/( REESE LIBRARY OF THE UNIVERSITY OF CALIFORNIA. Received Accessions No. <&&0/ Shelf No. .. THE VOLTAIC ACCU M ULATOR AN ELEMENTARY TREATISE. BY EMILE REYNIER. TRANSLATED FROM THE FRENCH BY J. A. BERLY, C.E., A.I.E.E., ETC. WITH SIXTY-TWO ILLUSTRATIONS. E. & F. N. SPON, 125, STRAND, LONDON. NEW YORK : 12, CORTLANDT STREET. 1889. PREFACE. THIS Treatise describes, in a didactic manner, the whole of the practical and scientific acqui- sitions made, in the domain of the Voltaic Ac- cumulator, from Plante to our days. It brings together, summarises, explains, and classifies the notions, theories, and inventions relating to secondary currents, and reviews the principal applications of the lafter. It is an elementary work, with an easy begin- ning, a sufficiently developed descriptive part, a simple technology, and a practical complement. The First Part deals with the Principles and comprises two chapters, one devoted to defi- nitions, which have been made as clear as pos- sible ; the other to Voltameters or primitive secondary cells. This second chapter ends with a classification of accumulators, the different species of which are comprised under four heads or genera. The genera, considered in a practical point of view, are of very unequal importance ; but a a 2 iv PREFACE. certain one amongst them, although not in ex- tensive use at the present moment, is destined to play an important part in industry. They should, therefore, all be studied with the same care, and especially as the examination of the various volta- metric systems, even including the disused ones, generalises, enlarges the subject, and opens the mind to general views which might remain un- perceived by electricians confining themselves to the study of the actually preponderating genus. The Second Part is devoted to the description of the known accumulators, which are interesting and original. In this part of the work, perhaps, more than in the other parts, I have had to correct some errors of attribution which spread to the detriment of deserving workers. The resti- tutions and eliminations which had to be made have caused my nomenclature to differ from those previously adopted. I must give an explanation of this fact. The history of secondary currents does not, up to 1880, present any difficulty : it is given in a most complete form in Gaston Plante's masterly work upon the subject. The industrial importance of the accumulator, long perceived by clear-sighted minds, becomes evident to everybody in 1881. The unexpected success of Faure's invention excites hopes, emulation, appetites. Innovations, improve- PREFACE. ments and plagiarisms spread from numerous quarters. The systems, apparently in great variety, only repeat themselves under various denominations, resulting in a confusion which some have taken advantage of. Some more or less important theoretical or practical works have, in the midst of this confusion, changed paternity. I have, in the higher interest of truth, sepa- rated the inventions and the plagiarisms, and carefully omitted the latter. Historical rectifications require proving. The theoretical works and the inventions mentioned in this book, are, as much as possible, accompanied with references to their origin periodical, book, patent, &c. I am thus enabled to claim equi- valent references from contradictors. The attentive reader will acknowledge my im- partiality. Should he require to find in this book a known system, he will find it on the condition of seeking for it under its proper designation.* The Third Part (Technology) contains the formulae and numerical data necessary for the calculations relating to the utilisation of secondary currents. * The author does not pretend to be infallible. Some real inventions, not published in France, may have been involuntarily omitted, and he will always be glad to receive any correction or claim accompanied with references. vi PREFACE. The applications of accumulators, in the Fourth Part, might have been made the subject of seve- ral volumes, but it was necessary to limit their description. The essential notions of each appli- cation have been given without going into the details of special mechanical arrangements ; in the principal cases, the successive transformations of energy and the coefficients relating to each of them have been indicated. The product of these coefficients is the practical efficiency of the secondary batteries in any given case. These applications, although in a state of infancy, are indicative of the important place which voltaic accumulation will soon take in industry. Not more in this book than in my previous works has the subject been magnified. How could the range of this novel art, which places in man's hands all the forces of nature, be exaggerated ! EMILE REYNIER. PARIS, ibthjune, 1888. CONTENTS, PART I. PRINCIPLES. CHAPTER I. DEFINITIONS. PACK Voltameter with metallic electrodes .... 3 Secondary electromotive force secondary current . . 5 Secondary polarities . . . . . . . . 5 Voltaic accumulators or secondary batteries . . 6 Miscellaneous voltameters 7 CHAPTER II. VOLTAMETERS. Platinum voltameter: dilute sulphuric acid . . Lead voltameter : dilute sulphuric acid " Lead voltameter : solution of sulphate of copper . . 16 Lead voltameter : solution of sulphate of zinc 18 Carbon voltameters Copper voltameters : alkaline zincates 23 Voltameters with alkaline amalgams . . 2 4 Industrial voltameters . . Classification of accumulators .... 2 5 vin CONTENTS. PART II. VOLTAIC ACCUMULATORS. CHAPTER III. PLANTE ACCUMULATORS. PAGE Plant's original secondary cells . . . . . . 29 Secondary cells with parallel electrodes . . . . 31 Spiral accumulators . . . . . . . . . . 33 Chemical reactions in Planters secondary cells . . 35 Formation .. .'. .".' .. .. .. 36 Accelerated formation .. .. .. . . .. 38 Voltaic capacity . . . < . , . . . . 40 Constants ,, ,. .. . , 41 Autogeneous formation : heterogeneous formation . . 42 CHAPTER IV. ACCUMULATORS OF THE PLANTE TYPE. AUTOGENEOUS FORMATION. Accumulators, surface formation . . . . ; . 43 Foliated accumulators . . . . . . . . . 43 Tommasi accumulators . . . . . . . . , . 44 De Kabath accumulators .. .. , ,.. .., 44 Lead wire accumulators . . . . . . ..- 46 Simmen accumulators .. .. .. .. .. 47 Simmen and Reynier accumulators f , f . . . . 49 Lead shot accumulators .. .. .... 52 CONTENTS. IX PAGE Plaited electrode accumulators . . . . . . . . 52 Increase by formation . . ' * . . ... . . . . 56 Increase by discharge . . . . . . . . . . 57 Gross increase . . . . . . - . . . . . . 58 Quick autogeneous formation, compressed by the in- crease .. .. .. .. .. .. 59 Reynier accumulators . . . . . . . . . . 60 Electrodes rendered permeable by the elimination of an auxiliary metal . . . . . . . . . . 66 Monnier (Denis) accumulator . . . . . . . . 67 Sulphuretted electrode accumulators . . . . . . 70 CHAPTER V. ACCUMULATORS OF THE PLANTE TYPE. HETEROGENEOUS FORMATION. Accumulators with oxides or insoluble lead salts juxta- posed to conductive supports, Camille Faure system . . . . . . . . . . . . 71 Accumulators with reticulated electrodes filled with finely-divided lead, Volckmar system . . . . 76 Accumulators with socketed oxides, Faure- Volckmar system . . . . . . . . . . . . 77 Sellon's gratings of lead and antimony alloy . . . . 79 Faure-Sellon- Volckmar accumulators . . . . . . 80 Modifications to Faure-Sellon- Volckmar accumulators 87 Double electrodes .. .. .. .. .. 87 Modification in the compositions of the liquid, by Mr. Charles Philippart . . 89 Mounting in column, by G. Philippart . . 91 Mixed accumulator, Faure-Reynier system .. .. 92 Juxtaposed amalgam, Nezeraux accumulator . . . . 95 Agglomerate oxides of lead electrodes 96 CONTENTS. PAGE Aron's metallodiums and metallodions '.. .. 97 Tribe, peroxide of lead electrodes . . . ; . . 98 Frankland, agglomerate electrodes .. :';;.' .. 98 Tamine, R., agglomerated electrode accumulators . . 98 Fitz-Gerald lithanode . . . . . . . . . . 99 Electro-chemical formation .. .. .. .. 100 Montaud accumulators .. .. .. .. .. 103 CHAPTER VI. MISCELLANEOUS ACCUMULATORS. Lead-copper accumulators . . . . . . . , 107 Lead-zinc accumulators .. .. .. .. .. in D' Arsonval and Carpentier accumulators . . . . 112 Reynier accumulators .. .. .. .. .. 113 Bailly accumulators .. .. .. .. .. 119 Tamine solution .. .. .. .. .. 120 Alkaline zincate accumulators ; de Lalande and Chape- ron recuperative batteries . . . . . . . . 121 Commelin-Desmazures-Baillache accumulators .. 124 CONTENTS. xi PART III. TECHNOLOGY. CHAPTER VII. TECHNICAL GENERALITIES CONCERNING ACCUMULATORS. PAGE Constants . . . . . . . . . . ^7 Electromotive forces .. .. .. .. .. 138 Resistance .. .. .. .. .. .. 139 Power . . . . . . . . . . . . . . 140 Voltaic capacities . . . . . .' . . . . 141 Useful or normal voltaic capacity . . . . . . 142 Work 143 Discharge diagrams . . . . . . . . . . 144 Charge and discharge regimens . . . . . . 145 Conservation of the charge .. .. .. .. 146 Efficiencies . . . . . . . . . . . . i^ Maximum efficiency proper . . . . . . . . I ^j Normal efficiency proper .. .. .. .. j^ Practical efficiencies .. .. .. .. .. I ^ 2 Weights in relation to power and work . . . . 15 2 Life of accumulators .. .. .. .. .. j^ Redemption .. .. .. .. .. .. j^ Formula of merit of a system of accumulators . . 155 xil CONTENTS. PART IV. APPLICATIONS. CHAPTER VIII. APPLICATIONS OF ACCUMULATORS. General remarks on the charge of accumulators . . 159 First applications of secondary couples by Mr. G. Plantd .. 161 Applications to scientific researches .. .. .. 162 Applications to telegraphy, telephony, clockwork, &c .. 164 Application to electric lighting .. .. .. .. 166 Application to the current regularisation of machines ; regulating voltameters .. .. .. .. 168 Welding of metals .. .. .. .. .. 173 Production of motive power .. .. .. .'. 178 Electrical locomotion on tramways . . . . . . 182 Electrical locomotion on roads .. .. .. 189 Electrical navigation . . . . . . . . . . 190 Future application of accumulators to aerial naviga- tion.. .. .. .. .. .. .. 195 Transmission and distribution of energy by means of secondary currents .. .. .. .. 197 Translation or displacement of energy by means of accumulators .. .. .. .. .. 199 Land-carriage of energy . . . . . . . . 199 Water-carriage of energy .. .. .. .. 199 Caption of natural forces by means of accumulators . . 200 LIST OF ILLUSTRATIONS. 1 . Voltameter with metallic electrodes . . . . 3 2. Voltameter and galvanometer . . . . . . 3 3. Voltameter charged by a primary battery . . . . 4 4. Discharge of a voltameter through a galvano- meter . . . . . . . . . . . . 5 5. Voltameter with lead electrodes .. .. .. 12 6. Voltameter with lead electrodes charged by a battery . . . . . . . . . . . . 12 7. Discharge of a voltameter with lead electrodes . . 14 8. Plante' s first secondary cell . . . . . . 30 9. Plan of a Plante accumulator with parallel elec- trodes 3 2 10. Plante accumulator with parallel electrodes . . 32 11. Two Plante accumulators joined in tension .. 32 12. Plante accumulator, spiral pattern .. .. 33 1 3. Plante' accumulator charged by a battery . . . . 34 14. De Kabath electrode .... 45 15. De Kabath accumulator .... 4 6 1 6. Simmen electrode ...... 48 17. Simmen and Reynier electrode .. 51 1 8. Plaited electrode .. .. .. 53 19. Triple-fold lead electrode .. .. 54 20. Reynier electrode, old pattern . . 54 21. Increase of a plaited electrode .. 55 22. Reynier electrode before its formation . . 61 23. Reynier electrode, formed . . 61 24. Isolating fork . . . . 64 xiv LIST OF ILL USTRA TIONS. FIG. PAGE 25. Reynier accumulator .. .. .. .. 65 26. D. Monnier accumulator, longitudinal section .. 68 27. , transversal section .. .. 68 28. Faure electrode, elevation .. .. .. ... 72 29. , horizontal section .. .< 72 30. Faure accumulator, spiral pattern .. .. .. 73 31. Faure- Volckmar grating electrode .. .. 77 32. Faure- Volckmar plate electrode .. .. .. 78 33. Faure-Sellon- Volckmar accumulator .. .. 81 34. Faure-Sellon- Volckmar plate electrode .. .. 81 35. Faure-Sellon-Volckmar grating electrode .. .. 82 36. Section through Faure-Sellon-Volckmar grating electrode.. .. ... .. .. ., 82 37. Faure-Sellon- Volckmar accumulator, E.P.S. manu- facture .. ,. ., .. ,. .. 86 38. Section through a double electrode .. ... 88 39. Double electrode . . . . . . . . . . 88 40. Faure-Reynier accumulator, compound pattern . . 92 41. Detail of a positive electrode with stiffened edge .. .. 93 42. Positive electrode with stiffened edge .. .. 93 43. Battery of compound accumulators . . . . 94 44. Montaud electrode .. .. .. .. .. 104 45. Montaud collector .. .. ;. .. .. 104 46. Montaud comb .,< ... .. .. .. 105 47. Montaud accumulator , , .. .. .. 105 48. Copper accumulator .. .. .. .. 109 49. D'Arsonval and Carpentier accumulator . . . . 112 50. Lead-zinc accumulator, old pattern .. .. 114 51. Isolating cage of the old pattern of lead-zinc accu- mulators .. .. .. .. .. .. 114 52. Positive electrode of the old pattern of lead-zinc accumulator .. .. .. .. .. 114 53. Plaited electrode, old pattern ... 115 54. Negative electrode with pocket, old pattern .. 116 LIST OF ILLUSTRATIONS. xv 55. Lead accumulator, old pattern suspended zinc- electrodes .. *.. .. .. .. 117 56. Reynier positive electrode .. .. .. .. 118 57. De Lalande and Chaperon battery, horizontal pattern . . . . . . . . . . . . 122 58. , vertical pattern . . . . 123 59. Diagram of the discharge in a Faure-Volckmar accumulator . . . . . . . . . . 144 60. Diagram of the slow discharge in a Fitz-Gerald accumulator . . . . . . . . . . 148 6 1. Diagram of the rapid discharge in a Fitz-Gerald accumulator . . . . . . . . . . 149 62. Experience of Messrs. Plante' and Niaudet .. 179 PART I. PRINCIPLES CHAPTER I. DEFINITIONS. VOLTAMETER WITH METALLIC ELECTRODES SECONDARY ELECTROMOTIVE FORCE : SECONDARY CURRENT SE- CONDARY POLARITIES VOLTAIC ACCUMULATORS, OR SECONDARY BATTERIES. Voltameter with Metallic Electrodes. V (Fig. i) is a glass vessel containing water acidulated with sulphuric acid. Two platinum wires, not touching FlG each other, are immersed into the liquid, and come out of the vessel through a plug at the bottom. FIG. 2. If these wires are joined to the terminals of a galvanometer G (Fig. 2) it will be observed that B 2 4 DEFINITIONS. no current is passing. The two conductors being physically symmetrical towards the liquid, there exists no reason why a difference of potential should be established between them. But this system, which is inert in itself, may become active by the action of an external electrical source. If we join the two conductors respectively to the two poles of a battery (Fig. 3), inserting the FIG. 3. galvanometer in the circuit : the needle is deflected and indicates the passage, in the circuit, external to the battery, of a current travelling from its positive to its negative pole. Within a short time of the closing of the circuit, some gaseous bubbles are emitted from the two immersed conductors. The volumes of gas liberated may give the measure of the quantity of electricity which is passing through the circuit : whence the name of voltameter given to the apparatus, and, in a general manner, to any system of two conductors immersed in an electrolysable liquid. DEFINITIONS. 5 Secondary Electromotive Force : Secon- dary current. The voltameter acquires, by the passage of the current, an electromotive force, and thus becomes a true voltaic couple, called secondary couple, and which gives an electric current called secondary current. This secondary current can easily be verified. If we disconnect the battery, and join the elec- trodes of the voltameter directly to the terminals of FIG. 4. the galvanometer (Fig. 4), the needle of the latter is at once deflected, indicating the passage of the secondary current. Secondary Polarities. The respective polarities of the two conductors are indicated by the direction of the deflection: the electrodes which were respectively connected with the positive and negative poles of the charging battery have become respectively the positive and negative poles of the secondary couple. Or, in other words: the poles of the electric source DEFINITIONS. respectively give their names to the corresponding electrodes of the voltameter. Thus during the charge, the secondary couple is in opposition to the source. The electromotive force of the latter being superior, gives the direction of the charging current, which passes through the voltameter, crossing from the positive to the negative electrode, through the electrolysed liquid. When the voltameter is discharged, the secondary current travels from its positive to its negative electrode in the external circuit, as is the case with all voltaic batteries. This is ex- pressed in a comprehensive manner by saying that the secondary current travels in a direction opposite to that of the primary current (see Figs. 3 and 4). These phenomena, which are only mentioned in this place, will be explained further on. Voltaic Accumulators, or Secondary Batteries. A voltaic accumulator is a volta- meter capable of storing a large quantity of electric energy, of keeping it, if necessary, during a certain time, and giving it back without too great a loss in the shape of a secondary current. Mr. Gas ton Plante was the first to invent a voltaic accumulator fulfilling these conditions. (March 1860). Several physicists had, before him, observed secondary currents ; some secon- dary batteries had even been constructed ; but DEFINITIONS. nobody had perceived the possibility of giving these apparatuses the power, the capacity, the permanence and the efficiency necessary to utilisable accumulators. Since Mr. Plante's works, the expression secondary battery has acquired a signification which it did not previously possess ; it has become synonymous with the word voltaic accumulator. Miscellaneous Voltameters. Numerous voltametric systems may be obtained by varying the nature of the two electrodes, and of the liquid. But all the combinations thus obtained are not fit to produce utilisable secondary currents, or to serve as a basis for systems of accumulators. In fact the number of workable accumulators is limited. The study of these voltametric systems must logically precede that of the secondary batteries which derive from them. Such is the order of exposition adopted in this work. Considering the principles of the principal systems of accumulators, their fundamental properties are described under the elementary form of the voltameter. The generae being thus characterised, the species will naturally become classified under them, and their study may be reduced to the examination of the particularities special to each of them. CHAPTER II. VOLTAMETERS. PLATINUM VOLTAMETER: DILUTE SULPHURIC ACID LEAD VOLTAMETER: DILUTE SULPHURIC ACID LEAD VOLTA- METER : SOLUTION OF SULPHATE OF COPPER LEAD VOLTAMETER : SOLUTION OF SULPHATE OF ZINC CARBON VOLTAMETER COPPER VOLTAMETER : SOLUTION OF ALKALINE ZINCATE VOLTAMETERS WITH ALKALINE AMALGAMS INDUSTRIAL VOLTAMETERS CLASSIFICATION OF ACCUMULATORS. Platinum Voltameter : Dilute Sulphuric Acid. This voltameter, set up in the form illus- trated (Fig. i), and charged with a battery, gives a secondary current which rapidly decreases to zero. The discharge must be observed as soon as the primary current is interrupted. The secondary current is, as in all voltameters, due to the chemical reaction of the substances produced by the electrolysis, upon the electrodes and around them. The positive is superficially oxidised, surrounded with oxygen, and some unstable compounds : ozone, oxygenated water, persulphuric acid ; the negative is superficially reduced, surrounded with hydrogen and, no doubt, somewhat allied with that metal. VOLTAMETERS. With the exception of the hydrogen and the oxygen respectively fixed upon the electrodes, the products of electrolysis are spontaneously and rapidly decomposed or dissipated ; which explains the prompt weakening of the secondary current. If each electrode is covered with a tube, as is done in the experiment of water electrolysis, the hydrogen and oxygen are imprisoned upon the electrodes. The voltameter thus charged may give a current of small intensity but of long duration. It is a kind of rough accumulator, keeping its charge ; accumulator feeble but constant ; of a limited but definite capacity, of a small but measurable efficiency. The platinum sulphuric-acid voltameter is found at the very early stage of the history of secondary currents. It is curious to notice that Carlisle and Nicholson, when operating upon the elec- trolysis of water, unwittingly constructed an appa- ratus vaguely resembling an accumulator. But it is Gautherot who firstly discovered the exist- ence of secondary currents (1801), with platinum and silver wires having been used in the electro- lysis of salt water. A little later on, Ritter constructed his secondary batteries, made of metallic discs, separated by washers of cloth, wetted in a salted solution. Volta, Marianini, and Becquerel demonstrated that the secondary currents have a chemical 10 VOLTAMETERS. origin. Mattenci obtained some currents from some strips of platinum previously dipped into oxygen and hydrogen. Grove next constructed his gas couple, composed of two platinum strips dipped in dilute sulphuric acid, and covered with test tubes containing, one some oxygen, the other some hydrogen. From eight to ten of these couples, connected in series, constitute a battery capable of decomposing the water of a voltameter inserted in the external circuit. The spectacle of the analysis of water by its own synthesis is thus obtained, and the volumes of gases in the test tubes can be seen progressively decreasing as they increase in the voltameter. This beautiful experiment is illustrative of the chemical origin of the secondary currents and of the reversibility of voltameters. It also demonstrates the similarity of action between ordinary batteries and accumulators. In effect, a Grove battery, charged with gases prepared outside the apparatus, is a real primary battery, chemically prepared ; it does not, however, essentially differ, as regards its general properties, from a voltameter charged by the passage of an electric current. In reality, the primary batteries, chemically charged, cannot all be regenerated by electro- lysis ; the secondary batteries, electrically charged, VOLTAMETERS. 1 1 cannot all be regenerated by chemical additions. But these discrepancies' of a practical order have nothing absolute. An accumulator is a battery which can be regenerated by electrolysis. The physico-chemical laws regulating the batteries are applicable to the accumulator. The latter are particular instances of the former. The platinum sulphuric-acid couple offe elegant demonstration of these fundamen principles. Its proper place is therefore at the beginning of the general study of voltameters, although it is an accumulator which is not utilisable. Lead Voltameter : Dilute Sulphuric Acid. This voltameter, the most important of all, supplies the principle of nearly all the accumu- lators used in the laboratories and industrially. Its properties have been discovered by Mr. Gaston Plante (1859). Lead being a comparatively cheap metal, the electrodes may be constructed of large sizes, so as to amplify the results to be obtained. The two wires of the classical voltameter are, in this instance, replaced by two large sheets (Fig. 5), placed in a glass jar and isolated from each other in the parts dipping into the liquid. 12 VOLTAMETERS. FIG. 5, When the circuit of a battery is closed upon this voltameter (Fig. 6), the acidulated water is FIG. 6. VOLTAMETERS. 1 3 electrolysed. The colour of the negative elec- trode, which was originally the grey colour of lead oxidised in the atmosphere, changes for the lighter tint of reduced lead, and this electrode, in a short time, emits some hydrogen. At the same time, the oxygen fixes itself upon the positive electrode, the surface of which gets covered with peroxide of lead. The peroxidation attacks the internal face more readily than the external one but, ultimately, equally affects the latter. When all the surface is peroxidated, oxygen bubbles begin to appear ; this phenomenon indicates that the voltameter has received all the charge which it is capable of receiving. Thus charged, the voltameter can act as a voltaic couple, but only for a very short period. If these electrodes are connected to the terminals of a somewhat sensitive galvanometer (Fig. 7), the secondary couple discharges itself in the wire of the instrument, causing the needle to be deflected. During the discharge, the negative electrode gets darker and the positive one lighter. The double reaction thus enacted is the fixation of one equivalent of sulphuric acid upon each electrode, and the carriage of one equivalent of oxygen from the positive to the negative. That is to say there is, upon the positive electrode : PbO 2 + SO 3 = SO 4 Pb + O. VOLTAMETERS. And upon the negative electrode When the voltameter is charged anew, the reverse chemical reactions take place, bringing the sulphate of lead to a state of reduced lead on FIG. 7. the one part and of peroxide of lead on the other part ; but this second charge acts on a larger quantity of materials, because the lead and the peroxide (regenerated from the sulphate) are in a permeable state, which allows the electrolytic * This chemical interpretation of the discharge phenomena is posterior to Mr. Planters researches. VOLTAMETERS. 15 action to reach the subjacent lead, and to pene- trate more deeply, especially on the peroxidised side. Thus on every new charge, the chemical action reaches deeper. The result is a corresponding increase in the capacity of accumulation. Mr. Gaston Plante has given this progressive increase the name of formation, or forming. When a voltameter is deeply formed, it is capable of a comparatively large quantity of electricity : it then can rightly be called secondary couple or accumulator. The forming process is quicker with the posi- tive side than with the negative : hence the necessity of reversing the accumulator from time to time, that is to say of intervening its communi- cation with the source for changing the direction of the charge. Mr. Plante", who is the creator of the lead electrode accumulator, has shown how far the forming process may be carried on by means of charges, discharges, reversions of current and rests methodically practised. This important question of forming will be discussed in the chapter on accumulators. Mr. Plante has observed that the electromotive force of voltameters varies to an important extent. * ' Recherches sur 1'ElectriciteY page 53 and following. 1 6 VOLTAMETERS. The study of these variations has been since made, and the measurements of those relating to the more important systems given.