is very extensive, when two a day are given. The patient suffers no pain during the irradiation, except perhaps when the pressure is applied to ulcerated or bony parts, e. g., near the nose. After the treatment symptoms of erythema solare appear, the irradiated part becomes a little red, the redness very soon increases markedly, and at the same time slight swelling shows itself and burning pains are felt, the skin becomes softer and unevennesses disappear. Often 24 to 48 hours later a large blister forms, filled with serous fluid; this dries away in 6 or 8 days to small readily-removable scabs. There is never any loss of substance below the blister. When the blister has exfoliated, considerable redness is left, which only passes away after months. To prevent infection of the blisters a dressing is applied of boracic lotion or zinc ointment. After a week or fortnight, when the reaction has disappeared and the scabs have fallen off, ') For the skin of the cluck, which yields readily t<> pressure, the com mvex, for the forehead concave, and for the temples plane, (Finsen, Schmidt, Berliner klin. Wbchenschr., [901, No. 32.) 5 oo RADIO-THERAPY the same place may be irradiated again, later even more than once; in fact, this is necessary if the therapeutic effect is to be lasting. When one spot seems to have been sufficiently treated a neighbouring spot is treated in the same manner. In this way the treatment proceeds from spot to spot, until the whole part attacked has been exposed to the influence of the light. The treatment should begin at the periphery of the lupus region, and the light must be so directed that in each area of illumination a piece of the apparently healthy skin in the immediate neigh- bourhood is also included. After the sitting the spot is marked round with a pencil and so indicated; then the dressing is applied. The compressor, having been cleansed with ether, alcohol, and a solution of carbolic, must be steeped for an hour in carbolic and then placed on the side filled with distilled water. The rock-crystal lenses of the concentrators are cleaned once or twice a week with ordinary water and afterwards rubbed with cork; those near- est to the carbon points are further brushed down thoroughly after each sitting and covered with flannel caps to prevent too rapid cooling and consequent cracking {Schmidt) . When a patch of lupus has been sufficiently treated the nodules and the raised edges of the lesions become flattened; where formerly confluent nodules formed continuous lupous infiltrations appear now isolated nodules with strips of healthy skin between. By degrees these isolated nodules also disappear; the light reaches not only the superficial but also the deeper lying ones. Ulcers grow less both in surface extent and in depth, and cicatrise. The redness of the skin gives place to normal colouring. The cosmetic result as regards the appear- ance of the scars is excellent. The scars are smooth and soft, the losses of substance are slight and only such as arose from the morbid processes, not from the treatment, which does not affect the normal tissues. Gaston, Baudoitin and Chatin report hypertrophic and keloid scars, as well as smooth scars, in several cases healed by means of the Lortet-Genoud apparatus 1 ). *) Soc. de dermatolog., April i, 1902. PHOTOTHERAPY 501 Finsen's treatment, beginning as it properly does at the periphery and taking in always the neighbouring healthy skin, has the effect at once of checking the spread of destructive lupous processes. The action of the light on lupus is not only an immediate, but also a lasting one, going on even after the treatment has stopped. Suspicious spots have often been known to resume a healthy appearance during the course of several months after treatment with the rays has been suspended. Fhisen concluded from this that the tubercle bacilli are killed by the light in a much shorter time than is required for the slow process of transforming the diseased reddish-brown tissue into healthy skin of a normal colour. It seems to the author doubtful whether this bactericidal power of light is really the essential curative force in this treatment. He would rather, with S. Bang, 1 ) G. J. Miiller,") Gleboivsky, Serap'm, Sack (cf. below) and H- E. Schmidt*) lay stress on the action of the light in producing inflammation. Light seems to him to act as an irritant penetrating, like the Roentgen-rays, very deeply. Its action goes deeper than that of many chemical irritants, e. g., pyrogallic acid, resorcin and lactic acid, the effect of which is weakened by the albumen com- pounds soon formed. The light irritant stimulates the granu- lation tissue, which is usually but little inclined to change into connective tissue, to the formation' of connective tissue and cicatrices. Probably the extraordinarily powerful illumination acts on the diseased tissues, which are specially sensitive to light and less able to resist its action, as a hyper-irritant, and this, as is well known, kills the cells. By this means the morbid tissues are destroyed and prepared for reabsorption. There is a further circumstance which may make for the favourable action of light, viz., the artificial and Lining hyper- emia produced by it in the diseased area. We know that in the treatment of various tuberculous processes hyperemia has been aimed at again and again, and that good therapeutic ') VII Congr. (1. deutsch. dermatol, Gesellsch., Breslau, 1901. ') [bid. s ) Berlin, klin. Wochen chr., 1901, No. .32. 502 RADIO-THERAPY results have thereby been gained. We need mention here only Biers treatment of tuberculous affections of the joints, with which in this respect we may compare the action of the old Koch tuberculin (Neisser, Scholtz), and that of the penetrating chemical caustics, pyrogallol, resorcin (Ehrmann) , and lactic acid (Max Josepli). As the result of this hyperemia the chemical products of the bacteria are said to be accumulated, a circumstance which is inimical to the bacteria themselves; Bier holds further that hyperemia promotes the formation of connective and scar tissues J ) . Light, in the author's opinion, acts in the case of all such affections exactly in accordance with the action which all physi- ological irritants, following a universal law, exercise: it acts partly as a stimulus and partly as a strong irritant, paralysing and destroying. He recognises in these rays, as in the Roent- gen-rays, just those kinds of irritants which have a specific action and are of special therapeutic value : 1. Because of the specific quality of the rays; 2. Because of their power of penetrating deeply. The latter quality is specially important in treating deeply- lying granulomata, for the other remedies, such as copper sulphate, camphor, etc., which have been used for ages to stimulate torpid granulations, ulcers, and wounds to the forma- tion of connective tissue and scars, have only a superficial action. Glebowsky made a histological study of the process of *) Since the compressor drives away the blood from the diseased spot dur- ing the treatment, and thus tends to prevent the hyperemia aimed at, E. Lang's theory as to the pressure of the capsule being an essential curative fac- tor seems to the author unfounded. His assertion (Wiener dermatolog. Ge- sellschaft and IV Internat. Congr. f. Dermatologie und Syph., Aug. 1900, Compt. rend., p. 171) that he cured lupus by pressure with the lens alone is quite unique and has not been confirmed. On the contrary, G. J. Muller reports (VII Congr. der deutschen dermatolog. Gesellschaft, Breslau, Ver- handlungensber, p. 471) that he found no result from glass pressure tried experimentally for weeks for as much as eight hours at a time, but that a distinct effect was noticeable from the action of light alone on sensitive spots without pressure. Bang and Lesser (ibid.) have observed the same. PHOTOTHERAPY 503 healing in cases of lupus of the skin under the influence of light treatment, and arrived at the following conclusions 1 ) : Pieces of skin removed for examination 24 hours after irradiation showed the vessels dilated and the sur- rounding parts infiltrated with migrating leucocytes. Besides this, it was seen that the interstices of the con- nective tissue were somewhat wider, and that there was slight vacuolisation degeneration which was clearly marked in the giant-cells. In pieces removed after 48 hours the same phe- nomena were much more marked, and there was, Fig. 105. — Giant-cell from a case of lupus two days after Finsen treatment. (Glebowsky-S erapin, die Veranderungen im Lupusgranulom unter der Einwirkung des concentrirten Bogenlichtes nach der Finsen'schen Methode. Verhandl. d. D. dcrmat. Gesell. VII Congr. p, pyknosis ; v, vacuolised nuclei; k, fat.) further, fatty degeneration of the protoplasm and necrobiotic changes in the nuclei of the granuloma-cells, especially in the giant-cells (pyknosis and chromato- lysis, Fig. 105). After repeated sittings these destruc- tive appearances in the giant-cells increased, and finally the cells disappeared entirely. This happened on an average after 4 to 5 irradiations. The processes of degeneration in the epithelioid elements were much less marked as compared with those in the other granuloma 1 ) C. Serapin, Ueber die Veranderungen im Lupus granulom unter der Einwirkung des concentrirten Bogenlichtes, etc. V 1 1 Congr. d. deutsch. dei matolog. Gesellsch. Vcrhandlungsbericht, p. 500 ff. 5 04 RADIO-THERAPY ' elements {a point of difference from the changes in the lupus growth after treatment with the Roentgen-rays, when such varieties of effect have not been observed, (cf. p. 287 ff) ; but Glebowsky and Serapin noticed in them changes of a purely progressive character, e. g., elongations of the nuclei and the cell-bodies and elements of a spindle shape were met with, which seemed at times to pass into fibres. The lymphoid elements of the lupus, too, showed during the acute reaction rather pronounced fatty degeneration, and later on oval and spindle-shaped cells were observed amongst them. As the process of reaction advanced and died away the cell elements in the granuloma disappeared more and more, beginning with the upper layers of the corium, and the connective tissue became more and more con- spicuous (Fig. 106). Only at the end of the treatment were the numerous blood vessels contained in the granu- loma quite obliterated. According to A. Sack's investigations on lupus, ulcus rodens, and naevus vasculosus planus *) the blood-vessels are the first point affected by the light. The endothe- lium lining their walls swells and grows rapidly and endarteritis results, with final obliteration of the vessels. The retrogressive changes in the character of the cells which show themselves, and are in part of a necro- biotic nature, are purely elective, attacking only certain less persistent elements of the disease tissue, whilst the other elements both within and without the morbid growth are stimulated to activity. Since at each sitting only one small spot can be treated, and as this has to be treated again more than once, the whole process of cure cannot but be of long duration; precisely how long depends on the intensity and extent of the disease. Small isolated lesions can be cured in a few sittings, but large growths may need to be treated for a year or more, and tax severely the patience of both doctor and patient. In order to shorten J ) Miinchen. med. Wochenschr., July 8, 1902. PHOTOTHERAPY 505 the period of treatment, very extensively affected parts which are much infiltrated and darkly pigmented are first treated with pyrogallol ointment, and especially deep-seated nodules mav be destroyed by the cautery. In the light treatment of lupus vulgaris, just as in the X-ray treatment, it is well to make a break with the treatment after a powerful reaction, so that it may be seen, when the acute Fig. 106. — A Lupus nodule after four sittings. (From Glebowsky-Serapin 1. c.) (a) Blood vessels with hyperplasia of the endothelium, (c) Granu- lation elements between the epithelioid cells, (f) Connective tissue. effects have died away, whether it is advisable to continue the treatment. According to Forchhammer, 1 ) generally after some lapse of time, when the reaction has died away and the whole part is again in a normal condition, there are remains of the disease left in the shape of isolated deep-seated nodules. It is, there- fore, necessary to watch the case carefully and to give, where necessary, short supplementary treatment once or several times, as the case may be. In the case of not too extensive and inveterate lupus growths ') VII Congress d. deutsch. dermatol. Gesellsch.. Breslau, 1901. 5 o6 RADIO-THERAPY of not more than 10 years' standing the average duration of the first treatment may be taken as 3 to 4 months. Cases of greater extent and longer standing are likely to require longer treatment, and complete cure is in such cases more uncertain, in great measure on account of the changes brought about in the lupus tissues in the course of the disease, and by the treat- ment previously tried for it. These changes are of the nature of fibrous scar-tissue, intense brown pigmentation, and consid- erable infiltration (Forchhammer) , and they all render it more difficult for the light to penetrate the tissues. Both F'insen and his fellow-workers lay special stress on the importance of keeping the patients under observation for a long time' after treatment. Although the method gives the most favourable results (according to Forchhammer, 85% of cures), there is yet a small number of cases (2 to 3%) in which it fails. Then there are the cases in which the disease attacks the mucous membrane, but even when it is localised at the body orifices, the gums, the palate or the tongue, it may be treated by this method (Lebon, 1 ) Torok and Schein 2 )) . With a considerable number of patients there are relapses. Forchhammer reports that this is especially the case with patients who neglect to come up for inspection after the end of the treatment, or with cases where there is extensive inflammation of the mucous mem- brane, or, finally, with patients who are attacked very soon after treatment by severe and debilitating disease, e. g., erysipelas or influenza. Brocq 3 ) mentions one case in which irradiation produced always the most violent eczema and oedema, so that it could not be adopted. According to M. Morris and E. Dore*) cases of lupus are unsuited to the Finsen treatment, which are accompanied by much scarring and pigmentation and great vascularisation and thickening of the skin, and those which occur in certain regions ') La Phototherapie, Paris, Societe d'editions scientifiques. 1901. 3 ) IV Intern. Congr. de Dermatologie. Paris, 1900. *) Brit. Med. Journ., Feb. 9, 1901. PHOTOTHERAPY 507 (eyes, mouth, nostrils). Leredde and Pautier recommend pre- paratory treatment with scarification and cauterisation in cases where previous remedial efforts have produced sclerosis ' ) . There are a few drawbacks to set against the advantages of this method, its efficacy, its elective action on lupus whilst preserving all sound tissue, its painlessness, its excellent cos- metic results, its freedom from unpleasant and unexpected after-effects. The method demands a large plant, which is costly both to buy and to maintain in operation (on account of the powerful current required) ; it necessitates a trained staff of attendants, and by its tedious course it makes great demands on the patience of both doctor and patient, and requires from both considerable powers of physical endurance. Com- parisons have been drawn between the light treatment and the Roentgen-ray treatment, and the latter method has been termed the more simple, quick and cheap. Many (Kiimmel and others) have, therefore, recommended that isolated lupus patches should be treated by the Finsen method, and larger areas of disease with the Roentgen-rays. Objectively consid- ered, the Roentgen treatment is certainly simpler; the tube needs only to be directed rightly on the patient, and, provided he remain still, he can be then left to himself and there is no need of specially trained attendants. The duration of the single sittings is much shorter than with the Finsen treatment, and the Roentgen-ray treatment is just as painless; the area which it is possible to treat each time with the X-rays is much larger than with the Finsen treatment, and the appearance after treatment is quite as good. But on the other hand we must consider that even though the Roentgen treatment does not require so efficient a staff of attendants it presupposes in the operator great experi- ence and practice, and demands from him, not indeed the same physical endurance, but the capacity of judging correctly and measuring the intensity of irradiation, the suitable time oi exposure, etc., whilst with the Finsen method no such niceties have to be taken into account. Further, in many cases, from the Roentgen treatment there ') Soc. de Dermatolog., April 1, rgo2. 5 o8 RADIO-THERAPY can only be assurance of definite results if violent and painful dermatitis, persisting to the end of the cure, be accepted as part of the process; and its results are by no means always so evi- dent as with the rival method. There is probably not much difference between the two methods as regards either their value in lupus of the mucous membrane or the total length of time required for a cure. With each method the main treatment needs to be followed by sev- eral periods of supplementary treatment. We may say indeed that the advantages of the physical treatment of lupus are not to be sought in any shortening of the time of treatment (which is generally not less than that required by any of the previous methods), but in the fact that they are conservative and almost painless and give excellent cosmetic results. These considerations point to the X-ray treatment as being suitable in cases where, for reasons not connected with the dis- ease itself, the light treatment cannot be used, and on the other hand a suitable Roentgen apparatus is available. Finsen's method and its results have received recognition on all hands. Numbers of medical men have travelled to Copenhagen to see and study the light treatment on the spot. The present writer is one of those who have had an opportunity of inspecting the arrangements of the Finsen Institute, and he can only express admiration of the excellent way the whole thing is planned, the high scientific attainments of the heads of depart- ments {Bang, Forchhammer, Ryn \JLarsen\, Bie) and the zeal and enthusiasm with which they work to further the good cause. Finsen's statements have already been amply confirmed by the most eminent authorities. Lassar, Lesser, Jadassohn, Sabouraud, Petersen, Malcolm Morris, Leredde and Pautier, Elders, Burgsdorf, Mackenzie, Dore, Sequeira and many others report similar experiences. Treatment with concentrated sunlight is carried out in just the same way as with the arc-light apparatus; only care has. to be taken to keep the stand of the concentrating lens con- stantly in a right position with regard to the sun. As has already been mentioned, various simplifications of PHOTOTHERAPY 509 the Finsen apparatus have been designed {Foveau-Trouve, Lortet and Genond), and quite satisfactory results are said to have been attained with short exposures (1^ to 30 minutes: Gaston, Bandonin, Chatin, Foveau de Courmelles, 1 ) Du Castel, 2 ) Lebon,-) Gaston, Baudouin and Chatin*)). The new iron electrode lamps do not seem to be so suit- able as the Finsen apparatus for the treatment of lupus vulgaris. S. Bang 4 ) himself writes that "the Finsen apparatus have maintained their supremacy unrivalled in the treatment of deep-seated affections such as lupus vulgaris; for these we should advise against the iron light." St rebel, too, says B ) : "As the light from the electric spark and from the iron electrode lamp can only act on the superficial skin because of its prepon- derance of ultra-violet, which is absorbed in the epidermis to a great extent, the earlier Finsen method still maintains its position; the deap-seated lupus nodules must be treated with light rich in colour rays, which alone can penetrate deeply." Bang would have his apparatus used in cases where with simple and cheap means a powerful reaction of the skin and a superficial bactericidal action is required. Kromayer, Liese, Belove, Kattenbracker and Sehiff claim to have had good results with the Kjeldsen lamp in cases of lupus vulgaris and erythema- tosus, alopecia areata, acne rosacea, eczema, syphilitic ulcers, condylomata, faevus, and ulcerating haemorrhoids. Alopecia Areata. Since this affection is believed by many dermatologists to be of a parasitic nature, and since light kills bacteria and stimulates the growth of hair whilst producing local inflammation of the skin, 6 ) O. Jersild') suggested the application of the light treat- ment to alopecia areata. l ) Lc median, 1902, Nr. 7, Bruxelles. *) L. c. 3 ) Soc. de dermatologie, A.p. 1. 1902. *) Deutsche med. Wochenschr., 1902, No. 2. s ) L. c., p. 62. *) The methods of treatment usually tried aim also at producing hyper semia by means of chemical, mechanical (Jacquet), and electric irritants (Ehrmann, Bordier). 7 ) Annalcs de dermatologie, [899, p. 20. 510 RADIO-THERAPY His method is much the same as that indicated by Finsen for cases of lupus vulgaris. The concentrated light used is from very powerful light sources. The hair is cut oft round the patches in a zone of one to two centimetres. The illumination starts at the periphery in the healthy part and advances gradually towards the centre. One or two sittings of an hour and a quarter are given each day. Jersild thinks it is not necessary to use a compressor on the morbid spots; the skin is cooled down now and again by moistening with cold water. If carried out rightly the treatment is painless. Each diseased spot is irradiated only once. The duration of the treatment depends naturally on the extent to which the disease has spread. The immediate result of the treatment is to stop at once the further falling oft of the hair at the spots treated (Spiegler, 1 ) Jersild 2 ) ). After a longer or shorter time (at the earliest after eleven days — Jersild) lanugo appears on the bald patches, and this gradually becomes pigmented and thicker. The more recent the origin of the disease, the better are the prospects of cure; this method of treatment is of no use in cases of universal alopecia areata of many years' standing. The results, as reported by Jersild, are very encouraging. According to Forehhammer's statistics, 30 cases out of 49 were cured in Finsen's Institute. Sabonraitd's experience was less happy 3 ). He reports that no specially good results were attained in active cases of alopecia areata by this method, but that it was successful with more chronic cases, limited in extent. Sabouraud, too, attributes the effect of the light treatment in alopecia to the local congestion it produces 4 ). 1 ) VII Congr. d. deutschen dermatol. Gcsellsch., Breslau, p. 469. 2 ) Mittheilungen aus Finsen's med. Lichtinstit, I, p. 113. 3 ) In a letter kindly sent to the author recently, the distinguished French investigator writes: "J'ai experimente pendant six mois la phototherapie de Finsen dans la pelade. Et j'ai ohtenu des resultats mediocres, beaucoup plus mediocres que l'Ecole de Copcnhaguc me semblait les annoncer dans le trait- ment de cette maladie." 4 ) Quoted by H. Lebon, La Phototherapie, Paris, 1901, p. 22. PHOTOTHERAPY 511 L u pits Ery I h c m a I osiis . Finsen, Bang, Forchhammer, 1 ) Leredde, 2 ) Petersen,') Sabouraud, 4 ) G. J. Miiller 6 ) and others have tried treating this affection with the concentrated arc-light. It acts quite satisfactorily in fresh cases, but with cases of longer standing, and especially if the lupus erythematosus is generalised, it often has no effect. Still, according to Leredde, there have been cases which could not be effectively treated by other methods where the light treatment has brought about distinct improvement. Leredde strongly recommends treating the plaques beforehand with high-frequency currents. Sabourciud combines the light treatment with scarification and galvano- puncture. /. M. H. Macleod 6 ) treated 5 cases of lupus erythema- tosus by the Finsen method; two were decidedly improved, two showed no change, and one showed obvious change for the worse. Epithelioma. Finsen, Petersen, Bnrgesdorf and others have seen distinct improvement from the light treatment with superficial epithe- liomata in the early stages. Seqiteira prefers treatment with the Roentgen-rays for this disease. Ncevus vascularis. According to Forchhammer, the light treatment reduces materially the deep red colour of this disease, and in some cases the affection was entirely cured. Petersen observed with one case, in which the nasvus extended from the forehead to the eyelid, that there was improvement not only in the part of the ') Congres pour 1 'etude de la tubcrculose, Paris, 1898, and Dermatol- og. Congress, Breslau, 1901. 