* In the lead sulphuric-acid voltameter, the secon- dary electromotive force can, after an intense charge, reach 3 volts ; it soon decreases to 1*9 or 1*8 volt, and then slowly falls down to zero. The normal electromotive force of the appa- ratus is about i 9 volt. The fugitive increase noticeable immediately after the charge is due to the presence of unstable products such as oxygen, ozone, persulphuric acid, &c., which are spon- taneously decomposed.! Lead Voltameter: Solution of Sulphate of Copper. This voltameter resembles the pre- ceding one (Fig. 5) ; its electrodes are made of lead, but the sulphuric acidulated water is replaced by a solution of sulphate of copper. It can be charged with two Daniell cells or one single Bunsen, since the use of copper salt lowers the secondary electromotive force. During the charge, the positive electrode is peroxided, and takes the flee tint, as in the acidu- lated water voltameter ; the negative electrode * " Sur les variations de la force e'lectromotrice dans les accu- mulateurs," in the work ' Piles Electriques et Accumulateurs,' by E. Reynier. t Gaston Plant**, loc. cit. VOLTAMETERS. 17 becomes rapidly covered with a galvanic deposit of pure copper. If the lead electrodes are new the escape of gaseous oxygen soon appears upon the peroxidised electrode. The metal continues to be deposited upon the coppered electrode as long as there is a supply of it in the electrolyte the solution be- comes gradually discoloured. When the sulphate of copper is entirely decomposed, an escape of hydrogen takes place from the negative electrode. The discharge of this voltameter, like that of the previous one, comprises three phases. The secondary electromotive force is, at first, surele- vated : it can reach 1*7 or i * 8 volt immediately after an intense charging ; but only i 5 volt if the primary current is low. In any case the electromotive force rapidly falls to 1*25 volt where it remains during the greatest part of the discharge, to afterwards fall toward zero. The chemical reactions of the discharge consist in the sulphatation of the two electrodes. There is, on the positive : PbO 2 + SO 3 = SOJPb + O ; and on the negative : Cu + SO 3 + O = SO 4 Cu. The sulphate of copper is dissolved, and restores its blue tint to the liquid. c 1 8 VOL TAME TERS. It must be observed that, in the negative electrode, it is the superficial deposit of copper which constitutes the active part of the electrode, the lead plate only playing the part of support and conductor to the electrolised metal. This conducting support might be made of copper, carbon, or any insoluble metal other than lead. Lead, however, is more suitable for an experi- mental voltameter, as it does not introduce any complication in the phenomena under observation by the production of an initial and a final electro- motive force due to the heterogeneity of the plates. The sulphate of copper voltameter keeps its charge well enough. Its negative electrode receives its galvanic deposit without previous preparation : the forming of the couple, necessary only to the positive, may then be affected by successive charges, without any reversal. Notwithstanding this advantage, the sulphate of copper couple has remained inferior to the Plante couple for reasons which will be hence- forward explained. Lead Voltameter : Solution of Sulphate of Zinc. This voltameter differs from the former one in this respect that its liquid is a solution of sulphate of zinc (Fig. 5). When it is placed in the circuit of a battery, the positive electrode soon turns flee tint of lead per- VOLTAMETERS. 19 oxide, whereas the negative becomes covered with pure zinc. The gaseous oxygen escapes from the positive electrode when its surface is entirely peroxidised. An escape of hydrogen from the negative takes place almost from the beginning, as the deposited zinc is actively attacked by the liquid. This hydrogen is, therefore, not liberated directly by electrolysis ; its escape is due to disso- lution of the electrolised zinc. The discharge of this voltameter offers two principal phases.* In the period immediately following the charge the electromotive force is surelevated to 2*8, 2*6, 2 * 5 volts ; but it soon falls to its normal value which is 2 ' 4 to 2*3 volts and remains, during a certain time between 2 * 3 and 2 volts. Then it suddenly falls to about 0*6 volt, after which it slowly goes down to 0*4 volt. This second period is longer than the first one. It terminates by a comparatively rapid fall toward zero. Different chemical reactions correspond to these two periods of the discharge. During the first, there is sulphatation of the two electrodes, with carriage of one equivalent of oxygen from the positive to the negative as in the former voltameters : PbO 2 + Zn + 2SO 3 = SO 4 Pb + SO 4 Zn. Positive Negative Positive Negative electrode. electrode. - electrode. electrode. * Emile Reynier, ' Stances de la Soci& Franchise de Physique,' 4 Avril, 1884. C 2 20 VOLTAMETERS. This first phase only of the discharge is utilisable. The average corresponding electromotive force is 2 3 volts. During the second period there is sulphatation of a second equivalent of zinc at the negative electrode, with carriage of one equivalent of hydrogen upon the positive sulphate of lead, which resolves itself into metallic lead and sul- phuric acid. SO 4 Pb + Zn + SO 4 H = Pb + S0 4 H + S0 4 Zn Positive Negative Positive Negative electrode. electrode. electrode. electrode. The average electromotive force corresponding to this second period is about 0*55 volt. If the voltameter is recharged, the quantity of affected material will be larger than the first time, because the positive lead, firstly peroxidised by the charge, then sulphated by the first portion of the discharge, has finally returned to the perme- able metallic state. It is then fit to become more deeply peroxidised during the second charge- there is formation. We will in the chapter on lead-zinc accumu- lators further discuss this matter which is of interest owing to their high electromotive force. We must not proceed further without noticing this feature of the system, in which a complete discharge completely reduced the peroxide of lead into permeable metallic lead ; which allows of VOLTAMETERS. 21 forming zinc accumulators pretty quickly and without reversal. Carbon Voltameters. Some inventoi attempted to use carbon plates as electro^^^, perhaps thinking of utilising the absorbing proper^ ties of this material in order to retain and store the gases generated by the electrolysis. But the gas-absorbing capacity of two carbon electrodes corresponds to a very feeble quantity of elec- tricity. With sulphuric acidulated water, the products of electrolysis retained by two carbon electrodes are complex and unstable. The secondary electromotive force rapidly decreases. Imme- diately after the charge it can reach 3 volts, but spontaneously falls, within a few minutes, lower than i volt. After a prolonged electrolysis, the positive plate is attacked and becomes rapidly disag- gregated ; the negative one also becomes altered, though much slower. A blackish mud drops to the bottom of the cell and the electrolyte becomes tinted with carbonated brown materials formed at the expense of the plates. This destruction of the electrodes occurs, more or less rapidly, with all kinds of electrolytes. Carbon, therefore, does not appear to be a suitable material for use, as electrodes, in a durable accumulator ; it could, at the utmost, be used 22 VOLTAMETERS. at the negative only as a support to a galvanic deposit. This explains the general failure of carbon accumulators. We must, however, mention Mr. Varley's attempt. His accumulator was constituted by carbonised cardboard electrodes immersed in a solution of sulphate of zinc and manganese : the primary current deposited zinc upon the positive, and peroxide of manganese upon the negative electrode. The secondary electromotive force of a carbon zinc-manganese voltameter may exceed 3 volts ; but it soon falls to the neighbourhood of 2 and then much under 2. A persevering study of this system might lead to some practical re- sults if the electrodes, and particularly the posi- tive one, were not condemned to perish in a short time. Previously to Mr. Varley's attempt, Mr. Maiche had tried (1881) the electrolytic regeneration of Leclanch6 cells, which are zinc-manganese couples. Nothing has resulted from it. More recently, Mr. Basset * has tried some accumulators with electrodes made of carbon immersed into pasty electrolisable mixtures com- posed of metallic oxides impregnated with saline solutions such as sesquioxide of iron and proto- chloride of the same metal, protoxide of lead, and * French patent No. 179,710, i7th November, 1886. VOLTAMETERS. 23 nitrate of lead, &c. The failure of these various combinations might have been foreseen for many reasons, the principal of which is the destruction of the positive electrode. Copper Voltameters : Alkaline Zincate. An electric current crossing, between two copper electrodes, a solution of potassium or sodium zincate, oxidises the positive electrode and de- posits zinc upon the negative.* Electrolised zinc forms a good galvanic layer, not much attacked in open circuit ; the sub-oxide of copper is, on the other hand, almost insoluble in the liquid. The stable products of the electrolysis being well fixed upon the electrodes, the secondary couple can retain its charge. Its normal electromotive force is inferior to i volt ; it is, as with every voltameter, greater at the moment of interruption of the charging ; its value then depends on the electromotive force of the source and the intensity of the primary current. The alkaline zincate voltameter seems suitable for the storage of voltaic energy. Messrs, de Lalande and Chaperon, who have discovered its properties, have, some time ago, tried to utilise it in the construction of accumulators. Messrs. Commelin, Desmazures, and Bailhache have * De Lalande and Chaperon. 24 VOLTAMETERS. recently worked in the same direction with a certain success. Voltameters with Alkaline Amalgams. The primary cells which have the highest electro- motive forces are those the soluble electrode of which is an alkaline metal (potassium, ammonium, sodium) allied with mercury. It is, for example, known that the electromotive force of the couple potassium amalgam, sulphuric acidulated water, peroxide of lead, is three and a half volts. A similar secondary couple may be obtained by using a leaden plate as positive electrode, sulphate of sodium as electrolyte, and mercury contained in a porous jar as negative electrode ; a platinum wire, dipping into the mercury, constitutes the negative pole of the couple. The secondary cur- rents obtained from this voltameter are of short duration owing to the impossibility of preserving an alkaline amalgam in contact with an aqueous solution. Besides, the available quantity of electricity is small, for the alkaline metals only ally themselves with mercury in feeble pro- portions. Industrial Voltameters. Amongst the nu- merous voltametric combinations which can be devised by varying the electrodes and the liquids, only a few are utilisable in the construction of accumulators, for we must discard : VOLTAMETERS. 25 1. The systems in which the use of precious materials, such as gold, palladium, platinum, silver, is required. 2. Those necessitating the use of carbon as a positive electrode. 3. The combinations containing more than one soluble metal transportable as a galvanic deposit. 4. The systems the utilisable electromotive force of which is too low. 5. Those emitting corrosive or obnoxious fumes. Therefore the sulphuric acid voltameters with gold, silver, copper, iron, zinc, aluminium com- binations worked out by Mr. G. Plante are not industrial. The study of these systems, the characteristic properties of which are described in the master's work, has been laid aside by us. The seven combinations here studied are the only interesting ones, considered in respect of the production of secondary currents. And yet is it necessary, at the very outset of the study of accumulators proper, to abandon three of them : those with platinum electrodes, with carbon elec- trodes, and with alkaline amalgams. Classification of Accumulators. The voltametric systems capable of storage are thus reduced to the number of four; whence four genera of accumulators. 26 VOLTAMETERS. Each of these genera comprises various com- binations, modes of forming, &c., giving rise to numerous species. The existing accumulators must therefore be divided into four genera, i. e. : 1. The Lead sulphuric-acid genus, to which is attached the name of the learned Mr. G. Plante, who discovered it and its first species. The Plant6 genus is the original one, and most im- portant of all ; it is almost exclusively used in industrial practice. 2. The Lead sulphate of copper genus, very little in use. 3. The Lead sulphate of zinc genus, very little used until now, but interesting owing to its high electromotive force and some special properties. 4. The Copper alkaline zincate genus, the first appearance of which has, recently, been noisily proclaimed. PART II. VOLTAIC ACCUMULATORS CHAPTER III. PLANTE AC CUMULATORS. PLANTE'S ORIGINAL SECONDARY CELLS SECONDARY CELLS, WITH PARALLEL ELECTRODES SPIRAL ACCUMULATORS- CHEMICAL ACTIONS IN PLANTE'S SECONDARY CELLS FORMATION ACCELERATED FORMATION VOLTAIC CAPACITY CONSTANTS AUTOGENEOUS FORMATIONS HETEROGENEOUS FORMATION. Plantd's Original Secondary Cells. During the course of his studies on voltameters, Mr. Plante found "that the secondary electro- motive force of a voltameter with lead electrodes in acidulated water was more energetic and persis- tent than that of other metals." * He therefore adopted lead and acidulated water as the essen- tial materials for his secondary batteries (March 1860) ; this selection was a fortunate one, for, up to the present time, no better electro-chemical system has been discovered. To obtain a secondary cell of low resistance, Mr. Plante gave its electrodes a large surface. His first couple was composed of two long lead plates placed one upon the other, separated by * ' Recherches sur 1'ElectriciteY page 34. PLANTE ACCUMULATORS. a rough cloth, and rolled into a spiral, an arrangement copied from Offerhaus and Hare's primary battery. The apparatus (Fig. 8) was immersed in a glass vessel containing a solution of one volume of sulphuric acid in ten of water. FIG. 8. The total surface of the two electrodes exceeded one square metre. This secondary couple, after a charge of a few minutes' duration from two Grove cells, gave an intense but short-lived current. The cells thus constructed were soon rendered useless through some internal contacts. The isolating cloth soon become altered in the PL ANTE A CCUMULA TORS. 3 1 acidulated water, and allowed contacts between the electrodes to take place.* Secondary Cells with Parallel Elec- trodes. In order to obviate this inconvenience, Mr. Plante adopted (1868) an arrangement of parallel plane plates, alternately positive and negative, the plates of same polarities being con- nected together, outside the liquid, by means of external prolongations. The lead plates, placed very near each other, were arranged vertically in a rectangular gutta-percha trough, and separated from each other by means of isolating sticks. The end sides of the trough were grooved internally so as to receive the ends of the electrodes, and maintain the latter in their position. Fig. 10 represents an accumulator of this description. Fig. 9 is a plan illustrating the details of the arrangement. The positive plates are pro- longed in a, b, c ; the negatives in a, b', c ; the first series are connected with the terminal P, and the second one with terminal P'. The conductors from the primary battery are attached at P and P'. B and O are clips between which wires intended to be heated to redness or fused by the secondary current are attached. These clips are in elec- * The internal contacts are principally due to a kind of incrusta- tion of the partition, which, becoming impregnated with lead and oxygen, creates a derivation between the plates. PL ANTE ACCUMULATORS. trical communication with the terminals P and P' respectively. A commutator M allows of the et'6'c' FIG. 9. FIG. 10. FIG. ii. discharging current being interrupted or estab- lished. Fig. ii illustrates two couples constructed in the same manner and joined in tension. This PL ANTE A CCUMULA TORS. 33 illustration is taken from a paper by Mr. Plant6, published in the ' Annales de Chimie et de Phy- sique ' in September, 1868. As far back as that date, this celebrated physicist already employed this arrangement, which is now extensively used in the construction of industrial accumulators. Spiral Accumulators. A little later on, Mr. Plante returned to his previous arrangement of spiral electrodes, which has the advantage of being economical of construction, and fitted in glass cells, through which the succession of phenomena can be observed. The rough cloth was then super- seded by some indiarubber isolating bands Fig. 12 illustrates the couple so modified and FIG. 12. its mode of fabrication. Fig. 13 shows it in its glass vessel, and surmounted with an ebonite D 34 PLANTE ACCUMULATORS. cover : the latter is provided with two clips, A, A', intended for clipping the wire to be heated or fused by the discharging current, and also with FIG. 13. an interrupter, R, of a simple and commodious description. A primary battery of two small Bunsen cells charges the apparatus. This pattern has become almost classical, and hundreds of them have been sold for laboratory PLANTE ACCUMULATORS. 35 purposes. It is with this form of accumulator that the inventor carried out 'the original and beautiful experiments which have been described in his masterly researches. Chemical Reactions in Plantd's Second- ary Cells. The chemical reactions, correspond- ing to the discharge, in Planters accumulators consist, as we have already said, in the production of two equivalents of sulphate of lead : PbO 2 + 2 S0 3 + Pb = SOJPb -f- S0 4 Pb Positive Negative Positive Negative electrode. electrode. electrode. electrode. the charge producing converse reactions.* * In order to destroy certain errors of attribution it is neces- sary to recall, here, the history of this theory of the double sulphatation. Mr. G. Plantd had, for a long time, verified the presence of the sulphate of lead in his secondary couples ; but considered this sulphate as an accessory product, and not as the normal result of an electrolytic attack. Several authors have, after Mr. Plantd, admitted that the electro-chemical actions only took place between the lead and the constituents of water ; the sulphuric acid being, in their opinion, a simple auxiliary conductor. Messrs. Gladstone and Tribe were the first (1882) to admit that the sulphuric acid had a direct action upon the electrodes. In an Essai sur la The'orie chimique des Accumulateurs (' Socie'te' Frangaise de Physique,' 4th April, 1884), the author of this book examined and discussed the various theories expressed at that time, and pronounced for that of the double sulphatation, in favour of which he produced some new and decisive arguments. This paper, vigorously criticised, must have been extensively^ circulated, for it was reproduced in the ' Stances de la Socie'te',' y'Electricien,' ' Le Journal de Physique,' in the book ' Piles Electriques et Accumulateurs/ &c. It cannot, therefore, be but surprising that certain authors, D 2 36 PLANTE ACCUMULATORS. The secondary current given by a new couple is of a short duration, because the impermeability of the compact lead limits the electro-chemical action of the charge and of the discharge. Formation. We have already explained how the duration of the discharge is increased by suc- cessive charges. This increase in the voltaic capacity of the accumulator is the result of a superficial modification of the plates, which, becoming permeable up to a certain depth, allow of the electro-chemical actions to exert themselves upon a greater weight of material. This progres- sive modification in the structure of the lead has been designated, by Mr. Plant6, under the appella- tion of formation. If a couple is always charged in the same di- rection, the positive electrode will become more formed than the negative one, whence the neces- sity of, from time to time, effecting reversals ; that is to say, of interverting the polarity of the electrodes. Mr. Plante observed that it is advantageous to allow an interval of rest of several days between tardily converted to the theory of the double sulphatation, attribute it to Messrs. Crova and Garbe, who waited until the ist January, 1885 (* Comptes Rendus de 1'Acade'mie des Sciences ') to proclaim it \ or to Mr. Tschelltzow, who only contributed (ditto, 8th June, 1885) a thermo-chemical verification, already foreseen, by measuring the heat due to the formation of the peroxide of lead. PL ANTE A CC UMULA TORS. 3 7 the reversals, so as to give the oxide and the reduced metal deposit time to acquire the crystal- line texture, and to firmly adhere to the surface of the electrodes. The intervals of rest, of which mention is made above, between the changes of direction of the primary current, have a consider- able influence. Thus a secondary couple, the plates of which have been submitted, during a few consecutive hours, to the action of the primary current, being abandoned to itself for a month, without being discharged, and then re-charged in a contrary direction at the end of that time, will give a discharge of a duration double that which it formerly had." * This increase in the voltaic capacity by means of rest appears to be the result of the action of a local couple constituted by the peroxide of lead and the subjacent metallic lead couple, f the chemical action of which would be expressed by the equation. PbO 2 + Pb -f 2SO 3 = 2SO 4 Pb. One equivalent of peroxide of lead thus pro- duces two equivalents of sulphate, which are capable of giving, by a subsequent charge, two equivalents of peroxide or of reduced lead. As regards the solidity and the good adherence thus obtained, it can no doubt be explained by * ' Recherches sur 1'ElectriciteY p. 35. f Gladstone and Tribe. 38 PLANTE ACCUMULATORS. the production in the acidulated water, of an over- saturated solution of sulphate of lead, which slowly deposits the salt upon the electrodes in a state of firmly aggregated crystals.* This aggregation of the sulphate, therefore, is obtained by a chemico-physical process analogous to that to which the setting of cement is due, according to Mr. Le Chatelier's new theory. Mr. Plant6 has given out the method to be followed for forming his couples by means of successive charges and discharges, with prolonged rests and reversals effected at opportune times.f Accelerated Formation. The ordinary method is long, expensive, and almost imprac- ticable industrially. The aim of inventors who, after Mr. Plante, attempted to perfect the accu- mulators, has been especially to shorten and to consolidate the formation. Mr. Camille Faure was the first to succeed in rapidly obtaining considerable voltaic capacities (1880). With him, the accumulators enter into an industrial era. The brilliant results obtained by Mr. Faure and proclaimed by his co-worker J * Emile Reynier. t Loc. tit., pp. 53, 54 and 55. I ' Comptes Rendus de I'Acad&nie des Sciences ' Meeting of the 1 8th April, 1881 : Note sur la pile secondaire de Mr. C. Faure, par E. Reynier. ' Socie'te' d'Encouragement ' Meeting of the 22nd April, 1881 : Lecture and Experiments on the Faure Battery by the same. PLANTE A CCUMULA TORS. 39 stir the emulation of inventors who, in large numbers, come and try their hands at a subject almost neglected up to then. Mr. Plante himself recommences the study of his accumulators with a view to their practical applications, and discovers new means of accele- rating their formation. The celebrated physicist at first recommended the heating of the couple during the passage of the primary current. " . . . this elevation in the temperature has for its effects, by expanding the metallic pores of the lead (metallic plates), to facilitate the penetration of the electrolytic action ; that is to say, the deep peroxidisation of the positive plate, and, conse- quently, the reduction at the same depth, of the negative plate oxidised by a previous action. It also facilitates, by the contrast of the succeeding cooling, the crystalline aggregation of the peroxide of lead and of the reduced lead, and which consti- tutes a state of things favourable to the production of the secondary current, and to the conservation of the charge produced. " The duration of formation of secondary couples is thus considerably shortened, at the same time the qualities which render them valuable in numerous applications are maintained." * This process has not been put in industrial * Gaston Plant, French patent No. 144,101, 2$th July, 1881. 