2 ) Bulletin genera! de therapeutique. 3 ) VII Congr. d. deutschen dermatolog. Gesellsch., 1901. ') L. c. °) L. c. 8 ) Brit. Med. Assoc, meeting at Manchester, July 30, 1902. 512 RADIO-THERAPY forehead treated, but also in the part of the naevus on the upper lid, which of course could not be irradiated. Other Skin Diseases. Treatment with intense light irradiation has been tried with a variety of other skin diseases (acne vulgaris, Finsen; furuncu- losis, Strebel, Barbensi; acne rosacea, Finsen, Strebel; rhi- nophyma, Leredde; psoriasis, G. J . Midler, Strebel, Barbensi; sycosis parasitaria and non-parasitaria, Finsen, G. J. Midler; biskra-button, Petersen; favus, Finsen) ; the experience gained is still limited, the results varying and uncertain. Varicose ulcers, too, septic wounds, fistulae after operation on bubo, etc., are said by G. /. Midler and others to heal more quickly under light-treatment. Finsen 1 ) recommends also concentrated light- treatment for bacterial affections which are not quite superficial, and where there is the possibility of ren- dering the tissues partially or entirely anaemic. Such, e. g., would be the case with tuberculous affections of the smaller joints and the extrenrties in the case of small children; here the tissues are very transparent, and might readily have the blood expelled with an Esmarch bandage. G. Hnrtado claims to have cured arthritis tuberculosa in the elbow-joints by this means 2 ). The author is not aware if there are any further experiences of the kind. It has been already mentioned (cf. p. 321) that sun-baths have, under certain conditions, proved effica- cious with such complaints. Venereal Diseases. G. Barbensi and Strebel*) treated primary syphilitic 1 ) Ueber d. Anwendung von cone. chem. Lichtstrahlen, Leipzig, 1899. p. 50. 2 ) Revista Ibero-Americ. de C. Med., 1901, No. 12. ') Revista critica di Clinica Medic., quoted in Fovean dc Courmcllcs, L'annee electr., 1902, p. 392. PHOTOTHERAPY 513 chancre, gummata, and soft chancre with concentrated light and irradiation with ultra-violet rays (from iron electrodes or spark-light) ; the local specific lesion in the case of primary chancre is said to heal quickly under this treatment, but secon- dary eruptions are not thereby prevented. The light-treatment would, therefore, have to be combined with mercurial treatment, or iodide treatment in the later stages. According to Strebel, with venereal ulcers two or three irradiations suffice to heal the sore within a few days. There is no evidence of distinct influence on glandular swellings. The Therapeutic Use of Other Sources of Light. § 68. In the method treated of in the foregoing chapter the voltaic arc is the source of the light used for irradiation. In Strebel's method the light of the condensed spark from an induced current of high tension is used. It has long been known that this light is very rich in ultra-violet rays, and experts in photography and spectrography have for many years made use in their spectroscopic and photo-spectrographic experiments of the induction spark between suitable metal alloys, strengthened by Ley den jars 1 ). In view of experiments in other quarters which had estab- lished the fact that ultra-violet rays have a powerful bactericidal effect, it was to be presumed that light irradiation from the induction spark would have a specially powerful effect in this direction. Marshall Ward 2 ) and Strebel*) have furnished the practical proof of this. Strebel showed that the spark of an induction coil at a sparking-distance of 20 cm. kills all kinds of microbes at 70 to 140 cm. distance in a few minutes, and, if the objects are brought to the source of light, within a space ') Rood (Fortschr. der Physik. 1864, p. 257). Berthelot (Ann. Chim. Phys. (7) 19, p. 150). Totnmasi (Beibl. Annal. Phys. Clicm.. 1886, p. 427), E. H. Cooks (Philos. Mag., 1899. Ser. 5, Vol. XXXVII, p. 40). and others have shown that the silent, dark electric effluvia of influence machines and Ruhmkorff induction coils also contain many ultra-violet rays, and have the same actinic action on photographic preparations as light rays. z ) Proc. of the Roy. Soc. of London, [894, Vol. I. IV. p, 472 ff. 3 ) Deutsche med. Wochenschr., 1901, Nos. 5, 6. 5 1 4 RADIO-THERAPY of time which compares well with any results gained with the arc-light. The effect on the skin of rays from the induction spark is precisely the same as that of those from the voltaic arc; they, too, produce erythema and pigmentation. The biological action of the induction light is in large part the action of ultra-violet rays. Rays of greater wave-length are present to so small an extent that any possible action on their part would be quite subordinate. Further investigations have yet to determine what part in the known and still unknown action of this irradiation is played by the "electric waves" originating in the spark. One reason in favour of using spark-light is that with it, as with metal electrode arc-lamps, the source of light can be brought quite close to the object, and the effect of the light thus increased. Bearing this in mind, and also the circumstance that the light source proper does not require such careful guard- ing and regulating as the apparatus before mentioned, and that it can be packed in small compass, the Strebel spark-light appa- ratus would seem to be specially suitable for use in cases where it is desired to bring the action of the ultra-violet rays to bear on the body cavities. The Strebel instrument for producing this light consists of a small spark-induction coil, or it may be a large one, but in any case only a small spark-gap is used. A Leyden jar (or a battery of such jars) is inserted parallel with the spark-gap, i. e., one pole joined to the inner, the other to the outer, foil. The so-called capsule apparatus for irradiating the external skin consists of a short ebony tube, 6 cm. broad, which is closed on one side by a quartz lens, on the other by a concave mirror of magnalium metal. The conducting wires pass through the wall of this apparatus and terminate in one or more pairs of aluminium electrodes, which stand opposite to each other, a short distance apart, in front of the concave mirror (Fig. 107). Gorl 1 ) inserted insulated aluminium balls one behind the other in the shape of an "S" between the electrodes. The spark flashes from ball to ball along the "S." *) Munchcn mecl. Wochenschr., 1901, No. 19. PHOTOTHERAPY 515 + Air is forced into the capsule through an opening by means of a small bellows, and this both prevents the electrodes from becoming heated and drives out the ozone and metallic vapour formed by the spark 1 ). The apparatus serves as both light source and compressor, and is pressed by the patient himself against the part of skin to be treated. For the irradiation of the cavities of the body Strebel con- structed similar instruments, shaped to fit the parts to be treated, like catheters, etc. The instru- ments are intended on insertion to have the effect of causing local anasmia through pressure and the stretching of the mucous mem- brane. The idea of this apparatus may be good, but the way in which it is carriec 1 out, /'. e., by glass tubes, etc., into which insu- lated wires pass, makes it of doubt- ful practical value. Glass is used as material for the apparatus, without regard to the fact that glass is a powerful absorbent of ultra-violet, and that, therefore, very few of the ultra-violet rays of the induction spark traverse it. It is true Strebel directed that quartz windows should be put in the instruments opposite the sparks, but so far as we are aware this is never done. With glass apparatus of this kind, it would only be after very long irradiation that any biological or therapeutic action whatever could be expected. The introduction of a glass catheter into the human urethra is not without its danger. We may recall that not long ago a case was mentioned where a glass sound Jj Fig. 107. — Strebel Instrument. l ) The light itself 1 cold 5 i6 RADIO-THERAPY broken off in the urethra, which could only be removed by operation. Strebel proposed as another form of s^ark-light the rays given out by the opening spark of a Wagner hammer with an induction apparatus. Strebel showed that this light, when the interrupting-spark is produced by aluminium contacts, is very rich in colour rays, though not to so marked an extent as the voltaic arc-light, and is even richer than the latter in ultra-violet. Cooling arrangements have to be provided, as this light is very hot. Both the writer 1 ) and Strebel 2 ) have pointed to the possi- ble therapeutic utilisation of the ultra-violet rays in the electric brush-light. Strebel constructed a small condenser, which pro- jects these electrical discharges in a circular plane. S. Leduc, too, gave directions for a suitable apparatus 3 ). His condenser is insulated in a capsule with a quartz end, and can be used as a compressor. Five to ten of such apparatus can be inserted in one current and several patients thus treated at the same time. Irradiation for a quarter of an hour to an hour each time, every one to three days, is applied with this apparatus, accord- ing to the length of time before the action shows itself. According to Strebel, the treatment proceeds rapidly with this capsule apparatus, as a patch 5 cm. across may be at once irradiated. We have so far only Strebel' s report of results from this method. He claims to have had very good results: Lupus vulgaris (distinct improvement after several irradiations of three-quarters of an hour) ; venereal ulcers (healing after sev- eral irradiations of half an hour) ; obstinate psoriasis (8 sittings of an hour and a half each) ; a plaque of herpes tonsurans as large as a 5 mark piece (21 irradiations of half an hour); sycosis (12 sittings of 25 to 30 minutes — simultaneous epila- tion) ; eczema madidans (two sittings) ; ulcus cruris (healing 1 ) Die physiolog. Wirkungen der Polentl. Sitzungsber. d. k. Akad. d. Wissensch. in Wien, Math, naturw. Classe, Vol. CIX, Part III, 1900, p. 652. ■) L. c. *) Quoted in L'annee electrique, 1901, p. 389. PHOTOTHERAPY 517 after 9 to 20 sittings), and alopecia areata (8 sittings). This treatment is said to have been markedly successful with dis- eases of the mucous membrane, arresting the discharge and causing the disease to disappear (Huor albus blenorrh. — irradiation for 20 minutes every fourth day, combined with salt water douches; chronic metritis — 10 intrauterine irradiations; gonorrhoea, in the male — 5 or 6 sittings of 15 minutes each; otorrhoea — 10 sittings of 15 minutes; venereal warts — 3 sit- tings). Strebel himself allows that this treatment may possi- bly produce violent irritation of the mucous membrane (inflammatory swelling, pain on micturition, etc.). Even when carried out for a very long time the treatment of lupus vulgaris with electric brush-light does not produce completely satisfactory results. Of this the author has con- vinced himself with his own electrode, which (cf. plate Fig. 7) gives out brush-light very freely. He could, indeed, perceive distinct improvement 1 ) with lupus ulcers, and a visible ten- dency to skin over; but constantly, after a longer or shorter time, there was a relapse. With the forms of light-treatment so far described the ^sources of light used were bodies which were made to shine, i. e., to give out light rays, by their heat energy being raised to the point at which light irradiation begins. As we (p. 385) have seen, besides this there are other kinds of light develop- ment: luminescence, which are produced by external agency, indeed, but with no corresponding rise in temperature. The literature of medicine in the last few years describes various attempts to turn this kind of light to therapeutic account. We might include the induction spark amongst light of this order. The light produced by electricity in the rarefied atmosphere of Geissler tubes is, in spite of its apparent feebleness, good actinically, having a considerable proportion of ultra-violet rays, as has been proved by the researches of Norley,') H. }V . Vogcl, ') Die Verwendung dcr Spannungselektricitat, etc. Referal f. d. VIII Congr. d. deutschen dermatolog. Gesellsch., Berlin, [901. Verhandlungsber., p. 71. 2 ) Photograph. Mittheilungen, 1S71, Vol. VIII, p. 102. 5 i8 RADIO-THERAPY Caprion, 1 ) and others. This light is cold. Strebel availed himself of the photo-chemical property of glow light by con- structing instruments for the irradiation of the cavities of the body, in which helium was used as the gaseous medium. He reports the light from this apparatus as being strongly bacteri- cidal, penetrating the tissues well. He uses this light chiefly for the treatment of affections of the mucous membranes, in simi- lar manner to the light of the induction spark. Certain physiological and therapeutic effects have been reported of another group of luminous phenomena: fluorescence and phosphorescence. By fluorescence we understand a peculiar self-luminosity of certain bodies which is evoked by light rays and lasts only as long as the irradiation. Fluorescence is a peculiar effect of absorbed light. Fluorescent light contains, as a rule, only wave-lengths which are not smaller than those of the light producing it. When, e. g. } we examine the fluorescence of quinine solutions we see that the action which produces the fluorescence is peculiar mainly to the short-waved light. But in this fluorescent light there are also kinds of light of greater wave-length than that of any component of the light producing the fluorescence; there are, however, none of shorter wave-length. The law that fluorescent light cannot contain light of less wave-length than the exciting light does not apply to other substances, e. g., eosin, fluorescin, and naphthaline red. The quality of producing fluorescence is, as we have seen, common to those rays which have the most marked physiological effect (the ultra-violet, Roentgen- and Becquerel-rays) . This is remarkable for the reason in particular that these rays, according to our theories, are not closely related. It seems natural to look for the common source of the physiological action in their power of producing fluorescence; that this is so seems proven: (i) by the capacity of the animal tissues for fluorescence, proved by various investigators, and (2) by the 1 ) Photographed Spectra, London, 1877. PHOTOTHERAPY 519 peculiar biological effect of fluorescent light, as shown by Tappeiner and Raab. H. v. Tappeiner 1 ) induced O. Raab to test the action on infusoria of the fluorescent light obtained by the illumination of phenylacridin. Paramcecicum caudatum in a suspended drop in a damp chamber was the subject of this experiment. It was seen that paramoecia, in an acridin solution ( 1 in 20,000), died in sunlight in 6 minutes, in diffused daylight in about 60 min- utes; but if kept in the dark they were alive after 6,000 minutes (100 hours) . An eosin culture, mixed in an eosin solu- tion ( 1 in 800), arranged in the green part of the spectrum of a powerful electric arc-light, broken up by a quartz prism, showed after two to four hours' exposure all degrees of injury, even to death. The other parts of the spectrum (which induced the fluorescence of eosin but little) had no effect on the culture. When a paramoecia culture in an acridin solution ( 1 in 20,000) was arranged so that all the light reaching it had to pass through a 4 to 5 cm. layer of a concentrated acridin solution ( 1 in 500) the light no longer took effect; the paramoecia were healthy after a week, even when exposed to sunlight. But when a quinine solu- tion was taken as screen the light acted as usual, obviously because now the screen absorbed only the inactive ultra-violet rays, and not the violet rays which produce fluorescence in acridin. This last experiment proves at the same time that it is not the fluorescent light which is harmful, but the process of fluorescence stimulation itself, v. Tappeiner sums up the results of his experiments as follows: Light becomes highly injurious to paramoecia in the presence of acridin, phenylacridin, eosin, and quinine, in solutions in which these substances in them- selves (in the dark) are hardly, if at all, poisonous. This action of light is closely connected with the fluorescent quality of the substances named. The injurious power, however, lies not in the fluorescent light produced, but in the process of its production. O. Raab surmises that we have here a conversion of the ') Miinchener med. Wochen chr., i<)00. No. i. p. 5, and Zeit sell rift f. Biologie, Vol. XXXIX. 5 20 RADIO-THERAPY energy of the light rays into chemical energy, analogous to that of chlorophyll, which also is a highly fluorescent body. There is only this difference, that this conversion is the cause of death to the paramoecia, whereas to plants it is the condition of con- tinued life. v. Tappeiner holds that this kind of light action comes into play with those animal organs and fluids (skin, retina, blood and lymph serum) which have the capacity for fluorescence. He surmises, too, that the cause of the skin inflammation noticed by Wedding 1 ) in beasts fed on buckwheat lies in the fact that substances get into the body which are capable of fluorescence. A species of luminosity very closely allied to fluorescence is phosphorescence (according to Becqnerel, fluorescence is only phosphorescence of very short duration). A large number of bodies, under the influence of powerful illumination, especially from light sources which emit a large amount of ultra-violet rays, radiate a soft light precisely similar to that of fluorescence. In phosphorescence, however, the radiation persists for an appreciable, often even for a considerable, time after the illumi- nation has ceased, whilst fluorescent substances shine only during its continuance. A considerable number of natural and artificial substances have this quality of phosphorescence to an evident extent: among natural phosphorescent bodies ("light-absorbers" and "light-magnets"), we may mention diamonds, calcareous spar, and chlorophane. Artificial phosphorescent bodies include the sulphates of the alkali earths, which are obtained by heating sulphur with limestone, barytes, or strontium salts. Sulphide of calcium, which has a violet phosphorescence, is the best and most brightly phosphorescent substance known up to now. This substance is called after its discoverer "Balmain's luminous colour." The colours of phosphorescent light are not only dependent on the chemical composition of the substances which emit, but they are to a large extent dependent on their physical nature ') Cf. p. 332. PHOTOTHERAPY 521 and their temperature. The intensity of phosphorescent light is increased by heating. Like fluorescent light, phosphorescent light consists of rays of greater wave-length than the exciting light; there is much in favour of the assumption that in phos- phorescent light energy is given off which has been taken from the absorbed light of the exciting light source. We have as yet, unfortunately, no well thought out theory, free from all objections, as to the process of transforming the light move- ment of the exciting light into that of the phosphorescent light {A. Lampa) . The light of the best and most brightly shining phosphorescent substances excited by daylight is comparatively weak; according to Eder, 1 ) when in immediate contact with a bromide of silver gelatine plate, it acts about as powerfully as the light of one normal candle at 50 cm. distance. Phosphor- escent light has always a far weaker effect than the light which excited the phosphorescence. Seebeck and Becquerel discovered the remarkable fact that the yellow and red rays counteract the action of the violet rays, extinguishing, or at any rate, considerably weakening, the brightness produced by them. Whilst fluorescent plates are used to render visible the ultra-violet spectrum (this spectrum producing visi- ble fluorescent rays on the regions whereon it falls), phosphorescent plates are used, according to Becquerel, to make ultra-red visible. If, e. g., one brings into the dark a plate covered with Balmains luminous colour, which has been exposed to daylight and is therefore luminous, the luminosity will disappear where ultra-red rays fall and a negative picture of the spectrum will be given. It is, perhaps, permissible to connect this remarkable fact with certain effects of the red end of the spectrum on animal tissues; all the more since it is proved that certain tissues are capable of fluorescence, and that the process of inducing fluor- escence produces changes in the tissue. Rays of phosphorescent light give in general a continuous *) Ausfiihrl. Handb. d. Photogr., I, i, p. 461. 5 22 RADIO-THERAPY spectrum extending into the blue. The colour of the radiated light is independent of the colour of the exciting rays, i. e., a certain luminous substance gives off always the same light, be the exciting light blue or violet or white. The duration of phosphorescence after illumination varies with different bodies. There is no connection between the intensity of the phosphorescent light and the duration of the luminosity. As may be seen from the tables in Eder's "Recepte und Tabellen fur Photographie und Reproductionstechnik,"page 72; the photographic effect (brightness) of blue phosphorescent sulphide of calcium diminishes rapidly after the light impression has been received. If we take the brightness immediately after illumination as 100, after 18 seconds it will be 56.5; after 45 seconds, 25.1; after 1 minute 35 seconds, 14. 1, etc. The luminous power of phosphorescent colours, too, lessens quickly after the light impression, more rapidly in the first few seconds after insolation than later. After the discovery of the X-rays, H.Becquer el, 1 ) and simul- taneously with him a number of other physicists, expressed the opinion that phosphorescent bodies under suitable experimental conditions may be made to emit dark rays capable of acting on the photographic plate after passing through opaque bodies, and, in consequence, to exercise the same kind of action as Roentgen-rays 2 ) . This induced the author to make some experiments with a view to testing the possible biological effect of phosphorescent light. Herr Hofrath Eder placed at the author's disposal for this purpose a standard light plate. This consists of a layer, enclosed within two glass plates, of the so-called Balmain lumi- nous colour, i. e., of a mixture of sulphur compounds of calcium, barium and strontium, which emit an extraordinarily powerful and long-lasting phosphorescent light. (The duration of the brightness is only relatively long — cf. above.) *) Fourth edition, Knapp, Halle, 1896. z ) Compt. rend., 1896, p. 420. PHOTOTHERAPY 523 To make the phosphorescent plate shine, 2]A cm. of magnesium ribbon was burned and the flame moved to and fro as close as possible to the surface of the glass. The plate then shone out with a very beautiful intense blue light in a slightly darkened room. As the lumi- nosity of the phosphorescent substance lessens rapidly, the illumination with magnesium light had to be repeated every three minutes. A longer piece of magne- sium ribbon was not burned, as the brightness gained by 2 l /> cm. could not be increased. This luminous layer was brought as close as possible to a diffuse culture of staphylococcus pyogenes aureus on agar in a Petri dish, a very shallow dish being chosen for the experiment, in which a threefold thick nutritive medium was poured. A sheet of non-transparent paper, in which a cross had been cut out, was inserted between the culture and the phosphorescent plate. This was done to make it possible to distinguish between the growth of the irra- diated and the non-irradiated parts. For three hours the experiment was continued, the phosphorescent plate being illumined every three min- ute? with a piece of magnesium ribbon i)/> cm. in length, and then laid again on the open dish. During the illumination with magnesium light the culture was, of course, put away in a dark place, so as to be kept unaffected by any action of the powerful chemical rays of the magnesium light. After 3 hours the culture was placed in the incubator. The next day the nutritive medium was covered with a thickly packed even growth, which showed no trace of variety of development. The experiment was repeated in the same way for 6 hours but gave the same negative result, as did also a typhus culture with like treatment. Phosphorescent light, therefore, of the intensity available for these experiments, has no influence on bacterial growth. Quite recently C. Roth has employed the light radiated by 524 RADIO-THERAPY phosphorescent bodies in various affections of the cavities and passages of the body, and has, according to his accounts, obtained favourable results in cases of chronic nasal catarrh. Any result of this kind would appear from the above described experi- ments to be in no wise due, as Roth seems inclined to believe (Zeitschr. f. angew. Chemie), to a deleterious action of phos- phorescent light on bacteria. Looking back on the results of investigation thus far in the realm of phototherapy, we see that, thanks to the work of photo-chemists and physicists and thanks to the initiative of numerous medical men, we already possess considerable knowl- edge of the peculiar qualities and effects of light, and are in a position to turn this force of nature to practical therapeutic account. There remain, however, many great gaps in our knowledge which cannot be filled up without further hard work. Especially does it seem advisable in future, side by side with the close observation of all the circumstances under which the more carefully studied highly refrangible short-waved rays come into action (e. g. } besides the chemical activity also the brightness of the light, the quantitative determination of the absorbed rays, etc.), to study also the manner in which the less refrangible long-waved rays act (e. g., those that penetrate more deeply into the tissues), as well as the way in which various tissues and organs react to illumination with rays from this region of the spectrum. APPENDIX TO THE TREATMENT BY X-RAYS In the endeavour to place the "dosage" of this treatment on a more exact basis, several writers have suggested auxiliary apparatus for denoting the amount of the radiant energy employed (the intensity of the X-rays). As has been pointed out (p. 245), Beclere, Gas ton, On din and others recommend the spintemeter and radiochromometer. We have observed that neither of these instrument: appears to be quite adequate, in the case of the spintemeter for the following reasons: The spinte- meter is designed to give the spark equivalent to the degree of hardness of the tube. But no account is taken of the fact that various induction coils produce varying electric energies, which come into action in equal-sized sparking-distances. Conse- quently a Roentgen-tube of a certain vacuum, inserted in the equally large spark-gaps of induction coils of different con- struction will give rise to varying phenomena. If, c. g., we insert a vacuum tube, which in a voltohm coil of 25 cm. spark- ing-range corresponded to a spark-gap of 7^ cm. into the spark-path of a Dessauer apparatus (which, as is well known, gives more powerful secondary currents), we should have with the Dessauer apparatus a whole sheaf of sparks at a distance (8 cm.) across which, with the first apparatus, no spark could flash. The data given of the spintemeter hold good, there- fore, for the apparatus of the experimenter concerned alone, not necessarily for other apparatus. In order to make the results of the individual apparatus available for all it would be neces- sary to give also the construction of the apparatus, and thereby make it possible to calculate the given values in terms of other apparatus — in any case a matter of some difficulty. It is well known that the X-rays produce certain colours in many substances (Villard, Holzknecht). Holzknecht deter- mines the amount of X-rays absorbed by a certain salt (the 526 APPENDIX composition of which is not given) by comparing the colour resulting in this body from irradiation with a standard scale of shades. From the intensity of the colouring, that is, from the corresponding number in the scale of comparison (H) conclu- sions may be drawn, according to Holzknecht, as to the amount of X-rays absorbed, and, therefore, also as to the probable physi- ological effect of the same amount of rays. In using the chromo-radiorieter, the apparatus is placed on the part of the exposed surface of skin which is most adjacent to the tube-focus. The tube is either kept working at one sitting till the desired darkening effect is reached (this is determined by comparison with the standard scale), or, where the treat- ment is to be extended over several sittings, the apparatus may be packed away in some non-transparent receptacle until the next sitting. If the sittings occupy more than 5 days, the irra- diation may be pushed a little beyond the regulation "dose," since the skin recovers somewhat between the sittings. INDEX Aberration. 378, 379. Absorption of ligbt, 380. Absorption of ultra-violet rays. 388. Absorption-spectrum, 384. Accumulators, 27. Accumulators, capacity of, 29. Accumulators, charging of, 216. Accumulators, discharging of, 218. Accumulators, power of, 29. Acetylene-light. 475. Acne pilaris, 267. Acne vulgaris, 237, 300. Acne rosacea, 300. Actinic rays, 293. Actinium, 351. Actinometer, 375. Adrenalin, 494. After treatment, 235, 278. Aigrette, 115. Albedo. 373. Alopecia areata, 237, 272, 509. Alopecia, persistent, 299. Alopecia, pityroides, 275. Alternating currents, 48. Alternating currents of high frequency, 88. Alternating current machines, 49. Ampere, 22, 32. Amperemeter, 39. Ampere-hour, 32, 46. Amplitude, 51. Analgesia, 166. Anaesthesia, 104. Angle of incidence, 377. Angle of reflection, 377. Angstrom's unit, 383. Anode, 25, 188. Anode-rays, 191, 229. Anti-cathode, 202. Anti-cathode, over-heating of, 202. Arc-lights, 43. Arc-light lamps, 479. 486. Arc-light baths, 488. Armature. 50. Athermanous bodies, 388. Augmenting Index, 14. Aureola, 117. Auromin, 370. Auto-conduction. 100. B Bacteria, influence of Becquerel rays on, 355- Bacteria, effect bf electricity on. 140. Bacteria, effect of high-frequency cur- rents on. i_'d. Bacteria, effect of light on, 401. Bacteria, effect of X-rays on, 305, 312. Balmain's luminous paint, 520. Barium, 351. Battery, electric, 15. Battery, galvanic, 24. Battery connection, 34. Battery poles, 24. Biliary calculi, 304. Bismuth, 351. Bipolar treatment, 101. Blepharitis, 271. Bolometer, 387. Breaks. See Interrupters. Bremer lamp, 487. Brush-discharge, 116. Brush, faradic, 103. Butterfly patch, 298. Cathode, 25, 188. Cathode rays, 159, 187, 231. Cathode rays, nature of, 188. Callus, effect of X-rays, 305. Calorescence, 385. Capacity, 7, 12. Capacity of accumulators, 29, 32. Carcinoma, 294, 302. Cascade-battery, 15. Channel rays, 191. Charging, electrical, 5. Chemical action of light, 303. Chemical action of X rays. 104. Chemical action of Becquerel-rays, 352. Chlorophyl, influence of Becquerel-rays on, 350. Chlorophyl - f unct ion. 396. Chondro sarcoma, 303. Chromoradiometer, 525. ( oinmntator. .)<). Compressors, 493. Concave-grating, spectroscopic, 3')-'. Concentrating apparatus for arc-light, 495. 528 INDEX Concentrating apparatus for sunlight, 508. Condensation, 100. Condenser, 12, 57. Conductors, 3, 19, 20. Constant-current machines, 49. Corpuscles, x, 390. Coulomb, 32. Coulomb's law, 6. Crookes' radiating matter, 189. Cumulative effect of X-rays, 241. Current closed, 32. Current collector, 50. Current interrupter, 64. Curve, chemical, 388. Curve, height of, 388. Curve, thermal, 388. D D'Arsonvalisation, 100. D'Arsonval's apparatus, 93, 95. Dark cathode space, 188. Decade resisting principle, 508. Deflection, 391. Degeneration, vacuolisation, 154, 342, 503. Density, electric, 6. Depigmentation, 241. Dermatitis from Becquerel-rays, 359. Dermatitis from high-frequency cur- rents, 161. Dermatitis from X-rays, 337. Dermatitis from X-rays, prognosis of, 347- Dermatitis from X-rays, treatment of, 347- Dermatitis papillaris capillitii, 229, 237, 270. Dermo lamp, 486. Diabetes, 167. > Diathermanous bodies, 388. Dieletric, 13. Dieletric, constant, 13. Diffraction, 391. Dioptric, 378. Discharge point, 6. Discharge, caterpillar, 120. Discharge, silent, 120, 513. Discharge, oscillating, 16. Disconnector, 60. Dispersion of light, 281, 377. Dispersion of light, abnormal, 390. Distance, influence of, 235. Distance effects, xiii. Drossel-tubes, 215. Dynamos, 37. Dyne, 7. Eczema, 237, 295, 455. Electricity, free, 12. Electricity, bound, 12. Electricity, negative, 3. Electricity, positive, 3. Electricity, friction, 3. Electricity, static, 12. Electricity, voltaic, 19. Electric current, 8. Electric current, magnetic effect of, 45. Electric equilibrium, 12. Electrical oscillation, 87. Electric spark, 13. Electric meters, 46. Electric vibrations, physiological effects of, 163. Electro-dynamometer, 40. Electrolysis, 25. Electrolyte, 25. Electro-magnet, 49. Electro magnetic theory of light, 87. Electro-motor, 52. Electro-motive power, 9, 19, 22, 33. Electrode for monopolar coil-discharges, 149. Electrons, xi, 26. Electrostatic discharge, 116. Electroscope, 6. Electro-therapy, 162. Elements, galvanic, 21, 24. Elephantiasis, 177, 237, 301. Energy, electrical, 7. Epidermis, absorption of light by, 430. Epithelioma, 237, 391, 511. Erythema or Eczema solare, 415. Erysipelas, chromotherapy in, 457. Erythema from X-Rays, 254. Etiolation, 396. Exposure, influence of length of, 235, 245- Extra current. 54. , Eye, effect of Becquerel-rays on the, 361. Eye, effect of light upon the, 436. Eye, effect of magnetic field on the, 184, 310. Eye, effect of X-rays on the, 308. Faradic brush, 103. Farad, 12. Faradisation, 99. 114, 275. Favus, 237, 263. Field, electric, 8. Field, magnetic, 7. Filtration of light, 384. Fissura ani, 179. Fluorescence, 188, 385, 518. Fluorescent-screen, 202. Focus-tubes, 202. Folliculitis barbae, 266, 267. Foucault's currents, 56. Foucault's interrupter, 68, Focus of lenses, 379, INDEX 5 2 9 Franklinisation, 114, 162, 172. Franklin's plate, 14. go. Fraunhofer's lines, 386. Furunculosis, 300. Galvanic current, 21. Galvanic current, heat and light effects of, 41. Galvanization, 163. Galvanism, 19. Galvanometer, 38. Geissler tubes, 89. Generator, 52. Gramme's ring, 50. Grating, 391. Growth movement, 397. H Hair, loosening of, by X-rays, 253. Hair, falling, cause of, 346. Heat rays, ix, 325. 387. Heliotropism, 398. Henoque's method, 107. Hertzian rays, 88. Hertzian waves, 197. High-frequency currents, 85. Hirschmann's electrolytic interrupter, 77- . . Histological investigations, 152. Hot wire instruments, 41. Hyperesthesia, 104. Hypertrichosis, 237, 276. Hyper-ultra-violet rays, x, 364. Hysteresis, 45. Impeding-resistance, 64. Impotence, 173. Incandescent light, 42. Incandescent light baths, 466. Induced current, 48. Induction, 47. Induction, electro, 52. Induction, electro-static, 12. Induction-spark, microbicidal action of. 513- Influence, 7. Ions, 26. [onisation, [96. Intensity, chemical, of sunlight, 451. Intensity, chemical, of artificial light- sources, 464. Intensity, chemical, of electric current, 22, 32. Intensity, chemical, of X-rays, determi- nation of, 240, 245, 247, 525. Intensity, chemical, of X-rays, influence of, 235. 246. Interference of light, 391. Interruption, influence of rate of, 247. Interrupters, 57. Interrupters, electrolytic, 59, 7J> 75, 77, 79. 80. Insulators, 4. Invisible discharge. 117. Irritability movement, 397. Iron arc-lamp, 405, 485, 486, 509. Jar residue, 15. Joule's law, 41. J K Katoptrik, 377. Keratitis, light treatment of. 464. Kohl's electrolytic interrupter. 75. Latent period after light-treatment, 417. Latent period after X-ray treatment, 312. Lead, radio-active, 352. Lead fuses, 41. Lenard rays, 190. Lenses, 378. Lenz's law, 56. Lepra, 237, 294. Levy's interrupter, 70. Ley den-jars, 15. Lichen ruber planus, 298. Light cathode band, 188. Light-power of the sun, 450. Light, 369. Light, stimulating action of, 409, 415. Light, destructive action of, 397. Light-filters, 407. Light and air-baths, 454. Light-sources, 470. Light-strength, 372. Light-rays, 372. Light, electro-magnetic theory of, 370- Light, emission theory, 369. Light, undulatory theory, 369. Light, deflection of, 391. Light, refraction of, 378. Lines of force, magnetic, 8. Luminescence, 517. Lupus erythematosus, 177, 237, 298, 364. 5] 1. Lupus vulgaris, 236, 240, 281, 364, 498. M • Machines, electrical, 17. Magnetic field, physiological effect of, 120. Masks, 260. Magnetic induction, 48, 53. Mas-age electrical, 1 77- Measles, chromotherapy in. 457. 53° INDEX Measurement of electric current, 38. Measurement, technical, 32. Mechanical concussion, 161. Mercury interrupter, 66, 71. Metabolism, influence of high-frequency currents on, 106. Metabolism, influence of light on, 439. Metabolism, influence of X-rays on, 305. Meters, 46. Moist chamber, 407. Monopolar coil discharge, 143. Monopolar voltaic current, 181. Morton's currents, 85. Mucous membranes, 174. Multiple-phase currents, 51. Mycosis fungoides, 237, 294. N Naevus flammeus, 237, 301, 364. Nsevus pigmentosus pilosus, 229. Nsevus vascularis, with light-treatment, 511- Nails, changes in, after X-rays, 340. Neef's hammer, 65. Nervous system, influence of d'Arsonval- isation on, 109. Nervous system, treatment of, 172. Nerves, influence of X-rays on, 305. Neuralgia, 303. Normal candle, 373. Normal candle lamp, 373. Nutation, 398. O Obesity, 167. Ohm, 30, 34. Ohm's law, 33. Opening-spark, 57. Optical axis, 377. Optogram. 437. Osmosis, 215. Osteoperiostitis, 305. Ozone, 325. Parallel connection, 37. Peletier's jars, 396. Pemphigus foliaceus, 298. Penetrator,' 203. Period, 57. Peritonitis, tubercular, 304. Permeating electricity, 182. Phase, 51. Phosphorescence, 188, 385, 520. Photometer, 374. Phototaxis, 478. Pigment changes from X-rays, 252. Pigmentation after light treatment, 420. Pitchblend, 351. Plate, collecting, 12. Plate, condensing, 13. Plate interrupter, 81. Platinum interrupter, 79. Platinum, deposit on Roentgen-tubes, 202. Plant seeds and X-rays, 320. Polarisation of current, 26. Polonium, 351. Pole-finding, 217. Potential, 6, 8, 10. Potential-difference, 9. Primary coil, 52. Protozoa, action of X-rays on, 320. Prurigo, 298. Psoriasis, 237, 296. Quantity, 7, 12. Q R Radiochrometer, 206, 245. Radium, 351. Radium-rays, 190. Ramification of current, 36. Rays, short-waved, 383. Red-room, 456. Reflex-excitability, influenced by X-rays, 305- . Reflection of light, 377. Refraction, 378. Resistance, 30. Resistance, ballast, 31. Resistance, specific conducting, 30. Resistance, unit of, 33. Resistance, external, 34. Resistance, internal, 34. Resonator, Hertz's, 92. Resonator, Oudin's, 95. Resonator, bipolar, Rochefort's, 96. Rheostats, 30. Rheostat lever, 31. Rheotome, 57. Rheumatism, 304. Roentgen-apparatus, installation of, 219. Roentgen-apparatus, depreciation of, after use, 227. Roentgen-rays, 187. Roentgen therapy, 229. Rotary current, 51. Ruhmkorff coil, 57. Sarcoma, 294, 302, 303. Scarlatina, chromotherapy in, 457. Schulmeister's interrupter, 69. Sclerodermia after X-rays, 279. Sclerosis, with light-treatment, 507, 512. Scrofuloderma, 290. Secondary coil, 27, 52. INDEX 53i Seeds, germinating power of, 355. Selenium, 376. Self-induction, 54. Self-induction, co-efficient, 55. Self-potential, 55. Sensitometer, 375. Shimmering light, 117. Short current, 27. Short-circuiting of coils, 227. Shunt circuit, 38. Siemens' double-T-magnet, 49. Siemens' dynamo, 49. Siemens' interrupter, 80. Simon-interrupter, 79. Sinusoidal-currents, 104. Skiameter, 206. Skin, atrophy of after X-rays, 278. Skin diseases, 174. Sleep-movements, 398. Solenoid, 45. Sound waves, 200. Spark-discharge, stimulating action of, 121. Spark-discharge, delay of, 353. Spark-gap, 64. Spark inductor, 56. Spectroscope, 383. Spectrum, 381, 386. Spectrum, cold-lines in, 387. Spintemeter, 345, 525. Staphylococcus, 316. Subjective phenomena after X-ray irra- diation, 255. Sun-baths, 453. Sulphate of lead, 351. Sycosis, 22,7, 2< 56- Sycosis parasitaria, 271. Telangiectasis after X-rays, 279. Tension, terminal, 37. Tension, surface, 7. Tension connection, 15. Tesla-currents, 89. Therapeutical application of high-fre- quency currents, 165. Thermo-electric current, 44. Thermo-pile, 217. Thorium, 351. Thrombosis, 301. Transformer, Tesla's, 88. Transparency of tissues, 425. Transverse vibration, 197. Trichotylosis, 262, 271. Tropho-neurotic theory, 334. Tuberculides, 280. Tubercular ulcers. 290. Tuberculosis of bone, healed under X rays, 304. Tuberculosis with light-treatment, 454, 51J - 1 uberculosis of lungs, treatment by X- rays, 305. Tuberculosis treated by high-frequency currents, 170. Tubes, Roentgen, degree of hardness of, 205. Turbine, mercury interrupter, 69, 72, 73. U Ulcus perforans, 291, 295. Ulcus, rodens, 291. Ulerythema sycosiforme, 267. Ultra-red rays, 383. Ultra-violet rays, 325, 383. Ultra-violet rays, discharging properties of, 195, 390. Ultra-violet light, 190. Unit of resistance, 33. Unit of electro-motive force, 33. Unit of current capacity, 33. Unit of light, 373. Uranium salts, 351. Urticaria pigmentosa, 301. Vacuolisation, 155. Vacuum, 205. Vacuum penetrator, 203. Vacuum. Muller-Uri, 203. Vacuum, Voltohm, 204. Vacuum, M. Levy, 204. Vacuum, Dessauer, 204. Vacuum, with water-cooling, 204. Vacuum-tubes, 201. Vacuum-tubes, adjustable, 208. Vacuum-tubes, regulation of, 208. Vacuum-tubes, arrangement of, 224. Vacuum-tubes, importance of condition of, 242. Variola, chromotherapy in, 457. Verrucae, 301. Visceral complications after X-rays, 307. Vitiligo, 420. Volt, 9, 33. Volta induction, 52. Voltmeter, 39. Voltholm-tubes, 204. W Wehnelt's interrupter, 59. Wheatstone's bridge, 37. Whirl currents, 5(1. Wind, electric, 7, 1 13. Work of electric current, 22, 33. 532 INDEX x X-ray, stimulating effect of, 320. X-rays, elective action of, 284. X-rays, the nature of, 196. X-rays, penetrating power of, 187. X-rays, physical properties of, 188. X-rays action on fluorescing bodies, 187, IQI - X-rays action on photographic plates, 187, 192. X-rays action with varying distance, 192, 196. X-rays, chemical action of, 194. X-ray apparatus installation, 215. X-ray method of treatment, 243. Zeemann's phenomenon, 391. LIST OF AUTHORS Abney, 385. 386, 466, 483. Abraham, P. S., 300. Aducco, 443. Afanasjew, 351. Akopenko. 459. Albers-Schonberg. 77, 205, 248, 259, 266, 269, 282, 286, 289, 296, 327. Ames, 325. Andre, 486, Andresen, 376. Angelucci, 437. Anthony, W. A., 187. Apery, 472. Apostoli, 107, 140, 166, i68, 326, 348. Arago, 1 19. Arloing, 402. Arnold, 414. Aron, 46. Aronstam, N. H., 290. d'Arsonval, 79, 90-95, 100, 104-113, 121, 125, 132, 140, 167, 223. 310, 328. 387, 402, 438. Aschkinass, xv, 199, 319, 354- Auerbach, 412. Aufrecht. 468, 473. Ausset, 304. Axenfeld, 308, 322. Backman, 457. Baedeker, 104, 108- no, 167, 173- Bagge, Ivar, 290. Balmain, 520. Balthasard, 326. Balzer, 279. Bang, 404-407, 449. 463, 4*5. 499, 501, 508, 511. Banister, 239. Barbensi, 512. Bardet, 309. Barlow, 449, 456. Barthelemy, 174, 248, 256, 279, 281, 307, 334. Bary, 352. Basch, no, 114. Batelli, 200. Baudet, 178. Baudouin, 500, 509. Baxendell, 450, 452. Bazy, 304. Beard, 114. Beauregard, 313. Bechard, 442. Bechderews, 427, 443, 459- Beck, 313, 403. Beck, C, 302. Beclard, 409. Beclere, 245, 525. Becquerel, 44, 190, 351, 361, 385, 464, 520. Bedard, 304. Beer, B., 184, 310. Behrend, 29, 252, 279. Beijerinck, 409. Below, 468, 472, 509. Benedikt, 166, 248, 280. Benkert, 457. Benoist, 206, 245, 257. Berg, Otto, 191, 231. Bergman, 248. Bergonie, 304. Berliner, 421, 449, 456. Berlioz, 106, 313. Bernard, 245. Bert, 413, 418, 445. Berthelot, 165, 352, 513-. Berthold, 410. Bertin, 308. Berton, 313. Besnier, 267. Beurmann, 494. Bidder, 442. Bie, 405, 443. 445, 457, 508. Bier, 502. Billings, 403. Bine, 460. Bisserie, 112, 174-177. 180, 248. Black, 449. Blaikie, 313. Blaise. 313. Blanc, 454. Bloch, 363. Blunt, 402. Boas, 69. Boczar, 250, 266. Boeder, 408, 472. Boese, 28. Boisseau du Rocher, 173. Bois-Reymond, 419. Boll, 437. Bollaan, 174. Bolleau, 292. Bolton, 140. Boltzmann, 197. Bonetti, 95. Bonome, III, 140, 313. Bordier, 174, 335, 509. Bordin, 400. Borrisow, 439. Bouchacourt, L., 85, 115. Bouchard. 166, 422. Bowles, 324, 422. Brahams, Ph., 183. Brandes, 309. Bremer, 481. Broca, 239, 486. Brooke, A. G., 294. Brocq, 174-177, 506. Brown-Sequard, 414, 441. Briicke, 418. Buchner, 403, 408. Budge, 414. Budinger, Th., 414, 437. Biittner, 187. Bukofsky, 266. Bum, 167. Bunsen. 24, 375, 464. Burci, 140. Burgsdorf, 508, 511. Burnett, 413. Caffarena, no. Cailletet, 118. Calderone, 265. Caldwell, 79. Camp de la, 294. Campenon, 305. Camus, L., 447. Candler, 472. Capranica, 305. Capriati, 164. Caprioni, 518. Carmichael, 195. Carre, 17. 534 LIST OF AUTHORS Carvalho, 109, 114. Caspari, W., xv, 319. 357- Cattani, 404. Cauchy, 382. Chabaud, 193, 215. Chabry, 174. Chalupecky, 309, 311. Chamberlain, 292. Chanteloube, 304. Chatzky, 164. Charcot, 44. Chardonnet de, 389. Charpignon, 448. Charrin, no, 140, 402. Chassanowitz, 440. Chatin, 486, 500, 509. Chatiniere, 457. Chaves, Br., 271. Chmiliewsky, 402. Ciechansky, 454. Cohen, 414. Cohn, T., 3, 108, no, 140, 168, 173. Clark, 33, 289, 302. Claudet, 458. Cleaves, 472. Colardeau, 207. Colleville, 295, 465. Colombo, 181, 472. Conrad, 238. Corrado, 158. Cornu, 383, 389. Coudres, Th. des, 199. Cooks, E. H., 513. Crookes, 189, 197, 208, 351- Cruet, 167. Curie, 351, 361. Daitsch, J., 441. Dandrieu, 402. Daniel, J., 24, 238. Danielewsky, B. J., 164. Danlos, 363. Darbois, 426. Darieix, 309. Darier, 307, 310, 340. Davenport, 161. Davy, 479. Denoyes, 107. Debierne, 351. Deprez, 65. Descamps, 304. Despeignes, 302. Dessaignes, 426. Dessauer, F., 29, 63-66, 204, 215, 245, 250, 525. Destot, 115, 141, 304. Dewar, 386. Didsbury, 167. Dieudonne, 403-408. Dobereiner, 118. Dogel, 444. Donath, B., 34, 187, 200, 221. Dore, E., 506, 508. Dorn, 354. Dort, van, 290. Doumer, 85, 104, no, 168, 180. Doutrelepont, 288. Downes, 402. Drigalsky, 473. Drossbach, G. P., 389, 405, 484- Drummond, 388. Dubard, 115, 141, 304. Dubois, ill. Ducastel, 290, 304, 497, 509- Duclaux, 402. Ducretet, E., 95, 208. Dumstrey, 280. Dupre, 437. Dworetzky, 408, 443, 459, 463, 478. Ebert, H., 188, 190. Eder, J. M., 187, 192, 205, 230, 324, 335, 356, 369, 375, 386, 394, 425, 450, 458, 462, 465, 483, 521. Edwards, W., 409. Ehlers, 508. Ehrmann, S., 176, 237, 243, 253, 270, 275, 280, 294, 338, 348, 419, 477, 502, 509. Egau, P. R., 290. Einthofen, 105. Eisenlohr, 383. Eijkman, P. H., 302. Eliot, 324. Elster, 351. Engel, 457. Engelmann, 161, 403, 4ii, 437- Ernecke, 65. Escherich, 304. Esselbach, 383. Esmarch, v., 403, 408, 512. Eulenburg, 439. Exner, F., 19. Exner, S., xiii., 386, 419. Faraday, 25, 48, 92, 105, 113, 116. Fatigati, 402. Faure, 27. Feddersen, 16. Feilberg, 457. Feldman, 482. Fere, Ch., 184, 443, 460. Ferguson, 293. Festner, 457. Finsen, U., 25, 48, 92, 105, 275, 284, 369, 405, 410, 417, 421, 426, 430, 438, 449, 455, 458, 463, 478, 483, 488, 492, 498, 501, 506, 509, 512. Fiorentini, 313, 316. Fizeau, 57, 458. Flammarion, 397. Flemming, 176. Forchhammer, 505, 508, 510. Forster, 239, 241, 312. Foucault, 47, 56, 66, 68, 458. Foveau de Courmelles, 85, 169, 186, 239, 245, 290, 310, 325, 327, 449, 474, 490, 496, 509. Frankenhauser, F., 369. Franklin, 90, 94, 119. Frantzius, 313. Fraunhofer, 383, 386. Friedenthal, 140. Frister, 230. Froscani, 140. Fubini, 440. Fuchs, E., 437. Fuchs, S., 310. Gadeau, 279, 364. Gadneff, 426. Gaiffe, 121. Gaillard, 403. Gaisberg, S., v., 481. Gaudil, 171. Garbaso, 200. Gassiol, 188. Gassmann, xiv., 155, 206, 243, 247, 252, 269, 287, 289, 341. Gastou, 174, 250, 257, 266, 269, 306, 500, 509, 525. Gatschowsky, 478. Gatti, 310. Gaugain, 117, 119. Gaule, J., 443. Gautier, 106, 178, 300. Gebhard, 309, 369, 408, 426, 440, 466. Geissler, 89, 188, 402, 517- Geitel, 352, LIST OF AUTHORS 535 Genderen, 437. Genoud. 31 3> 315. 449. 496, 509- Geyser, 289. Giesel. 352-359' Giesson, 152. Gilchrist, 323, 340. Gilmann, John G, 302. Gintl, 198. Giunti, 403. Glatzel, 495. Glebowsky, xiii., 155, 416, 449, 501, 504- Gocht. 187, 2^2. 281, 289, 327- Godnew, 410, 441, 443. Goethe, 444, 460. Gorl, 449, 514. Goldstein, xv.. 114, 189, 336, 352. Golgi. 