40 PLANTS ACCUMULATORS. practice. Mr. Plante" appears to have abandoned it for the following one, which is used with much success by several makers. " This process consists in simply submitting the secondary couples to a kind of deep cleansing by means of nitric acid diluted with the half of its volume of water, leaving them immersed in the liquid during twenty-four to forty-eight hours. The couples are then emptied, thoroughly washed, filled with a solution (one tenth) of dilute sulphuric acid, and submitted to the action of the primary current. A portion of the lead is no doubt dissolved during the immersion in nitric acid, but not sufficient to apparently reduce the thickness of the plates ; and owing to the metallic porosity the chemical action is not confined to the surface of the plates, but reaches their interior ; it creates new molecular intervals, and consequently facilitates the ultimate penetration of the electro- lytic action of the primary current. Secondary couples thus treated can, in eight days, after three or four reversals, give discharges of long duration, whereas the same results could only be obtained after several months of the ordinary treat- ment." * Voltaic Capacity. - - The specific voltaic capacity of well formed Plant6 accumulators * Gaston Plant, ' Comptes Rendus de 1'Academie des Sciences,' 28th August, 1882. PLANTE A CCUMULA TORS. 4 1 depends on the thickness of the electrodes. The thinner the electrodes the greater the capacity, but also the greater the fragility of the couples. With electrodes one millimeter in thickness, and of sufficient stiffness, Mr. Plante obtains a capacity of about 36,000 coulombs (10 ampere- hour) per kilogramme of lead. Constants. The utilisable normal electro- motive force of a Plante or similar pattern accu- mulator is about i ' 9 volt ; but it is higher in the first moments after the charge, and particularly during the charge itself, This fugitive surelevation of the secondary electromotive force increases with the intensity of the charging current and the electromotive force of the source ; it is due to the presence of unstable bodies which spontaneously decompose after the interruption of the charge. The stable bodies only remain : the reduced lead, the peroxide of lead and the sulphuric acid, the definite reactions of which correspond to the normal discharge, under a fall of potential of i 9 volt, The internal resistance of Plante's accumulators is low owing to the good conductivity of the liquid ; and the lower in proportion to the greater surface of the plate. Forming, when it does not exceed certain limits, lessens the resistance. The influence due to the reduction of the distance between the electrodes is less than that due to 42 PL ANTE ACCUMULATORS. the development of their surfaces and to their degree of formation. A formed couple the distance between the electrodes of which is 5 millimeters, and the total surface of the said electrodes 50 square decimeters (800 sq. in.), has a resistance of 0*04 to 0*06 ohm. This low resistance of the Plante accumulators renders them fit for the production of currents of greater intensity than the most energetic primary batteries. . Autogeneous Formation : Heterogeneous Formation. After the study of Plant6 accumu- lators comes the description of various species of accumulators belonging to the same genus. These species, already numerous, will be grouped under two principal series, according to their method of forming. (It is known that the formation consists in rendering accessible to elec- trolysis a certain weight of active material upon each electrode.) In Plante's original accumulators and those of the same description, the active materials are issued from the metal itself of the electrodes : these accumulators belong to the first series, and shall be designated as autogeneous formation accumulators. The other species belong to the second series : that of heterogeneous formation accumulators. CHAPTER IV, ACCUMULATORS OF THE PLANTE TYPE : AUTOGENEOUS FORMATION. ACCUMULATORS, SURFACE FORMATION FOLIATED ACCUMU- LATORS TOMMASI ACCUMULATORS DE KABATH ACCU- MULATORSLEAD WIRE ACCUMULATORS SIMMEN ACCU- MULATOR SlMMEN AND REYNIER ACCUMULATORS LEAD SHOT ACCUMULATORS PLAITED ELECTRODE ACCUMU- LATORS INCREASE BY FORMATION INCREASE BY DIS- CHARGE GROSS INCREASE QUICK AUTOGENEOUS FORMA- TION, COMPRESSED BY THE INCREASE REYNIER ACCUMU- LATORS ELECTRODES RENDERED PERMEABLE BY THE ELIMINATION OF AN AUXILIARY METAL MONNIER AC- CUMULATORSULPHURETTED ELECTRODE ACCUMULATOR. Accumulator Surface Formation. To render accessible to the action of electrolysis a given weight of active material, such is the object of formation. The desired weights can be obtained by giving the electrode surfaces a great development : a superficial attack will then be sufficient to secure the required mass. This is the surface formation which is effected in accumu- lators with laminated electrodes, lead wire, lead shot electrodes. One kilogramme of lead, laminated to the thickness of i millimeter, develops a surface of 44 ACCUMULATORS OF THE PLANTE TYPE. 1 8 square decimeters. The surface being in- versely proportional to the thickness, lead lami- nated to -^Q millimeter thickness will develop a surface of 1 80 square decimeters per kilogramme. The Tommasi and de Kabath accumulators are based on this principle. Tommasi Accumulators* --The electrodes of the Tommasi accumulators are vertical leaden plates about 2, millimeters thickness, and provided with cross vertical partitions, cast with the plates, and making with the latter an angle of 30 or 40 degrees. The spaces of about 5 millimeters, left between these partitions, are filled with lamellated lead sheets about y 1 ^ millimeters in thickness. The formation rapidly oxidises these lamellated sheets at the positive pole, and converts them into spongy masses which are retained on their sup- porting plates owing to the inclination of the compartments. The positive electrode only is formed, so it is necessary to reverse, at least once, the direction of the charging current in order to successively form the two electrodes. These reversals are compulsory with all accumulators of the Plante genus of autogeneous formation. De Kabath Accumulators. In these accumula- * French patent No. 143,555, 3 rd September, 1881, taken out by La Socie'te' Universelle d'Electricite' Tommasi, for Perfectionne- ments dans les piles secondaires. AUTOGENEOUS FORMATION. 45 tors, the electrodes are made of very thin leaden strips, horizontally superposed in a narrow leaden box (Fig. 14) ; all these strips are made FIG. 14. to be in intimate contact with the boxes by means of an energetic compression exerted on the ver- tical edges of this perforated plate. In order to prevent the strips from screening one another, the inventor has given every other one an undulated shape : whence the name of fluted accumulators. The pattern most in use (Fig. 15) weighted 36 kilogrammes, distributed as follows : 10 positive and negative electrodes.. Sulphuric acidulated water T V - Wooden case lined with ebonite 21 Kg. 6 3 The formation is effected by a series of succes- sive charges and discharges, with a few reversals and is quickened by adding, during the first 46 ACCUMULATORS OF THE PL ANTE TYPE. two hundred hours, T^ of nitric acid to the solution. A voltaic capacity of 12,000 coulombs or 3*33 FIG. 15. ampere-hours per kilogramme of lead is obtained after 500 hours' forming. Lead Wire Accumulators. - - One kilo- gramme of lead, drawn to a diameter of one millimeter, develops a surface of 35 square decimeters ; the surface developed for a given weight of lead is in an inverse ratio to the diameter of the wire. In the first lead wire accumulator, the elec- trodes were made of cables * which arrange- ment had this advantage that all the parts of the * Emile Reynier, French patent No. 142,777, i6th April, 1881. AUTOGENEOUS FORMATION. 47 electrode were in thorough communication with the external charging circuit. Mr. Tommasi * has wound some i mm. diameter leaden wires round leaden plates 2 mm. thick. Messrs. Arnold and Tamine have used leaden wires of different forms : concentrical helixes, spiral plates, small straight lengths soldered at their ends to a leaden frame, &c. These various systems, incompletely worked out, had several defects, the most serious of which was the high price of lead wire. Simmen Accumulator. Mr. Simmen has in- vented a very ingenious process for the economical production of leaden wire of all diameters and lengths. This process consists in pouring some melted lead in a heated metal box, the bottom of which is provided with holes of convenient shapes and sizes. The melted metal flows through these holes and is suddenly cooled by falling into a tank full of water. The wire so manufactured does not possess the regularity of drawn-wire ; it is more or less coarse, and all its parts are so interwoven with each other that it would not be suitable for ordinary purposes ; but it is perfectly suitable to the construction of accumulators. * Socie'te' Universelle d'Electricitd Tommasi, French patent No. 143,101, loth August, 1881, Pile secondaire Nouvelle. 48 ACCUMULATORS OF THE PL ANTE TYPE. Mr. Simmen has made some electrodes with his wire. In his first plates (Fig. 16), the spun FIG. 16. wire was encased in a box made of laminated lead. This box screened a large proportion of the wire, thus reducing to a considerable extent the advantage of a great surface development ; its cost destroyed the economy realised in the manu- facture of the wire. These inconveniences of the perforated box are not atoned by any increase of solidity ; on the contrary, this envelope is rapidly formed and infallibly gets cut toward the level of the liquid, allowing the fibrous mass which it supports to fall at the bottom. A UTOGENEOUS FORMA TION. 49 Mr. Simmen had to abandon this unfortunate reminiscence of the de Kabath accumulator. With the assistance of another inventor, he tried to find a better use of his wire, which proved such a cheap finely divided lead. Simmen and Reynier Accumulators.* The supporting cage or box being condemned, means had to be found for aggregating the leaden wires. The cabling and the coiling were out of question with such intricate masses of material. But a close examination of some specimens soon led to the discovery of a precious property which allowed of its being utilised. Simmen's wire is not smooth. Seen by the microscope it is composed of a succession of tear- shaped drops, of a series of irregular bodies alternately inflated and depressed. These rugosi- ties are advantageous ; they increase the surface and render the wire fit for felting. A handful of material, kneaded with the hand and then flattened with a hammer, at once agglomerates into a felted mass of a certain strength. It was therefore thought that fibrous materials, submitted to energetic compression within solid matrixes, would produce some resisting felts. The trial was successful.. A parcel of threads, compressed in a press or stamp, becomes a solid * French patent No. 168,155, 8th April, 1885, 'Electrodes d'ac- cumulators en plomb.' Emile Reynier, and Adolphe Simmen. E 50 ACCUMULATORS OF THE PL ANTE TYPE. plate, which is, however, permeable, and contain- ing millions of cells. The mean density of the plates depends upon ths pressure exerted upon them. This density has been regulated to 8, so that the empty spaces or cells occupy about one-third of the plate. Not- withstanding the apparent disorder of these lumps of threads which are crushed by compression without any preparation whatever, the solid and the hollow parts happen to be regularly distri- buted ; haphazard has its laws. The capillary structure of the felts secures a quick forming, a large voltaic capacity and a good internal conductivity. These properties can be exalted or attenuated at will : the strength and the duration of the electrode increase with the thickness of the thread used ; the rapidity of forming and the voltaic capacity, on the contrary, increase with their slenderness ; whence the possibility of securing, according to the require- ments of the cases, one or the other of these desiderata. In practice, the threads of the negative and positive electrodes are made of T % and -$ mm. diameter respectively. A leaden frame, provided with suspending appendices, is cast round the felted sheet, acting as a support and a conductor to it (Fig. 1 7). The following figures apply to a specimen of felted plate having been in ordinary use. AUTOGENEOUS FORMATION. Width of the plate .. .. 140 millimeters. Total height 245 Thickness 4 Weight of the felt .. .. 700 grammes. Total weight 1300 External surface of the electrode 5 ' 4 square decimeters. Total developed surface, positive electrode .... 50 Total developed surface, negative electrode .. .. 125 ,, Voltaic capacity per pair of electrodes 17 ampere-hours. Voltaic capacity per kilo- gramme of felt .. .. 12 ,, Voltaic capacity per kilo- gramme of plate . . . . 7 ' 3 , , FIG. 17. Felts of indefinite lengths can be obtained by laminating. The wire lead, on coming out of the E 2 52 ACCUMULATORS OF THE PL ANTE TYPE. draw-plate, falls on an endless travelling table, which takes it between a pair of cylinders where it is felted at the requisite thickness. This pro- cess, more rapid than the compression with matrixes, gives some cheap leaden felts which will find use in the construction of secondary batteries. Lead Shot Accumulators. i kilogramme of lead divided in spheres, i mm. diameter, develops a surface of 52 square decimeters. The surface is in an inverse ratio to the diameter of the spheres ; shot much smaller than i mm. can easily be obtained. Fine shot, therefore, develops an enormous surface, but each individual shot can only par- ticipate, efficaciously, to the voltaic actions, on the condition of being in good electric communication with the pole. Fine lead shot has been used by Mr. d'Arsonval, at the positive plate of a secondary couple which will be hereafter described with the sulphate of zinc accumulators. Plaited Electrode Accumulators. Accu- mulator electrodes of large surface, and the parts of which are totally accessible to the electrolytic actions, can be obtained by plaiting, concertina fashion, some laminated lead strips. This AUTOGENEOUS FORMATION. 53 arrangement is simpler, and more effective than the layers of foliated lead or the encaged strips. In order to increase the strength and the life of plaited electrodes, Emile Reynier, at first reinforced them by means of a hemming, or ribs transversal to the plaiting cast with the plate before its being plaited. (Fig. 18). FIG. 18. The transversal zones, thus reinforced, connect the parts of the electrodes rendered fragile by the forming ; * cuts in the simple parts can no longer cause the breaking of the electrode. In an old and well-known pattern of plate, the sheet of laminated lead, i mm. thick, was first * French patent No. I53,9J5> 2 3 r , Weight of the plaited pannel . .. 600 grammes Total weight 1200 grammes External surface of the electrode . . 5 square decimeters Total developed surface .... 21 Voltaic capacity per pair of plates 14 ampere-hours. The voltaic capacity of the plaited plate is about 1 2 ampere-hours per kilogramme ; but the A UTOGENEOUS FORMA TION. 63 dead weight of the frame being equal to that of the pannel, the capacity of the whole is only 6 ampere-hours per kilogramme of plate. In order to obtain a better specific utilisation of the lead it is necessary to reduce the proportional weight of the frame. This has been done in another pattern of electrode, the particulars of which are as follows : Length of frame 125 millimeters Height .. .. 500 Total height of the plate .. .. 570 ,, Thickness 5 ,, Weight of the plaited pannel . . i 500 grammes Total weight 2*250 External surface of the electrode 13 square decimeters. Developed total surface . . . . 50 Voltaic capacity per pair of plates 36 ampere-hours In this case the voltaic capacity of the whole reaches 8 ampere-hours per kilogramme of plates. The forming is carried out according to Planters method ; it is comparatively quick, and especially if, as recommended by him, care is taken to pre- }- viously attack the electrodes with nitric acid. This operation may be energetically pushed, as, owing to the structure of the plate, the fall of the superficial materials is not to be feared, the said materials being firmly secured by compression. The distance between the folds is regulated in such a manner that the average density of the active portion may be from 6 to 6 5. The density 64 ACCUMULATORS OF THE PLANTE TYPE. of compact metallic lead being 11*4, there is at first a certain amount of play between the folds ; but the increase fills the gaps, cements the strips, and gives the four sides of the frame an apparent convexity which is an indication of a strong internal compression (Fig. 23). The electrodes are suspended and bear on a frame of varnished wood placed on the cell ; to each of them a length of nickel wire is soldered, and this wire is secured by a screw into the corresponding hole of a nickelled brass collector. The isolation of the plates is secured by means of vertical indiarubber rings, or, what is better, by wooden or ebonite forks (Fig. 24). FIG. 24. The number of plates is an odd one, so that the \ first and the last ones are negative. AUTOGENEOUS FORMATION. The small pattern, with five normal plates (Fig. 25), is mounted in ! a glass jar. The larger size patterns, with 9, 13, or 27 plates, are mounted in sandstone jars lined with a bituminous varnish FIG. 25. which renders them impermeable to sulphuric acidulated water. All these accumulators can be taken to pieces for inspection, renewals, &c., without the assistance of a specialist. The large plates of 2*250 k, mounted in the same manner, constitute the series of deep accumulators. F 66 ACCUMULATORS OF THE PLANTE TYPE. Electrodes rendered Permeable by the Elimination of an Auxiliary Metal. Thick plates may be rendered permeable by alloying to the lead an auxiliary metal which is afterwards eliminated. In a patent already mentioned,* Mr. Tom- masi claims " the use of a spongy metal due to V the electrical decomposition of an alloy of lead and tin." Later on, Messrs. Fitzgerald, Crompton, Biggs, and Beaumont f have indicated, with the same object, some alloys or mixtures of lead and other metals : zinc, sodium, antimony, potassium, iron, cadmium, silver, or several of these metals. They mention, as examples, the following alloys : 2 to 4 parts of lead with i of antimony 8 i of zinc 300 50 of zinc and i of sodium. They add : " We do not use tin in any of our alloys, because we found that it could only be eliminated with great difficulty and that, should any tin be left when the plates form the electrodes of a battery, it will slowly dissolve, be deposited, and create false contacts between the electrodes." The results of their researches have not been made known by these inventors. * No. 143,555, 3rd September, 1881. t French patent No. 149,200, 25th May, 1882. Perfectionne- ments dans les piles secondaires. AUTOGENEOUS FORMATION. 67 Monnier (Denis) Accumulator. Mr. Denis Monnier appears not to have been aware of the aforementioned experiments* when he tardily patented his lead-alloyed electrodes f . Mr. Monnier selected zinc as an auxiliary metal, in the proportion of 4 to 8 per cent. The alloy is only a real one in the proportion of i per cent. ; the surplus being merely a mixture. This mixture, effected at a high temperature, is an imperfect one, owing to the difference of density of the two metals ; it is, however, obtained by means of certain tricks of the trade. The electrodes are plates 3 mm. thick. The zinc, being eliminated by repeated immersions in caustic lixiviations and sulphuric acidulated water, leaves a numerous series of small holes which render the lead porous, permeable in the whole of its thickness to electrolytic actions. This mode of preparing the electrodes is not without some analogy with the deep scourings obtained by Mr. Plante with nitric acid. The elimination of the zinc must be completed by the formation. Under the action of the electric current, the direction of which is several * The author of this book, also, was not acquainted with these anteriorities when he described the Monnier accumulator before the ' Socie'te' des Ingdnieurs Civils ' (4th July, 1884), and in " Le Gdnie Civil' feth August, 1884). t Denis Monnier, Professor to the Geneva School of Chemistry ; French patent No. 152,607, i3th December, 1882, ' Perfectionne- ments aux accumulateurs d'electriciteV' F 2 68 ACCUMULATORS OF THE PLANTE TYPE. times reversed, the two electrodes, each positive by turn, liberate the last traces of zinc, in a state of sulphate of zinc, which dissolve in the liquid. The sulphuric acidulated water must be frequently renewed, otherwise the remaining zinc would be indefinitely vehiculated from one electrode to the other, and the formation could not be completed. The repeated scourings, the numerous lixivia- tions, and the necessary reversals with frequent renewals of the liquid, make the formation of the plates tedious and costly ; but the result is well worth the trouble and expense. Monnier's electrodes have an elevated voltaic capacity, are compact, homogeneous and durable. The stiffness of the electrodes allows of a simple and strong mounting, as illustrated in the FIG. 26. FIG. 27. longitudinal section, Fig. 26, and in the transversal one, Fig. 27. The accumulator is composed of an even AUTOGENEOUS FORMATION. 6c number of similar plates alternately positive and negative, and placed very near each other. Each plate is provided with a boss coming outside the liquid ; the bosses on the positive plates are all on one side, and those on the negative plates on the opposite side of the accumulator. The positive and negative electrodes are all joined together respectively, by means of a rod of ebonite passing through the holes in the bosses, and they are maintained apart by means of the interposition of isolating washers. This compact ensemble is supported by two transversal bars, and is main- tained, at each end, by means of two grooved wooden panels, the grooves of which receive the edges of the vertical plates. The jar is made of sandstone. The following data refer to a ten-plate accumu- lator : Total surface of the ten plates no square decimeters. Weight of each plate .. .. 1900 grammes of the ten plates .. 19 kilogrammes ,, of the liquid (acidu- lated water T V) .. 4 of the jar 4 Total weight 29 Voltaic capacity 144 ampere-hours Intensity of the normal dis- charging current . . . . 23 amperes Intensity of the charging current 13 5 > The voltaic capacity is\7'6 ampere hours kilogramme of plate. 70 ACCUMULATORS OF THE PLANTE TYPE. The Monnier accumulator is not in industrial use ; but there is no reason for this, as it is a good apparatus. Sulphuretted Electrode Accumulators. The sulphuretting of lead electrodes, previous to the formation, quickens the latter. This process is attributed to Mr. Schulze. The plates are sulphuretted to a certain depth by means of an addition of brimstone heated in contact with them. They are formed by the Plant6 process. The sulphur, carried away with the gases of the electrolysis in a state of sulphuretted hydrogen and sulphurous acid, leaves some porous lead at the surface of the electrodes. No data exist as regards accumulators thus formed. CHAPTER V. ACCUMULATORS OF THE PLANTE TYPE. HETEROGENEOUS FORMATION. ACCUMULATORS WITH OXIDES OR INSOLUBLE LEAD SALTS JUXTAPOSED TO CONDUCTIVE SUPPORTS : CAMILLE FAURE SYSTEM ACCUMULATORS WITH RETICULATED ELEC- TRODES FILLED WITH FINELY DIVIDED LEAD : VOLCKMAR SYSTEM ACCUMULATORS WITH SOCKETTED OXIDES : FAURE-VOLCKMAR SYSTEM SELLON'S GRATINGS OF LEAD AND ANTIMONY ALLOY FAURE - SELLON - VOLCKMAR ACCUMULATOR MODIFICATION TO FAURE - SELLON - VOLCKMAR ACCUMULATORS : DOUBLE ELECTRODES MODI- FICATIONS IN THE COMPOSITION OF THE LIQUID, BY MR. CHARLES PHILLIPART MOUNTING IN COLUMNS, BY G. PHILIPPART MIXED ACCUMULATOR : FAURE - REYNIER SYSTEM JUXTAPOSED AMALGAMS : NEZERAUX ACCUMULA- TORS AGGLOMERATE OXIDE OF LEAD ELECTRODES : ARON'S METALLOIDIUMS AND METALLOIDIONS ; TRIBE PEROXIDE OF LEAD ELECTRODES ; FRANKLAND AGGLO- MERATED ELECTRODES ; R. TAMINE AGGLOMERATED ELEC- TRODE ACCUMULATORS ; FITZGERALD LITHANODE ELEC- TRO-CHEMICAL FORMATION : MONTAUD ACCUMULATOR. Accumulators with Oxides or Insoluble Lead Salts juxtaposed to Conductive Supports Camille Faure System. Well- formed Plante's electrodes are composed of a metallic lead core, covered with a permeable layer the active portion of which is peroxide on the positive and reduced lead on the negative. 72 ACCUMULATORS OF THE PLANTE TYPE. In Plante's process of formation, these per- meable materials are produced from the elec- V trode's lead itself (autogeneous formation). Mr. Camille Faure* has obtained at once some electrodes with thick layers of active FIG. 28. H f materials, by coating some lead plates with pastes of sulphate of lead, or of oxides of lead backed by felt partitioning (Figs. 28 and 29). Electrodes thus prepared can be formed with a * French patent No. 139,258, 2oth October, 1880, " Perfection- nements aux batteries galvaniques et applications de ces batteries aux locomotives dlectriques" ; French patent No. 141,057, Qth February, 1881, " Perfectionnements dans les dispositions et la construction des couples-batteries secondaires." HETEROGENEOUS FORMATION. 73 single charge of 150 hours. The formation con- verts the pulverulent masses into solid, porous and conductive crusts of reduced lead, and of peroxide of lead more or less mixed with sulphate of lead. The Faure accumulators, like those of Plante, FIG. 30. are composed of a greater or smaller number of alternating plane electrodes, or of a single pair of spiral wound electrodes (Fig. 30). A committee of the jury of the Paris Exhibition 74 ACCUMULATORS OF THE PLANTE TYPE. of Electricity (January 1882), has carried out a series of experiments upon the Faure accumu- lators, the results of which have been communi- cated to the Academic des Sciences.* The battery experimented upon consisted of 35 round couples weighing each an average of 43 * 7 kilogrammes ; the electrodes, coated with a layer of 10 kilogrammes of oxide of lead per square meter, weighed about 30 kilogrammes. The 35 accumulators charged in series during 22 hours 45 minutes, with a current of 1 1 to 6 * 36 amperes, received 694,500 coulombs under an average fall of 9 1 volts. The discharge, which lasted 10 hours 39 minutes, with a mean intensity of 16*2 amperes, and a mean potential of 61*5 volts, gave off 619,600 coulombs. We deduce from these data : Average potential of the charge for i accumulator 2*6 volts. Fall of potential utilised during the discharge 1*76 Voltaic capacity per kilogramme of accumulator 14,000 coulombs. Voltaic capacity per kilogramme of electrodes 20,653 Proportion between the quantities given off and received 0-89 * Note of Messrs. Allard, Joubert,' Potier, and Tresca, presented at the meeting of the 6th March, 1882. HETEROGENEOUS FORMATION. 75 Proportion between the potentials of discharge and charge .. '.. .. 0-675 Electrical efficiency of the battery . 0*89 x 0*675 = '6o Available energy per kilogramme of accumulator 2,500 kilogrammetres. Weight of accumulator necessary for the production of one electrical horse-power per hour 108 The immediate results obtained with the Faure system have deeply impressed the elec- tricians ; they, for the first time, gave an exact idea of what services could be expected from secondary couples, which until then had scarcely been appreciated outside the laboratory where the couples in use had been laboriously formed. The defects of Faure accumulators made them- selves apparent, at the same time as its qualities, and the principal of those were the short duration of the felts, the disaggregation and fall of the permeable crusts which the increase infallibly separated from their supports. This mode of supporting the active materials by means of felt partitions had to be abandoned. But the principle of heterogeneous formation, by additions of oxides, remains in force, and is the basis of the system of accumulators actually the most in use industrially, the Faure-Sellar- Volckmar system, which will be hereafter described. 76 ACCUMULATORS OF THE PLANTE TYPE. Accumulators with Reticulated Elec- trodes, filled with finely divided Lead : Volckmar System. Mr. G. Philippart en- deavoured to avoid the inconvenience of the par- titioning, without doing away with the advantages of the heterogeneous formation. He succeeded in this, by making use of thick plates, perforated with holes, cells, or reticules containing the active materials. This ingenious device has been patented by Mr. E. Volckmar.* The first plates manufactured by Mr. G. Philippart, were made with sheets of laminated lead 3 or 4 mm. thick, and mechanically per- forated ; the cells, which were numerous and very close to each other, were garnished with very finely divided lead, in the shape of foils, threads, or, even better, in a state of chemical precipitate or frothy lead.f Lead foils or threads take a long time to form, whereas the forming of frothy lead is compara- tively quick ; the plates garnished with it acquired, after 150 to 200 hours' charging, a large voltaic capacity. Frothy lead is obtained by precipitating the lead, with zinc, from its nitrous or acetic solution. The material thus obtained is very costly, and its use is less convenient than that of the lead oxides. * French patent No. 145,218, 8th October, 1881, " Nouveau systeme de piles secondaires." \ The use of frothy lead in accumulators was mentioned in Mr. Tommasi's, French patent No. I43>555> 3 r d September, 1881. HETEROGENEOUS FORMATION. 