159. Gorbazewicz, 442. Gottstein, 140. Graber, 413. Graetz, L., 381, 481. Graf, Ch.. 183. Graffenberger, 439, 442. Greiner and Friedrichs, 207. Grenee, 183. Gross, 313. Grouven, 243, 250, 263, 269, 280, 287, 289, 358. Grunmach, 3, 280, 289. 295, 303. 313. 362. Guarinoni, 409. Guelcher, 28, 44. Guichard, 309, 313. Gnillanme, 107. Guilloz, Th., 108. 168. Gundelach, 207, 213. 245. 316. Gyllenkreutz, 440. Hagcn, 28. Hahn, 237, 248, 266, 269, 280. 286. 296. Hall-Edwards, 250, 289. Haller, in. Hallopeau, 279, 364. Hallwachs, 389. I tammer, 422. 448. Hammond, 442. Hankel, 462. Harless, 414. Harrington, 412. ( [arris, 1 [8. Hartley. 38" 1 la\ as, 250, 281. Hegger, 437- , Helmholtz, xi. I [emptinne, A. v., 194. Henocque, 107. Hermann, 184, 421. Merschel, 387. 458. Hertz, H., x, 87, 92, 189, 199- 370. 390. Hertzog, 482. Hess, C, 157. Himmel, 286, 289, 311. Himstedt, F., 120, 352, 361, 437- Hirschmann, W., 72. 77, 212, 245. Hittorf, W., 189. 213, 230. Hodge, 157. Hofmann, K. A., 351. Holetschek, 452. Holland, 290. Holmgren, 437, 440. Holzknecht, G., 190. 237, 273, 313. 319. 334. 445, 525. Hoorweg, L., 105. 1 [oppe-Seyler, 418, 438. Hortatler, 427. II uber. A.. 492. Hueter, 282. Huggin, 386. Humphreys, 391. Ilurtado, G., 512. Huyghens, 369. Hummel, 41. Ishewsky, 183. Jackson, 202. Jacquct, 177, 509. Jadassohn. 290, 508. Jaksch, v.. 460. Jankan, 326, 335- Janowski, 402. Jaquot, 177. Jaumann, xv, 353. Javal, 3 r '-'- Jegorow, 444- Jellinek, S., 158. 160, 165. Jeney, Jersild, O., 509. Johnson, 202. 302. John 1'in, James C, 279. Jo 1 I'd. 1 1 \iv. 243, 321. I. eph, Max. 502. . B., 290, 437. Josing, I.. (<>i Jou 'i. 408. Jutassy, 237, 248, -''id. -77- 281. 289, 295, 300, 34". Kahane, Max. 171, 173. Kaiser, G, 178. 230, 250, 259, 479- Kalischer, 187. Kaposi, 236, 250, 268, 270, 299, 323, 335. Kattenbracker, 468, 472, 5°9- Kaufmann, x, xiii, 196, 199, 206, 354. Ka> ser, xv, 3. 369, 386. Kellog, 449. 466, 468, 489. Kelvin. Lord. 102, 197. Kessler, 478. Kibbe, 340. Kienbock, 205, 237, 242, 248, 257, 272. 275, 281, 305. 312, 319. 329, 338. Kime, 427, 494. Kindler, 169,. 174. King, E. E., 238. Kirchhoff, G, 86, 87, 383. 386. Kiribuchi, 157. Kirmisson, 290, 304. Kistiakowsky, xiv. Kjeldsen, 486, 509. Klemm, 156, 161, 402. Klemperer, 140. Knox, 290. Koch, 403, 502. Korner, R, 3, 369. Kogan, B., 441. Kohl, Max, 99, 121, 223, 250. Kohlrausch, 20. Kolle, 238. Kondratiew, 408, 473. Kopp, 229. Kotliar, 402. Korybnt-naskiewicz, 157 Kreidl, A.. 310. Kromayer, 509. Krohn, 457. Kriiger, 140. Krukenberg, 457. Kruse, 402, 405. Kiihne, 156, 436. Kinnmel, 237, 2X2, 289, 3^7. 507- Kurella, H., 85, 96, 106, [64. Kurlbaum, F.. 204. Kutschuck, 473. Kuznitzky, 183. Labarsch ' )stertag, 140. l.alibr. 107. I acaille, 107. Lahmann, 449. 536 LIST OF AUTHORS Lamberts, 157. Lampa, A. V., ix, x, 3, 391, 521. Lancashire, G. H., 269, 281, 285, 290, 293. Lancaster, 304, 305. Lang, E., 502. Langley, 387, 45 1. Lapinski, 290. Laquer, 474. Laquerriere, 140. Larsen, A. L., 376, 403, 483, 508. Lassar, O., 369, 508. Laulanie, no. Lazat, 106. Learning, 412. Lebon, 506, 509, 510. Lecercle, 306. Leclanche, 24. Lecher, E., xv, 3,87, 120. Leeds, 483. Ledoud-Ledard, 403. Leduc, St., 85, no, 516. Lemstrom, 165. Lenard, Ph., 189, 191, 199, 390. Lengyel, v., 352. Lenz, 49, 56. Leonard, Lester, 210, 326. Leredde, 177, 507, 511. Leroy, L., 72. Lesser, 502, 508. Lewandowsky, 114. Levack, J. B., 293. Levy, Max, 63, 70, 71, 74, 79, 204, 212, 215. Levy-Dorn, 280. Leyden, 15, 513. Liebermeister, 454. Liese, 509. Lindholm, 457. Lion, V., 257, 266, 269, 271, 282, 289, 300, 338, 342. Llaberia, 300. Lodge, 197. Loeb, 395, 410, 413, 442 Loebel, 448. Lowenthal, 439, 471. Loewy, A., 108, no, 168. Londe, A., 72, 187, 201, 203. Lopriore, 320. Lortet, 313, 315, 449, 496, 509. Luebbert, 402. Lugaro, 158. Luraschi, 313. L'Orosi, 141. Mach, L., 494- Macintyre, 238. Mackenzie, 408. Macleod, M. H., 511. Magini, 157. Maier, M., 361. Majorana, 195. Makawejew, 478. Maklakow, 416, 422, 423- Maldiney, 320. Mann, 158. Mangin, 378. Maragliano, V., 105. Marangoni, 193. Marcuse, J., 447. Marcuse, W., 229, 238. Marmier, 141. Marti, 439. Martin, 449. Martinaud, 403. Martre, 107. Mascart, 118. Masch, C, 451. Masson, 119. Mauduyl, 114. Maxwell, Clark, 87, 92, 370- Mehl, 449, 461. Meidinger, 24. Mendelsohn, 140. Meril, 292, 302. Merk, L., 250. Mery, P., 305. Meyer, St., 352. Michelson, 200. Mies, J., 239. Minck, 313. Minich, K., 277. Minin, 472, 478. Mizuno, T., 58. Mohler, 391. Moller, M., 187, 291, 324, 369, 415, 419, 432, 440, 449, 468, 490. Moleschott, 419, 440, 448. Momont, 403. Monckhoven, 464. Mongour, 304. Monseaux, 279. Morgan, 293. Morris, M., 506. Morrow, P. A., 290. Morton, 85, 293. Mosso, 443. Moutier, 109, 168. Miihsam, 313, 316. Muller, 122, 187. Miiller, C. H. F., 208, 395. Muller, E. K., 182. Muller, G. J., 250, 310, 494, 501, 502, 511. Muller, H., 414. Miiller-Pouillet, 3, 369. Muller-Uri, R., 203. Muraoka, ix, 200. Mygind, 457- Nagel, W. A., 361, 487. Narkiewicz-Jodko, 181. Neisser, 283, 288, 502. Neef, 65, 67, 119, 220. Nesnamow, E., 463. Neumann, I. V., 85, 176, 266, 274, 285, 289, 300. Newman, 289. Newton, 370. Nicolou, 257, 270. Niels, 369. Nikolski, 172. Nissell, 159. Nobele, J. de, 290. Norley, 517. Novak, V., 192. Ogneff, 416, 436. Oleinikow, G., 460. Oppolzer, E. v., 451. Ortt, 200. Ott, 149- Otterbein, 449, 461. Oudin, 85, 92-104, 110- 113, 132, 167, 174, 223, 248, 256, 281, 307, 311, 328, 334, 339, 348, 364, 525. Pacinotti, 355. Palaz, 481. Paltauf, 491. Pansini, 402. Parker, 413. Parville, de, 414. Pautier, 457. Payne, 296. Pearsons, 174. Pease, D. H., 140. Pech, van, 441. Peekham, 403. Peletier, 396. Perdu, 454. Perntner, 451. Perpens, 437. Perrin, 196, 199. Petersen, v., 508, 511. Petri, 129, 135. Pettenkofer, v., 408, 441. Pfaundler, 3. Pfeffer, 156. Pfliiger, 105, 157, 184, 188, 436. LIST OF AUTHORS 537 Phisalix, no. Piacentini, 440, 442. Pick, Ph. J., 253, 434. Pickering, 450. Picton, 449, 456. Piorry, 449, 456. Plante, 27. Platten, v., 442. Pleasanton, 461. Pliicker, 184, 188. Poey, 410. Poggendorff, 63, 184. Pokitonoff, 237, 300. Pollak, 28. 81. Poncet, 448, 454. Potonie, 395. Ponza, 444, 460. Porcelli. 355- Porter, 205, 208. Pott, 313, 441. Pollitzer, J., 271. Prausnitz, 408. Pringsheim, 396, 401. Prochownik. 140. Provazek, S., xiv, 243, 321. Pscheidl, W., 3. Pugh, 293. Puluj, 198, 213, 215. Purkinje. 310. Pusey, 187, 250, 281, 289, 293- Queen & Co., 208. Quenisset, 302, 306. Querton, L., 108. Quincke, 440. Raab, O., 519. Radiguet, 59, 95. Radman, G. H., 290. Radzikowsky, 164. Rasch, E., 487. Raspe, 402. Raum, J.. 369, 416, 440, 443. 461. Reale, 108. Regnier, 167. Reichenbach, Baron, 184, 460. Reid, 323, 326. Reinhardt, 414. Reiniger, 31, 71, 85, 250, 486. Remond, A., 85, 115. Rendu, 304. Renzi, de, 108, 473. Reyn, 419. Revillet, 326. Richardson, 403, 404. Richarz, 73. Richer, P., 239. Ridolfi, 119. Riecke, E., 330, 369. Rieder, 174, 313, 327, 369, 454, 467, 473- Riehl, 238. Riess, 119. Righi, 195. Rinehart, J. F., 293. Riviere, 171, 306, 313. Rochefort. O., 96-98. Rockwell. 114. Rodari, 182. Rodet, 308. Rontgen, 191, 196, 201, 507- Roiti, 196. Rona. 289. Ronchi, 441. Rood, 513. Roscoe, 450, 464. Roth, C, 523. Roth, M., 469. Rouillies, 304. Rouviere, 107. Roux. 157, 403. Rubens, x. Rubenstein, 286. Riihlmann, 119. Ruhemann, 403, 472, 481. Ruhmer, 57. Ruhmkorff, 79. Ruotte, 245. Rusconi, 416. Ryn, 508. Sabouraud, 274, 508. Sabrazes, 213, 306. Sack, A., 501, 504. Sagnac, 195. Sainton, 304. Salomon, 279, 346. Salmonsen - Wertheim, 59- Sambuc, 313. Santori, 402. Scharling, 441. Schaudinn, xiv, 320. Schaum, K., 392. Schein, 250, 254, 257, 264, 301, 348, 506. Schell, 289. Schenk, 403. Schenkel, 206, 247, 252, 269, 289. Schickhardt, 403, 408. Schifr, E., 175, 178, 230, 237, 240, 250, 266, 271, 275, 280, 289, 293, 509. Schmid, Ch., 250, 289. Schmidt, G. B., 190, 230. Schmidt, H. E., 442, 499, 501. Schnetzler, 409. Scholtz, 237, 248, 252, 257, 263, 269, 282, 288, 294, 312, 316, 329, 342, 502. Schouli, E., 457. Schrotter, v., 464. Schuckert, 378, 489. Schuler, Th., 457. Schiirmayer, 259. Schulmeister, L., 69, 149, 474- Schumann, V., 389. 494. Schultz, 242, 313, 403. Schweidler, E. v., 353. Secchi, 484. Sederholm, 280, 289, 295. Seebeck, 521. Seifert & Co., 223. Seguy, G., 207, 302, 306. Sehrwald, 193. Sella, 195, 238, 252. Selmi, 440, 442. Sequeira, 291, 508, 511. Serapin, 501, 503. Sharpe, 280, 289, 295, 300. Sholefield, 289. Siemens, W., 49, 121, 48S. Sigaud de la Fond, 114, 223, 250. Simon, 79, 80, 81. Simony, 451. Sinapius, 304. Sjogren, 237, 280, 289, 290, 295. Smirnow, 140. Smith, 289, 293. Sokolovv, 303. Solucha, 427. Sonnenburg, 289. Sorel, 237, 301. Soret, 301. Sormani, 313. Southgatc, Leigh, 304. Spath, 140. Spasski, N., 109. Spicgler, 266, 269, 500. Spieler. 313. Spilker, 114. 140. Spitaler, 452. Squance, J. C, 290. Stahl, 400. Starke, H., 195. Startin, J.. 281. Stein, v., 478. Steinach, 414. Stcmbo, 179, 303. 538 LIST OF AUTHORS Stenbeck, 237, 289, 290. Sternthal, 359. Stokes, 462. Stoney, xi, 199. Storer, 462. Strandgaard, 457. Stratter, 242, 329. Strassburger, 414. Strasser, 469, 471. Strauss, 177, 351. Strebel, 358, 363, 369, 404, 425, 428, 439, 449. 463, 468, 469, 471, 473. 489, 499, 509, 512, Si 7. Strieker, 491. Sudnik, R., 171, 179. Sule, 192. Swendson, 457. Tanger, 346. Tappeiner, H. v., 519. .Tarkhanoff, 306. Taylor, 293, 300. Tesla, N., 86, 88, 89, 90, 108, 120. Thalen, 323, 328, 386. Thayer, 449, 461. Thielee, 178. Thomson, J. J., x, xi, 86, 118, 195, 199, 324- Thompson, E. P., 47, 187, 284. Thouvenin, 320. Thurnwald, 290. Tichomirow, 478. Tieghem van, 397. Tizzoni, 404. Torok, 250, 254, 257, 264, 301, 348, 506. Tolomei, 141. Tommasi, 5 J 3- Tourette, Gilles de, 460. Tripet, 107. Triwus, 443. Trouve, 473, 494, 496. Tschdanow, 179. Tudor, 28. Tuma, J., 328. Turner, 478. Tyndall, 385, 402, 437- Uffelmann, 408. Ullmann, K., 281, 300, 408. Upensky, 478. Uskoff, 412. Unna, P. G., 152, 155, 259, 340, 415, 421, 449, 456. Valenta, E. V., 142, 192, 205, 324, 335, 425, 429- 462. Valenza, 158. Vas, 157. Vedding, W., 487. Veiel, 449, 454, 456. Verworn, 156, 412. Vial, 140. Vieira, 250, 257. Vietti, G., 108. Vigouroux, 114. Villard, P., 194, 245, 354, 525. Villari, 196, 352. Vinaj, G. S., 108. Viola, no. Vogel, H. W., 369, 482, 489, 517. Voigt, 302. Voit, 441. Voller, 77, 189, 192. Volta, 19. Vosmaer, 200. Wade, 313. Wagner, 516. Walker, Norman, 266, 290. Wallentin, J. G., 3- 18. Walkhoff, 358. Waller, A., 397. Walsh, 307. Walter, B., 3, 54, 60, 77, 116, 133, 192, 200, 205. 210, 214, 336, 354, 456. Ward, Marshall, 402, 405, 513. Warnecke, 376. Wassilief, 172. Waterhouse, 459. Waters, 449, 456. Watson & Sons, 203. Weber, 40. Wedding, 420, 520. Wehnelt, A., 59-62, 73- 79, 94, 100, 120, 191, 200, 212, 217, 221, 247. Weichselbaum, A. V., 113, 122. Weigert, 152, 288, 341. Weldor, 302. Widmark, 416, 422, 433, 448, 462, 490. Wiechert, E., 199. Wiedemann, E., 3, 1 16, 119, 188, 385. Wien, W., 199. Wiesner, 396, 451. Wild, 203, 214, 311. Wilke, 217. Wilkinson, 114. Williams, Chisholm, 175, 293- Wimshurst, 18, 120. Winkelmann, 196. Winkler, F., 85. Winogradsky, 408. Winternitz, W., 456, 469. Wittich, 419. Wittlin, 313, 403, 408. Wolters, 421, 449. Wolff," M., 313- Wollaston, 393. Wood, N., 280, 300. Woyzekowsky, 327. Wwedensky, 413. Young, 370, 409. Zarubin, 187. Zechmeister, 250, 271. Zeemann, 199, 231. Zehmann, 347, 391. Zeit, 319. Ziemssen, v., 237, 266 289, 295. NOTES O N INSTRUMENTATION (Published in connection with the English Translation of RADIO-THERAPY, by LEOPOLD FREUND) BY Clarence A. Wright, F.R.C.S.(E.), F\F.P.S.G. Member of the Rontgen Society, and of the British Electro-thera- peutic Society, Associate Editor of the Journal of Medical Electrology and Radiology, etc. ILLUSTRATED 1 NEW YORK REBMAN COMPANY, 10 West 2}r> Strii i, Cor. >th Aveni i. LONDON AGEN l'S : REBMAN, LIMITED [29 Shafti Vvk., London, W. C. 1904 NOTES ON INSTRUMENTATION SOURCE OF ELECTRIC ENERGY.— As the choice of an electro- motor or source of electrical energy is a matter of primary importance, it were well to preface our remarks on the more recent advances in instrumentation by a short preliminary survey of this subject. The question first to be decided by the reader, is the form of treatment that he is desirous of adopting. As far as Phototherapy goes, he must remem- ber that treatment by the Finsen Arc Lamp requires a continuous current of about 80 amperes at 50 volts. A Finsen-Reyn Lamp, in working off the same current, consumes 20 amperes at 55 volts. Lamps of the Lortet-Genoud type on a continuous current supply require only one half this amount of current, but they consume an additional 6 amperes when working off an alternating one. The little Dcrmo lamp of Dr. Bang takes a continuous current of about 60 volts and 5 to 10 amperes. The more powerful and efficacious Strebel Lamp consumes 7 amperes at 50 to 100 volts on a continuous or alternating main. It is evident therefore that the form of apparatus to be used for Pho- totherapy must have a considerable influence on our selection of a source of electrical energy. Again, for Radiography and Radiotherapy, we notice that we require a current of very high electro-motive force (50 to 500 thousand volts), but of small amperage (1.6 to 10 m/a, according to the degree of vacuum of the focus tube). We can obtain the necessary current direct from a static ma- chine, or indirectly by means of some form of Induction-Transformer, which, when actioned by a current of low voltage, will produce in its secondary cir- cuit one of the required tension. Inasmuch as portability, or the amount of floor space available, is a question of moment, Spark Coils will be found by far the most suitable form of apparatus for our purposes, more especially as they can also be turned to account for High Frequency Treatment. For coils yielding a spark of 12 to 16 inches in air — the size most suitable for general use — a current of 4 to 12 amperes at 16 to 80 volts will be required, accord- ing to the form of interrupter employed. It is obvious, therefore, that the source of electricity best suited for practising all these three branches of Physico-therapeutics must be one which can furnish us with a current of 60 to 80 volts at 16 to 20 amperes. The problem, therefore, resolves itself into a consideration of the forms of elec- trical energy capable of furnishing the necessary amount of current. The re- strictions imposed by environment and the conditions of life, under which the practitioner must work, to a large extent determine his choice of a source of electrical energy. In towns, where a current from the commercial main i^ available, he is naturally anxious to use it. In order to do so it is necessary for him to ascertain the nature of the current supplied, whether continuous or alter nating; its voltage, and in the case of an alternating current, its frequency as well. CONTINUOUS CURRENTS.— In working off the commercial mam., where a continuous current of 100 to no volts is supplied, a sliding shunt re sistance or rheostat, -with crank to vary the number <<\ volts, and a small slid ing resistance to regulate the amperage, can with advantage be used. Where a current of higher voltage is laid on, the waste entailed by the use of a rheo- stat i. very great, and it is more advantageous under the circumstances to employ the currenl to work a motor transforflter or to re-charge accumula- 2 RADI0-THERA1Y tors. For the latter purpose a lamp resistance may be introduced into the cir- cuit. As the light of these lamps can be turned to account in lighting a hall, room, or the wing of a house, the large amount of current flittered away in making the carbon filaments incandescent need not add to the expense of working. ALTERNATING CURRENTS.— In working off a street alternating main three methods can be adopted : (a) The tension of the current to be employed can be raised by a step- up transformer, and a Koch rectifier employed to render it uni-directional or pulsating. (b) One or other phase mav be suppressed, and the current rendered uni-directional by a rectifier; and employed to operate the coil or to re-charge accumulators. (c) The current may be transformed by means of a motor-transformer, for use on alternating mains. mulators. (K. Schall, London.) Fig. ib. ACCUMULATORS (Figs, ia and ib).— Where the current from the main is not available, but facilities exist for getting accumulators re-charged. Secondary batteries, with an individual cell capacitv of 45 to 60 ampere-hours, may without detriment be substituted for it. They can be charged by means of hand dynamos or Thermo-piles, the last-named being a source of electrical energy whose possibilities have not yet been developed to its fullest extent. The absolute constancy of the current from the latter source leaves nothing to be desired. They are easily started, work with a minimum of attention, and, with fair use, last for years without requiring any repairs. They can be ac- tioned by the heat from a gas, oil or spirit flame. Although much has been said in favor of accumulators on the score of portability, it must be confessed that they bear transportation badly, being very sensitive to jars, while the buckling of the plates, the dropping of the lead and the frequent reburning that the lugs require are other sources of annovance. Thev are. on the other NOTES ON INSTRUMENTATION 3 hand, admirable as stationary storage batteries. For up-country stations, like India, where labour is cheap, the band dynamo shown in Fig. 2 is to be recom- mended to charge accumulators with. Where gas. oil or petroleum is avail- able as a motive power, a dynamo worked by a y 2 H. P. motor can be em- ploved. CONTINUOUS CURRENT DYNAMO.— In working off an alter- nating street current, or from commercial mains supplying a continuous cur- rent at very high voltages (200 to 300 volts), a rotary converter is an advan- tage. The initial outlay ; s heavy, but it saves the needless flittering away of Fig. _-. I land Dynamo. (Isenthal, London.) current in passing through a shunl rheostat. For working a Finsen \iv Lamp on high voltage mains it is indispensable. The continuous current dynamo is alway> tin mosl suitable installation for up country stations; a gas or petroleum engine furnishing the motive power. PRIMARY BATTERIES. 1 1" this ver) expensive and rather trouble- some source of electricity is selected, il must be noticed that only cells with a very small internal resistance are suitable for the purpose. Even among these, cells where two dil'l'eieiit acids are used, like the I'.uilscn or Grove, re quire too much attention for the purpose. We have, therefore, to fall hack NOTES ON INSTRUMENTATION 5 on the Bichromate cells, whose chief objection is their want of constancy. To obviate this difficulty, care must be taken that the two electrodes are suf- ficiently far apart to allow oi the circulation of a wide stream of acid between them, and also that they be of the largest dimensions possible, with the zinc plates well amalgamated. These precautions taken, the only objection to them is that of expense, which is decidedly greater than that of electricity derived from any other source, currents of high voltage (ioo volts) inclusive. Having so far dealt with the sources of electricity, we may next con- sider Induction Coils and the accessories tending to their proper working, care being taken to point out the factors upon which their efficiency depends, and any drawbacks attending their use. INDUCTION COILS. — Introduced by Masson and improved by Ruhmkorff, the} attained to a very high degree of excellence in the Spottis- ode Coil (Fig. 3), which in 1877 excited the admiration of the scientific world. This coil was furnished with two interchangeable primaries, in one of which the layers were subdivided and could, by a novel mechanical ar- rangement, be connected cither in series or parallel. The secondary of the coil consisted of 280 miles of wire (with a total resistance of 110,200 ohms), wound in four sections, the two outer being of wire of somewhat larger sectional area. Each section was wound in flat discs, of about 200 layers. The total number of turns in the secondary was 341,850. Strange to say, the condenser of this coil was not larger than that usually fitted to coils of much smaller dimensions. It consisted of 126 sheets of tinfoil (18 x 8% inches) sepa- rated by a double layer of varnished paper about one-hundredth of an inch thick. The coil, with 5-quart Grove cells, gave a spark of 28 inches of air; with 10 similar cells one of 35 inches; and with 30 such cells sparks ranging from 27V2 to 42 inches. Tt is evident, therefore, that even as early as the year 1877. the principles underlying the manufacture of large coils were well under- stood in England. Although passable Radiographic work has been done in the field with coils of smaller size, those most suitable for the purpose should yield a spark of 10 to 16 inches in air. In the selection of coils one has first to consider their efficiency, the value of the materials and devices used in their construc- tion, and lastly, the arrangements that exist to fit them to the varying con- ditions of focus tube vacuum, and of the interrupter employed. EFFICIENCY. — The true criterion of efficiency is the amount of elec- trical energy that can be transformed. This quantity is the product of two factors; the electro-motive force and the amperage of the derived current. The former determines the spark length of the secondary circuit; the latter can roughly be gauged by the number, brightness and thickness of the sparks passing between the knobs of the discharger; so that with coils giving sparks of the same length we may say that the one which produces the greatest number of fat. bright sparks, is the best. In deciding this point, it is impor- tant to remember that the volume of sparks of maximum length and intensity must be obtained with a relatively high number of interruptions (800 or more) per minute. CONSTRUCTION OF COILS. (Figs. 4 and 5.) The utility of a spark-coil for heavy discharges depends upon two factors, namely, the perfec- tion of its insulation and the quality of the materials used in its construction. INSULATION of the various parts is -retired by the us,- of hard rub- ber or ebonite tubes; that of the various sections and layers by the use of hard paraffin wax, or better still, by employing a semi-solid viscid hydrocarbon similar to that used as an insulator in tin- Rocheforl Transformer. The in- sulation of the wire- of the primary and secondary is best carried out by using only the besl double silk-coated wire in the construction of these parts. The perfection of insulation, on the whole, may be said to depend upon the exclusion of air, whose inferii>ritj as an insulator to the hydrocarbons is too well known to require comment. Seme makers endeavor to secure this by prolonged immersion of the wire- in melted wax, removing the excess in wind- ing. This plan, however, is too crude to be entirely relied upon, so the various parts, when wound, have to be .main treated to a bath of the same material. Others employ methods better fitted to secure perfect insulation, bul these are 6 RADIO-THERAPY carefully guarded as trade secrets. The use of cotton for coating the con- ducting wires is in every way to be condemned. It is a pity to sacrifice ef- ficiency for the sake of a slight reduction in the price. THE QUALITY OF MATERIALS.— All materials used in the manu- facture of Heavy Discharge Induction Coils should be of the best quality. Soft, well-annealed iron is best suited to minimize loss of power by hyster- esis. Lamination or division of the metal core in a direction parallel to the flow of magnetism, coupled with insulation of the adjacent plates or wires with thin paper, varnish or paraffin wax. will reduce the Eddy currents to an al- most negligible amount. For this reason, it is usual to make use of the best annealed transformer iron wire for the cylindrical core, on which the primary NOTES ON INSTRUMENTATION 7 is wound: insulation against Eddy currents being secured by thorough im preghation with paraffin wax and -parking between the core and primary by binding round with tapes similarly treated. The wires employed for the primary and secondary circuit sin mid be the best annealed double-silk-coated copper, and not cotton-covered wire-, which arc sometimes substituted for the sake of cheapness. Each layer of the primary should be insulated from tho adjacent to it by sheets of paraffined paper, and the primary as a whole further insulated by immersion in paraffin wax. It is for the same purpose carefully separated from the secondary bj a stout tube of ebonite, which is closed in at both ends by discs of the same material. A.s the -train on the dielectric, din- to the difference of potential between the contiguous turn-, is diminished by sectional winding, the sub-division of the secondary into sections, each only a fraction of an inch in thickness, is a point upon which -tress should be laid in ordering coils. Each section when wound should be thoroughly impreg nated by soaking in hot paraffin wax and further insulated from the two ad- jacent sections by a thin disc of ebonite or sleeves of well-paraffined paper. The wire ends should he soldered with resin alone — no acid being used, and the insulation of the joint- strengthened, by binding over with waxed silk. ■ Fig 10-Inch Spark Coil. (IVatson 6 Sons, London.) The coil, when complete, i- usually fitted with ebonite flanges and finished with an ebonite cover, the end- of the secondary wire being a' the same time broughl to two 1,,-;,.