77 Accumulators with Socketted Oxides : Faure-Volckmar Systems. The defects of each of the two primitive systems have been done away with by garnishing Volckmar's cells with Faure paste. The reticulated plates which support the active materials are lead gratings, as light as possible, cast in moulds (Fig. 31). The taper necessary FIG. 31. for unmoulding is taken by halves on each side of the plate, so that the shape of the cell is that of two truncated pyramids joined at their small basis, the large basis being level with the external planes of the plate. The blocks of active materials socketted into these tapering cells, are held in their middle, and, so to speak, riveted in the supporting grate. The garnished plate (Fig. 32) brings the active materials in contact with the liquid on the near totality of its surfaces ; for the edges of the 7 8 ACCUMULATORS OF THE PL ANTE TYPE. gratings, reduced to a minimum, and coming flush with the surfaces of the plate, only show as straight lines on the said surfaces. FIG. 32. The pastes for garnishing the cells are made of oxides of lead, firmly gauged in sulphuric acidu- lated water. Peroxide of lead is used for the positive and protoxide of lead for the negative plate. The gauging produces a small quantity of sulphate of lead in a supersaturated solution ; when drying, the sulphate slowly becomes solidi- fied into the mass and hardens. The setting of the paste takes place in the same manner, and owing to analogous chemico-physical phenomena, as that of mortar. The forming does not produce any apparent increase, for the density of the pastes is such that their conversion into peroxide and reduced lead, takes place without expansion or contraction. HETEROGENEOUS FORMA TION. 79 This happy result, whiqh the inventors obtained without seeking for it,* secured the success of the heterogeneous formation in the Faure-Volck- mar accumulators. As regards the increases by discharge, they are in this instance subdivided into numerous parts ; the expansions produced in each cell do not ex- ceed the plastic faculties of the active materials. In fact, the negative electrodes have a very long life (some say indefinite). The positive electrodes, on the contrary, perish after a short time, owing to a destructive for- mation of the grating, the metal of which X becomes more and more peroxidised. The support thus attacked increases, expands up to rupture, warps, and sometimes comes into con- tact with the negative plates, and ultimately drops the active materials which it contained. These accidents are the cause of frequent repairs and renewals of the positive plates. Sellon's Gratings of Lead and Antimony Alloy. The destruction of the positive gratings is considerably delayed by making them of lead and antimony, f * The study of increase is subsequent to the Faure-Volckmar invention. f J. S. Sellon, English patent 3987, 1881, " Secondary batteries or magazines of electricity." French patent 147,831, loth March, 1882. ' Perfectionnements aux piles secondaires ou accumulateurs d'e"lectriciteV 8o ACCUMULATORS OF THE PLANTE TYPE. This alloy is harder than lead, and possesses, when cooling, a property of expansion, owing to which the castings are of great neatness. For these reasons, antimony, which is indispensable with positive gratings, is also introduced, although in reduced proportion, into the negative ones, the stiffness of which is increased thereby. Faure - Sellon - Volckmar Accumula- tors. The lead and antimony alloy used by Mr. Sellon in the construction of the Faure- Volckmar accumulators has, in a certain measure, given these apparatus the strength and duration they were deficient in. The couples thus perfected are designated " Faure-Sellon- Volckmar accumu- lators." They are made of numerous patterns, differing in sizes, thicknesses, and number of plates. Fig. 33 illustrates a specimen of French manufacture set up in a wooden jar internally lined with lead. Fig. 34 illustrates one of its electrodes, an eleva- tion and vertical section of which are shown in Figs. 3^ and 3 ^respectively. The specimen illustrated in Fig. 33 is one com- paratively heavy, intended for lighting stations : some lighter types are constructed for tramway traction. The data relating to two patterns especially selected respectively amongst the lighting and traction types, are given in the two following tables. HE TER OGENE US FORMA TION. 8 1 FIG. 34. 82 ACCUMULATORS OF THE PL ANTE TYPE. By way of additional information, a third table, giving similar data in reference to a very light couple, has been added to the two above men- A IMIMIMIMIMIMIMIMIMIMIMIMIMIMI Ml Ml "I MlMi Ml Ml M< Ml "I Ml Ml Ml Ml Ml IMI Ml Ml Ml"! Ml Ml Ml Ml Ml Ml Ml Ml Ml MlMlMlMlMlMlMlMlMlilMlMlMlMlM! MIMIMIMIMIMIMIMIMIMIMIMIMHIMI 111 Ml II Ml Ml II II Ml 11 Ml Ml Mill* Ml Ml Ml Ml Ml FIG. 35. FIG. 36. tioned. This unique apparatus has been con- structed by Mr. G. Philippart with a view to ascertain to what inferior limits can be brought the weights of plates and of accumulators com- pared to the energy and the work. The gratings are only 2 mm. thick ; they are reticulated so as to hold a weight of materials equal to their own weight. The delicate and expensive plates give some surprising results ; but their manufacture and use would require an amount of attention out of pro- portion with the existing uncertainty of the indus- trial practice. HETEROGENEOUS FORMATION. FAURE-SELLON-VOLGKMAR ACCUMULATOR. STATIONARY PATTERN FOR LIGHTING STATION. Wooden and Lead Jar. f Length Sizes of plates 310 millimetres. 215 005 8 9 208 sq. decimetres. 2-350 kilogrammes. 400 millimetres. 200 60 kilogrammes. 40 amperes. 60 400 ampere-hours. 1 08 watts. 0-97 H.-P. per hour. 0-29 ampere. 10 ampere-hours. 3 408 kilogrammes. 272 62 G 2 84 ACCUMULATORS OF THE PLANTE TYPE. FAURE-SELLON-VOLCKMAR ACCUMULATOR. PORTABLE PATTERN FOR TRAMWAY TRACTION. Ebonite Jar. f Length Sizes of plates < Height . . . . I Thickness Number of plates, positive negative .. Useful surface of the 1 7 plates Weight of each plate the 1 7 plates External sizes of the f Len 8 th accumulator \ I Height Weight of the complete accumu- lator, full of liquid Intensity of the charging current Intensity of the discharging current Voltaic capacity Useful normal energy ... Utilisable total work Regimen of discharge per square decimetre of plates Regimen of discharge per kilo- gramme of plates Voltaic capacity per kilogramme of plates Voltaic capacity per kilogramme of permeable material Weight of accumulator corre- sponding to i H.-P. energy Weight of plates, corresponding to i H.-P. energy Weight of accumulators corre- sponding to i H.-P. electrical work Weight of plates corresponding to i H.P. electrical work 150 millimetres. 150 004 8 9 7 2 square decimetres, o 600 kilogramme. I0'2 170 millimetres. 13 230 13 kilogrammes. 10 amperes. 20 120 ampere hours. 36 watts. 0-3 H.-P. per hour. 0*28 ampere. 2 amperes. 12 ampere hours. 36 260 kilogrammes. 204 43 34 HETEROGENEOUS FORMATION. FAURE-SELLON-VOLQKMAR ACCUMULATOR. EXPERIMENTAL PATTERN WITH THIN PLATES. Ebonite Jar. ( Length Sizes of plates < Height . . V Thickness Number of plates, positive negative .. Useful surface of the 25 plates Weight of each plate the 25 plates External sizes of the f Length accumulator. . . } Wldth I Height Weight of the complete accumu- lator full of liquid Normal intensity of the charging current .......... Normal intensity of the dis- charging current ...... Voltaic capacity ...... Useful normal energy Utilisable total work Regimen of discharge per square decimetre of plates Regimen of discharge per kilo- gramme of plates Voltaic capacity per kilogramme of plates ........ Voltaic capacity per kilogramme of permeable material Weight of accumulator corre- sponding to i H.-P ..... Weight of plates corresponding to i H.-P ......... Weight of plates corresponding to i H.-P. electrical work . . Weight of plates corresponding to i H.-P. electrical work . 150 millimetres. 150 002 12 !3 1 08 square decimetres. 0-245 kilogramme. 6-125 k 170 millimetres. 130 9-700 kilogrammes. 10 amperes. 20 155 ampere hours. 36 watts. 0-36 H.-P. per hour. 0-186 ampere. 3-25 25 ampere hours. 5 200 kilogrammes. 16-120 86 ACCUMULATORS OF THE PL ANTE TYPE. The English manufacture of Faure-Sellon- Volckmar accumulators, monopolised by the Electric Power Storage Company, offers a great variety of types, Fig. 37 being an illustration of one. FIG. 37. The glass jars used by this Electric Power Storage Company, more particularly for stationary purposes are, it appears, stronger than would be supposed ; they very seldom break, afford a good isolation and great facilities for the inspection of the couples. They make the positive plates slightly thicker than the negative, With the exception of detail of construction, and the par- ticular setting up of certain patterns, the English HETEROGENEO US FORMA T1ON. 8 7 manufacture does not differ much from the French, and gives equivalent results. The Faure - Sellon -Volckmar accumulators manufactured in Belgium, Austria, and America, are not possessed of any particular feature worth noticing. Modifications to Faure-Sellon-Volckmar Accumulators. Amongst the numerous im- provements which the Faure-Sellon-Volckmar accumulators have been subjected to, several of them deserve noticing. Double Electrodes. At the origin of the indus- trial exploitation of accumulators, it often hap- pened that the active materials got detached from their supports, and this more particularly in the case of positive plates. These accidents were due to a defective manufacture, and to faults committed in the management and use of the batteries. It was thought that the fall of the cakes of active materials could be prevented by shutting them into taper cells, the small dia- meters of which were situate externally. Grat- ings were, to that effect, cast with only one tapering, and two of them, riveted together, constituted one electrode. The tapers of the two plates thus joined were opposite each other, and turned toward the interior of the plate, so as to form cells swollen in their middle. 88 ACCUMULATORS OF THE PLANTE TYPE. Figs. 38 and 39 are illustrations of a double plate, being a vertical section and an elevation respectively FIG. 38. FIG. 39. The manufacture of these plates is complicated ; their dead weight is greater than those of single plates ; the active materials which they contain are only accessible to the liquid through some reduced surfaces ; whence diminution of the voltaic capacity, increase of the internal resistance and lowering of the charging and discharging regimens. These serious defects are not compensated by HE TEROGENEO US FORMA TION. 89 an improved behaviour of the active materials, the fall of which appears, on the contrary, to be accelerated. ' An important trial of the double plates took place in 1883 and 1884 with a large battery of accumulators erected at the Hotel des Postes ; the results were bad. Modifications in the Composition of the Liquid, by Mr. Charles Philippart. Certain applications, such as to carriage traction and boat propulsion, require the use of very large electrical power combined with a restricted total weight ; the normal output of ordinary accumulators then be- comes insufficient. It should be increased without reducing the thickness of the plates, the strength of which must be preserved. Mr. C. Philippart has succeeded in this direc- tion by adding some oxygenated water in the liquid of the couples.* The result was an increase of the output regimen which could be brought to 4 amperes per kilogramme of ordinary plates. The fall of external potential, besides, increased from o i to 0*2 volt, and there was a notable increase in the voltaic capacity. Mr. C. Philippart, at first, depended on the oxidising action of the binoxide of hydrogen, but soon perceived that the results obtained must * French patent, No. 159,933, 25th January, 1884. ' Nouveau systeme pour depolariser les piles secondaires.' Charles Philippart. 90 ACCUMULATORS OF THE PL ANTE TYPE. be attributable to some other reasons. In effect, the liquid keeps its properties for a long time, and is capable of supplying numerous intense dis- charges, without a renewal of oxygenated water ; this negatives the aforesaid theory electrolytic deoxidisation. The inventor now attributes the increased energetic action of the liquid to a sulphate (or polysulphate ?) of binoxide of hydro- gen. This sulphate of binoxide would liberate some sulphuric acid in a particular state and possessed of greater affinities than that coming out of the sulphate of protoxide. The liberated binoxide of hydrogen would be resulphated at the same rate that it gets desulphated, thus remaining fit to electrically carry an indefinite quantity of sulphuric acid. Some recent experiments seem to confirm this theory. Mr. C. Philippart has observed that the addition, in sulphuric acidulated water, of certain non-oxidising sulphates give the same results as that of oxygenated water. Sulphate of ammonia, notably, gives some remarkable results. The amplified discharges obtained with the new liquids necessarily cause an augmentation in the increase by discharge, with the consequent tendency to push the active materials out of their cells. In order to render the plates fit to re- ceive, without degradation, some greater expan- sions, their construction should be altered. This question is now being studied, HETEROGENEOUS FORMATION. Mounted in Column by Mr. G. Philippart. A secondary battery of some importance contains several hundred parts, such as jars, electrodes, isolating pieces, collectors, junctions, &c., the whole being costly, cumbrous, difficult of removal and handling. At the beginning of his researches, Mr. Faure attempted to simplify secondary batteries by constructing some accumulators with parallel electrodes similar to ordinary trough voltaic batteries.* This idea has also been worked out by several other inventors, but none have succeeded in ob- taining the perfect watertightness of the trough compartments and isolation of the juxtaposed couples. Mr. G. Philippart gives to multiple accumu- lators a form which is more easy of practical realisation. | In this system, the electrodes are double ; they are conical or truncated, positive on one face and negative on the other. These cones are piled up vertically, one inside the other, with interposition of isolating material. The liquid is introduced in the watertight compart- ments formed by every two successive cones, and there are as many couples, minus one, as there are cones. * French patent, No. 139,258, 2oth October, 1880. t French patent, No. 157, 139, 2 1st August, 1883. ' Construction nouvelle des accumulateurs electriques.' G. Philippart. KP/fe.- ^ 92 ACCUMULATORS OF THE PLANTE TYPE. The cones are made of a cast core of lead and antimony, covered on its two faces with a paste of oxides of lead. Some grooves, cast with the cores, constitute the cells which hold the active materials. In order to render this system practical, the cast cores with cells should be of large dimensions, not too heavy and perfectly sound ; the difficul- ties of obtaining these results do not seem insuperable. Mixed Accumulator: Faure- Reynier System. Before closing the chapter of oxide accumulators, we will describe this combination of a Faure negative with an autogeneously formed plaited positive. This system was established by the author of this book in the workshops of the Geneva Society of Mechanical Construction. The jar of this accumulator (Fig. 40) is made FIG. 40. of a leaden sheet, the borders of which are up- lifted but not soldered, externally supported by HETEROGENEOUS FORMATION. 93 a long rectangular wooden trough. This leaden box, the bottom of which is covered with peroxide of lead m m, constitutes the negative electrode of the accumulator. A strip of lead N, externally soldered to it, serves as a connecting piece. The positive electrode (Fig. 42) is made of a long leaden strip, plaited, and slit along all the folds so as to offer the whole of its surfaces to the electrolytic action. In order to prevent this electrode being cut in any portion of its length by a deep formation, it has been strengthened in its FIG. 41. FIG. 42. middle part, by means of two superposed folds (Fig. 41), ef which folds upon c d, and^/^ which folds upon a b. After this double folding length- wise, the strip is plaited crosswise ; then all the folds are slit from the border to the medium edge. One of the ends of the electrode emerges from the liquid, and to it is attached a strip of soft lead for connection purposes ; P is a binding screw. The two electrodes are separated from each 94 ACCUMULATORS OF THE PLANTE TYPE. other at the sides by means of lateral glass strips V, V, V, and at the bottom by means of longitu- dinal and transverse sleepers. FIG. 43. The accumulators are placed in a rack (Fig. 43) and connected in the usual manner. HETEROGENEOUS FORMATION. 95 This pattern is an economical one to manufac- ture and use : lead, peroxide of lead, wood, and sulphuric acid are the only materials used in its composition ; it requires very little attention, and the renewals are as cheap of cost as easy to effect. Sixty of these couples have been in use during several months, for the lighting of the " Bouffes," Geneva.* Juxtaposed Amalgam : N6zeraux Ac- cumulators.f The active portion of Neze- raux's plates is a mass of spongy lead obtained by the elimination of the mercury in an alloy of mercury and lead. This amalgam contains one part of mercury, to two parts of lead ; it is obtained by fusion in an iron pan. It is left to crystallise by cooling, and then reduced to a fine powder. The core of the electrode is a grating set in a projecting frame. The pulverulent amalgam is applied on both faces of the grating until it reaches an even level with it, and then agglom- erated by pressure. Immersion in sulphuric acid- ulated water, and exposure to atmospheric air knead the mass and give it cohesion. The plates thus prepared are submitted to the forming current which peroxidises the positive and * March 1883. t * La Lumire Electrique,' 23rd and 3oth May, 1885. 96 ACCUMULATORS OF THE PLANTE TYPE. eliminates their mercury. The current being reversed, the negative become positive* and get, in turn, peroxidised ; whereas the ex-positive be- come negative and pass into a state of very per- meable reduced lead. The eliminated mercury is gathered at the bottom of the forming jars. According to the inventor, plates thus formed are possessed of a very great strength and long duration. They could give up to 25 ampere hours per kilogramme, this high capacity resulting from the large proportion of permeable materials which represent the three-quarters of the weights of the plates. The charging and discharging regimens may vary from -J- to 3 amperes per kilogramme, and the electromotive force of the couples is a little higher than that of other systems of the Plante type. These accumulators have never been used in- dustrially, and one has to rely on the inventor for the data. A priori, the juxtaposed amalgam plates seem to be costly, owing to the losses of mercury. The manipulation of this metal in large quantity would prove more injurious than that of lead. Agglomerate Oxides of Lead Elec- trodes. In the Faure system, the first industrial attempt at heterogeneous formation, the active materials, of feeble cohesion and feebler adherence, are held against their support by means of per- HETEROGENEO US FORMA TIOA. 9 7 meable partitions. The reticulated plates, which constitute an important progress, hold the materials without the help of any partition ; their defect resides in the excessive weight of the grating, which amounts to two-thirds of the total weight. The Nezeraux plates show a tendency to reduce the dead weight by giving predominance to the weight of the permeable mass. The object, in the following systems, has been to still more reduce the weight of the conducting support in favour of the active materials ; agglom- erating the latter to give them cohesion, and a better internal conductivity. Aroris Met allodiums and Metallodions* Dr. H. Aron, of Berlin, has given the name of metallodions to metallic oxides agglomerated with collodion upon lead or carbon conducting supports. Peroxides of lead and of manganese may be used as positive electrodes in primary batteries. He calls metallodiums permeable metallic agglomerated materials, indirectly obtained by the electrolytic reduction of the metallodions, or directly by the agglomeration of very finely divided metals. Metallodions of peroxide of lead and of reduced * Belgian patent, 3oth June, 1882, mentioned in Mr. Tribe's work. H 98 ACCUMULATORS OF THE PLANTE TYPE. lead have been proposed as positive and negative electrodes for electric accumulators. Tribe Peroxide of Lead Electrodes* The inventor has indicated the use of peroxide of lead in the state of compressed masses, or natural and contained in isolating porous jars. He has not described the mode of attaching. Frankland Agglomerated Electrodes.\ The active material of these plates is a hardening mixture composed of an oxide of lead other than the peroxide ; of dilute sulphuric acid, and of an acid solution (phosphoric, chlorhydric, oxalic, &c.) suitable to the formation of insoluble or little soluble lead salts. These mixtures, applied on conducting supports, set and harden rapidly. R. Tamine Agglomerate Electrode Accumu- lators. Tamine plates are obtained by the following process : "A certain quantity of rosin or other agglomerating material cements, under the enormous pressure of about 300 atmospheres, a mixture of peroxide of lead electrolytically obtained and of lead filings, or of lead pieces, blade, thread, strip, &c., shaped. The object of * Belgian patent, 28th February, 1883, mentioned by Tamine. t Belgian patent, I5th March, 1883, mentioned by Tamine. HETEROGENEOUS FORMA TION. 99 the latter is to obtain a good distribution of the current in the interior of the electrode." In practice, the inventor substitutes minium for the positive and litharge for the negative electrodes to peroxide of lead. The respective proportions are : POSITIVE ELECTRODE. Rosin 5 parts. Conductive metal 75 Minium 20 ,, NEGATIVE ELECTRODE. Rosin 3 parts. Conductive metal 45 Litharge 12 The positive agglomerate can be used with copper or zinc accumulators ; the negative electrodes are then copper, zinc, or carbon plates. Mr. Tamine does not give the voltaic capacity of his agglomerate electrodes. It cannot but be small, owing to the feeble proportion of active materials indicated in his formulae. Fitzgerald Lithanode. f The lithanode is a cohesive and conductive agglomerate composed * ' Recherches the'oriques et pratiques sur les accumulateurs electriques,' par Ren Tamine, Mons, 1885. t D. G. Fitzgerald, English patent 4671, 1885. ' Improvements in the manufacture of elements for voltaic batteries.' H 2 100 ACCUMULATORS OF THE PL ANTE TYPE. of lead oxides mixed with a solution of ammonium sulphate and powerfully compressed ; ammonia is liberated and the sulphate of lead cements the mass. The compression gives the plates a sufficient cohesion to enable them to stand with- out a metallic support. They are provided with a thin laminated platinum conductor. The density of lithanode is from 7-5 to 7 * 9 ; its voltaic capacity is from 20 to 25 ampere-hours per kilogramme. The plates are about 6 mm. thick, and are mounted with celluloid isolating supports in jars of the same material. Lithanode, which is a good material for positive plates, does not appear to be so suitable for negative plates. The Fitzgerald accumulators which have been tested were a combination of lithanode positive with Faure-Sellon-Volckmar negative. These couples are remarkably light : the total weight corresponding to i horse-power electrical work being only 31*5 kilogrammes. Electro-chemical Formation. The me- thods used in the formation of accumulator elec- trodes are mostly chemical or electrical ; however, the special qualification of electro -chemical shall be reserved for the process consisting in the off- hand formation of the two electrodes by means of a double electrolytic deposition of peroxide of HETEROGENEO US FORMA TION. I O I lead and reduced lead borrowed from or vehicu- lated by the liquid. As far back as 1872 Mr. G. Plante* explained the principle of electro-chemical formation in a paper on the use of secondary currents for accu- mulating or transforming the effects of the voltaic battery. He expresses himself as follows : "It is, after all, a galvanic deposit of peroxide of lead which it is proposed to obtain in these secondary couples, deposit which should be as thick as possible in order to accumulate, in that shape, the work of the battery, and, at the same time, sufficiently adhering to the surface of the plate to go through, without becoming detached, an indefinite series of successive reductions and reoxidisations. " This consideration led me to try to obtain the peroxide of lead on the plates at the expense of the liquid, in order to be able to produce a thicker coating and, to that effect, to use a liquid com- posed of a more or less dilute solution of a lead salt. But then water acidulated with sulphuric * Mr. G, Plantd was the first to use the expressions accumulator, accumulation, storage of the voltaic energy, which have been, of late, so frequently used. He assimilated his secondary couples to apparatus which, in mechanics, serve for the accumulation of work, such as hydraulic accumulators, springs, &c. ; he has determined one of the factors of their efficiency, and observes that " a well- formed secondary couple with lead plates constitutes a real accu- mulator of the work of the voltaic battery." (Recherches sur 1'ElectriciteY 1879, paragraphs 89, 91, and 92.) 102 ACCUMULATORS OF THE PLANTE TYPE. acid cannot be used any more, this acid precipi- tating the salt of lead ; and, if other acid solutions containing that metal be used, the lead deposits on the negative plate in the shape of crystalline needles which very soon establish some contacts with the positive plate, and thus stop any ulterior de- composition. " Should alkaline solution be used, lead de- posits in a spongy shape, rapidly increasing in volume*, give rise to the same inconveniences as before ; moreover, the peroxide of lead, once deposited, shows no tendency to be attacked by the alkaline solution, as it is in sulphuric acid, so that, in those conditions, a very feeble secondary current only is obtained. I have therefore, until now, used nothing else but -^ sulphuric acidulated water which has always produced, by its action upon the peroxide of lead, secondary currents of intensities greater than any other acid or alkaline solutions."! Electrodes formed in an alkaline solution of lead must be transferred to a sulphuric acidulated * The galvanic deposition of lead under that form, which we might jcall " Saturn sponge," offers a curious effect of a kind of mechanical combination of lead and hydrogen. This gas is neither combined nor chemically allied to the metal, for it disappears by simple pressure ; but it contributes in swelling, in a remarkable manner, the volume of the metal, similarly to the ammonia gas in an amalgam of ammonium. t 'Les Mondes/ I4th and 2ist March, 1872, vol. xxviii., pp. 425 to 431, and 469 to 477. HETEROGENEOUS FORMA TION. 1 03 water -bath. This has been done by Mr. Montaud. Montaud Accumulators . -The electrodes of the Montaud accumulators are made of laminated lead plates which are formed off-hand', by electro- chemical depositions, in a bath of lead and potash heated to about 100 C. The electric current deposits upon the positive plates some compact and adhesive peroxide of lead, and some diffuse spongy lead on the negative. The positive plates are ready for use after coming out of the bath and being washed in a stream of water. The negative must be submitted to a great pressure, which agglomerates the frothy lead and fixes it to its support. Lead thus agglom- erated resembles ordinary metallic lead, but it is permeable. The formation in the plombite bath is very quick: lasting only 15 to 30 minutes. The intensity of the current must be about 600 am- peres for each square meter of electrode to be formed. The plates are rectangular (Fig. 44), indented at one of the top corners, and double-folded at the other. They are cut two at a time, the indenture of one supplying the necessary material for the fold of the twin one. In the reinforced corner a square hole is punched. The negative plates 104 ACCUMULATORS OF THE PLANTE TYPE. alternate with the positive ones, the indentures of the one corresponding with the thick parts of the FIG. 44. other. Two collectors of square section (Fig. 45), made of lead and antimony, are passed through the square holes of the positive and the negative FIG. 45. plates respectively, and they are fixed to them by autogeneous soldering. The distance between the plates is maintained by means of wooden vertical combs (Fig. 46) ; some smaller horizontal combs complete the appa- HETEROGENEOUS FORMATION. 105 ratus, and bring the .electrodes into a compact whole. (Fig. 47). FIG. 47. The woodcut shows all the plain corners bent upon one another over the collectors and covered 106 ACCUMULATORS OF THE PLANTE TYPE. with a conducting strip (all soldered together autogeneously). The combs round the plates form some wooden girdles which isolate them from the walls of the jar. The latter are made of varnished sandstone, glass, ebonite or wood lined with lead. According to Mr. Montaud, the following result per square meter of electrodes, is obtained. Regimen of charge .. .. 10 amperes. discharge .. 20 Utilisable voltaic capacity . . 34 ampere-hours. With negative electrodes i millimetre thick, and positive 2 millimetres, the square meter of electrodes weighs about 9 kilogrammes. The previous data, reduced to the kilogramme of electrodes, therefore become : Regimen of charge . . . . i * 1 1 amperes. discharge .. 2-22 Utilisable voltaic capacity 3*77 ampere-hours. The regimens of charge and discharge are good, but the voltaic capacity is low. CHAPTER VI MISCELLANEOUS ACCUMULATORS. LEAD-COPPER ACCUMULATORS LEAD-ZINC ACCUMULATORS D'ARSONYAL AND CARPENTIER ACCUMULATORS; REYNIER ACCUMULATORS ; BAILLY ACCUMULATORS ; TAMINE SOLU- TION ALKALINE-ZINCATE ACCUMULATORS : DE LALANDE AND CHAPERON RECUPERATIVE BATTERIES ; COMMELIN- DESMAZURES-BAILHACHE ACCUMULATORS. IT has been explained in Chapter II. that the industrial voltametric systems numbered only four, giving rise to as many genii of accumulators, viz. : 1 . The lead-sulphuric acid genus, or Plante type. 2. The lead-sulphate of copper genus. 3. The lead-sulphate of zinc : the two latter sometimes being a combination of Plant positive with soluble negative. 4. Copper-alkaline zincate, entirely different from Plante's. The numerous species of the first genus have been described in Chapters III., IV., and V. The three last genii, of less importance, are described in the present chapter. Lead-Copper Accumulators. The essen- tial properties of this type of accumulators have 108 MISCELLANEOUS ACCUMULATORS. been explained in the description of the lead- sulphate of copper voltameter. The utilisable electromotive force of this secondary couple is, as we saw, about 1*26 volt. To make a lead-copper accumulator it is suffi- cient to immerse some Plant6 positive plates in a solution of sulphate of copper in the presence of conductive strips unattackable by this liquid. The chemical reactions of the charge are : SO 4 Pb + SO 4 Cu, Aq -f = PbO 2 + 2SO 8 , Aq + Cu iPositive Liquid. Negative Positive Liquid. Negative Electrode. Electrode. Electrode. Electrode. When discharging, the converse reactions take place, with redissolution of the sulphate of copper produced at the negative electrode. The first lead-copper accumulator appears to have been proposed by Mr. Sutton, in 1881.* It was made of a copper vessel, filled with a solution of sulphate of copper in the midst of which was suspended a lead electrode. The copper vessel, which played the part of negative electrode, fatally became attacked and eaten up. The support to the electrolytic deposit must be insoluble in the liquid, and especially when the said support is used as the containing vessel. An ordinary Plante accumulator, spiral or parallel strips, becomes a copper accumulator if * Scientific Notes, 124. MISCELLANEOUS A CCUMULA TORS. 1 09 copper is introduced in its liquid. No benefit would result from this transformation, as the loss of electromotive force of the couple resulting from it would exceed o 5 volt. Besides, the apparatus would soon be out of service, owing to the par- ticles of copper falling to the bottom of the cell, and on the isolating bands, and creating internal contacts. I FIG. 48. The author attempted to avoid this last incon- venience by suspending the electrodes (Fig. 48). 1 10 MISCELLANEOUS ACCUMULATORS. In this accumulator, the positive was a plaited plate similar to that described and illustrated in Fig. 20 ; it was suspended between two plates of plain laminated lead, in a solution of sulphate of copper. Here, the particles of copper, detached from the cathode, fall to the bottom -of the jar. They do not create contacts, but are lost to the action of the liquor, into which they cannot be again dissolved by ultimate discharges, whence the weakening of the solution and a reduction of the voltaic capacity. It is therefore preferable to adopt the arrange- ment in which the negative electrodes are hori- zontal ; the copper is thus retained on the cathode, which, becoming the anode during the discharge, restores the lost copper to the voltaic circulation. That is what the author did at the time of the Nantua experiments, March 1883. One portion of the accumulators used were sulphate of copper, and constructed horizontally and similarly to those illustrated in Figs. 40, 41, 42, 43. To transform this mixed pattern into a copper accumulator, the minium was suppressed and the sulphuric acidulated water replaced by a solution of sulphate of copper. The electrolysed copper fell to the bottom of the leaden jars. These lead-copper accumulators are of an easy and economical con- struction ; they keep the charge satisfactorily. But their electromotive force is low and their voltaic capacity, in function of their weight and MISCELLANEOUS ACCUMULATORS. 1 1 1 volume, small, owing to the small solubility of sulphate of copper in acidulated water. They are, in fact, less advantageous than accumulators of the Plante type, excepting in the very few cases where a fall of potential lower than 1*25 volt is only utilised. Lead-Zinc Accumulators. The essential properties of this system have been described in the voltameter chapter. It was shown that the reactions of the charge were expressed by the equation SO 4 Pb -f- SO 4 Zn, Aq -\- = PbO 2 -f 2SO 3 , Aq + Zn. Positive Liquid. Negative Positive Liquid. Negative Electrode. Electrode. Electrode. Electrode. The utilisable discharge producing the converse reactions. The electromotive-force of the lead-zinc system is 2 * 36 volts or one half volt more than that of the Plant6 system ; the electromotive force of the charging current slightly exceeds the utilisable fall of potential, a fact the importance of which will be explained in the following chapter. Theoretically, the lead-zinc system is the lightest of all known secondary couples. Its construction is economical. In industrial practice they would, therefore, hold the first rank were it not that they have the grave defect of losing their charge through the 1 1 2 MISCELLANEOUS A CCUMULA TORS. spontaneous dissolution of the zinc in open circuit. There are several types of lead-zinc accumu- lators. FIG. 49. D'Arsonval and Carpentier Accumulators* One of the patterns created by Mr. d'Arsonval is * French patent 133,884, 28th November, 1879; d'Arsonval and Carpentier, ' Couples secondaires a Electrodes de mdtaux diffErents.' The author mentioned, amongst others, binoxide of manganese as a substitute for peroxide of lead. In an addition of the i$th March, 1881, they propose to elec- trolyse the chloride of zinc with two-carbon electrodes ; the chloride would be liquefied by its own pressure, and the zinc would be gathered in a basin of mercury. A second addition, dated I7th August, 1881, mentions the use of bromide and iodide of zinc, the iodine and bromine solutions of which would act as chloride. M ISC ELL A NEOUS A CC UMUL A TORS. 1 1 3 illustrated in Fig. 49. This couple has the ap- pearance of an ordinary battery with a porous cell. The zinc is outside. The positive elec- trode, placed in the centre, is a carbon plate surrounded with very fine lead shot. The fractioning of the positive and the intro- duction of a porous cell are the cause of an in- creased interval resistance ; besides, the zinc electrode being without an insoluble support, cannot be of a long duration. In another pattern, which is not illustrated, the electrolysed zinc was gathered upon mercury. Reynier Accumulators. The capital defect of lead-zinc accumulators is, as we have already said, the spontaneous attack of the electrolysed zinc. The said attack is proportional to the surface of the negative, all other things being equal. The dissipation of energy will be reduced by relatively reducing the surface of the negative electrodes ; this is precisely what has been done in Reynier accumulators by combining plaited positive with plain negative plates. The first accumulators of this system were improvised at Nantua, in February, 1883. Their appearance was most primitive (Fig. 50). The positive electrode was made of a long sheet of thin lead with reinforced borders, plaited, and slitted, and wound round a wooden form, i 1 1 4 MISCELLANEOUS A CCUMULA TORS. (Fig. 52) ; the negative was a plain lead cylinder lining the outer vessel. A wicker cage (Fig. 51) separated the two electrodes, which rested on a wooden cross at the bottom. The outer vessel was a pine- wood pail, FIG. 50. FIG. 51. FIG. 52. tarred internally, and firmly bound together by copper binding. The active surfaces were 105 square decimeters for the positive electrode and 1 8 for the negative. The accumulator weighed, complete, 22 kilo- grammes ; its voltaic capacity was 300,000 cou- lombs, its resistance o * 06 ohm., its normal output 15 amperes. These rough apparatuses answered well in the MISCELLANEOUS A CCUMULA TORS. 1 1 5 experiments for which they had been devised. The pattern was soon discarded, but it deserved mentioning as being the first specimen of zinc accumulator industrially experimented upon. Later on, the inventor suspended his plaited electrodes (Fig. 53), as has already been described FIG. 53. in the chapter on Planters accumulators, with autogenous formation ; he has used these plates as positive, in zinc accumulators. The negative electrodes are protected from a local attack by a well-kept amalgamation. To that effect the lead sheet supporting the zinc I 2 1 16 MISCELLANEOUS ACCUMULATORS. deposit was folded so as to form a kind of pocket (Fig. 54) containing a solid piece of zinc and mercury amalgam, as rich as possible in mercury. The accumulators were composed of a larger FIG. 54. or smaller number of plaited positive electrodes alternating with the pocket negative, from which they were isolated by means of vertical glass tubes (Fig. 55). These couples were garnished with sulphuric acidulated water. The first charge liberated the MISCELLANEOUS A CCUMULA TORS. 1 1 7 hydrogen on the negative surfaces, and scoured them thoroughly ; the discharge dissolved some zinc and liberated some mercury, which soon amalgamed the whole surface of the lead sup- ports. The following charges deposited on these supports the dissolved zinc, and the excess of FIG. 55. mercury kept on the amalgamation ; things occurring very much as with Mr. Radiguet's amalgamating support, more recently devised by 1 18 MISCELLANEOUS ACCUMULATORS. him for his primary batteries with chromic mixtures. The zinc accumulators are now made with Reynier's new pattern of positive plates (Fig. 56). Couples provided with these comparatively thin plates are much more compact than the old ones. A given size of vessel contains twice as many electrodes. All the negative plates are constituted by one FIG. 56. single lead strip, folded Greek-wise. The amalgam of zinc pockets have been suppressed. The local actions are attenuated : i, by the use of distilled water and pure zinc ; 2, by a salt of mercury solution ; 3, by an addition of pure MISCELLANE O US A CCUMULA TORS. I 1 9 sulphate of ammonia salt, the protective action of which had been pointed out by the author.* The following data apply to an 8 positive plate accumulator : External length . . . . 23 millimetres. Width 23 Height 32 Total weight . . . . 20 kilogrammes. Weight of the 8 -positive electrodes . . . . 9 600 ,, Weight of the 9-negative 2 400 Weight of the liquid .. 4*300 Electromotive force .. 2*37 volts. Approximate internal mean resistance . . o 005 ohm. Regimen of charge . . 1 6 amperes. discharge 40 Voltaic capacity .... 80 ampere-hours. This accumulator is remarkable for its power ; but its working is poor, and the conservation of its charge imperfect yet. Its use is indicated in certain particular cases, especially for the regulation of a current, and the prolongation of a service for a short time after the stoppage of the machines. It is half the cost of Planters accumulators of equal power, and gives a more perfect regulation. Bailly Accumulators. The information respecting this accumulator is scarce. The only * Piles electriques et accumulateurs. ' Experiences sur 1'attaque locale des zincs en circuit ouvert.' 1 20 MISCELLANEOUS ACCUMULATORS. specimen seen by the author* was made of a rectangular vessel containing a flat porous cell in which a thick plate of amalgamated zinc was immersed. Some lead scrapings or shavings, pressed between the two vessels, constituted the positive electrode. The porous vase contained a certain quantity of mercury for keeping the zinc amalgamated. This artifice improves the con- servation of the charge, but the use of porous cells prevents the multiplication of the electrodes, makes the apparatus heavy, and considerably increases its internal resistance. The zinc, having no insoluble support, threatens destruction after a few discharges ; it must, from time to time, be reversed. Tamine Solution. Mr. Tamine has, re- cently, f given the following solution as suitable for the lead-zinc accumulators : Saturated solution of sulphate of zinc i ooo parts. Dilute sulphuric acid, T V solution. . 500 Sulphate of ammonia 50 Sulphate of mercury 50 The sulphate of ammonia, and the sulphate of mercury are first dissolved ; the solution is poured * At the Ville de Paris Chemistry and Industrial Physical Laboratory, t ' L'Anne'e dlectrique,' Ph. Delahaye, 1888. MISCELLANEOUS A CCUMULA TORS. 1 2 1 in the acidulated water, after which the sulphate of zinc is added. This liquid does not differ much from that used by Mr. Reynier. Alkaline Zincate Accumulators de Lalande and Chaperon Recuperative Ac- cumulators. The zinc couple potash solution oxide of copper is energetic and constant. Messrs, de Lalande and Chaperon, who are the first to have used this voltaic combination, have succeeded in making of it a very good primary battery, the reversibility of which they men- tioned. * Fig. 57 illustrates one type of these batteries. A is a watertight tank of copper or sheet-iron ; it constitutes the external vessel of the battery, and its positive electrode. The bottom is covered with oxide of copper. The horizontal zinc D D is supported, at its four corners, by four isolating blocks L L placed in the corners of the trough ; it is folded vertically at one of its ends, which * French patent No. 143,644, 25th June, 1881, * Systemes de piles electriques.' De Lalande and Chaperon, the authors, say, " Our batteries are essentially reversible." French patent No. 150,454, 3rd August, 1882, ' Perfectionne- ments aux piles electriques.' De Lalande. The author mentioned some secondary batteries with alkaline liquors and solid depo- larising agents, such as oxides of silver, of mercury, of manganese, of lead, of nickel, of cobalt, &c. French patent No. 158,945, 3rd December, 1883 ; same subject? de Lalande. The author claims the amalgamated bronze, or of any other amalgamated metal support for the zinc. 122 MISCELLANEOUS ACCUMULATORS. receives the negative terminal M. The trough is three-quarter filled with a solution of caustic potash or soda. This solution must be protected from the action of the carbonic acid in the air by means of a watertight cover, or, which is better still, by a layer of heavy petroleum. In some other types the electrodes are vertical, the positive being constituted by agglomerates of FIG. 57. oxide of copper (Fig. 58) or by some copper baskets filled with oxidised copper. The negative electrode is not much attacked in open circuit. In closed circuit, there is dissolution of zinc with formation of alkaline zincate and reduction of the oxide of copper. It was at first admitted that these chemical actions could be expressed by the equation : Zn + Ko, HO + CuO = ZnOKO -f Cu + HO.* L'Electricien,' ist August, 1883. MISCELLANE OUS ACC UMULA TORS. 1 2 3 According to a new theory of Mr. Finot, the reducive action would be exerted not on the bin- oxide of copper, but on the protoxide, and would interest two equivalents of copper : Zn + KO, HO + Cu 2 O = ZnOKO + 2Cu + HO. The well known de Lalande and Chaperon batteries are constant, energetic, and waste little in open circuit ; their electromotive force is only FIG. 58. 0*8 volt but their resistance is very low. They can supply intense currents. Their description would not have found place in this work had it not been for their reversibility that is to say, the property which they ought to possess of being regenerable by electrolysis. 124 MISCELLANEOUS ACCUMULATORS. It is certain that Messrs, de Lalande and Chaperon have perceived this reversibility, that they have mentioned and studied it ; it is equally certain that they have not succeeded in securing it. As accumulators, de Lalande and Chaperon couples have, therefore, nothing more than a historical interest. Messrs. Commelin, Desmazures, and Bailhache have succeeded in making some reversible alkaline zincate couples. Commelin, Desmazures, and Bailhache Accumulators.* -The positive electrodes of these couples are porous copper plates obtained by the compression of copper dust under a pressure of 600 kilogrammes per square centimetre (9000 Ibs. per square inch). The material for these plates is some very finely divided metal obtained by the electrolytic reduction of copper scales in a bath of caustic soda. The operation is conducted in large and shallow copper basins ; the scales are thrown into this tank, which constitutes the negative pole of the apparatus ; a horizontal sheet of copper, suspended at a short distance from the bottom, constitutes the positive electrode. Powder-dust thus obtained is easily cleared by pressure of the small quantity of water * French patent No. 183,285, 3rd May, 1887, ' Perfectionne- ments dans les accumulateurs d'electricite" [sic] et dans toutes les piles e'lectriques en ge'ne'ral.' MISCELLANEOUS ACCUMULATORS. 125 which it contains. A given weight of it s then spread in a steel mould, in which it is agglo- merated by a single pressure. A sheet of metallic gauze placed in the copper dust aggregates the latter : it consolidates the electrode, and retains the pieces which might become detached by breaking. The compressed plates are set in a copper frame terminated with a tinned tail. The porous copper is oxidised, and, in that state, would not give good results. It must be deoxidised before introducing it in the accumu- lator. To that effect, it is submitted to a previous electrolytic reduction, in a deep tank containing a bath of soda or potash. The impurities of the liquid and of the electrodes fall to the bottom of the tank ; the liquid, purified by the operation, is decanted for use. The necessity of reducing the copper shall be explained hereafter. The negative electrodes are made of amalgam- ated tinned cloth of iron wire ; the tin holds the mercury, which would not remain on the bare wire. The cell is made of tinned sheet steel, held together by a system of hooking, and rendered watertight before the tinning, so that no leakage can occur through the attack of the tin. This tank is connected with the negative electrodes resting at the bottom. The particles of electrolysed zinc 126 MISCELLANEOUS ACCUMULATORS. which might become detached from their support, fall at the bottom of the tank ; they enter into the discharging circuit, and are taken up again by the liquor. The composition of the liquid is as follows : Water i ooo Zinc .. 144*67 Combined potash '.. 200-82 Free .. 313*72 The positive electrodes are enclosed in parch- mented paper cells, maintained by vertical glass rods which isolate them from the negative. The parchments are machine sewn. The seams are not watertight at first, but soon become so through the action of the liquid, which causes an intimate adhesion of the paper with itself. The parchment receives, in caustic alkali, a profound alteration it swells and becomes brittle. But it can remain in that state and act for a long time without breaking, if not disturbed by a mechanical action. The partitioning is of great importance ; it may be said to be indispensable. Its duty is explained by Mr. Finot's theory. According to this chemist, the reactions corre- sponding to the discharge are expressed by the equation : Zn + KO, HO, Aq + Cu 2 O = ZnO, KO, Aq + 2Cu -f HO. MISCELLANEOUS A CCUMULA TORS. 1 2 7 It is not some binoxide of copper, CuO, but some protoxide, Cu 2 O, which is reduced. This opinion seems confirmed by the appearance of the electrodes, which are of a pink colour and not black. The charge, it is true, tends to produce some binoxide of copper ; but this binoxide, somewhat soluble in caustic alkalis, is transformed into protoxide by its contact with copper. CuO -f Cu = Cu 2 O. The protoxide of copper being colloid, cannot traverse the parchment partition. Imprisoned round the copper, it becomes decomposed, as has been said, and does not get mixed with the alkaline zincate. The latter salt, being also colloid, cannot go and diffuse itself towards the copper. The frank separation of the two electro- lytes causes a pure zinc deposition, and a neat formation of protoxide of copper. The oxidation of the positive is not thoroughly effected without the parchment cell, and the zinc deposit is sullied with copper ; whence a want of adherence and some parasite local actions. A couple without partitions being charged, irregularly rises up to 2*8 volts ; as soon as the charge is interrupted, the electromotive force rapidly decreases passing from one value to another by jerks, and falling down to o* i volt. The binoxide of copper is not the active agent 128 MISCELLANEOUS ACCUMULATORS. of the positive electrode ; it could not even exist in contact with reduced copper. Its presence in important quantities in the plates would prevent the regular working of the couples ; whence the necessity of a previous reduction of the positive plates before mounting. Mr. Finot does not appear converted to his own theory, for he has recently, promoted another one :* " During the charge of the copper accumulator may be observed," he says, " a curious phenome- non which it may be useful to describe, as it would have a tendency to demonstrate that if the oxygen is not combined with the copper, it may very possibly be occluded, owing to the particular properties of the porous plates. "In effect, when charging the apparatus, the level of the liquid rises from the beginning, and continues its progressive ascension until the charging is stopped. The inverse phenomenon is observed when discharging. The level of the liquid gradually decreases, and reaches the start- ing point only when the accumulator is fully discharged. If the oxygen combined with the copper, no rising of the liquid would take place at the beginning, and the level would rise only when the whole of the copper is combined. Then only, the oxygen filling the pores of the plates would * ' Bulletin de la Socie'te' Internationale des Electriciens,' meeting of the 7th December, 1887. MISCELLANE OUS ACC UMULA TORS. 1 2 9 increase the volume of the liquid in taking its room. At the discharge, on the contrary, the oxygen should immediately disappear, and the liquid take again its normal level a few minutes after the closing of the circuit. But this is not what happens." These observations appear insufficient to demonstrate the occlusion of the oxygen in the positive. Could not the ascension of the liquid during the charge be more simply explained by the change of volume of the two electrodes, one oxidised, the other covered with zinc ? In the model of accumulator which will be described, the volume of the positive plates is about 330 cubic centimeters ; their weight increases, and their density very probably decreases, when, owing to the charge, they pass into a state of oxidation ; the resulting increase of volume, added to the volume of the deposited zinc (80 cubic centi- meters according to calculation) might justify a perceptible ascension of the liquid in narrow cells the total section of which is 1 20 square centimeters only. To settle the question, the densities of the liquid and of the positive plates should be deter- mined after the charge ; the total volume of the electrodes (liberated zinc included) and of the liquid should be deducted. These easy calcula- tions might do away with the hypothesis of an occlusion of oxygen in the positive plates. The following complete data apply to a large K 1 30 MISCELLANEO US A CCUMULA TORS. model of great output, combined for the propul- sion of a torpedo boat of the French navy. Total weight of the accumulator 10 kilogrammes. Weight of the 5 positive plates not charged i*9 2 5 Weight of the 6 negative plates idem 1-050 Sizes of positive plates f height 280 millimetres. (density about 6). {width.. 125 c height 300 Sizes of negative plates j width ^ I2 ^ Surface of the positive electrodes 35 square decimeters. negative .. 37-5 f length .. 150 millimetres. External size of jar J width . . 