-, terminal-, mounted on tin- ebonite cover or on the flanges. To obviate the risk of breakage during transport and to lessen the -train upon the ebonite coating, the coil should he connected with the box- base bv suitable supports. . ■ In some coils each section »f the secondary i- shoped. a- it is wounds over the tube containing the primarv wire, and to tin- tube the ebonite flange are permanently titled.' In other-, the tube bearing the primarj is removable, and can he withdrawn and another inserted (a- in Fig. 6), so a- to make it suitable tor use with various interrupters The latter arrangement also facili- tates the detection and repair of any breakdown in the insulation oi the pi mary, without disturbing the wiring of the secondary circuit. I,, the older type of cod- intended for use with a platinum interrupter on currents of low voltage, the contact -witch (commutator) and sparking pillars are mounted upon the ha-'' hoard of the coil. This arrangement, though well adapted for the purposes for which it was intended, is no longer necessar) The introduction oi the more modern type ol interrupters, work ing 0I1 currents of higher voltage, ha- led to the transfer ol the commutatoi Fig. 6. Large Coil, with Condenser. (Isenthal, London.) Fig. 7. Divided Primary. (Sanitas Elcctl. Co., London.) NOTES OX INSTRUMENTATION to a wall switchboard, where all the other regulatory apparatus are gathered, the sparking pillars being at the same time removed' from the baseboard. The only reasonable plea that can be put forward for the retention of spark- ing pillars, is that they are. when titled with the point and disc discharging terminals, of service in ascertaining the polarity of the current. As this can equally well be established by other means, their use can be easily dispensed with. This arrangement, besides simplifying the coil and reducing its size, commends itself to all on the groundwork of expediency; for it is ever v\ to avoid proximity with the coil in adjusting the contacts. The tendency to convert the base board of the coil into a miniature- switchboard is on the wane (at any rate, in the case of large Coils) and one seldom now sees a large coil, which consists of more than the coil itself and its condenser, each pro- vided with its own terminals. ADAPTABILITY. — The two chief devices for suiting the coil to the varying degree of vacuum in the focus tube and to the various classes of in- terrupters are the arrangement for altering the self-induction of the primary and that for varying the capacity of the condenser of the coil. The arrangements for altering the self-induction of the primary circuit 8. Coil. Divided Primary Carried to Base. (H. IV. Cox, Ltd., London.) Fig. 9. "Vril" Interrupter. of the coil followed the introduction of the electrolytic break. Makers at first tried to meet the difficulty by supplying coils with two or more interchange- able primaries so as to suit the self-induction to the various types of inter- rupters employed, but a more scientific realization of the principle was soon arrived at in the sub-divided primary- the cud of the different layers of which an- carried to separate terminals, which can be connected in parallel or in 50 as to vary the self-induction to the requirements of both tubes and interrupter. A device by which these combinations can be effected is shown in Fig. 7, but a more convenient arrangement is to carry the wires leading to the various layers to the base board, or to the wall switchboard, where the> can be more conveniently altered without approaching the coil. THE SUBDIVIDED CONDENSER (Fig. 8).— The addition of a condenser to a coil was firsl suggested by Fizeau. It was primarily intended to make the break of the primary circuit more sudden and complete by pre- venting the spark (due to the extra current) from passing between the con- tact studs of the interrupter. It also serves another purpose. By accumu lating the energy of the self-induced extra current at "break" and discharging io RADIO-THERAPY it, a moment later, through the primary circuit, it hastens the demagnetization of the core, and thereby increases the E. M. F. of the induced direct current in the secondary circuit. The size and capacity of the condenser are usually proportioned to the maximum length of the spark, but some coils are fitted with a subdivided condenser and a mechanical device whereby each or all of its subdivisions can be thrown in or out of the circuit. This allows of an ex tensive degree of regulation of the size and intensity of sparks obtained from the secondary terminals. The best types of coils possess both these regulations. ACCESSORIES. — The two most important accessories for convenience in working coils are the commutator and the lead fuse, the latter being in most coils conspicuous by its absence. The commutators most commonly used with the spark coil are the Rhumkorif, the de Watteville, the Sicmctis-Halske, the Castcx. In working with modern types of interrupters the commutator. is best mounted with the other accessories on the wall switchboard or upon a table distributor. As much of the efficiency of spark coils depends on the nature of the arrangement for automatically interrupting the flow of the current in the primary circuit, it will be wise to consider them at some length. INTERRUPTERS. — The chief type of interrupters in use at present are : (a) The Vibratory Interrupter. (b) The Rocking Mercury Interrupter. (c) The Mercurv Motor Interrupter \ Notary Jype 1 ( Dipper type / ji -r, -r> . -r, , \ The Brush- Sector Tvpe (a) Ihe Rotarv break - t-.-, ^ - L r ( bum lype (e) The Electrolytic Interrupter -. T ■ • , ;,.'"" J 1 / Liquid lype (/") The Jet Break. VIBRATORY INTERRUPTERS.— The older type of spring platinum Interrupter is rapidly falling into disuse, the few remaining representatives of this class, like the "Vril" Break (shown in Fig. 9), maintain their popularity for small coils by reason of the fine adjustment which, by allowing the core to become nearly saturated before breaking the contact, induces a higher E. M. F.. 111 the secondary circuit. The difference in the electromotive force which can be thus obtained is very great, while at the same time the wear on the contact-studs, by the sparking set up at "break" is reduced to a minimum. It must, however, be remembered that the heat so engendered, even if mini- mized, is not without its effects upon the contact spring, the untempering of which is mainly responsible for the increase of sparking. To obviate this difficulty, the resiliency of the spring is now abolished and the suddenness of interruption at the point of maximum saturation promoted by a simple me- chanical device. A light piece of flat metal, balanced on its edge, is substi- tuted for the movable contact, and is maintained in position, while the cur- rent is passing, by spiral spring, whose tension can be easily regulated. The adjustment for contact duration is thereby increased and the interruptions can be timed to always occur at the phase of maximum induction. The maximum voltage that can legitimately be employed with a plat- inum break, should not exceed 36 volts. For coils yielding sparks of 18 inches and over, every form of platinum interrupter is unsuitable, as the contact surfaces are too rapidly destroyed by the powerful sparking which takes place. In working with these some form of mercury break or more modern interrupters should be emploved. THE ROCKING MERCURY INTERRUPTER is fast becoming an object of antiquarian interest. The best model of this group is the "Interrup- teur oscillant a movement rectiligne" of M. Rochefort. In it the movement of the dipper is perfectly perpendicular to the surface of the mercury, as may be gathered from concentric rings that form upon the surface of the isolating fluid. It can furnish any number of interruptions up to 1.200 per minute. The rapidity of oscillation is regulated by an adjustable weight. The amount of current consumed in working it is very small. NOTES ON INSTRUMENTATION ii Another electro-magnetic interrupter of the dipper typo is that of .1/. Radiguet. In it both the fixed and moving contacts are made of copper, no mercury being employed. It allows of a fair degree of adjustment for contact duration and for speed, and i- by far the best electro magnetic inter- rupter with which I am acquainted. THE MERCURY MOTOR INTERRUPTER (Dipper Type) (Fig. 10). There are several varieties of this interrupter on the market. In all of them an electric motor is employed to effect the dip and withdrawal of a platinum tipped rod from contact with the mercury. In a go.nl interrupter of this type, the dipper should enter quite vertically, so as to prevent the stir- ring up of the mercury, which would interfere with the accuracy of the inter- ruptions. .Most forms of reciprocating breaks allow some degree of regulation for contact duration (by raising or lew Ming the level of the mercury) and for controlling the frequency of interruption (by regulating th< speed of the motor). The motor must he acttoned by a battery or circuit distinct fr< that of the coil. Interruptions ranging from 800 to 1,200 per minute can be obtained, the intensity of the discharge from the secondary terminals being Fig. 10. Dipper Interrupter. (H. IV. Cox, Ltd., London.) most intense. They arc constructed for all E. \i. F. between 12 to too volts, and are almost noiseless in action: hut are open to the same objections that can he levelled against all fornix of mercury break. The mercury after a time requires cleaning; for the intensity of the spark in the contact -pace tends to oxidize it. and by so doing, to hamper the suddenness of the break. This is more especially the case when run with a current of high voltage upon the primary- of the coil. THE MACKENZIE-DAVIDSON INTERRUPTER (Figs, n and 12) i- the sole representative of tin- rotarj metal and fluid contact interrupter on the market. In it. a small motor, fixed in a slanting position, actions the -haft, the metallic blade of which makes and breaks contact with the mercury. The axial rotation of the shafl thus causes the interruptions. The speed o\ the motor and the rate of interruption air controlled by a miniature rheostat. This interrupter is simpler in constructs n than any of tin- dipper type, and runs more quietly, owing to tin- absence of reciprocating motion: hut the ad- justment for contact duration is limited. In tin newer model the position of i-Vip .notor has been altered. When run with 12 to 20 voll on the primary, .1 12 RADIO-THERAPY comparatively small number of sparks are elicited, with a higher speed and a suitable resistance in the circuit, a higher E.M.F. (up to ioo volts) can be employed without breaking down the coil. Where a very high number of Fig. ii. Old Mackenzie-Davidson Interrupter. (H. IV. Cox, Ltd., London.) interruptions must be obtained, the mercury motor breaks of this type yield place to the rotary interrupters. ROTARY BREAKS. — In this class of interrupters, the separation of the contacts is effected by the movement of a revolving disc or drum, actioned by an electric motor. The tendency to spark at break is diminished by sub- mersion of the contacts and drum in petroleum or alcohol. The two chief types of this break are The "Film" Type and the "Brush Sector Contact Break." The Film type consists of a rotary drum fitted with copper segments (with their apices directed downwards) and one or more contact brushes, which press firmly against its curved surface. To insure perfect electrical contact and minimize friction, a film of mercury (pumped from a cell in the bottom of the jar) is spread between the two contact surfaces, which along with the drum are Fig. 12. New Mackenzie-Davidson Interrupter. (H. IV. Cox, Ltd., London.) immersed in paraffin oil. By sliding the rod bearing the brush in a direction parallel with that of the axis of the drum and by regulating the speed of the motor, the relative period of contact and interruption, as well as its frequency, XOTES OX INSTRL MUX T. I TIOX 13 can be altered at will. Every interrupter of this type which is actioned bv a separate motor requires to be started before the current is switched on to the primary of the coil, so as to prevent the damage that the rush of an exces- sive, heavy current might produce. An interrupter of this class is shown in Fig. 13- THE BRUSH SECTOR CONTACT BREAK.— In all types of tins interrupter, the circuit is made and broken by two contact brushes pressing against a segmented revolving copper cylinder. The absence of mercury and the consequent cleansing it entails is an advantage. It is, moreover, perfectly silent in action. There is. however, some wear on the brushes, due to this steady and continuous pressure against the rotating copper sectors. The drum is actioned by an electric motor. The circuit remains closed as long as the two systems of brushes press against the same segment of the cylinder. The rapidity of interruption, which varies from 800 to 1.200 per minute, is L*= Fig. 13. The "Fram"' Break. controlled in part by regulating the speed of the motor, and in part by an adjustment of the movable brush. ELECTROLYTIC INTERRUPTERS.— In this type of interrupters advantage is taken of the interruptions, caused by the increase of current density generating sufficient heat to vaporize the electrolytic fluid and thus produce an insulating sheath about the surface of the anode or at the aper- ture of communication between the inner and outer jars of the Caldwell liquid interrupter. The two chief sub-groups, into which this class is subdivded are (1) The Wehnelt or "Film," and the Simon-Caldwell or "Liquid" interrup- ters. The "FILM" type (Fig. 14). In this type the interruptions are caused by the formation of a film of non-conducting vapor or gas about the active electrode, which is the anode. As the break in the circuil is instantaneous and complete, no condenser is needed. The apparatus lias been said to work with a minimum E. M. F. of 16 to 24 volts; but the besl results are obtained with a current of 50 to 120 volts. The number of interruptions varies with the voltage of the current and the area of the exposed platinum surface, but is always very high. It is important, therefore, that both these factors should be easily controlled, the former by a rheostat, the latter by varying the length and sectional area of the platinum dip exposed. \, the effects are in a meas ure proportionate to the size of the wire employed, interrupters, with three or more wires of different gauges, are an advantage. With a voltage of 40 to 100 volts, it answers admirably for short runs, but if used continuously for 14 RADIO-THERJIV half an hour or more, the acid grows hot until it at length stops the working. To diminish fatigue caused by the excessive generation of heat in the elec- trolyte, a leaden pipe, through which cold water is kept circulating, sometimes forms the passive electrode. In other forms of this apparatus, the container is made very large. Some makers seek to minimize the production of heat Fig. 14. Electrolytic Film. & Son, London.) {Watson Fig. 15. Pinion Interrupter. (Sanitas Electrical Co., London.) by enclosing the break in a large container through which cold water is kept circulating. The substitution of the sulphates of magnesia and of potash alum for the acidulated solution also tends to retard the generation of heat. Interrupters of this type require but little attention and are easily kept in order, but the loud humming noise they make while working is a great draw- back to their use. THE LIQUID ELECTROLYTIC INTERRUPTER (Fig. 15).— This was simultaneous and independently described by Dr. Simon and Mr. Cald- well, in the year 1899. In it the interruptions are brought about by the evap- oration of the electrolyte at the aperture connecting the two chambers. The frequency of interruption is proportionate to the strength of the current, the size of the aperture and to some extent also to the inductance of the circuit. The size of the aperture is altered by the movement of a pointed rod of non- conductive material, thus allowing some control to be exercised over the fre- quency of the interruptions. The liability of the inner tube to be damaged by the unequal expansion of the glass of which it was made led to the sub- stitution for it of perforated porcelain discs, which now form the septum between the two containers. The very considerable heating of the electrolyte during the working of the break, requires some of the various methods mentioned in dealing with "Film" Interrupters to be adopted. NOTES ON INSTRUMENTATION 15 THE JET INTERRUPTER.— In this interrupter a jet of mercury conveys the current, while a revolving drum carrying two or mure metallic segments (according to the voltage of current) makes the circuit by inter- secting this stream. The break is instantaneous and complete. The duration of contact can he varied by raising or lowering the contact plate relatively to the jet. The number of interruptions is easily controlled and can he varied from 800 to 12,000 per minute. This break yields a thicker spark of greater intensity than that obtained by any other method. It is silent in action, and can be adapted to any E. M. F. from 1 _' to 250 volts. A small rheostat controls the speed of the motor, while a large one is usually interposed between the coil and the mains. This is the only interrupter that automatically switches off the current traversing the primary circuit. In the Wodal Interrupter (Fig. 16), the mercury pumped from the reservoir is forced through a number of small apertures arranged axially, instead of a single one. The contact-duration is varied by altering their number by means of a regulating screw. APPARATUS FOR USE WITH ALTERNATING CURRENTS.— To obtain a pulsating or uni-directtonal current in the secondary circuit of an Induction Coil, when a commercial alternating current is the only source of energy available, it is advisable to adopt one of the following expedients: (a ) Convert the alternating current into a continuous current by means of Motor-Generators or Electrolytic Rectifiers. ( /> ) Convert the alternating current into an intermittent current by suppressing one phase by means of an Electrolytic Break, a Synchronized Platinum or Rotary Interrupter. Fig. [6. II mini Interrupter. (Sanitas Electrical Co., London.) MOTOR GENERATORS (Fig. 17).— This is the most perfect and momical way of working with commercial alternating currents. A steady flow of currenl is available and the arrangement an c wers admirably. Its drawbacks are as follows: The initial cost of the installation is great, and the introduction of machinery, which, nnlers carefully erected, in the base menl of the house by preference, mi- Lip vibration. It needs t,, he started at the machine, besides requiring a certain amount of attention for regulation etc. Motor Transformers, 10 he of real service, should have a secondan i6 RADIO-THERAPY output of not less than 300 watts. A rheostat for starting and controlling the speed of the alternating motor is indispensable. ELECTROLYTIC RECTIFERS.— The principle underlying their ac- tion is the great resistance (due to polarization) that the current has to en- counter when the aluminium electrode is the cathode. In its simplest form — Fig. 17. Motor Generator. (Schall, London.) the Graetz Aluminium Carbon Cell — the aluminium is the smaller and active electrode, which polarizes rapidly and offers a high resistance to the passage of the current when it is the cathode; but freely allows the passage of the current when it is the anode. The resistance of each cell is calculated to be sufficient to stop a current of 22 volts from passing. Its efficiency is about 35 per cent, less than that of the supply circuit. The cells in working grow hot, and when a certain temperature is reached polarization ceases. Special precautions have, therefore, to be taken to prevent this. The cells are some- times placed in a zinc container, through which a stream of cold water is kept circulating; but the use of hollow lead pipes (with cold water circulation) as the large passive electrode is to be preferred. A form of electrolytic rectifier, which of late years has attracted much attention, both on account of the sim- plicity of its construction and its high efficiency, is the Nodon Valve (Fig. 18). In it, the active electrode is a slender rod, made of an alloy of aluminium and zinc; while the passive electrode is the iron container. The electrolyte is a solution of phosphate of aluminium, which is deposited as a thin film upon the active electrode, when it is the cathode. This is sufficient to prevent the passage of any current below 22 volts in this direction. When the aluminium is the anode, the current flows freely. The cells heat up slowly when working. When they have been lying idle for some time, a small resistance between them and the mains is needed to start polarization. The number of cells (connected in series) which should be inserted into the primary circuit depends on the voltage employed. The chief advantages of electrolytic rectifiers are : (a) Complete independence of the periodicity of the commercial cur- rent, or of any change in the same. (b) The entire absence "of all noise and motion. (c) The small amount of attention required. (d) Their high efficiency (65%) and low cost as compared with motor generators. NOTES OX INSTRUMENTATION 17 Sometimes the starting-up process is unduly prolonged or quite impos- sible. This shows that the cells require to be cleaned. Apart from the heat engendered by fatigue is that due to defects in the aluminium alloy, the boiling over so caused being often productive of a short circuit. ELECTROLYTIC BREAKS.— Both the "Film" and "Liquid" types are available for use on alternating mains. They act by suppressing one phase of the current. In the WEHNELT type, the current only passes when the platinum is the anode. The chief objection to their use with alternating currents is a great waste of platinum. They are also very liable to fatigue with prolonged working. The current is, moreover, but imperfectly converted into a uni-directional one, unless the primary of the coil is specially wound to allow of a variation of its self-induction. When the CALDWELL type is used, the smaller lead electrode is replaced by one made of aluminium; but even then it is, at its best, only a poor substitute for the more efficient elec- trolytic rectifiers, which it seeks to replace. In the SYNCHRONIZED PLATINUM BREAK the vibration of a bar-magnet, whose movements are synchronized with one phase of the com- mercial current, gives rise to the interruptions. The objections to its use are that it not only wastes one phase of the current, but also is only available for use with coils of small or medium size. It is. besides, rather noisy, requires Fig. is. "Nodon" Valve Rectifier. (Isenthal, London.) much delicate adjustment and frequent attention, as well as presenting all the other disadvantages of the ordinary platinum interrupter. The idea underlying the construction of THE SYNCHRONIZED ROTARY BREAK (Figs. [9 and 20), is to interrupt the current once in either phase and at the moment of maximum intensity. As the circuit is open iS RADIO-THERAPY for one phase only of the current, the flow is intermittent. The rapidity of the interruptions is determined by the periodicity of the main and is capable of no variation. The conditions under which these interrupters attain their maxi- mum of efficiency is where the interrupter-spindle and that of the synchroniz- ing motor are firmly coupled together without any elastic or slipping couplings. Jet Interrupters and Turbinia Breaks, when so coupled together, give the best results. The motor has to be started by a flywheel driven by hand-power until the correct speed is arrived at. It has further to lie adapted to the dynamo which feeds it. If the dynamo runs smooth and maintains a constant fre- quency, the results are excellent; but this cannot always be secured. Another objection to its vise is its great cost. Fig. 19. Synchronized Turbine Interrupter. (Sanitas Electrical Co., London.) STATIC MACHINES (Figs. 21. 