085 I height .. 400 Weight of the jar i kilogramme. liquid (with pot- ash) density 1-55 6 Weight of the 1 1 electrodes and of the paper 3 Electromotive force in open cir- cuit Utilisable fall of potential . . 0-75 volt. Regimen of charge 15 amperes. discharge .... 48 Output per square decimeter of electrodes .... .... 0-67 Duration of the charge . . . . 30 hours. discharge.. .. 9^ Total voltaic capacity . . . . 450 ampere-hours. Utilisable 413 Electrical power at the discharge 3 ' 67 j ^^"^^ Total electrical work .. .. 0*42 horse-power hour. Weight of plates corresponding to the work of i horse -power hour 7 ' 083 kilogrammes. MISCELLANEOUS ACCUMULATORS. 1 3 1 Total weight corresponding to the work of i horse-power hour 23 800 kilogrammes. Weight of plates corresponding to the power of i electrical horse-power 60*700 Total weight corresponding to the power of i electrical horse- power 204 The above figures have been communicated by Mr. Commelin. The liquid used is a basis of zincate of potash ; zincate of soda appears to have been abandoned, as its corresponding charge and discharge regimens are low and it produces creeping salts. The practical trials have given somewhat different results ; they confirm the fact that in these, as in other accumulators the output may be forced, but at the cost of an important loss out of the total weight. Thus in the experiments carried out at Le Havre in September, 1887, on board a small torpedo boat * the following figures occurred : Weight of accumulators corresponding to i horse-power hour work . . . . 33 kilogrammes. Weight of accumulators corresponding to i horse-power work 166 * ' Le Figaro,' 23rd September, 1887. K 2 1 3 2 MISCELLANE OUS ACC UMULA TORS. In the experiments carried out on shore, in March last, on a ic-ton battery intended for the propulsion of a submarine boat the following results were obtained : Weight of accumulators corresponding to i horse-power hour's work . . . . 37 kilogrammes. Weight of accumulators corresponding to i horse-power 170 The weight of 1 66 to 170 kilogramme per horse- power is not extraordinary, and had already been obtained in November, 1886, with Reynier's light plate accumulators during some experiments carried out at the Concorde Bridge. But as regards the weight in respect of the horse-power hour, the C.D.B. accumulator is superior to the majority of lead couples. It must not be concluded, from the foregoing, that the alkaline zincate accumulators will super- sede those of the Plante type. Industrially considered, the following points must be taken into account. 1. The weights : It has been seen that the F.S.V. accumulators, and those of Fitzgerald, can, in certain conditions, be advantageously compared with the C.D.B. 2. The volume : The lead accumulators are, for a given weight, less cumbersome, having denser electrodes and containing less liquid. 3. The efficiency : From all the information in MJSCELLANE US A CC UMULA TORS. 1 3 3 our possession, it appears to be about the same in the two kinds. 4. The cost : The cost of the C. D. B accumu- lators is not known, but copper and potash are much more expensive than lead and sulphuric acid. 5. The duration: Plante's type of accumulators are vulnerable through their positive plates ; but the latter have been considerably improved of late. The C D B's positive seem to be more durable ; but how will the necessary amalgamation of the negative behave ? How long will the parchments last ? What will become of the liquid, incom- pletely protected from carbonisation ? Do not the assertions of the inventors as to the longevity of so young a system require some practical confirmation ? The great and deserved success of the C. D. B. accumulators and their adoption for naval warfare should not be a cause for relaxing the industrial and technical study of the other systems. Messrs. Commelin, Desmazures and Bailhache have, in the way inaugurated by Messrs, de Lalande and Chaperon, obtained immediate results which testify to great cleverness ; by the exercise of equal cleverness in developing the qualities of the other systems of accumulators the result would no doubt be to obtain some much lighter and very much cheaper accumulators. Before closing this chapter, we must repeat that 1 34 MISCELLANEO US A CCUMULA TORS. the positive plates of these zincate accumulators may be constructed of metals other than copper. Mr. Desmazures, in his patent, claims the use of agglomerated platinum, silver, cobalt, nickel aluminium, manganese, iron, &c., powders. The electromotive force of silver is greater than that of copper, but the former metal is heavier, and especially much more expensive, than the latter for a similar number of chemical equiva- lents ; Mr. Desmazures has, notwithstanding those drawbacks, indicated its use for the accumu- lators intended for the lighting of . workmen in mines. PART III. TECHNOLOGY. CHAPTER VII. TECHNICAL GENERALITIES CONCERNING ACCUMULATORS. CONSTANTS : ELECTROMOTIVE FORCES ; RESISTANCES POWER VOLTAIC CAPACITIES WORK DISCHARGE DIAGRAMS CHARGE AND DISCHARGE REGIMENS CONSERVATION OF THE CHARGE EFFICIENCIES : MAXIMUM EFFICIENCY PROPER ; NORMAL EFFICIENCY PROPER PRACTICAL EFFI- CIENCIESWEIGHTS IN RELATION TO POWER AND WORK LIFE OF ACCUMULATORS : THEIR REDEMPTION FOR- MULA OF EFFICIENCY OF A SYSTEM OF ACCUMULATORS. THE preceding chapters give, on the best known accumulators, some numerical data which might be found sufficient in practice ; but the arrangement of these indications is not sufficiently compact for anyone to easily take a general sur- vey of the question. In this third part, the data spread out in the book are brought together, completed, and com- pared. The concrete notions acquired by the reader will enable him to accept these generalis- ations with their appropriate technical form. Constants. The electromotive force is ap- proximately the same for all the accumulators of similar genus ; the resistance, on the contrary, TECHNICAL GENERALITIES depends upon the setting up of the couples, their dimensions, and other particularities. Electromotive forces. We must distinguish : 1. The electromotive force proper which is that of a charged accumulator, measured on an open circuit, or on a circuit of great resistance, some time after the cessation of the charge. 2. The mean utilisable fall of potential in normal discharge. 3. The minimum difference of potential during a very slow charge, made with a source of electro- motive force slightly exceeding that of the accu- mulator. 4. The mean difference of potential during a normal charge. These various values are known for the three first kinds ; but the information respecting the fourth is incomplete and not very precise. Minimum Mean Genus. Electro- motive force. Mean utilisable fall of potential. difference of potential during a very slow difference of potential during a normal discharge. charge. volts. volts. volts. volts. Plant^ lead-lead 1-86 1-8 i'95 2*2 Lead-copper . . * . 1-26 I *2 1-42 1-6 Lead-zinc 2'37 2- 3 2-4 2-6 Alkaline zincates 0-8 (?) o'75(?) 2-4 10 * See the note : ' Sur les variations de la force e'lectromotrice dans les Accumulateurs ' in ' Piles electriques et Accumulateurs.' CONCERNING ACCUMULATORS. 139 In the accumulators of the Plante type the degree of formation should be taken into account. The values given here have been obtained from couples of an average formation, the liquids of which had received no addition of any adjunct ; a thorough formation would give a slight increase in these figures ; the composition of the liquids also influences the values of the electromotive force. Resistance. The resistance of accumulators depends on the composition of the liquid, on the surface and distance of the plates, on the temper- ature and, for couples of the Plante type, on their degree of formation. In a given accumulator, the resistance is very variable. It is smaller during the discharge than during the charge ; sometimes a period of dimi- nution occurs at the beginning of the discharge, but it is always greater at the end than at the beginning. - A long period of rest much increases the re- sistance of accumulators of the Plante type. This phenomenon is due to the spontaneous sulpha- tation of the active materials. After one or two new charges, the resistance returns to its ordinary values. The resistance of an accumulator cannot there- fore be predicted. Many manufacturers are silent upon that point ; they might, however, as a piece 140 TECHNICAL GENERALITIES of information, mention an average figure which might guide those interested. In the four kinds of accumulators studied, the resistance is generally very low : o * 05 to o * oo i ohm, according to the patterns and sizes. Power. Power must not be mistaken for work. Power is homogeneous to the product of ,a force by' a speed, or to the quotient of a work by a time/ The power of an accumulator, expressed in watts or volt-amperes, is given by the formula. in which e is the fall of potential in volts, in the exploited circuit, and I the intensity of the current in amperes. The powers of i kilogrammeter per second, i horse-power, and i kilowatt, are respectively equal to 9*81 watts, 7^6 watts, and 1000 watts ; whence : P = el watts = - - kilogrammeters per second, 9 ' oi el . = horse power, 7#6 = - kilowatts. 1000 e and I may vary considerably in the discharges of a same accumulator. This point will be again considered when on the subject of regimens. CONCERNING ACCUMULATORS. 141 The value of e I would be maximum, for a given accumulator when e = - . E being the electromotive force of the con- sidered accumulator. The external power, in 1 watts, would then be : r being the resistance, supposed to be the accumulator. But this condition of discharge is impossible of realisation, even for a few minutes. With the known accumulators, the power which cannot be exceeded, corresponds to e E x 0*9. The normal powers generally correspond to values of e approximating E x 0*96 (see the previous table). Voltaic Capacities. A distinction must be made between : 1 . The total capacity which is that obtained with a discharge of the accumulator pushed as far as possible. 2. The useful or normal capacity which is that supplied by the discharge of a well-charged accumulator working at its normal regimen ; discharge stopped before the fall of potential has decreased more than 5 to 6 per 100 below its 142 TECHNICAL GENERALITIES average value. The useful or normal capacity is the true capacity of the accumulator, that which must be understood when no other qualification is applied to the term voltaic capacity. 3. The capacity of charge, or quantity which may be made to pass through a couple normally discharged, before it refuses the charge. (The refuse is marked by a copious disengagement of gas, showing that the active materials are com- pletely charged and cannot any more fix the products of electrolysis). Useful or Normal Voltaic Capacity. The voltaic capacity varies, in accumulators of a given genus and weight, according to the struc- ture and the formation of the apparatus. For the species of the Plante genus, it is customary to give the capacity in reference to the weights of the electrodes. But the comparisons between accumulators of different kinds are given in respect of the weights of the complete accumu- lators for, in the three kinds having one soluble electrode, the comparative weight of the liquid and of the vessel, are greater than in the Plant genus. The capacities of the various accumulators have been indicated at the time of their descrip- tion. As a more general indication we give hereafter the capacities per kilogramme of accu- mulator. CONCERNING ACCUMULATORS. 143 Plantd genus from 2 to 17 ampere-hours. Lead-copper 3 8 Lead-zinc 3 8 Alkaline -zincate o 41 ,, It will be seen, further on, that the regimen of discharge have an influence upon the utilisable voltaic capacity. Work. The utilisable electrical work of an accumulator is expressed in volt-coulombs or joules by the formula W = Q,, in which Q is the voltaic capacity in coulombs, and e the mean fall of potential in the external circuit. The quantity Q is equal to the product of the mean intensity of the current I expressed in amperes, by the time / given in seconds : Q e \te\ i kilogrammeter = 9*81 joules; i horse-. power-hour = 270,000 kilogrammeters ; i ton meter = 9180 joules. The external electrical work of an accumulator may, therefore, be cal- culated in joules, in kilogrammeters, in horse- power hours and in ton meters by the formulae : W= Qe = I / joules, Q^ I*w 9. --__._ __ . _ _ . _ ^ . tW . . - . Jjs;-;; A If 1 1 I 1 1 1 1 it I 1 1 1 1 1 1 I 1 i I _ .__:lZ__iu_. , ~j a 2 - i % - B 6 7 it-. >. 1*' a 3 jo n i?. is w 'jg' ^ ..,-5,1 FIG. 59. Fig. 59 is the diagram of the discharge given by two old Faure-Volckmar accumulators dis- CONCERNING ACCUMULATORS. 145 charged in series.* The discharge was effected immediately after the charge : thus the curves indicate, at starting, the effects of the fugitive super-elevation of the electromotive force due to the primary current ; they are sustained, well stretched, for a certain length, then, from a certain point, fall rapidly. This is the critical point at , which, in practice, the work of the couples should be stopped. The voltaic capacity is proportional to the area of the intensities curve ; the external electrical work is proportional to the area of the powers curve. Charge and Discharge Regimens. For one same accumulator, the normal intensity of the charging current is always smaller than that of the discharging one. The practicable regimens are higher in propor- tion to the development of the electrode's surfaces. For a given weight, thin plate accumulators admit and emit more intense currents than thick plate ones. The composition of the liquids has still more influence on the regimens, than on the electro- motive force of accumulators. The regimen of charge may, in the couples of the three first kinds, vary between o * 2 and * Experiments carried out in October 1883, by Messrs. Fichet, Hospitalier, and Jousselin. L 146 TECHNICAL GENERALITIES i * 5 ampere, and the regimen of discharge between o 4 and 3 amperes per kilogramme of accumulator. In the accumulators of the last genus, the regimens appear to be : Charge. Discharge. With the zincate of soda 0*5 to i ampere 2 to 3 amperes. potash i to 2 4 to 6 The moderate regimens only give good results as to regularity of current, work, and efficiency of the batteries. The diagrams Figs. 60 and 61 (pp. 148, 149) illustrate the influence of the regimen. They illustrate the expression of the discharge of a Fitzgerald accumulator weighing 10-285 kilogr., and containing 6^725 kilogr. of plates . The discharges with a forced regimen (Fig. 61) give a less useful work and, consequently, a poor efficiency. At the same time they cause a dimi- nution in the duration of the electrodes. Conservation of the Charge. Considered from the point of view of the conservation of the charge, the Plant6 type is the best, the lead-zinc the worst. The conservation of the charge mainly depends upon the degree of formation of the couples, and upon their internal and external isolation. * Experiments by Mr. G. Philippart. CONCERNING ACCUMULATORS. 147 In incompletely formed accumulators, the heterogeneity of the plates determines some para- sitic local actions which more or less quickly exhaust the charge. The nature of the isolating substance, and of the containing vessel, has a great influence upon the conservation of the charge ; glass, porcelain, compact sandstone, ebonite, caoutchouc, and gutta percha are good materials ; wood is inferior ; tissues and felt are bad. In order to avoid losses through external deri- vations, it is a good precaution to place the ac- cumulators upon blocks of impermeable material ; when the vessels are metallic, this becomes in- dispensable. It would occur that if a primary battery with a high resistance, and a higher electromotive force was opposed to an accumulator at rest, the spon- taneous discharge ought to be attenuated ; * this presumption has, however, not been submitted to experimentation. Efficiencies. There are : 1. The maximum efficiency proper of accumu- lators ; 2. Their normal efficiency ; 3. Their practical efficiency. * Prospectus of the ' Societe La Force et la Lumiere,' Exposi- tion d'Electricite, 1881. L 2 148 TECHNICAL GENERALITIES 27 26 25 2\ 23 22 21 20 19 18 17 16 16 1% 13 12 11 10 1 2 ! I ' X ^ . . = ^a e= = * ^ w^ ^ = I -~ 1 **^ - * --H --^ S^ r !" 6 5 * 3 Z ires. V il ' 1 < 1 1 2 a * 5 6 - 2 8 9 10 11 J.2 13 14.15 16 J2heL FIG. 60. CONCERNING ACCUMULATORS. 149 27 26 25 2 < 4 X- '*, Z 1 I JJ MI c = = =4 i . -. 1 01 2 3 5 6 78 "heures FIG. 61. 150 TECHNICAL GENERALITIES Maximum Efficiency Proper. In all accumu- lators, the secondary electromotive force is higher during the charge than during the discharge ; whence the necessity of giving to the source a higher electromotive force than that which shall be utilised during the discharge. The proportion between the second and the first forces is the co- efficient of reduction. Accumulators do not take all the charge which is given them ; they do not keep all the charge which they have taken ; parasitic discharges in- cessantly occur, during any rest, during the dis- charge, and even during the charge. These losses are caused by : local actions between the liquid and the electrodes, derivations inside or outside the accumulator, &c. The result is that the quantity of electricity (coulombs) restored is smaller than that furnished. The proportion between the first of these quantities, and the second is the coefficient of restitution. If the coefficient of reduction and that of restitution are measured separately in the most favourable conditions, and we make the product of these two factors, we obtain a fraction which is the maximum efficiency proper of the accumulator under observation. The author has measured the coefficient of reduction in the three first kinds.* He found : * See 'Sur les variations de la force e'lectromotrice dans les Accumulateurs,' in ' Piles dlectriques et accumulateurs.' CONCERNING A CCUMULA TORS. 1 5 I Plante genus o 95 Lead copper .. .. .. 0-87 Lead zinc 0*98 The coefficient of restitution was only measured for the first genus. Mr. Plante found it equal to o * 885 for a normal discharge. In slow discharge it can reach 0*92. The maximum efficiency proper of accumulators of the Plante genus would therefore be : 0-92 x 0-95 = 0-87 It must not be forgotten that the maximum efficiency proper is a limit which could not be reached in practice. Its value cannot be determined for the three last kinds for the want of one factor : the coeffi- cient of restitution of the second and third kinds, the coefficient of reduction of the fourth. Normal Efficiency Proper. If the reduction and restitution are measured in the conditions of the normal charge and discharge, the normal co- efficients of reduction and restitution are obtained, The normal coefficients of reduction may be deducted from the figures given page 138. NORMAL COEFFICIENT OF REDUCTION. Plante genus .. .. = 1-8:2-2 = o'8i8 Lead copper .. .. = 1-2:1-6 = 0-750 Lead zinc .. .. = 2-3 : 2*6 = 0-885 Alkal. zincate . . .. =0*76:1 = 0-760 152 TECHNICAL GENERALITIES The normal coefficients of restitution, known only for the first and fourth kinds, are respectively o * 88 and 0*92. Wherefrom, NORMAL EFFICIENCY PROPER. Plante genus .. = 0-818 x 0-88 = 0-720 Zincates .. V. = 0-760 x 0-92 = 0-699 Practical Efficiencies. Practical efficiencies are inferior to normal efficiencies proper because their coefficients of reduction are independent from the accumulator. These coefficients vary in number and value according to the transformation of energy neces- sary to each kind of application. For instance, the coefficients of reduction are smaller in number and importance in the case of lighting, than in an application to the traction of vehicles. So that each accumulator possesses only one maximum efficiency proper, only one normal efficiency proper, and several practical efficiencies, variable according to the uses to which it is applied. The practical efficiencies shall be indicated, for a certain number of particular cases, in the chapter of applications, the 8th. Weights in Relation to Power and Work. It is useful to estimate the weights of accumulators in relation to their power and work. CONCERNING ACCUMULATORS. 153 The relations vary according to the adopted regimens. By increasing the output the power is increased, but the work is reduced, as well as the efficiency and the duration of the accumulators. The following are the weights respectively corresponding to the power of i horse-power, and to the work of i horse-power hour, for some known species values established for acceptable regimens. Designation of the Accumulator. Weight of accumulator corresponding to the power of I horse-power. Weight of accumulator corresponding to the work of I horse-power. Plante, spiral pattern, very well formed kilogrammes. 2OO kilogrammes. 180 Voltameter regulator,* Plante pat- tern, Ville de Paris model 110 180 Reyneir, light plate pattern 208 63 Denis Monnier lighting 525 85 Faure, 1881 540 108 Faure-Sellon-Volckmar lighting . . 408 62 tramcar . . 260 43 ,, ,, ,, experimental 20O 25*5 Fitzgerald 2OO 3I-5 Reynier, lead-zinc I6 3 80 C. D. B., potash-zincate (laboratory experiment) 2O4 23-8 C. D. B. potash-zincate (industrial experiment) 170 37 * See page 171. 154 TECHNICAL GENERALITIES Life of Accumulators. The data concern- ing the life of accumulators are only known for the three first kinds, the fourth being of recent application and not having been submitted to the tests necessary for appreciating their solidity. In the accumulators of the first, second, and third kinds, the negative plates last a long time ; the positive, on the contrary have a limited duration. The renewals of positive plates considerably increase the price of the services rendered by accumulators. In order to attenuate the cost of maintenance the makers must construct these electrodes eco- nomically, and make them interchangeable so as to replace them with the least amount of trouble. For a given accumulator, the life of the positive plates depends upon the regimens of w.prk and the conditions of use ; so that it is difficult to give, in this respect, much precise information. Some makers guarantee, for the positive plates, 1000 hours' discharge for batteries submitted to carriages and shocks (electric locomotives, &c.) ; and 2000 hours' for the working in stationary positions ; but guarantees can, in such matters, only be consented to by the makers under certain conditions of use. Redemption. According to these vague figures, the redemption of a battery of accumu- CONCERNING A CC UMULA TORS. 1 5 5 lators (the positive plates of which only being subjected to frequent renewals) would vary from 20 to 100 per cent, per year. Formula of Merit of a System of Accu- mulators. In order to compare the various systems of accumulators, the engineer must find respecting each of them, the following items. E, electromotive force. e, utilisable fall of potential. Q, voltaic capacity. I, normal intensity of the discharging current i, normal intensity of the charging current. P, power. W, work. Normal coefficient of reduction. ,, ,, restitution. Price of accumulators. Cost of renewal of the positive. Probable life of the positive and of the whole. From which he will deduct : Normal efficiency proper. Weight in function of power work. Price ,, power. work. Rate of redemption. 156 TECHNICAL GENERALITIES, &c. With these values, the formula of merit of any given system can be established by giving to each item the importance which it requires according to the intended application. A judicious selection among the competing systems may then be made. PART IV. APPLICATIONS. CHAPTER VIII. APPLICATIONS OF ACCUMULATORS. GENERAL REMARKS ON THE CHARGE OF ACCUMULATORS APPLICATION OF SECONDARY COUPLES BY MR. G. PLANTE APPLICATIONS TO SCIENTIFIC RESEARCHES APPLICA- TIONS TO TELEGRAPHY, TELEPHONY, CLOCKWORK, &c. APPLICATION TO ELECTRIC LIGHTING APPLICATION TO THE CURRENT REGULATION OF MACHINES: REGULATING VOLTAMETERS WELDING OF METALS PRODUCTION OF MOTIVE POWER ELECTRICAL LOCOMOTION ON TRAM- WAYS ELECTRICAL LOCOMOTION ON ROADS ELECTRICAL NAVIGATION FUTURE APPLICATION OF ACCUMULATORS TO AERIAL NAVIGATION TRANSLATION AND DISTRIBU- TION OF ENERGY BY MEANS OF ACCUMULATORS : LAND- CARRIAGE OF ENERGY WATER-CARRIAGE OF ENERGY CAPTION OF NATURAL FORCES BY MEANS OF ACCUMU- LATORS. General Remarks on the Charge of Ac- cumulators. Before reviewing the principal application of the voltaic accumulator it may be useful to call to mind a few notions respecting the charge of the couples. Accumulators can be charged by primary batteries or dynamo-electric machines, or by continuous current transformers.* The charging source is opposed, pole to pole, to the battery of accumulators ; that is to say, the * It is not impossible to charge accumulators with alternating currents. 