22 and 23) are the only direct- source of uni-directional currents of high potential and small amperage, like that required to operate a focus tube; and as such is better fitted for this pur- pose than to charge the condensers of a ///',i:/' Frequency Apparatus. Al- though generally said to derive its efficiency from Frictional Electricity, this popular belief is a very imperfect statement of the truth — at least in the case of modern Influence Machines, which derive the major part of their charge from Electro-Static Induction. For the subtle influence, which one electrified body has on all other conductors brought into proximity with it, has more NOTES ON INSTRUMENTATION 19 to do with their efficiency than the energy derived from friction. The three principal types of Influence Machines in common use are the HOLTZ. the VOSS, and the WIMSHURST. In the Witnshurst machine, both the circular discs, which are about J4 inch apart, are made to revolve in opposite directions; in the Holtz ma- chine, on the other hand, one plate — the larger — is permanently fixed, and has the other revolving much closer to it. In the earlier models the revolving plates were made of glass, whose liability to break when made to revolve at a high speed is mi great thai a sufficient supply of current, steady and ample enough for all purposes, could only be attained by the costly multiplication of gigantic plates, whose very size increased their liability to fracture. The substitution of ebonite and compressed mica plates is an improvement in the right direction, as the increase in -peed make- up for the diminished surface- FlG. 20. Synchronized Turbine Interrupter. (Isenthal, London.) capacity of the discs. The saving in floor -pace thus obtained is an important consideration. The chief type- of IVimshurst machine- upon the market are: ( 1 ) Machine- with multi-sector plate- and simple brushes. (2) Machines with multiple brushes and no sector, and machines of the mixed type, which combine the advantages of both systems- auto-excita- tion, with increased output. The only portable machine of the Witnshurst type with which I am acquainted is that manufactured b\ ,1/. Prault, of Paris. and described by Dr. Beclere in the "Archives d'electricite medicate" (July 15th. 1900). It was especially intended for radiographic work, weighs only 32 kilo-, and pack- away along with all accessories into a case measuring 82 by 87 by 5 ^ cm. ADVANTAGES AND DISADVANTACES OK Tl lb: STATIC MA- CHINE. — The simplicity of its construction, the absence of delicate and com- plicated apparatus, the independence ol the operator oi local contingencies and 20 RADIO-THERAPY circumstances, the minimum of attention required to maintain it in good working order, and the almost perfectly continuous current it produces are among its chief advantages. The low amperage, which unfits it to charge the condensers of a High Frequency machine, the liability of its surface to ac- Fig. 21. Static Film Machine. cumulate damp, and of the metallic sectors to oxidation, the erratic reversal in its polarity (especially when used for radiography), and its liability to electrical leakage and set up brush discharges, coupled with its large size and high initial cost, are among its chief disadvantages. It is better fitted for fluoroscopic examination than for radiographic work, the most probable rea- son being that a high potential difference in the electrical charges on its armatures is more easily maintained with a high resistance focus tube in the circuit than by the use of one of lower vacuum-resistance. To obviate the difficulty of using low-resistance tubes, Drs. Williams and Rollins have in- troduced into the circuit between one or other of the terminals of the tube and the positive or negative leads, a multiple spark-gap — a device which al- lows the radiation of the tube to be very largely modified so as to give hard or soft screenic effects. Before attaching the leads to the terminals of the tube, the polarity of the current should be ascertained by watching the charac- ter of the sparks that pass between the knobs of the dischargers ; these con- verge to a point at the positive, and spread themselves over a wider area at the negative pole. NOTES ON INSTRUMENTATION 21 APPARATUS EMPLOYED IN VIBRATORY ELECTRISATION. In untieing the apparatu- used in the treatment of diseases by currents of high frequency, we can for purposes of classification divide them into four chief gn tups : (a ) Apparatus employed in generating the oscillatory currents. (b) Apparatus employed in raising the tension of the currents of high frequency. ( c' ) Apparatus whose use is peculiar to the individual methods of application. (d) Instruments for measuring the amperage of the currents, etc. (a) APPARATUS EMPLOYED IN GENERATING THE OSCIL- LATORY CURRENTS. — Although Tesla has, by running an alternator with 384 poles at a very high speed (3,000 revolutions per minute), been able to obtain a current with a frequency of 10.000 periods per second, this mechan- ical process has not been generally adopted; the oscillatory discharge of con- densers, on the contrary, is the method most commonly employed. The period of vibration of the currents so obtained is measured by hundred-mil- lionths of a second. The number and arrangement of the condensers vary somewhat in different types of apparatus, but the principle underlying their application is the same in all. In the Carre & Tesla Transformers only one condenser is employed. Fig. 22. High Speed Sectorless Static Machine*. Its armatures arc connected with the secondary terminals of a high intensity spark-coil on the one hand, and with the discharging pillars of an adjustable park-gap on the other; while the solenoid of high frequency, which consists of 12 to 20 turns of stout copper wire, forms part of the circuit of discharge 22 RADIO-THERAPY between the external armature and the pillar of the spark-gap with which it is connected. The Texeira Transformer (Fig. 24) is in many respects the same, with the exception that in it a battery of Leyden jars (2 to 4 in number and con- nected in series) is substituted for the single condenser of which both Carre and Tesla make use. In the D'Arsonval Transformer (Fig. 25), and all modifications of this apparatus, two condensers are employed. The internal armature of each is connected with one of the secondary terminals of the induction coil and with the discharging pillars of the spark-gap; while the external armatures are Fig. 23. Static Machine. (Smith & Wade, London.) united by the small solenoid of high frecpiency formed of 15 to 20 spirals of thick copper wire. The apparatus of O'Farril & Lcbailly (Fig. 26) is a modification of the D'Arsoni'al Transformer in which the solenoid of high frequency is re- placed by a duplex resonator, with which the external armatures are con- nected. An apparatus somewhat similar is the Rochcfort model (Fig. 27), for use with two condensers. In it similar bipolar effects are obtained by the use of two ordinary resonators, the free extremities of their lowest spirals being directly connected with one another. NOTES ON INSTRUMENTATION The apparatus, however, which M. Rochefort most strongly recom- mends is that represented in Fig. 28. Here four condensers, divided into two batterieSj are employed. The internal armatures of these are connected with the terminals of the secondary o\ his transformer, which serves all the 24. I he 1 ex cira Transformer. Fig. 25. The D'Arsonval Transformer. purposes of a spark-coil, but with greater efficiency. The external armatures are connected with the two resonators, after the manner shown in Fig. 27; the use of the small solenoid of high frequency is entirely dispensed with. In all these transformers the capacity of the condensers employed is proportioned to the self-induction and resistance of the circuit, so as to main- C^O Fig. 26. Apparatus >>f O'Farril & Lebailly. Fig. 27. Rocheforfs Model for I Ise with Tw 1 1 ( "( mdensers. tain the oscillatory character of the spark discharges, which are the source of the alternating currents of high frequency. \ Hi. D'Arsonval type of apparatus is by far the most generally em- ployed, we can with advantage study its various parts in fuller detail. 24 RADIO-THERAPY CONDENSERS. — There are two types of condensers used by different makers in the construction of this transformer. The one is the Leyden jar, the other the plate condenser. The former are chiefly employed by instrument makers both in Germany and England ; the use of the latter is at present confined to France. The chief advantage claimed for the plate-condenser is that the dielectric can be more easily obtained of a uniform thickness, so that no undue electrical stress is brought to bear on any point of its coated surface. This lessens the liability of the glass to be pierced by a disruptive discharge passing between its two coats. By submersion in a bath of high- flash petroleum oil, these plate-condensers are rendered less liable to become oxydised, and so preserve their coats intact for longer periods than Leyden jars, which are not insulated in the same way. On the other hand, it has to be noticed that the inductive influence of the charge imparted to the internal armature of the Leyden jars is increased by their configuration, while at the same time the capacity of the jars can be more readily varied so as to alter the frequency of the oscillatory discharges passing between the discharging balls of the spark-gap. Fig. 28. Roche fort's Model for Use with Four Con- densers. Fig. 29. High-Frequency Apparatus, with Square Spark-Box. The Detonator or Spark-box (Fig. 29). — This useful accessory has been given various shapes by different makers, who have endeavored by various expedients to correct the several drawbacks attending its use. The passage of an oscillatory discharge between the knobs of the discharger gives rise to a loud reverberating cackling noise, which is nowise conducive to quieting the alarm of nervous patients. In the attempt to muffle the sound by enclosing the discharging knobs in a glass or earthenware spark- box, it was noticed that nitrous compounds were generated, which, by uniting with the moisture of the enclosed air, formed nitric acid. The deposit of this conducting fluid on the inner surface of the detonator increased the tendency NOTES OX INSTRUMENTATION 25 In its simplest form the spark-box consists of a cubical earthenware or glass box with vulcanite lid. As this does not entirely suppress the dis- agreeable sounds, it was considered advisable to further enclose it in a felt- lined wooden box. which, on account of its efficiency, is well named the silent spark-box. It figures in the apparatus shown in Fig. 30. As the fre- 1 ..,11, minium iiii'taiii at wy.trki-ntuittf iiim*H~ fllh.'-mmimlllllllllll /hSjMiiHlliJJIItiJJJ JIIJll jii iiiiiiifiiffiftfiiiiliiiaiiiiiuiiiiiiiitlllllllllllllll! II! - 1 1 ■"'iiui. ii(Hit ,, im tdkriiuj] llJI' HMU!MMiiil|||j|l|||ilM>>al|ll|{{|l{|i|| Fig. 30. New Model H. F. Apparatus, with Rotary Solenoid and Silent Spark-Box. {I sen thai, London.) quency of oscillation of the alternating discharge depends upon the resistance of the air-gap between the knobs of the discharger, it was considered advis- able to enclose it in a transparent cylindrical glass tube, fitted with vulcanite (felt-lined) caps, as in Fig. 31, through which the distance between the balls could be accurately gauged without opening the lid of the spark-box ; but as the same object can be more accurately effected by means of the graduated ^liiiBiiii"" 1 . 1 """ , I "H'"'''«'"»'»'««« 1111 "ii! (IVatson & Sons, London.) sliding-rod of the Silent Spark-Box there is no real advantage to be gained by the use of glass. The liability of the spark discharge to arc and so destroy the box has been met by the use of a magnalium detonator, which effectually prevents the deposit of moisture upon these surfaces. The movable arm of the detonator is, in the apparatus of some makers, spirally grooved or 26 RADIO-THERAPY threaded, to prevent any unintentional alteration of the distance between the knobs of the discharger, and to allow a finer graduation in its adjustment. The Small Solenoid of High frequency, so named from its intimate association with the armatures of the condensers, consists of 12 to 20 turns of coarse copper or mangano-copper wire, connected through the supporting pillars with the external coats of the condensers. As the amount of current passing into the body of the patient in the bipolar method of direct applica- Fig. 32. Contact Rod Regulator. tion and also in bipolar condensation depends on the self-induction of this circuit, the method employed to vary the number of spiral turns introduced into it is a matter of paramount importance. The five chief methods of control are as follows : The Sliding Contact Rod Regulator (Fig. 32). — This consists of a metallic rod permanently connected with one end of the small solenoid and fitted with an insulating handle By sliding along a groove in the supporting 33. Movable Contact-Point Regulator. Fig. 34. Adjustable Spring Catch. pillar it can touch any desired spiral, and by so doing throw out of the circuit one or more turns of the solenoid. In some models it passes into the in- terior of the solenoid; in others it touches the spirals externally. The tension of the current in the shunt circuit diminishes as the rod is pushed home, and increases as it is withdrawn. The brass tube-regulator that works in the interior of the solenoid of the Carre Transformer is a variation of this method of control. This arrangement allows a certain measure of general control, NOTES OX INSTRUMENTATION 27 dut no finer adjustment; besides this, the rod, when fully withdrawn, is liable to get in the way of the operator. The Movable Contact-Point Regulator (Fig. 33). — Tn this method the movable contact-point slides along a metallic conducting rod (directly con- nected with one of the supporting pillars of the solenoid, but insulated from the other, which also helps to support it). The free extremity, by touching the wire of the solenoid, can establish contact with any desired spiral. This allows of an irregular and somewhat coarse graduation of the intensity of the current, without any marked interruption of its tlux. provided the contact piece be broad enough to touch two adjacent spirals. The Spring Catch (Fig. 34). — This, the oldest and most crude method of control, is in every way objectionable. Every time the catch is removed for readjustment an interruption in the current is produced. An attempt has been made to remedy this by connecting the spring-catch with one extremity of the solenoid. Although in this case the How of the current is never inter- rupted, -till the removal of the catch from a spiral immediately throws into the direct circuit every turn of the solenoid, and as suddenly increases the intensity of the current in the derived circuit. The Revolving Solenoid. — In this form of control the wire solenoid is wound about an insulating wooden or ebonite cylinder, its terminals being attached to the two cheek-plates which serve as the axil of the cylinder. The rotations of the cylinder bring the convolutions of the wire in contact Fig. 35. Rotary Contact Piece. with the sliding contact poinl and allow of complete control over the intensity of the current passing into the derived circuit. Tlie Rotary Contact Piece (Fig. 35). — This type of control is the counterpart of that last mentioned. In it the rotation of a grooved central rod is made to convey its motion to the sliding contact wheel, which follows the gyrations of thr spirals while maintaining perfect contact with them. As the capacity of the wire employed in forming this solenoid is greater than that used on the diminutive revolving solenoid, a liner graduation of con- trol can thus he produced, for both capacity and self induction influence resonance, and by so doing the intensity of the current passing into the shunt lit formed by connection with the terminals of a resonator Ouditl. Of these five regulations, the revolving solenoid and rotary contact piece an th< best form of apparatus, as with them the flux of the current is never interrupted ami the graduation very delicate and line. Tin' intensity of the current in the derived circuit is best measured by the moving coil milliammeter, (b) APPARATUS EMPLOYED IX RAISING THE TENSION OF Till'. CURRENT. As there are time- when it is advantageous to in- 28 RADIO-THERAPY crease the tension of the currents employed in vibratory electrisation, several different kinds of apparatus have been constructed for the purpose. The chief of these are : (i) The Tesla Coil. (2) The Oudin Resonator. (3) The D'Arsonval Bipolar Coil of High Tension. (4) The Spirals of Guilleminot. (5) The Cones of Reus. (1) The Tesla Coil, the first in order of time of the apparatus devised for raising the tension of the current, was invented by Tesla in the year 1891. Fig. 36. The Tesla Coil. (Leslie Miller, London.) It essentially consists of an inner and an outer coil, with the former of which a condenser and spark-gap are connected in series. Both coils and the condenser are usually submerged in an insulating container filled with oil. The primary or inner coil consists of a few turns of stout copper wire, NO TES ON INS TR I 'MEN T. I Tl ON 29 while the secondary or outer is a single layer of many turns of hue copper wire, wound round the primary, from which it is carefully insulated. The apparatus can be fed by either a spark-coil or step-up transformer. It yields a plentiful supply of sparks of any desired length, but the noise made when working is deafening. (2) The On dm Resonator. — Although Herts had previously employed the phenomena of resonance in his experiments, it is to Dr. Oudin that the resonator owes its introduction into electrotherapeutics. He first, in 1892, made use of resonance effects to elevate the tension of currents of high frequency. The apparatus devised by him consists of a large solenoid of uninsulated copper wire, of medium thickness, wound spirally about a ver- tical cylinder of well-paraffined wood. The total length of the wire em- ployed varies from 45 to 60 metres, and its diameter from 2.5 to 3 millimetres. It makes 50 or more turns about a wooden cylinder 40 to 50 centimetres in height and 30 centimetres in diameter; while the distance between the spirals is about S millimetres. As forced resonance is more powerful in its effects than free resonance, the resonator was at first attached to one pole of the solenoid of high fre- quency ; the other pole remained free or was connected to earth. This arrangement, however, was soon modified. It was found that better effects could be produced by connecting both poles with the resonator. A subse- quent modification led to the solenoid of high frequency being suppressed and the resonator directly connected with the external armatures of the con- densers. The lowest spiral of the resonator was then united to one arma- ture, while a spiral four to seven turns above it was connected with the other armature by an adjustable clip. The resonator was thus divided into two solenoids — a lower and an upper. The lower, or primary, solenoid, of small size, consisted of the few turns of wire intercepted between the points of attachment of the two cords leading to the external armatures. In it circulated currents of both high and medium frequency, those of high fre- quency alone being free to pass into the upper solenoid; for the currents of lower frequency were close-circuited by it. The secondary or upper solenoid was longer, and was traversed by currents of high frequency alone; these, by reason of the self-induction ot the circuit, attained an enormous tension. When the three essential magnitudes — capacity, self-induction and resistance — of the two solenoids were by trial proportioned to one another, the upper spirals of the resonator and its free terminal were seen bathed in a lively brush discharge, like to that produced by a Tesla coil or influence machine. This effluve is made use of for therapeutical purposes, by connecting the free terminal of the resonator or one of its upper spirals with the wire lead- ing to the electrode. Although the calibre of the wire, which forms the resonator, does not appear to materially interfere with the production of these resonance effects, yet it ha-, according to Oudin, a considerable influence on the physical character of the effluve and spark. A line wire yields a spark, long, thin, sinuous and scarcely painful, with an effluve as poorly nourished; while with a wire of larger dimensions, both effluve and spark gain in force. This depends on the capacity of the wire rather than its self-induction, for every in- crease of capacity renders the spark more vigorous and painful. The manner in which connection was established between the poles of the primary solenoid of the resonator and the external armatures of the condenser- next attracted attention. It was recognised thai the nature of the arrangement that exists fur this purpose largely influenced the adjustment of the two solenoids ami the regulation of the effects produced. The crude and unsatisfactory method, in which a spring-clip or contact-hook is used to connect the wire from the external armature with the desired spiral soon gave place to others which allowed more perfect regulation and adjustment to be made without in any way interrupting the circuit. Ducretet and Bonnetti in- vented an apparatus in which a grooved contacl slip is made to revoke about a fixed resonator, and thus establish contact with the spirals; while Radiguet caused the resonator itself to rotate before a stationary contact-point. Both these methods allow of a more perfect graduation of effects and an easier 30 RADIO-THERAPY adjustment of the solenoids to each other, without any interruption of contact. The resonators above described, however, are only suitable for pro- ducing unipolar effects. If double effluvation is to be practised, the appa- ratus of Lebailly & O'Farril or that of M. Rochefort must be resorted to. In the former the primary solenoid is centrally situated, the external armatures being connected with two intermediate spirals. This creates two secondary solenoids, which are situated one on either side of the primary, and allows of bipolar applications to be made by connecting the wires leading to the electrodes with the free outer terminals of these two solenoids. Although the apparatus is an improvement on the unipolar resonator of Oudin, still it is not always easy to equalise the current density at the two poles, and for this reason that of M. Rochefort is to be preferred. In the Rochefort model {vide Fig. 28) four Leyden jars are employed. These are divided into two batteries, connected by their internal armatures with the secondary terminal of an induction transformer or spark-coil. The external armatures are connected with two separate resonators, those of each 1 lattery being connected, the one with the lower terminal of one resonator, the other with the uppermost spiral of the primary solenoid of the other resonator. When carefully adjusted, the density of the current traversing each of the secondary solenoids is equalised; and being of opposite sign. Fig. 37. Double Mode! Resonator. (Dean, London.) double effluvation can easily be practised and the effects produced readily controlled. The position of the resonator in the apparatus of different makers calls for a few remarks. In some apparatus, as in Fig. 37, the solenoid stands upright on the cabinet enclosing the condensers and spark-gap; in others, as in Fig. 38, it is permanently connected with the condensers; in others, again, NOTES OX INSTRUMENTATION 3i the resonator is horizontally placed so as to allow its inclusion in a cabinet; and lastly, it may be inverted and fixed by its base to the bottom of the base- board of the high frequency table, as in Fig. 39. As there is no special advantage gained by any of these peculiar arrangements beyond the mere matter of saving space, these eccentricities call only for a passing notice. Much mure important, however, is the arrangement for graduation. The Fig. 38. Single Model Resonator. (Dean, London.) crude method of regulation by the contact clip must only be mentioned to be condemned. The regulation by means of a revolving cylinder, running on rubbered tires, whose movements can be graduated by the movement of a handle, is the one most to be commended. Not less worthy of mention is the model shown in Fig. 40. Here adjustment is effected by revolving the sole- noid bv means of the insulating spokes fixed to the disc at its base. D'ARSONVAL'S BIPOLAR COIL OF HIGH TENSION.— This apparatus is made up of an inner and an outer coil, without any direct com- munication between them. The inner or secondary coil is formed of a single layer of medium-sized copper wire, making many turns about a central insu- lating cylinder. The currents derived from its terminals are employed in double effhiv.it ion. The outer or inducing coil rests on two insulating supports. It consists of four turns of thick copper wire, wound parallel, and at some distance from the inner coil. Its terminals are connected with the external armatures of the Leyden jars. This primary coil can be moved to and fro about the secondary. When centrally situated, the currents derived from the secondary terminals are of equal density and of opposite sign; but as it is made to approach one or other extremity, this proportion becomes altered, so that the density at one pole is increased while that of the other diminishes. 32 RADIO-THERAPY This allows of either bipolar or unipolar effects being produced, or effluva tion to be practised with currents of unequal density. GUILLEMINOT'S SPIRALS.— In resonators formed of wire wound into a helix or solenoid, the energy of the electrostatic field developed by the inducing spirals is only to a very limited extent utilised in the production of induced currents. For the form of the resonator of Oudin does not permit the powerful oscillatory field, created in the vicinity of the spirals, to be em- ployed in generating bipolar currents. Dr. Guilleminot has, however, by changing the form of the resonator from a helix to a spiral been able to utilise the energy of the field in producing bipolar effects. The results of his experiments were published in 1901. The resonator devised by him consists of a spiral of 15 to 20 spires of copper wire held in position by insulating cords which radiate from a central nave to the periphery of the circular frame work which supports it. The innermost spire has a diameter of 20 to 30 centimetres. The distance between the successive spires is about 18 mm. centrally, but somewhat increases towards the periphery. The central extremity Fig. 39. Small H. F. Apparatus, without Solenoid. (Iscntliai London.) of the spiral is connected with the nave, which provides a socket, into which the spider electrode of Truchot can be fixed, or with which any other electrode can be attached directly or by means of a flexible cord. The outer end of the spiral is connected with the binding screw fixed in the supporting frame. Such a spiral can be influenced by currents of high frequency derived from the external armatures of the condensers. The effluve, however, will differ according to the mode of connecting the armatures with the wires of thf spiral. For the central effluve obtained by influencing the outer spirals NOTES OX INSTRUMENTATION 33 is more soft and tractable than that induced externally by influencing the central spires. Bipolar effects can also be produced by placing one or more of the intermediate spirals in circuit with the outer coats of the Leyden jars. With a 16-inch spark coil and a primary current of 6 to 8 amperes, the maximum effect is obtained by connecting the armatures with a single spire. FlG. 40. II. !•".. with Solenoid under Table. This is the condition most favourable to the study of the phenomena of high frequency for the action of the inducing spirals on one another is thereby eliminated. In studying (from centre to periphery) the length of the sparks, which tend to pass between the spires, it is found thai they are least at the centre and increase up to the union of the '-4 internal with the 4 external spires, after which they rapidly diminish in size. These results are constant, what- ever be the intensity of the primary current or kind of spiral employed. The influence of two spirals on each other is equally interesting. The subject can be besl studied in considering separately — (a) The relative influence of an active and a passive spiral approached to each other. 34 RADIO-THERAPY (b) The interrelation of two active spirals which do not reciprocally influence each other. (c) The reaction between two active spirals which mutually affect each other. (a) The relative influence of an active and a passive spiral approached to each other. If the surfaces of the two spirals, brought in relation to each other, be parallel and their centres in the same horizontal line, the influence of the spirals on each other varies according to the direction of their winding. If the two spirals wind in a direction contrary to each other (Fig. 42), the brush discharge which issues from the central spire of the active spiral is diminished on both sides of it. At the same time an intense effluvation is induced about the central spire of the other. The closer the spirals are brought to each other, the more beautiful and intense do the interpolar effects become, a free exchange of effluve taking place between them. Fig. 41. D'Arsonval Bipolar Coil, High Tension. (Schall, London.) These interpolar effects are abolished and effluvation ceases when the central ends of the two spirals are joined by a conducting wire. The connec- tion to earth of the central spire of the passive spiral has but little influence on the effluve derived from the active spiral. When the two spirals wind in the same direction (Fig. 43) very differ- ent effects are produced. The brush discharge about the central spire of the active spiral is but little modified by its proximity to the passive spiral. It is only when the distance between them is less than 20 to 30 centimetres that it becomes asymetrical, being almost absent on the side facing the passive spiral and very vigorous on the side turned away from it. It presents the appear- ance of being blown away by the intensity of the charge induced in the passive spiral, which, however, is very meagre when compared to the free effluvation NOTES OX IXSTRL'MEXTATION 35 observed in the preceding ca-e. It is needless to say that no interspiral phenomena are produced nor doc- effluvation cease when the inner extrem- ities of the two spirals are coupled together. Connection to earth of the A £ ~a Fig. 42. Two Spirals in Contrary Fig. 43. Two Spirals in Same Direc- Directions. tion. central extremity of the passive spiral not only re-establishes the symmetry of the effluve of the active spiral, but also diminishes it. (&) Effects obtained with two active spirals which do not reciprocally influence one another. For purposes of demonstration, let it be supposed that A and B° are the peripheral extremities of the spirals, A and B respec- tively, and A and B* points in their first spires, which mark the end of the inducing circuit and the commencement of the induced, whilst L 1 and L 2 are two batteries of Leyden jars, whose external armatures are connected with the poles of the inducing spires. The effects observed will differ according to the method adopted in coupling the armatures of the condensers with the coils of the spirals, and also with the direction of winding of the spirals. v a Fig. 44. Active, not Influencing One Another. Case I. Where the flow of the current is homologous and centripetal in both spirals.— Here the direction of winding of the two spirals is the same ( Fig. 44). When mounted in quantity, the current derived from L 1 flow- from A to A

    , LI The effects of this mode of accouplement are: (i) The effluvation, which takes place between the central spires of Aw and Ew, is not abolished by connecting their inner extremities; on the contrary, the conductor by which connection is established itself becomes the centre of a lively brush discharge; (2) Connection to earth of the central end of one spiral tends to increase the effluve of the other, and when the spirals are mounted in tension this effluve attains to the length that it would possess had this spiral alone been placed in the circuit, being somewhat less dense, but more soft and tractable. Case II. Where the current flows centripetally in the one spiral and centrifugally in the otber (Fig. 45). — To bring about this result the spirals must wind in contrary directions. They may be mounted either in quantity or in tension. When mounted in quantity the inducing current derived from L 1 flows centripetally from A° to k in the spiral A and centrifugally from B

    L 2 and L 1 B° B

    B° B L 2 . (3) And judging by analogy of effect it will be so when a passive spiral is influenced by an active spiral, wound in the same direction as itself. On the other hand, a difference of charge is observed — (1) When the spirals are mounted in quantity, so that L 1 A° A B° and L 2 are the circuits of the inducing currents circulating in the spirals A and B. (2) When mounted in tension, so that L 1 A° A B<2> B° L 2 is the circuit of discharge between the condenser L 1 and L 2 . .(3). Judging by similarity of effects, when the active spiral is wound in a direction contrary to that of the passive spiral, with which it is in relation. NOTES ON INSTRUMENTATION 37 Effects observed where hvo active spirals mutually influence one an- other. — As the proximity of the spirals to each other and their mode of couplage, under certain conditions, gives rise to similar phenomena, it is evident thai the effects which accrue from a combination of both will be pro- portionately increased. For instance, if the two spirals A and B, wound in contrary directions and mounted in tension (so that L 1 A° A B° L 3 forms the discharge circuit of the inducing current), be approached to each other, tlic mo^t brilliant interpolar effects manifest themselves, and a lively brush discharge takes place between the central spires of A and B. These interpolar effects are abolished and effluvation ceases when the inner extrem- ities — A<;/// London.) tube, Belinger has suggested the use of semi-conductors — a wooden cylinder moistened with glycerine for the metallic coating. Although this method of regeneration is very premising, there is still a vast amount of room for improvement. BY OSMOSIS. — Another and the most promising method of regulat- ing the vacuum of a tube depends upon the fact that certain metals, more especially platinum, when heated to redness, become pervious to hydrogen. If a closed tube o! platinum be sealed into the auxiliary chamber of a focus tube, it will, when cold, be perfectly air-tight, but when heated to redness in the flame of a spirit-lamp, the hydrogen from the flame passes into the bulb, and thus lowers its resistance. As there is no limit to the supply of hydrogen that can thus be passed into the tube, its superiority to other methods i- obvious. The annealing of the platinum, however, requires the utmost care to prevent the possibility of leakage. This type of regenerator 1- largely employed, and a tube with this regulation is slTown in Fig. 64. In some make- of tube, facilities are also afforded for the removal of any excess of <_;a- that has been introduced into the tube, the principle of action being the same. I)K\ K'l'.S FOE COOLING TUIC TARGET.— The heating effects of the cathodic stream upon the anti-cathode placed in the exact focus when used with very strong exciting current- is very greal and it is always advantageous to the life of a tube to employ some device for limiting the excessive develop- menl of heat. The simplest of these is the use of heavy discharge targets, which consisl of a mass of metal faced with platinum, having a large thermal capacity, the tubular projection being often blackened to facilitate the radia- tion of heat from the target. Such a tube i- shown in Fig. 05. It is, 48 RADIO-THERAPY however, more advantageous to employ in conjunction with these a small porcelain disc, which is inserted between the sheet of platinum and the tubular shaft. This arrangement answers admirably, and the life of the tube is much prolonged by its use. The "contrast" tube, shown in Fig. 66, pos- FiG. 65. Heavy Anode Regulating Tube. (Schall, London.) sesses all these advantages. Another method of obviating the difficulty is by using water-cooled tubes, either by means of a water circulation or by making the anti-cathode hollow and filling it with a quantity of water, with a provision for the escape of the steam generated in working. The detrimental effects of the closing spark upon focus tubes when currents of high voltage are employed on the primary of the coil has lately been remedied by the introduction of "valve" tubes, which are inserted in series with the^ tube. The additional outlay this involves is counterbalanced by the saving effected in the increased length of life of the focus tubes. FLUOROSCOPES AND FLUORESCENT SCREENS.— The only two of the many salts that fluoresce under the action of the X-rays that are Fig. 66. Water-Cooled Contrast Tube. (Isenttyal, London.) Fig. 67. Collapsible Cryptoscope. (_H. IV. Cox, Ltd., London.) employed in the manufacture of fluorescent screens are Barium platino- cyanide and Calcium tungstate. The fluorescence of the former is a brilliant yellowish green; that of the latter is bluish-white and not so intense; but on account of its colour, it possesses a greater photo-chemical activity, and is therefore used as an intensifying screen for radiographic work. In the screens of English makes the barium crystals are larger and more thickly spread; in those manufactured on the Continent the coating is more evenly spread. A cryptoscope is a close-fitting box, intended to shut out all extraneous light from the screen. It is sometimes fitted with accordion folds (Fig. 67), NOTES OX INSTRUMENTATION 49 which allow the distance between the eye and screen to be adjusted; but the advantage does not compensate for the increased cost. INTENSIFYING SCREENS.— The fogged appearance of nega- tives obtained by radiographic exposures, more especially of those through the thicker parts of the body, is due. according to I'illard, to the fluorescence of the surrounding air. Of all the various attempts to prevent this by Fig. 69. Bunsen btand Tube Holder. (H. W. Cox, Ltd., London.) Fie. 68. Tube Holder, with Ball Weighl (Watson & Sons, London.) -rz- Frc, 70. Telescopic Tube Holder. {Dean, London.) 50 RADIO-THERAPY accelerating and intensifying the effects of the rays upon the sensitized film, the only method that has hitherto been attended with any measure of success is the use of certain substances which fluoresce when excited by the X-rays and act upon the sensitized film like ordinary light. Owing to the granular state of the fluorescent screen, the resulting radiograms somewhat lack definition, so that minor details, especially of the smaller osseous structures, are effaced. If a platino-cyanide of barium screen be employed for this purpose, the photo-films must first be colour-sensitized by treatment with a .01% solu- tion of erythrosine and drying in a perfectly anactinic chamber. In taking radiograms by this method, the intensifying screen is placed immediately above the film or plate, so that the rays must pass through it before they can act upon the plate. The substitution of amorphous calcium tungstate for the granular platino-cyanide in the preparation of the screen has allowed better skia- graphs to be obtained with ordinary dry nlates. In using such a screen the coated surface is placed in contact with the emulsion of the plate or film, which is placed nearest to the object to be radiographed. By combining the two methods, Max Levy has been able to greatly intensify the effects and proportionately shorten the duration of exposure. He employs a plate or film, coated on both surfaces with a sensitive emulsion, and placed between two intensifying screens. As contact with these gives double density to the negative the time of exposure is materially shortened. TUBE HOLDERS (Figs. 68, 69 and 70).— Although for experimental work the ordinary Bunsen retort holder with heavily weighted base allows of the tube being fixed in any desired position, still, for clinical purposes, we require a stand which will enable us to fix the tube at any height from the floor, and allow it to project far enough from its support to be brought over the operating table or couch. For this purpose a stand with a heavily weighted base and firmly- clamped projecting arm with swivel and ball joint is necessary. The projecting arm, which carries the tube and the connecting wires is always made of wood or ebonite, to prevent any spark from the terminals, in passing into the metal, perforating the tube. A B Fig. 71. High-Frequency Couch. (H. W. Cox, Ltd., London.) For use with overhead coils, and in offices where the amount of floor space is limited, the "WALL BRACKET'* type of tube-holder will be found very convenient ; while for portable installations a telescopic tube-holder is almost indispensable. COUCHES (Figs. 71 and 72). — Whenever radiograms have to be taken of a patient in the recumbent position, a radiographic couch will prove a very NOTES ON INSTRUMENTATION 5i useful accessory. It essentially consists of a strong wooden framework, over the top of which a sheet of canvas, thin leather or other material radioscopically transparent 1- stretched. By placing the tube below the couch, the patient can easily be examined with the fluorescent screen. In taking radiograms, a photographic plate is placed below the screen, and the tube brought as close to the body as is considered advisable. Couches fitted Fig. 72. Mackenzie Davidson Couch. {H. //'. Cox, Ltd., London.) with a plate-holder which can lie brought in contact with the part to be radiographed allows the radiographer to operate to the best advantage; as once the object is fixed with the fluoroscopic screen, no change in the position of the patient or tube is necessary to obtain a good skiagraph. Some couches are especially designed for localisation and stereoscopic radiography. In these the tube holder and plate-rest (although adjustable) are permanently connected with each other in order to maintain a certain fixed relation between the tube and object. The plate-holder is so constructed that the plates may be changed without disturbing the patient or causing him to alter his position, and the holder possesses cross and orientation wires, while both tube and plate-holder move simultaneously so as to bring the latter in relation to the particular part of the body to be radiographed. STEREOSCOPIC RADIOGRAPHY (Eigs. 73, 74 and 75) — Drs. Hedley, Mackenzie Davidson, Imbert and Bertin-Sams have shown that two radiograms taken with tubes 2 r 4 inches apart, when suitably mounted and viewed in a stereoscope, will give an object in proper relief. Radio- graphic stereograms, however, differ from ordinary stereograms in as much as it is immaterial which picture is mounted on the right or left-hand side of the stereoscope, as the change only produces a difference of aspect (i.e., gives the anterior or posterior view). In order to see objects in stereo- scopic relief on the fluorescent screen, two tubes must be placed with their target 2% inches apart. =0 that the distance between them is equal to the distance between the eye-. When, by means of a commutator, the discharge from an Induction Coil is alternately directed into one or other of these, whilst the operator looking through two openings in a screen fitted with a disc sector, which allows the eyes to be illuminated synchronously with the alternations of the discharge in the two tubes, the object viewed ceases to 52 RADIO-THERAPY appear as a flat shadow and stands out as an image which conveys the sense of actuality and relief. It is, of course, essential to the success of these experiments that the two tubes should have the same penetration, so as to excite the same degree of fluorescence in the screen. The trouble is to find two such tubes, and although the difficulty has been partially solved by the use of two bulbs with a medium of communication between them, it is not always possible in working with these to prevent the active tube sparking across to the inert, and thus confuse the shadows. We are therefore restricted to the use of soft tubes of comparatively little penetration, which correspondingly diminishes the fluoroscopic shadow effects. It must, how- ever, be admitted that stereoscopic radiography promises, when development is sufficiently advanced, to be the easiest exact method of localisation. Fig. 73. Stroboscope. (Schall, London.) Fig. 74. Stroboscope, Double Tube. (Schall, London.) DEVICES FOR RESTRICTING THE EFFECTS OF THE RAYS TO PARTICULAR AREAS.— The two chief devices employed for this purpose are ADJUSTABLE DIAPHRAGMS and TUBE BOXES. Adjustable Diaphragms. These consist of a skeleton frame, to which can be fitted, according to the needs of the moment, metallic diaphragms of sheet lead, or of some other equally opaque metal, with a central aperture of the required size. This framework is usually permanently connected with the tube-holder. Among later models we notice diaphragms in which the size of the aperture can be increased or diminished by removing or affixing ring- slips, and others in which this is effected by adjustment of the iris diaphragm. Tube Boxes (Fig. 76). — These are made of wood and lined with several layers of lead-foil similar to that used for lining tea-chests. The interior is insulated against sparking by a thick padding of felt. This arrangement practically prevents the rays from passing out except through a circular aperture, 3 inches in diameter, made in one side of the box. The size of the aperture can be further reduced by means of diaphragms of heavy sheet- lead. In order to prevent sparking from the lead plate a diaphragm of plate- NOTES ( ).V INSTRl T MENTA Tit > V 53 glas> is also inserted. In some models, instead of using lead-toil, the interior of the box is coated with several layer- of lead-paint. The size of the box Fig. 75. Commutator. (Scluill, London.) varies in the models of different makers, some being unnecessarily large anil cumbersome, while other-, arc too small to secure perfect insulation. Attempts Fig. 7''. Bracket Tube Box. (Schall, London > 54 RADIO-THERAPY have also been made by mechanical means to allow the position of the box being altered; but for use with the exploration couch the simpler models are the most efficient. These, when used for therapeutic applications to the face, require to be mounted on a pedestal or attached to a wall-bracket. MASKS. — These protections are made of either lead plates and covered with flannel or paraffined paper, or they are made of gauze or gutta- percha, moulded while warm to the shape of the part and covered with tinfoil. The edge of the holes cut into them being covered over with a layer of paraffinated or shellacked paper. In making exposures in the mouth, pharynx or vagina, a speculum of block tin can easily be improvised. The use of adhesive plaster and of ointments made of bismuth and zinc is only advisable when it is impossible by any other means to protect the tissues against burns. PROTECTIVE SCREENS.— These, in accordance with Elihu Thom- son's directions, are made of aluminium and earthed. They appear to absorb Fig. 77. The Apparatus of Lortet & Genoud. (JVatson & Sons, London.) the softest rays, which exert the greatest influence upon the skin {i.e., setting up a dermatitis) without affecting the more penetrative radiations. APPARATUS USED IN TREATMENT BY CONCENTRATED CHEMICAL LIGHT.