1 60 APPLICA TIONS OF A CCUMULA TORS. positive pole of the first is connected to the positive pole of the second, and the negative poles are similarly connected. The electromotive force of the charging source must be from 10 to 25 per cent higher than that of the secondary battery. Primary batteries are inconvenient and costly sources of electricity, but suitable for scientific researches and amateurs' installations. Dynamo-electric machines only are used in large and average size installations. They may be of the permanent magnet, or derived electro- magnets (shunt), or double winding (compound), or of the separate excitation type. Shunt-dynamos are the most convenient and the most in use. When compound dynamos only are available, the charging current is taken at the brushes and not at the terminals ; the machine, in this case, acts as a shunt-dynamo. It will always be necessary to take the proper precautions to prevent the return of the current of the battery into the charging dynamo, which may be due to a slackening of the speed, or to any other cause. If there is no good automatic disconnector available, it will be advisable to provide the circuit with one or more safety cut- outs, so as to prevent any secondary current of greater intensity than the primary one to deteriorate the dynamo. APPLICA TTONS OF A CCUMULA TORS. 1 6 1 The charging of accumulators with series- dynamos requires certain manipulations which are only practicable to skilled electricians. The charging dynamos may be driven by any kind of motive power, even the most irregular. Natural forces (water or wind) are economical. Up to the present, steam engines are the most in use. Gas, petroleum, and hot air engines are also beginning to be much used. The somewhat jerky motion of gas engines has no inconvenience when charging accumulators. First Applications of Secondary Couples by Mr. G. Plantd When making known the first accumulators, Mr. G. Plante did not fail to point out the usefulness of these precious maga- zines of electro-chemical energy. He at first suggested the use of his secondary couples in the room of primary batteries as an advantageous substitute in cases in which a powerful current of short duration is required. In ' Recherches sur 1'Electricite,' will be found the particulars of these applications such as : the incandescence of metallic wires and their use for galvano caustic ; dental surgery ; lighting of obscure parts of the human body ; explosion of mines ; lighting of candles, &c. (briquet de Saturne) ; eudiometric analysis of air, &c. ; medi- cal uses ; production of electric light in certain particular cases ; distribution of time ; application H 1 6 2 APPLICA TIONS OF A CCUMULA TORS. to railway brakes (Mr. Achard's patent) ; gal- vano-plastic operations ; prospecting and drilling in rocks ; glass engraving, &c. Mr. Plante has, for the majority of these appli- cations, indicated the means to be employed. Applications to Scientific Researches. It is par- ticularly as a means of scientific researches that Mr. Plant6 has mostly used his accumulators. With a two-cell nitric acid battery he charges, in quantity, a great number of secondary batteries which are joined in series for the discharge. The connections are easily effected by means of an ingenious commutator, well known to physicists. By turning it one quarter of a revolution forward or backward the coupling is obtained in quantity or in series. With his secondary couples of low resistances and his commutator, Mr. G. Plante obtains, in his laboratory, tensions of 100, 1000, 2000, 4000 volts with a primary source, the electromotive force of which is inferior to 4 volts. Accumulators, having become a powerful and commodious means of investigation, have enabled their inventor to realise numerous beautiful ex- periments, the record of which should be read in his * Recherches.' In this work will be found described and explained: the luminous sheathing obtained round one of the wires of a voltameter (40 APPLICA TIONS OF A CCUMULA TORS. 1 63 couples) ; the luminous globules in the midst of liquids (200 to 800 couples) ; the globular flames, voltaic egret and luminous figures (800 couples) ; the perambulating voltaic spark (800 couples) ; the sheafs of aqueous globules and the steam jets (400 couples) ; the gyratory motions of an electrified liquid vein (400 couples) ; the electric freshet (400 couples) ; the voltaic pump ; the electro-silicic light (60, 80, 350 couples, according to the liquid used) ; the electro-dynamic spirals (10 to 20 couples) ; the illumination of a Geissler tube with a continuous current (800 couples) ; the crateriform perforations (400 couples) ; &c. Pushing farther his researches with high ten- sions, Mr. G. Plante has invented the Rheostatic machine, which is one of the most beautiful physi- cal instruments. This apparatus transforms the current of a secondary battery of 600 to 800 couples, and brings it to the potential of electrical machines called statical, so that the highest ten- sions are obtained by means of a double trans- formation, with a starting point of 4 volts. The Rheostatic machine consists, in principle, of a certain number of condensators constituted by strips of mica covered with tinfoil, and arranged so as to be charged in quantity and discharged in tension. This apparatus gives sparks of i to 5 centimeters in length. These beautiful experiments have enabled Mr. Plante to explain several great natural pheno- M 2 1 64 APPLICA TIONS OF A CCUM ULA TORS. mena: globular lighting, chaplet lighting, hail, tornados and cyclones, aurora borealis, &c. These vast studies on Meteorology have been recently published in book form.* Owing to the considerable industrial importance which they have acquired, during the few past years, accumulators have monopolised, to the detriment of Mr. Planters purely scientific re- searches, a portion of the attention bestowed upon them. This portion of his work, although of less apparent usefulness to the vulgar is, for the physicist, a source of most important discovery upon the highest questions of natural philosophy. Application to Telegraphy, Telephony, Clockwork, &c. In telegraphic, telephonic, &c., exploitations, primary batteries, the use of which is costly, would be superseded with advan- tage by secondary ones periodically recharged. This substitution has already been effected at some important exchanges. The main quality required of accumulators intended for this kind of work is a good conser- vation of the charge. The motive power required for the periodical recharging of telegraphic and telephonic batteries, * ' Phnomnes dlectriques de 1'Atmosph^re,' by G.Plantd, Paris 1888. APPLICA TIONS OF A CCUMULA TORS. \ 6 5 is very unimportant. It has been calculated * that with i horse-power working 12 hours a day, the 3000 exchanges of the Paris telephonic system could be fed. This system employs 30,000 primary couples, mostly all Leclanche's. In telegraphic applications, the practical effi- ciency of accumulators, from the motive power down to the apparatuses, is the product of three factors : a. Transformation of mechanical work into electrical energy in the charging dynamo a = 0-85. 6. Normal efficiency proper of the accumu- lators b o* 72. c. Coefficient of loss : slow dissipation of the charge in the accumulators, the discharge of which is very slow, and for a long time differed c 0*7. Whence Practical efficiency = a X b x c 0*43. This figure is very advantageous, considering the cost of industrial motive power compared to that of primary batteries, which cost at least two francs per horse-power-hour, cost of manipulations not included. * Piles e'lectriques el accumulateurs : Sur le travail des piles Leclanche en service sur le reseau telephonique de Paris,' from experiments jointly carried out with Mr. A. Reynier, 1883. 1 66 APPLICATIONS OF ACCUMULATORS. Application to Electric Lighting. Electric lighting is, actually, the most important application of accumulators. The use of accu- mulators has the following advantages, ist, the security of the light ; 2nd, its regularity, the accumulators giving no abrupt variation of elec- tromotive force ; 3rd, the independence of the burners : when the surfaces of the accumulators have a great development their resistance is practically nil, so that their output can be regu- lated accordingly to the number of lamps in operation the lighting or putting out of a certain number of them does not influence the remainder ; 4th, the greater duration of the incandescent lamps, which are protected from destructive variations. It can be maintained that, alone, the electric lighting by accumulators is safe. That is why it has been made compulsory, in all the theatres, for the rescue service. The practical efficiency of accumulators, from the motive power to the wiring of the lamps, is the product of two factors. a. Transformation of the mechanical work in electrical energy in the charging dynamo, a 0-85. b. Normal efficiency proper of the accumula- tors, b = o* 72. Whence Practical efficiency = a x = 0*576. APPLICA TIONS OF A CCUMULA TORS. 1 6 7 It must be observed that the lighting direct by machine had the coefficient a ; so that the efficiency of the accumulator process compared to the direct process, is really that of the accu- mulators themselves, or 0*72. In fact the comparative efficiency is generally higher. For, in the case of accumulators the expense of energy is proportional to the useful consumption, whereas in the direct process this expense becomes relatively much greater as soon as the engineering materials cease to work in full, as it often is the case. When an important lighting station works for only a few hours daily, the use of accumulators permits of reducing the importance of the station. Thus in a theatre, where the average weekly lighting is about 32 hours, the motive power and dynamos might be of only one-third of what they have to be in the direct lighting process. Everything being considered, the use of accu- mulators in electric lighting reduces the cost of the installation, and is a guarantee of security and regularity in the working. The importance of a battery for a given lighting is easy of calculation. The number of accumu- lators to be joined in tension is the quotient of the necessary potential by the utilisable fall of each couple. The duration of the lighting being known, as well as the number of lamps, and their consumption in amperes, the voltaic capacity 1 68 APPLICA TIONS OF A CCUMULA TORS. (ampere-hours) of the required couples, and their output are easily deducted. The type of accu- mulator selected shall answer these requirements, which do not concord in all cases ; if a large output is required for a short time, the couples should be powerful, and they will not be com- pletely discharged ; if, on the contrary, only a small output of long duration is required, the accumulators must be of great capacity, and will not work at their maximum power. Owing to these considerations, a given system may answer in some cases and have to be rejected in others. When the capacity and the regimen shall exceed those of existing types, or those of handy sizes, several batteries, joined in quantity, may be used. Application to the Current Regularisa- tion of Machines ; Regulating Volta- meters. The speed of a dynamo is rarely uniform ; the rhythmed impulsions of the motor, the defects of the transmission, the variations of the resisting work, alternately accelerate and re- tard its average beat. The variations of electro- motive power resulting from these irregularities are more or less marked according to the degree of perfection of the installation ; and are more or less acceptable according to the required nature of light. For instance, if the lighting is effected by glow APPLICA TIONS OF A CCUMULA TORS. \ 69 lamps, small changes in the speed produce great variations in the brilliancy of the lights, the luminous intensity being nearly proportional to the sixth power of the difference of potential at the two distribution terminals. In lamps with large carbon filaments, these irregularities are attenu- ated, owing to the mass of the luminous material ; but in those with fine filaments, the use of which becomes prevalent, the variations are very noticeable and the more disastrous that they are synchronic in all the lamps. Accumulators, it is known, regularise the current, for their electromotive force varies in much less proportion than that of the charging motor. In those of the Plante type, the increase in the difference of potential amounts to only 8 per 100 of the excess of the electromotive force of the source. This explains how the lighting carried out with accumulators is always very regular, even with a defective mechanical installation. It is objected that this regularity would be too dearly paid for if the qualities of accumulators as a fly-wheel only were used to the exclusion of their qualities as a magazine. For this restricted use, the author of this work has proposed the use of economic secondary couples, the special features of which are a great surface of electrodes, a very low internal resistance, an intense regimen of discharges, a small voltaic capacity, and a small cost. I 70 APPLICA TIONS OF A CCUMULA TORS. These couples, which are not, properly speaking, accumulators, have been designated regulating voltameters. The question of capacity being eliminated in the realisation of regulating couples, the choice of combinations is extended. Besides accumulators of the Plante type, other voltaic systems may be used. The lead-sulphate- of-zinc couple appears to be the best of all, when a long conservation of the charge is not required. Its high electromotive force, 2 4 volts instead of i 9 volt, allows of a reduction in the number of the couples and in the resistance of the battery ; its variations are even less than those of the couple lead-lead ; lastly, when a certain capacity is required to work during 15 to 30 minutes in case of accident, it can be formed right off. The Reynier accumulator with plaited positive and plain negative plates, described page 1 1 8, is a good regulating voltameter. For this particular use, the positive plates are, as a rule, put into service without having been previously formed ; they are thus cheaper and last longer. In order to give these voltameters a certain capacity of accumulation, the positive electrodes are prepared by Mr. Plante's nitric acid method, thus acquiring the property of fixing a certain quantity of oxygen and sulphuric acid ; the nega- tives are formed at once by a deposit of electro- lytic zinc. A battery of voltameters, the positive APPLICA TIONS OF A CCUM ULATORS. I 7 1 plates of which have been well prepared, can prolong a lighting during half an hour, a space of time generally sufficient to remedy any defect which may be the cause of a temporary stoppage. With the surface of electrodes mentioned page 1 19, the zinc-lead couple may regularise a current of 50 to 75 amperes. Its electromotive force, under charge, being about 2 * 5 volts, 42 of these voltameters could regulate (and, if necessary, prolong) the lighting of 100 to 150 glow lamps of 15 to 1 6 candles; 50 lead accumulators of a double surface would be required to obtain the same results. The economy resulting from the substitution amounts to 65 per 100. So the voltameters are indicated as a substitute to accumulators wherever it is intended to regularise a lighting and take precautions against sudden extinctions. The regulating voltameters have already been applied in many instances. The most important is that of the large battery supplied by the author, in March 1887, for the Paris Hotel de Ville. It is of the type lead- lead, the Administration not daring to adopt the more advantageous type zinc-lead, the practical merits of which had not then been demonstrated. The couples are of the Plante type, of the classical spiral pattern ; but the details of con- struction have been adapted to the dimen- sions of the apparatuses and their destination. The two electrodes of each couples are rein- I 7 2 APPLICA T1ONS OF A CCUMULA TORS. forced by hemmings. The tails have been strongly reinforced and protected against the mechanical and electro-chemical causes of destruction. The isolation is secured by two wooden partitions separated by vertical jointed wooden rods ; the glass vessels or jars are protected from internal and external injuries, by means of felt buffers ; they are closed by a cover, which shelters the whole and moderates the evaporation. The cells are connected together in three equal and distinct series, by means of strong bolts of lead and antimony alloy. The electrodes have a considerable surface ; 480 square decimeters. The voltaic capacity can reach one million coulombs. The contract only stipulates for 300,000 coulombs sufficient to maintain the lighting during 20 to 30 minutes in case of an accidental stoppage of the machines ; a certain number of voltameters mounted in overcharge are then introduced into the lighting circuits for com- pensating the loss of electromotive force due to the stoppage of the works. The Paris Hotel de Ville battery is an example of a remarkable application of secondary couples to lighting. Batteries of 100 horse-power and over will no doubt be largely employed before long, but up to now no other one of that power is known to exist. The regulation of a current by means of a APPLICATIONS OF ACCUMULATORS. I 73 battery of voltameters costs a certain quantity of energy, proportional to the intensity of the current which it derives. The stronger the derived fraction, the stronger also and the more abrupt are the primary variations, and the more perfect becomes the necessitated regulation. The said fraction may vary between 2 and 10 per cent, with lead-lead couples, and i and 6 per cent, with the zinc-lead couples. It is empirically adjusted by increasing or ducing the number of voltameters in series, to increase or diminish their regulating influence When the voltameters are used for prolonging the lighting after the stoppage of the machines, the loss of potential due to the cessation of the primary current must at the proper time be compensated for. The simplest mode of doing it is to use a few additional voltameters : during the normal work- ing, this battery is joined in quantity with a similar number of couples taken at one end of the principal battery ; on the stoppage of the machine, the whole is coupled in tension, so as to obtain the required compensation. The change can be effected by means of any system of two-way commutator. Welding of Metals. The calorific effects of currents may be used for the working of metals and especially for welding. I 74 APPLICA TIONS OF A CCUMULA TORS. Reference to electrical welding of metals was first made by Plante in 1868 : " The discharges given off by these batteries, are," he said, " of a duration long enough for pro- ducing the most intense calorific effects, such as the fusion of platinum rods, iron, steel, &c. " Platinum may, by this means, be welded to itself with great facility. So can, a fortiori, the other metals, less refractory than platinum." * This process has been introduced into in- dustrial practice by Mr. Elihu Thomson f who succeeded in welding iron, steel, platinum, gold, cast-iron, brass, bronze, copper, German silver, zinc, tin, lead, aluminium, &c. The bars, tubes, or other pieces which it is intended to weld are firmly pressed against each other. A current of great intensity is made to pass from the clasps of the holder through the junction. The resistance at this point being highest, the two ends soon get to welding heat, and thus are intimately united. Mr. E. Thomson has welded rods of copper ii mm. diameter and steel bars of 22 mm. He estimates the current used at 20,000 amperes and \ volt.f This current was obtained with * Addition of the 2Qth February, 1868 to the French patent No. 78897, 1867 * Dispositions des batteries secondaires a lames de plomb et ses applications.' t 'The Electrical World,' translated into ' Revue Internationale de I'Electricite', 2oth May, 1887. J This figure seems exaggerated, considering the small sectional surfaces of the pieces welded. APPLICA TIONS OF A CCUMULA TORS. I 7 5 a self-exciting alternating current machine, and a transformator. The current required for the welding of a steel bar of 38 mm. diameter is stated to be 50,000 amperes, and corresponds to 35 horse- power for less than one minute. For such short operations, secondary couples would prove more advantageous than transfor- mators. The motive power could be reduced by 95 per cent. Accumulators of small electro- motive force (such as those of the second genus), specially constructed for a large debit and a small capacity, could be utilised ; they would be charged in tension and discharged in quantity. As the normal debit of accumulators may be trebled when it is desired to obtain short discharges without taking any account of the efficiency, some very intense currents could thus be obtained with a cheap battery. Electric welding may be carried out by means of the voltaic arc. In this case larger electro- motive forces and much smaller intensities are required. This process is more convenient than the other, and applies to more numerous cases. Sir William Siemens, Wallner, Cowles, &c., have applied the voltaic arc to the fusion of refractory metals ; but the first application of the arc obtained from accumulators to welding properly speaking appears to be due to Mr. A. de Meritens who used this process in the manu- I 76 APPLICATIONS OF ACCUMULATORS. facture of the Tommasi accumulators.* The same process was also in use at Mr. de Kabath's works in 1882. More recently, Mr. Benardosf has worked out a complete system for the industrial realisation of welding by means of the voltaic arc, applied to the most varied operations. The current is supplied by a battery of accu- mulators, the coupling of which may be effected in different manners. The metallic piece to be welded is the negative pole of the arc ; the positive pole is a carbon rod mounted in an appropriate holder. The voltaic arc produced between the pieces of metal and carbon is applied on the parts to be welded ; it constitutes a kind of powerful blow- pipe. The battery of accumulators is kept in charge of a dynamo working without interruption ; it is discharged intermittently and supplies secondary currents of much greater intensity than the primary one. The fall of potential and the intensity are regulated by some couplings and one rheostat. The accumulators are of small capacities and * French patent 146,010, 24th November, 1881, 'Mode of welding by Electricity.' t ' La Soudure Electrique par le proc^d^ Bernardos ' paper read by Mr. Riihlmann before the Electrotechnic Society of Berlin, translated in ' La Revue Internationale d'ElectriciteY 5th February, 1888. ' Proce'de's de soudure par 1'Electricit^ ' applied by Benardos and analysed by Kamenski. Translation by Przewoski : ' Memoires de la Socie'te des Inge"nieurs Civils,' February 1888. APPLICA TIONS OF A CCUMULA TORS. I 7 7 of large output. Mr. Benardos makes them, like Mr. de Kabath, with lead plates alternately plain and corrugated ; but he has replaced the old cages by suspended mountings imitated from Reynier's frames. Any other system of large surface accumulators may be used. The fall of potential in the arc varies from 40 to 175 volts. The intensity of the current is still more variable, but has not been indicated. It may be from 100 to 1000 amperes. These values are altered according to the nature and the mass of the pieces to be welded. The diameter of the carbon rod may be greater or smaller; it is sometimes 25 millimeters, and its length 250 mm. The hand of the operator must be protected by a cardboard shield, and his sight by coloured glass spectacles. When the operation is to last a certain time he uses a silk mask, coated with resin, and provided with a moveable perforated glass frame for breathing purposes. The neglect of these precautions might result in all the con- sequences of a sunstroke. Weldings of the most varied kinds are effected with the voltaic arc on refractory or fusible metals alike. Cast iron, for instance, can be welded by this, but not by the ordinary processes. With iron, steel, and cast iron, the flux used is sand or borax, which facilitate the separation of the slag resulting from the oxidisation of the metal. N I 7 8 APPLICA TIONS OF A CC UMULA TORS. The constants of the voltaic arc used being known, its power in calories 'per second may be calculated. If e is the fall of potential in volts, and I the intensity of the current in amperes, the calorific power P of the voltaic arc is P = 0-243 el calory-gramme-degree per second. Production of Motive-power. Messrs. G. Plante and A. Niaudet made, in 1873, a beautiful experiment which simultaneously demonstrated the reversibility of both secondary" couples and continuous current magneto-electric machines.* The terminals of a Gramme machine with magnet were connected to those of a Plante accumulator, formed but not charged (Fig. 62). The accumulator was charged by working the machine during a certain time ; the machine being stopped and left to itself, it immediately restarted at a slower speed, and in the same direction as during the charging. This important experiment, which nowadays does not excite any astonishment, contained the germ of the exploitation of the natural and in- dustrial motive powers by means of accumulators. Theoretically considered, it placed in evidence the antagonism of electromotive forces in a * 'Sur une experience d'e'lectro-dynamique,' by G. Plantd and A. Niaudet. ' Comptes Rendus de PAcade*mie des Sciences,' tome Ixxxvi., page 1259, 1873. APPLICA TIONS OF A CCUMULA TORS. 1 79 system composed of a voltaic source and a magneto-electric machine. The electromotive force of the source is nearly fixed ; that of the machine depends upon its speed. For a certain speed of the machine which may be called the critical speed, the electromotive forces are equal ; no current passes in the circuit. A greater speed causes the FIG. 62. electromotive force of the machine to predomi- nate ; it then expends some mechanical work, transforms it into electrical energy, and charges the accumulator. When the speed is, on the contrary, inferior to the critical speed, the voltaic electromotive force predominates ; the accumulator discharges itself and supplies some electrical energy, which the N 2 1 80 APPLICA TIONS OF A CCUMULA TORS. machine becoming a motor transforms into mechanical work. The mechanical theory of these phenomena has been established by Mr. Mascart.* If we call : E, the electromotive force of the voltaic battery, expressed in volts ; e, the antagonistic electromotive force of the machine, in volts ; R, the total resistance of the circuit, in ohms ; the theoretical mechanical power, P, of the machine is : P = - - kilogrammeters per second. " The gait of the motor depends upon the resisting work. When the motor revolves empty, its speed becomes such that e becomes nearly equal to E. The small amount of work produced is spent in frictions ; the result is the production of heat, and the useful work is nil. If, on the con- trary, the motor is blocked to rest, its electro- motive force and mechanical work are zero. But the calorific work is a maximum ; it is equivalent to E 2 I 2 R = - - kilogrammeters per second ; I being the intensity of the current in amperes. * ' Des machines magne'to-e'leclriques et e'lectro-dynamiques,' 'Journal de Physique,' July 1877. APPLICA TIONS OF A CCUMULA TORS. 1 8 1 The regimens of utilisation are to be found between these two extreme regimens which give no useful work. In any case, the theoretical efficiency of the machine, working as a motor, under the action of a battery of accumulators is : e E' Its practical efficiency is the product of three factors : a. efficiency proper of the machine which charged the accumulators: a = 0*85 ; b. efficiency proper of the accumulators : b = 0-72 c. efficiency proper of the electric motor. This efficiency c itself is the product of two factors. c'. electrical efficiency of the motor, depending upon its electrical resistance and especially of its gait: |-; c". mechanical efficiency of the motor or pro- portion of the utilisable to the total work (the difference between these two works being absorbed by the passive resistances). a The electrical efficiency ^ may vary between o and i ; in practice, when working at favourable speeds, it can be made to be equal to at least o 9. As to the mechanical efficiency, it is not, in well 1 8 2 APPL1CA TJONS OF A CCUMULA TORS, constructed machines, in which the frictions are small, inferior to o . 95. Thus c = c' x c" = 0-9 x 0*95 = 0-855. Consequently the practical efficiency, U, of an electric motor worked from an accumulator is, from the mechanical motor working the charging dynamo up to the pulley of the electric motor : U = X X ^=0-85 X 0-72 X o' 85 = 0-52. In certain cases, this formula is affected by other coefficients of reduction. The applications of the accumulators to the production of motive power, are too little practised at present ; they will play an important part in industry. We will again treat of this subject in the chapters on electrical locomotion on tramways and roads, electrical navigation and captations 'of the natural forces. Electrical Locomotion on Tramways. The application of accumulators to locomotion was proposed by Mr. C. Faure in 1880.