— In order to intensify the bactericidal effect of the solar rays and render them therapeutically effective, lenses and mirrors, which concentrate the rays and bring them to the definite focus are used. The appa- ratus which is the more often employed is a hollow bi-convex lens, filled with a solution of methylene blue or ammoniated sulphate of copper, so as to occlude the greater number of heat-rays. The amount of sunlight available for use in northern latitudes being very limited, it has been thought necessary to supply the deficiency by having recourse to artificial illumination. The light best fitted for this purpose is the voltaic arc, for that given out by incandescent lamps contains too few chemical ravs. NOTES OX INSTRUMENTATION 55 As the ray- from an arc lamp are divergent, special apparatus em- ployed must be provided for rendering them parallel before passing through the hollow lens which focuses them upon the part to be treated. The appa- ratus employed for this purpose consists of two cylindrical telescopic tubes, fitted with plano-convex lenses for rendering the rays parallel (the space between them being usually provided with a water-circulation) ; and the hollow bi-convex lens already described for focusing the rays on the part. This extension piece of the Finsen Lamp is mounted upon the metallic support of the lamp. In order to render bloodless the regions submitted to the action of the light, a compressor apparatus, which essentially consists of a slightly convex plate of glass set in a metallic frame, is employed. This is held in position by elastic bands or by being pressed firmly over the part to be treated. THE FINSEN ARC-LAMP consists of an arc lamp of 60 to 80 ampere-, in which die positive carbon is placed above the negative, so that the rays, in passing from the crater, are projected downward and outward. In „SANITAS" ELECTRICAL COMPANY LONDON.W. 75 Soho Square. Fig. 78. Dermo Lamp-. (Sanitas Electrical Co., London.) the axis of the rays issuing from the luminous point are four copper tele- scopic tubes of the kind already described, the lenses of which are made of rock-crystal so as not to intercept the chemical rays, each one being provided with a water circulation for cooling the rays as they pass out. THE APPARATUS OF LORTET AND GENOUD (Fig. 77).— In it the arc-light employed is feebler than in the Finsen, and consumes only 10 to 20 amperes. Tin- carbons are inclined toward- one another. It also 56 RADIO-THERAPY possesses a water circulation. The distal end of the screen is fitted with a compressor lens identical with that of the Finsen lamp. As the arc is brought quite close to the patient, the amount of light wasted is greatly diminished; so that a much larger area of skin can be efficiently treated at each sitting whose duration is at the same time considerably reduced. THE APPARATUS OF DR. SCHALL.— This was intended to allow operators working off the alternating commercial mains to enjoy the same advantages as those using a continuous current. This apparatus can also be used on the continuous current supply. In working off a continuous current the crater-like depression formed in the negative carbon prevents diffusion of the luminous rays ; but in use on alternating current mains both carbons are pointed, so that the light is dispersed equally in all directions. To prevent loss from this dispersion. Dr. Schall has introduced a reflector that can withstand the very high temperature of the arc. It consists of a disc of fine clay, into whose mass some oxide of magnesium has been incorporated. One side of the disc is hollowed out so as to form a cylindrical cavity, in which the points of the carbons protrude. A refractor that can be adjusted by means of a milled screw regulates the distance between the two carbon points, while the intercalation of a third carbon between these establishes the arc. It consumes a current of 8 to 10 amperes at 50 to 60 volts. THE DERMO LAMP OF DR. BANG.— As the amount of ultra-violet rays depends on the chemical composition of the substance of which the elec- trodes are composed, several attempts have been made to turn this factor to Fig. 80. Triplet Lamp. (Sanitas Fig. 81. Spark Lamp. (H. IV. Cox, Electl. Co., London.) Ltd., London.) account. Strebcl has experimented with electrodes of magnesium oxide, aluminium oxide and zircone. He has also made use of aluminium elec- trodes. Right has demonstrated that the electric arc passing between a positive electrode of zinc and a negative electrode of carbon produces purer chemical Ac ) TES OX INSTRUMEN TA TION 57 rays than the ordinary arc ; but it was Bang, the director of the Finsen Institute, who first succeeded in constructing a lamp with metallic electrodes suitable for phototherapy. This lamp is intended to yield a maximum of chemical rays, with a minimum production of heat ; by using iron for the elec- trodes, and reducing their heal resistance by a water circulation. For large lamps the whole of the electrode except the tip is cooled by being plunged in a container filled with water. This lamp is only suitable for the treatment of superficial cutaneous affections, as the rays possess no powers of deep penetration, but expend their whole energy on the cuticle. THE APPARATUS OF BROCHA & CHATIN.— It resembles the Bang Lamp in the use of metallic electrodes, but differs from it in possessing no refrigeration apparatus. It consumes much more current. The electrodes In,. 8_'. Light Bath, with Search-light. (Schall, London.) consist of a positive electrode of carbon with an iron cere and an ordinary carbon negative electrode. It is fitted with an automatic regulator and a metal screen for protecting the operator from the chemical effects of the light. It has four telescopic tubes, three of which air intended for treating patient-, the fourth for viewing the carbons. It consumes 15 to 20 amperes, to the absence of a water-cooling arrangement, one ha-, in using it, t<> rely on very energetic compression (while keeping the patient 3 or 4 inches from the arc ) to \>v>-\ enl burn Mil''. FINSEN-REYN LAMP. This apparatus also combines the advantage of the Ban^r Lamp with the original Finsen arc. Constructed on similar lines to tin- Lortel Genoud lamp, ;t produces better results, as one i nr . imount of ultra violel rays by the use of an iron core for the positive electrode. It requires to be used with a compressor len Till. TKII'I.KT LAMP (Fig. 80). This is distinguished by the 58 RADIO-THERAPY following features: It allows of carbon and iron electrodes to be used either separately or together, so as to produce a mixed light; so that it is equally applicable for the treatment of superficial and deep skin affections. THE STREBEL LAMP.— This is fitted with two positive carbon Fig. 83. Local Light Baths. (Watson & Sons, London.) electrodes with iron cores, and two ordinary carbon negatives, and is pro- vided with a reflector of magnalium, a rock-crystal lens and a water-cooling arrangement. It can be used for both deep and superficial diseases of the cutis. THE SPARK LAMP (Fig. 81).— This apparatus makes use of the Fig. 84. Search Light. (Scliall, London.) oscillatory discharge of a condenser as a source of ultra-violet radiations. The electrodes are of metal enclosed in a circular ebonite case, which is fronted by a compression lens of quartz. LIGHT BATHS (Figs. 82 and 8.3).— The use of light baths for the NOTES OX INSTRUMENTATION 59 treatment of diseases has of recent years attracted some attention. Their therapeutical effects differ according to the source of light-rays. A bath fitted with incandescent lamps produces heating effects alone; while those supplied with arc-lamps in addition supply the more chemically potent ultra- violet radiations. A bath of this nature is shown in Fig. 82. In this model the window is provided to allow the light from a powerful search-light to play upon the body of the patient. To prevent the skin being scorched, the rays are made to pass through a filtering screen of spectroscopieally tested blue glass, cut into narrow strips to allow them to expand under the influence of the heat without breaking. THE KAISER LIGHT TREATMENT (Fig. 84).— Dr. (7. Kaiser of Vienna has found that the blue and violet rays of the spectrum produce only a slight inflammation, and in consequence of this both circulation and metabolism are stimulated. The apparatus used consists of a powerful search- a ^W.WI«.MWta£>Ot*S>--- Figs. 85 and 86. Radium Applicators. (Watson & Sons, London.) light with magnalium reflector, a blue light-filter of spectroscopieally tested glass cut into narrow strips to prevent fracture from unequal expansion, and a hollow lens filled with a solution of methyline blue to which a small quantity of alum has been added. The light consumes a current of 16 am- peres at 55 volts. RADIUM THERAPY (Figs. 85 and 86).— In the experimental appli- cations of radium to diseased structures, the metallic salt is enclosed in a container like that shown in the accompanying woodcut (Fig. 85). The second applicator is intended for making applications to the tongue ( Fig. 86). ISENTHAL & CO 85 Mortimer Street, London, W. The most PERFECT and EFFICIENT INSTALLATIONS FOR Radiography, High Frequency, Electrotherapy, Sismotherapy, Light Baths, Radiotherapy. ELECTRICALLY ^HEATED STERILIZERS and other Medical Appliances and every kind of Electrical Instrument or Apparatus used bv up-to-date Physicians and Surgeons. LOWEST PRICES AND GREATEST SELECTION. Write for our NEW LIST, the most complete ever issued. We are not bound i< one system but can offer you the choice of all the best makes. ELECTRO-THERAPEUTICS. W. WATSON & SONS, "iotXTStT"' WATSON'S HEAVY DISCHARGE INDUCTION COILS For X-Rays, Lupus, Cancer, etc. WATSON'S HIGH-FREQUENCY APPARATUS For Neurasthenia, Rheumatism, etc. WATSON'S SPARK LAMP, LIGHT BATHS AND FINSEN TYPE LAMP For Lupus, Rodent Ulcer, Psoriasis, etc. Write for New Illustrated Price List and full particulars. Post Free on Application. FOR WATSON'S PRACTITIONER'S OUTFIT consisting of 6 inch Coil and "Vril" Contact Break, Accumulator, Rheostat, Tube-holder, 2 Tubes and Fluorescent Screen, complete in travelling case, £29.14.6 RADIOGRAPHY. WATSON'S HOSPITAL OUTFIT consisting of 10 inch Spark Coil and "Vril" Contact Break, Accumulator, Tubes, Tube-holder, Rheostat and Fluorescent Screen .... £42.16.6 Tubes from 18/6 each. Special Tubes for Electrolytic Breaks, 50/ COMPLETE SETS OF HIGH-FREQUENCY APPARATUS FOR HIGH- FREQUENCY CURRENT. only COMPLETE SETS OF HIGH-FREQUENCY APPARATUS, including Coil, Break, etc , from . . . £50.0.0 LARGE CAGE SOLENOID for Auto- induction, as illustrated . 15s ELECTRODES, from . 7/6 Full Instructions given with each Set. £10.10.0 FOR LIGHT THERAPHY. LIGHT BATHS for arms and limbs£5. 10.0 LIGHT BATH for trunk . £9.0.0 SPARK LAMP for Ultra- Violet Light .... £3.0.0 FINSEN LAMP . . £20.0.0 Estimates, Price Lists, Suggestions, post free on application ESTABLISHED 1837. W. WATSON & SONS, mJSffSSHSmt, 313 High Holborn, London, W. C. Branch : ,. t . I 78, Swanston Street, Melbourne, Australia 6, Forrest Road, Edinburgh we P° ls - ] w. W. Scott & Co., 78, Sauchiehall Street, Glasgow "THE SCIENCE OF THE SUNBEAM." THE DOWSING Radiant heat and Light treatment For Rheumatism, Gout, Arthritis, Lumbago, Sciatica, Sprain, Stiff and Painful Joints, and many Disorders of the Digestive Organs. The Dowsing Radiant Heat and Light Treatment is a new and successful method oi applying Light and Meat Rays ol great intensity to tile limbs and parts of the body. This system of treatment differs from all so-called hot-air applications, and it is claimed that greater benefit can be derived from the direct application of Luminous Heat Rays, which in the Dowsing system are thrown direct upon the body. The physiological action of the Dowsing Bath shows the following phenomena: — ( i ) Very marked redness in the skin. Particular excitation of the skin by the chemical (2) Very abundant skin perspiration and the rays and on the other part of pronounced bactericidal elimination of considerable quantities <>: carbonic properties, acid bv the lungs. Special action of the Luminous Rays on the I",) Acceleration of the pulse and increase of tern- red globules of the blood, the number of which perature of the subject : these tun phenomena are increases the oxygenation. less marked in proportion than in Turkish baths. Radiant Luminous Heat is the healing vehicle, par 141 Increase of the volume of solid materials of excellence, for gout and rheumatism, contusions, the urine and urea, and less uric acid. -.plains, etc.: .1 regards arthritis, very bad cases i=o t'.ieaier activity ol" the functions of general have been cured by continued baths. nutrition, and the elimination of organic oxidation FINALLY, among general affections, such as products. arthritis, obesity, anaemic and general debility, all Penetrating power of the heat rays much more are happily influenced i- the action ol Luminous than thai of obscure heat. Radiant Heat.— Le Doctew Gujienot(d , y1ix-les-8ains), The following are some opinions of leading - English Medical Men:— " In the Radiant I hat Electric 1 hat Baths we have an agent which, while supplying all the advantages of other hums of heat baths, possesses something more, namely, the luminous rays. By their use we may derive much of the benefit of sunshine as com- pared to that of other modes of heating." " If one considers for a moment tin- remarkable effects which can be produced by sun baths, it is forced upon the mind that in the luminous rays there are probably therapeutical effects not possessed by the non-luminous." "I consider the ideal source of heat for such a purpose is a luminous one." " The necessity of the human body for light and air i- of universal recognition, people ome anaemic when deprived of light. . . . There are some special therapeutic propel ties iii radiant heat." The Dowsing Apparatus is fully protected by a number of important patents, and the Radiant Heat Treatment is registered. The apparatus is supplied only for use by Medical Men, or Institutions. Hospitals, Nursing Homes, Ac, under their care. We have no agents, and the apparatus is not sold; the object being to prevent It falling into unqualified hands. The Profession is warned against copies and infringements offered as similar to the Dow sing System, the apparatus so made having no therapeutic value whatever. Pamphlets, with extracts from Medical Journals containing full particulars of the svslem, free < THE DOWSING RADIANT HEAT CO., LTD. Registered Office: 24 BUDGE ROW, CANNON STREET, E.C. Chief Estab bntents .<< LONDON, 28 York Place, Baker Street, W. BATH, 5 Oxford Row. BOURNEMOUTH, Glen Fern Gardens. / //. ilment "in also be obtained at i /■• vits : Bath ' m, Balham, I B i Bi hili Bi ■ ham, Bradford, Bristol, Bromlby, Buxton, Cambi i Cheltenham, Cork, Di iblani Eastbourne, ' Gi gov Hasting II itb, Hull, l.i Lbbd I.ivbi i>ooi , dod Wells, Lymington Ma ch k, Newcastle, Norwich, Norwood, Nottingham, Oldham, Oxford, Plymouth, Rudhill, Rvde, Si I ; ■ gh, Shankli , Sheffield, Soi rm : Veils, I - Wa i i r, West Kii hiai l Sp >, Yah I, Yi 'KK. Installation of X-Ray and High-Frequency Apparatus, showing Switch-table from which every- thing is controlled, and apparatus for Magneto 1 heraphy. Total price about £150. Installation for Sinusoidal by Dr. Smith. Galvanic and Faradic Water Baths. Static Machine and Vibrator for Massage. Total price about £100. Electrical Co. Ltd. 7a S0H0 SQUARE LONDON, W. MANUFACTURERS OF Complete Installationsof apparatus forall modern methods of treatment, by Light, Heat, Electricity and Physical Exercise, etc. Electrical Co., Ltd. fa S0H0 SQUARE LONDON, W. The whole of our appli- ances may be inspected in working order in our Showroom. Special Catalogues and detailed information on application. • Installation of Apparatus for Physical Exercise. "Sano" for Rowing, Hill Climbing, Pulling, ,f" a u- u, e °u rot ^ for the motion of Cycling and Horse-riding (combined or otherwise) with the attendant highly beneficial vibration of the whole body : and four other practical appliances for different purposes Total price about £55.15.0 Installation for the treatment of Skin Diseases by the carbon and iron light of the " Dermo " and "Triplet'' lamps and "Combined" Projector. Also Switchboard for Cautery, Galvanisation, Faradisation, Electrolysis, Cataphoresis, etc. Total price about £150.0.0 Installation for Light Bath treatment by "Com- bined" double light Baih with Arcand Incandescent Lamps, and with Projector for additional illumination from outside of actual seat of complaint. Portable Light Baths for local treatment of Trunk or Lime and Bidet for treatment of female diseases by light. Total price about £125.0.0 The various appliances referred to are fully protected by Patents In the United Kingdom and in many foreign countries. 1MPOK TAST ASSOL'SCEMENT JACOBl— A Portfolio of Dermochromes. By Professoi Dr. Jacobi, of Freiburg. Only Edition authorized to be published in the English language. The text trans- lated and adapted by J. J. Pringle, M B., F.R.< P., Physician to the Department for Diseases of the Skin at the Middlesex Hospital, London. I his work contains plates of Dermochromes beautifully reproduced in natural tints by a new Four-Colour. Process, illustrating t lit- Common Diseases of the Skin and Venereal Affections which the General Practitioner has frequent opportunities of observing in Ins daily practice. Each plate is accompanied by a page or more of explanatory text contain- ing practical points m treatment. The work, complete in two volumes, is published at the very moderate subscription price ot $15.00 in halt leather; $16.00 in lull flexible leather with gilt edges, thus bringing it within reach ot all General Practitioners and Students. So/./ only by subscription. A Prospectus and Specimen Piatt will be sent on receipt of card, " Charm of novelty . . . accurate delineations . . . faith- ful and litelike portrayal of flesh tints,"— Journal of Cutaneous Diseases. "Happiest results we have seen . . . Difficult to imagine a more useful atlas."- London Lancet. "Remarkable plates . . . Nothing could exceed the skill with which these plates are reproduced ! "— Medicine. "Surpassing in every respect anything that has previously fallen under our notice." — New York Medical Journal. " We have never seen their equal." — Canadian Practitioner. "Too much praise cannot be bestowed upon them." — American Medicine. " Finest plates ever seen in any work on skin diseases." — California Medical Jout nal. WILLIAMS— High Frequency Currents in the Treat- ment of Some Diseases. By Chisholm Williams, F.R.CS., Edin , etc. Electro-therapeutist to the West London Hospital, etc. Medium 8vo, 238 pages, with 7s illustrations. Price, $2.75. "It is with great pleasure that we welcome the tiist systemati treatise in the English language on the electrU currents ol high frequem j , or more specially the high frequeni . currents • >! d'Arsonval." — rV.':<' Yotk Medical Journal. NEW YORK I < »NDON Kl.BMAN COMPANY REBMAN LIMITED 10 Wis. 23D Strei 1 i=" Shai iiniuiky Avi . WAITE & BARTLETT MFG. CO. 217 East 23d Street, New York, U. S. A. HIGH-GRADE ELECTRO-MEDICAL APPARATUS Static Machine Piffard's High-Frequency Apparatus X=Ray Coil Piffard's~Ultra=VioIet Ray Lamp Piffard's Hand Arc Lamp Galvanic and Faradic Switch Boards for Commercial Currents, Alternating or Direct SEND FOR CATALOGUE ~-4 fm 0^ SPARK COILS for continuous-current with variable self-induction for any tension up to 250 volts. SWITCHING AND MEASURING TABLES with cased-in Wehnelt-Interrupter. SWITCH-BOARDS i n use with intei rupters having several contact pins 01 rotary interrupters. ROENTGEN-INSTALLATIONS foi Mili- tary home and field hospitals I Hie Roentgen-installations in all the hos- pitals of Saxony and a great number of the Prussian hospitals are supplied from my works). ALL APPARATUS and installations for Radio-therapy. STATIC-MACHINES for medical purposes, NEW! Intensity shades and protective spectacles fitted with lead glass; a pre- ventive against tlie bad effects 01 the Roentgen rays. ACCESSORY apparatus for ail purposes. HARDNESS-MEASURE for determining the hardness of tubes. CHR0M0RAD10METER foi dosage in the \-Ka\ treatment Ol lupus. RADIUM-BROMIDE chemically pure, giving astounding u-sults. Enclosed in capsules. Prices on application. etc. Highest efficiency at moderate prices. MAX KOHL, I h a e x m oTy z Estimates, Directions for Use, References, etc., sen/ free on application. NOTICE! Orders can he executed either direct or through the Agency ot Messrs. Isenthal & Co., 85 Mortimer Street, London, W. PLECTRICAL INSTRUMENTS FOR - 5urgieal and jYtedieal Purposes, jVCotoPs, X ftays, Cight ^aths. New Catalogue of over 200 pages will be sent free on application to — K. SCHALL, 35, Great Marylebone Street, LONDON, W. The First and ONLY ORIGINAL Journal ever published on X-Rays ! Annual Subscription $4.00 in Advance. PRICE, 36 CENTS NET With Postage, 40 cents" No. 44. ARCHIVES /9 m OF THE ROENTGEN RAY AND ALLIED PHENOMENA {Formerly Archives of Skiagraphy) PUBLISHED BY REBMAN COMPANY, 10, West 23rd St., NEW YORK REBMAN, LIMITED, 129 Shaftesbury Ave., London, W. C. CONTENTS. EDITORIAL: page Sir Oliver Lodge's Lectures 159 ORIGINAL ARTICLE: Lectures to Medical Practi- tioners on Physics Applied to Medicine. By Sir Oliver Lodge, F.R.S. Lecture I. On Rays in General . . . 1 SQ ITEMS OF INTEREST: Treatment of Cancer . .104 X-Ray Treatment of Cancer of the Uterus . . .164 THE ROENTGEN SOCIETY MEETING, NOVEMBERS, 1903. By Mr. Leslie Miller : Improvements in Induction Coils and High-Freojjency Resonators High-Frequency Apparatus . .65 1O9 THE ROENTGEN SOCIETY MEETING, DECEMBER 3, iqov 17', THE ROENTGEN SOCIETY MEETING, JANUARY 7, 1904. The Revelations of Radium. By Dr. George B. Batten DESCRIPTIONS OF PLATES '73 182 PLATES. PLATE CLXXXyil. Radiograph of Hand, Showing Injected Arteries. By A. G. Fryett, F.R.M.S. (Melbourne, Australia) PLATE CLXXXVII. Stereoscopic Radiographs of Elbow Joints, Arteries Injected. By A. G. Fkyett, F.R.M.S. (Melbourne, Australia) Size of Journal: Royal 4T.0, or 12^ x 10 inches. John J. Griffin & Sons, LIMITED. Makers of SCIENTIFIC APPARATUS. STATIC MACHINES IN \\ IMSHURST MACHINES FOR X=RAY WORK. INDUCTION COILS, MEDICAL MAHOGANY CASES coils, electrodes. FOR HAND OR MOTOR DRIVE. X = RAY TUBES, THERAPEUTIC TUBES, RADIUM. 2 2 6 Sardinia Street, LINCOLN'S INN FIELDS, LONDON, W. C. 433 STRAND, LONDON MANUFACTURER of Optical. Mathematical and Philosophical Instru- ments to the Government Departments. Apparatus for X-Ray Work, etc. INDUCTION COILS, APPS'S PATENTED INSTRUMENTS, small and large sizes, very highest efficiency and durability. All instruments guaran- i. All sizes i in. to 30 in. stocked. FOUR FEET SPARK COILS to order. SPECIAL PATTERNS will be made to order, including Pointless Sec- tions and Winding, Flat, also Conical, my 1868 Patterns, 4,000 ohms Resist- ance, io-in. Coils to order. IMPROVED MERCURY BREAK, £6 6 . This can be fitted to any Indu< 1 ion Coil. HOSPITAL X-RAY SETS, complete in every detail, from .£25 each. The "Model" set of X-Ray apparatus adopted for South Africa during the late war. with Batteries, Steam Motor, etc. HIGH-FREQUENCY APPARATUS ol the latest patterns. A SPECIAL SERIES OF COILS without Contacl Breakers, et< . specially mounted in a plain bul very durable manner, about two-thirds oi cata- ■ pi ii es. Any of the above Coils fitted so as to work with 100 or 200 volts. PRICES PER RETURN OF POST. X-RAY AND HIGH FREQUENCY APPARATUS. As supplied by us to H.M. Government, Middlesex Hospital, King's College Hospital, The General Hospital, Birmingham, The Cancer Hospital, Fulham ; and the Leading Hospitals and X=Ray Workers throughout the World. We are the Actual Manufacturers, and Guarantee all our Coils against Breaking Down. Extract from a letter from a large Medical Institution, referring to Coil and complete Accessories : — " You will, I am sure, be glad to know that the apparatus you fixed up for us gives every satisfaction; a great deal of work has been done with it." COX'S PORTABLE COMPLETE OUTFIT as supplied to H.M. Admiralty, War Office, the new Royal Yacht, and in use by a large number of Hospitals and General Practitioners in all parts of the World. HIGH FREQUENCY APPARATUS. N.B.— Our INDUCTION COILS and APPARATUS are not only less costly than other makers', but give results unexcelled by any of them. Our Illustrated List with Instructions upon How to Work siutftee. Lessons given in X=RAY and HIGH FREQUENCY WORK. HARRY W. COX, Ltd. 9, 10 and 11, CURSITOR ST., CHANCERY LANE, LONDON. ucs SOUTHt^ag F&C\l^, »7 000 2 22175 2