* The first industrial attempts are due to Mr. S. Philip- part, senior, in 1883. The author has given the description and the critique of these experiments in " rElectricien."f * French patent No. 139,258,20^1 October, 1880, ' Perfectionne- ments aux Batteries galvaniques et applications de ces batteries aux machines locomotives dlectriques.' t ist and 1 5th September, 1883. APPLICA TIONS OF A CCUMULA TORS. 1 83 This article, reproduced in ' Piles electriques et accumulateurs/ reviewed the use of variable couplings suitable for supplying the various regimens required by the variations of the resisting work ; it also explained the possibility of recupe- rating, by recharging the accumulators en route, a portion of the negative work corresponding to descents on rapid inclines. It combined with an estimate of the cost price and concluded in favour of the traction by accumulators as being cheaper than animal traction in countries where horses are dear to buy and to keep. These technical criticisms have received a practical sanction, excepting, however, the recupe- ration by recharging en route which has not yet been adopted : The following notions are extracted from the said article : The sum of energy required for propelling a vehicle on the forward and backward journey, on an accidented rail or tram track is composed of 1. The traction work proper, W, which is proportional to the weight M of the vehicle, to the length L of the road and to the coefficient of traction k W= M (in kilogrammes) x L (in meters) x k kilogrammeters. 2. The sum W of the elevating works, positive or negative, w\,w\,w^, . . . reaching from changes of altitudes h k 2 . . . . of the train on the inclines. 1 84 APPLICA TIONS OF A CCUMULA TORS. The elevating work is the product of the weight M of the vehicle by the difference of level. w\ = M (in kilogr.) x h (in meters) kilogrammeters. 3. The sum W" of the expenditures of live forces, positive or negative, w" ly w" 2 .... due to the starts and the stoppages. The quantity of live force so expended, each time, is M (in kil.) w i = - - X V 2 (speed in meters per second) kilogrammeters. A train which, starting from a station, comes back to it after a more or less accidented journey containing stoppages, has neither increased nor decreased its energy of position ; it has gained or lost no live power. We can write W' = w\ + w\ + . . . . = W" = w\ + w", + .,..= o Theoretically, the work of traction would amount to the rolling proper. In practice, on the contrary, the works of eleva- tion and starting are considerable, for the accumu- lators supply to all the positive elevations and all the starts ; and the negative works of descents and of stoppages are nearly entirely absorbed by the brakes. A portion of these negative works could, however, be recuperated. As was seen page 180, the theoretical me- APPLICA TIONS OF A CCUMULA TORS. 1 8 5 chanical power P of the electric motor, worked from accumulators is P = -J kilogrammeters per second. This formula indicates two modes of varying the motive power and the speed of the train. 1. The increase or decrease of E. 2. The decrease or increase of R. If E is made to vary by adding or subtracting some accumulators, the expenditure becomes unequal in the couples ; it is a great loss at the charge and at the discharge. If supplementary resistances are introduced, they become the seat of an emission of heat which, in certain cases, represents a considerable fraction of the total work. Lastly, neither method allows of the recuperation, that is to say, of the accumulators being recharged on rapid descents or abrupt stoppages, since with dynamos excited in circuit e is always smaller than E. Better results are obtained by means of coup- lings. The electric motor is provided with a distinct exciting circuit and artificial variations of E and R are concurrently utilised ; those of E are produced by some grouping of accumulators giving some distinct regimens ; those of R are effected in narrow limits, for the production of graded powers between the defined regimens obtained by the commutations. The various 1 86 APPLICA TIONS OF A CCUMULA TORS. groupings of the battery are obtained by means of a commutator ad hoc, easy of combination. This method has been used by several makers, who claim it as their own without regard to anterior publications. It should be completed by means of arrangements enabling to recuperate a portion of the negative works (descents on stiff inclines and sudden stoppages), by recharging the accu- mulators en route. The battery would take back a portion of its charge by absorbing some trans- formed mechanical work on the condition of making, at the proper time e <; E. The complication of means is only apparent. It is possible to arrange some commutators successively operating the groupings in the required order. By the simple working of a complicate instrument, the pilot could go from the highest positive power to the strongest negative, passing through all the intermediate regimens without having to reason about the effected combinations. As to the material fittings of locomotives or vehicles, it is a question of special mechanics which is not concerned in the frame of this work. The prime cost of traction by accumulators comprises firstly the cost of the motive power at the works, the maintenance and redemption of the motive power material ; then the accessory ex- penses of grease, oil, labour, and rents. The length of a line of tramway and its profile APPLICA TIONS OF A CCUMULATORS. 1 8 7 being known, as well as the kilometric run of the train and its weight in charge, one can, with the formulae given page 183, calculate the quan- tity of work daily supplied by the horses. The indirect amount of work to be done by accumu- lators is deducted therefrom, and the weight of accumulators required results from these estima- tions. The mechanical work produced by the factory where the accumulators are charged is very much greater than the work required from the horses. For the successive transformations of energy, from the pulley of the charging dynamo up to the driving wheels, introduce five coefficients of reduction, viz. : The three already known factors a 0*85 ; b 0-72 ; c 0*85. d, mechanical transmission of the power of the electric motor to the driving wheels d = 0*9. F, proportion of the useful weight to the weight carried : the additional weight of the electrical material being nearly the half of that of the train pulled, this proportion is 1:1*5 whence F = o* 66. Whence : Practical efficiency from the motive power at the factory up to the driving wheels : = 0X^X i 1000 , V.C, P $2< % x _ horse-power. N&fr?* ^^ ^ ,%,, ** The useful work Wu is the product of the useful exertion by the space run L (which is expressed in meters). A V 2 W u = F u L = k- x L ton-meters A V 2 = k L : 270 horse-power hours. These expressions have been verified up to speeds of 7 to 8 meters per second which are not exceeded in practice. In rivers, the water has a speed proper, u. To obtain a speed V 7 of the vessel, measured on the shore, a speed of V + u or V u must be produced according to the vessel running against or with the stream, V being the speed of the vessel proper. In the case of river navigation, V must be replaced by V = V u. 1 9 2 APPLICA TIONS OF A CCUMULA TORS. The formula governing an electric motor worked from accumulators is which has already been explained. The expressions of the values of P u and W u indicate the great difference existing between electrical navigation and land locomotion. The principal differences are well illustrated in the example given page 193. It will, from these considerations, be understood why some trials of petite vitesse navigation have succeeded, with ordinary primary or secondary batteries, by amateurs or inferior technical people. Grande vitesse navigation with large vessels of elongated shape could only be actually obtained with the most powerful accumulators. A middle speed run has been obtained by Mr. Krebs, with a torpedo boat of 8*8om. He ran 6 4 knots on the Seine (real speed, accounting for that of the stream 11,852 meters per hour), with Reynier accumulators,* and 6*6 knots (12,223 m - per hour) at sea, with Commelin-Desmazures- Bailhache accumulators.! These speeds are remarkable, considering the small tonnage of the vessel and its heavy shape, which gives the co- efficient an increased value. * Experiments of the Concorde bridge, November 1866. t Havre experiments, September 1887. APPLICA TIONS OF A CCUMULA TORS. 1 93 LAND ELECTRICAL LOCOMOTION. ELECTRICAL NAVIGATION. The useful exertion is inde- pendent of the speed. The useful power is propor- tional to the speed. For a given journey, the expenditure of work is, theo- retically, independent of the speed. A powerful battery is re- quired to obtain a great speed. A good distance may be covered, whatever the gait, with the batteries actually known. A portion of the elevating works and of the live powers may be recuperated for re- charging accumulators en route, the dynamo acting as a charger under the impulsion of the train in stiff inclines and sudden stoppages. The useful exertion is pro- portional to the square of the speed. The useful power is propor- tional to the cube of the speed. For a given run, the expen- diture of work is, theoretically, proportional to the square of the speed. An excessively powerful battery is required to obtain a great speed. With the known batteries it is impossible to go far at a great speed. At small speed, on the contrary, long runs may be obtained. No recuperation. 1 94 APPLICA TIONS OF A CCUM ULA TORS. The formulae used in the calculation of P u and W u, the useful power and work, have been re- ported. In order to obtain the effective power and work P and W, P u and W u must be divided by the product of the two coefficients, which are : d, mechanical transmission of the electric motor power to the propulser : ^=0*9. f t efficiency proper of the propulser. With good screws of comparatively large diameters /= 0'86, so that Pu Wu P = and W = . Q'774 0*774 The efficiency of the accumulators, from the charging dynamo to its final utilisation is the product of five factors : d and f, and the three coefficients a = 0*85, b = 0*72, and c 0*85, common to all the mechanical applications of secondary couples. We have therefore : Practical efficiency of accumulators from the charging dynamo's pulley to the final utilisation. = a X b X c X d X X / = o 40. The coefficient/^ it must be observed, appears in all the cases ; so that the use of accumulators increases the expenditure of work only in the proportion, i = 2 '14. a X b X c X d APPLICATIONS OF ACCUMULATORS. 195 That is to say, 2*14 horse-power must be ex- pended at the works to obtain i horse-power on the propeller's shaft. Future Application of Accumulators to Aerial Navigation. Primary batteries have already been successfully used for the propulsion of aerostats. The accumulators will, as soon as their lightness shall become comparable to that of the lightest batteries, become very useful for this same purpose. The weights of the lightest voltaic couples, primary and secondary, in function of i horse- power and i horse-power work per hour are given hereafter : Couple. Horse-power. Horse-power hour. Gaston Tissandier Amalgamated zinc-carbon, concentrated solution of bichromate of potash and sulphuric acid . . . kilogrammes. 7 Z kilogrammes. 20 C. Renard Non - amalgamated zinc, platinum plated silver, chromic, chlorhydric, and sulphuric acids Reynier's accumulator Lead zinc Faure-Sellon-Volckmar accumu- lator Experimental pattern Commelin - Desmazures - Bailhache accumulator /O 36 163 2OO 170 3 18 2S-5 37 1 96 APPLICA TIONS OF A CCUMULA TORS. The accumulators are left behind, especially when their weight is calculated in function of the power. But it may be hoped that they will one day be made to exceed in lightness even the lightest of primary batteries. In prevision of this fact we will give, hereafter, from Mr. C. Renard,* the expressions of the exertions and of the power required for the propulsion of elongated balloons, including the net and the car. If we call : D, the diameter of the balloon, in meters. V, its speed, in meters per second. F, the air resistance to the longitudinal motion of the apparatus. P u, the useful power of traction. P, the power on the propeller's shaft. We shall have : F = 0*01685 D 2 V 2 kilogramme. Pu = 0*01685 D 2 V 3 kilogrammeters per second. P = 0-0326 D 2 V'. If we apply this last formula to a balloon of 10 meters diameter, which we want to propel at a speed proper of 10 meters per second, we find, * " Sur les nouvelles experiences exe'cute'es au moyen du ballon dirigeable, ' La France.' " Note of Mr. C. Renard. ' Comptes Rendus de I'Acade'mie des Sciences,' 7th December, 1885. APPLICA TIONS OF A CC UMULA TORS. 1 9 7 for the value of the power to produce on the propeller's shaft, P = 0*0326 x 10 x io 3 = 3260 kgm. per second = 43'5H.P. Such a balloon could have a cube of 3140 m. and be directed in calm air or even in a moderately agitated atmosphere. Transmission and Distribution of Energy by Means of Secondary Currents. In a direct distribution of electric energy upon extended areas, the most costly item is the wiring. The redemption and maintenance of the conductors cripple the expenditure of exploitation. The transformers enable us to turn this difficulty. Primary currents of high tension, continuous or alternating, are used with long but thin conductors absorbing very little energy. At certain points of the circuit, these primary currents are made to pass through the transformators, where they in- duce secondary currents at the required potentials. Accumulators would, in the distribution of electrical energy in large systems, render more complete services than transformators. They can, in effect, be distributed, like the transformators, where required, and give currents of the desired tension. Some special advantages result from their use. 1 98 APPLICA TIONS OF A CCUMULA TORS. 1. The production and consumption are inde- pendent of each other ; the consumer is not, therefore, subject to the irregularities or stoppages which may occur at the generating station. 2. The generating station, owing to this inde- pendence, may work regularly 20 hours out of 24, in spite of the variations in the consumption. The importance of the works being calculated according to the sum of energy required to be produced in a day, the plant and system of conductors are constantly utilised at full charge ; whence a reduction of materials, and in the expenses of first establishment, maintenance, and redemption. So that the accumulator which brings security to the concern is] not an onerous auxiliary ; the economies which it procures largely compensate for its first cost. Better known, it will become indispensable as the surest and most complete of transformers, as the best agent of distribution of electrical energy.* * The efficiencies proper of induction transformers and of accu- mulators are respectively Alternating current transformers .. 0*94 Continuous current transformers (according to regimens of work) .. 0*875 to 0*780 Accumulators 0*72 The alternating current transformers have the highest efficiency ; but it distributes its energy under a form which allows only of its utilisation in calorific applications. The continuous current trans- formers are of a more general utilisation their efficiency approaches that of accumulators, of which they do not always possess all the advantages. APPL TCA TIONS OF A CCUMULA TORS. 1 99 Translation or Displacement of Energy. The accumulators, precious auxiliaries of trans- missions by conductors, enable the energy to be displaced without the help of a system of conduc- tors. The process, which is disdained by some because it is so simple, consists in charging the accumulators near the motive-power, and trans- porting them, ready charged, to the spot where they are to be used. Land-carriage of Energy. It is the translation effected on land, on carriages, or on wagons. This method, in use for many years, will render great services when it is logically practised, with light accumulators. Locomotion by accumulators gives us the spec- tacle of energy effecting its own translation, with an additional weight, which might consist of charged batteries travelling with their disposable energy. Water-carriage of Energy. It is the translation of energy on water. Floating is analogous to land carriage. It must, however, not be forgotten that petite vitesse water propulsion only requires a very feeble expenditure of work ; if the accumu- lators are capable of vehiculating their own energy, they can carry it on water at a smaller sacrifice of the work embarked. It is therefore useful to mention this mode of translation of energy, not used yet to this day. 200 APPLICATIONS OF ACCUMULATORS. Caption of Natural Forces. What has been said as regards the usefulness of accumu- lators for the transport and distribution of indus- trial forces, especially applies to natural forces. In the case of a constant hydraulic power, the direct utilisation of it only takes place at the times of consumption, or 1500 hours (lighting) to 3000 or 3500 hours (mechanical uses). With accumu- lators, the force may be capted almost without interruption, that is to say for more than 8000 hours per annum. When the force utilised is irregular, the direct process can only reckon its minimum power ; the accumulators enable its average power to be utilised regularly or not. Certain intermittent forces, such as wind, tides, &c., which are very little used, are easily exploit- able by means of accumulators. The caption of natural forces (actual energy) by means of secondary batteries, must gradually substitute itself to coal getting (fossil energy), which too exclusively supplies heat to our hearths and power to our engines. 400,000 miners are employed in coal fields. These maybe considered as real battle-fields since 100,000 tons of coals cost, as an average, the life of one workman.* Our sun, which caters to all the energies of * E. Jouffret : ' Introduction a la The'orie de 1'Energie,' page 150. APPLICATIONS OF ACCUMULATORS. 2OI nature, may also provide for all the artificial requirements of civilisation. " Of the heat which this star sheds in every direction, the earth, which is for it a small disc subtending an arc of 1 7 seconds,* only intercepts a fraction equal to unity divided by a number exceeding two milliards. This particle, however, is equivalent to the sum of heat which could be obtained by burning, daily, 500,000,000 tons of coals, or an amount equal to about 2000 times the annual production of all the coal-fields of the globe. It is this particle which constitutes life on our planet ; the movements existing in its atmosphere or at its surface, the vegetable and animal exist- ences, the battles which we sustain to increase our comfort or to inter-destroy one another, &c., are but effects, utilisations or abuses of it. " Very few indeed are the cases where energy comes from other sources. 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With II large plates, Svo, cloth, 12s. 6d, A Treatise on the Origin, Progress, Prevention^ and Cure of Dry Rot in Timber; with Remarks on the Means of Preserving Wood from Destruction by Sea- Worms, Beetles, Ants, etc. By THOMAS ALLEN BRITTON, late Surveyor to the Metropolitan Board of Works, etc., etc. With 10 plates, crown Svo, cloth, js. 6d. PUBLISHED BY E. & F. N. SPON. The Municipal and Sanitary Engineer s Handbook. By H. PERCY BOULNOIS, Mem. Inst. C.E., Borough Engineer, Ports- mouth. With mtmerous illustrations ', demy 8vo, cloth, I2s. 6u. CONTENTS : The Appointment and Duties of the Town Surveyor Traffic Macadamised Roadways- Steam Rolling Road Metal and Breaking Pitched Pavements Asphalte Wood Pavements Footpaths Kerbs and Gutters Street Naming and Numbering Street Lighting Sewer- age Ventilation of Sewers Disposal of Sewage House Drainage Disinfection Gas and Water Companies, etc., Breaking up Streets Improvement of Private Streets Borrowing Powers Artizans' and Labourers' Dwellings Public Conveniences Scavenging, including Street Cleansing Watering and the Removing of Snow Planting Street Trees Deposit of Plans Dangerous Buildings Hoardings Obstructions Improving Street Lines Cellar Openings Public Pleasure Grounds Cemeteries Mortuaries Cattle and Ordinary Markets Public Slaughter-houses, etc. Giving numerous Forms of Notices, Specifications,- and General Information upon these and other subjects of great importance to Municipal Engi- neers and others engaged in Sanitary Work. Metrical Tables. By G. L. MOLESWORTH, M.I.C.E. 321110, cloth, is. 6d. CONTENTS. General Linear Measures Square Measures Cubic Measures Measures of Capacity- Weights Combinations Thermometers* Elements of Construction for Electro- Magnets. By Count TH. Du MONCEL, Mem. de 1'Institut de France. Translated from the French by C. J. WHARTON. Crown 8vo, cloth, 4^. 6d. Practical Electrical Units Popularly Explained, with numerous illustrations and Remarks. By JAMES SWINBURNE, late of J. W. Swan and Co., Paris, late of Brush-Swan Electric Light Company, U.S.A. iSmo, cloth, is. 6d. A Treatise on the Use of Belting for the Transmis- sion of Power. By J. H. COOPER. Second edition, illustrated, 8vo, cloth, 15^. A Pocket-Book of Useful Formula and Memoranda for Civil and Mechanical Engineers. By GUILFORD L. MOLESWORTH, Mem. Inst. C.E., Consulting Engineer to the Government of India for State Railways. With numerous illustrations, 744 pp. Twenty-second edition, revised and enlarged, 32mo, roan, 6s. SYNOPSIS OF CONTENTS: Surveying, Levelling, etc. Strength and Weight of Materials Earthwork, Brickwork, Masonry, Arches, etc. Struts, Columns, Beams, and Trusses Flooring, Roofing, and Roof Trusses Girders, Bridges, etc. Railways and Roads Hydraulic Formulae Canals, Sewers, Waterworks, Docks Irrigation and Breakwaters Gas, Ventilation, and Warming^Heat, Light, Colour, and Sound Gravity : Centres, Forces, and Powers Millwork, Teeth of Wheels, Shafting, etc. Workshop Recipes Sundry Machinery Animal Power Steam and the Steam Engine Water-power, Water-wheels, Turbines, etc. Wind and Windmills Steam Navigation, Ship Building, Tonnage, etc. Gunnery, Projectiles, etc. Weights, Measures, and Money Trigonometry, Conic Sections, and Curves Telegraphy Mensura- tion Tables of Areas and Circumference, and Arcs of Circles Logarithms, Square and Cube Roots, Powers Reciprocals, etc. Useful Numbers Differential and Integral Calcu- lus Algebraic Signs Telegraphic Construction and Formulae. CATALOGUE OF SCIENTIFIC BOOKS Hints on Architectural Draughtsmanship. By G. W. TUXFORD HALLATT. Fcap. 8vo, cloth, is. 6d. Spons Tables and Memoranda for Engineers; selected and arranged by J. T. HURST, C.E., Author of 'Architectural Surveyors' Handbook,' * Hurst's Tredgold's Carpentry,' etc. Ninth edition, 641110, roan, gilt edges, I s. ; or in cloth case, is. 6d. This work is printed in a pearl type, and is so small, measuring only 2 i in. by if in. by i in. thick, that it may be easily carried in the waistcoat pocket. " It is certainly an extremely rare thing for a reviewer to be called upon to notice a volume measuring but 2$ in. by if in., yet these dimensions faithfully represent the size of the handy little book before us. The volume which contains 118 printed pages, besides a few blank pages for memoranda is, in fact, a true pocket-book, adapted for being carried in the waist- coat pocket, and containing a far greater amount and variety of information than most people would imagine could be compressed into so small a space The little volume has been compiled with considerable care and judgment, and we can cordially recommend it to our readers as a useful little pocket companion. "Engineering. A Practical Treatise on Natural and Artificial Concrete, its Varieties and Constructive Adaptations. By HENRY REID, Author of the ' Science and Art of the Manufacture of Portland Cement.' New Edition, with 59 woodcuts and 5 plates, 8vo, cloth, 15^. Notes on Concrete and Works in Concrete; especially written to assist those engaged upon Public Works. By JOHN NEWMAN, Assoc. Mem. Inst. C.E., crown 8vo, cloth, 4*. 6d. Electricity as a Motive Power. By Count TH. Du MONCEL, Membre de 1'Institut de France, and P'RANK GERALDY, Inge- nieur des Fonts et Chaussees. Translated and Edited, with Additions, by C. J. WHARTON, Assoc. Soc. Tel. Eng. and Elec. With 113 engravings and diagrams ; crown 8vo, cloth, *js. 6d. Treatise on Valve-Gears, with special consideration of the Link-Motions of Locomotive Engines. By Dr. GUSTAV ZEUNER, Professor of Applied Mechanics at the Confederated Polytechnikum of Zurich. Translated from the Fourth German Edition, by Professor J. F. KLEIN, Lehigh University, Bethlehem, Pa. Illustrated, 8vo, cloth, I2s. 6d. The French- Polisher s Manual. By a French- Polisher; containing Timber Staining, Washing, Matching, Improving, Painting, Imitations, Directions for Staining, Sizing, Embodying, Smoothing, Spirit Varnishing, French-Polishing, Directions for Re- polishing. Third edition, royal 32mo, sewed, 6d. Hops, their Cultivation, Commerce, and Uses in various Countries. By P. L. SIMMONDS. Crown 8vo, cloth, 4^. 6d. The Principles of Graphic Statics. By GEORGE SYDENHAM CLARKE, Capt. Royal Engineers. With 112 illustrations. 4to, cloth, 12s. 6J, PUBLISHED BY E. F. N. SPON. Dynamo- Electric Machinery : A Manual for Students of Electro-technics. By SILVANUS P. THOMPSON, B.A., D.Sc., Professor of Experimental Physics in University College, Bristol, etc., etc. Third edition, illustrated^ 8vo, cloth, i6s. Practical Geometry, Perspective, and Engineering Drawing; a Course of Descriptive Geometry adapted to the Require- ments of the Engineering Draughtsman, including the determination of cast shadows and Isometric Projection, each chapter being followed by numerous examples ; to which are added rules for Shading, Shade-lining, etc., together with practical instructions as to the Lining, Colouring, Printing, and general treatment of Engineering Drawings, with a chapter on drawing Instruments. By GEORGE S. CLARKE, Capt. R.E. Second edition, with 21 plates. 2 vols., cloth, los. 6d. The Elements of Graphic Statics. By Professor KARL VON OTT, translated from the German by G. S. CLARKE, Capt. R.E., Instructor in Mechanical Drawing, Royal Indian Engineering College. With 93 illtistrations, crown 8vo, cloth, $s. A Practical Treatise on the Manufacture and Distri- bution of Coal Gas. By WILLIAM RICHARDS. Demy 410, with numerous wood engravings and 29 plates ', cloth, 28j. SYNOPSIS OF CONTENTS : Introduction History of Gas Lighting Chemistry of Gas Manufacture, by Lewis Thompson, Esq., M.R.C.S. Coal, with Analyses, by J. Paterson, Lewis Thompson, and G. R. Hislop, Esqrs. Retorts, Iron and Clay Retort Setting Hydraulic Main Con- densers Exhausters Washers and Scrubbers Purifiers Purification History of Gas Holder Tanks, Brick and Stone, Composite, Concrete, Cast-iron, Compound Annular Wrpught-iron Specifications Gas Holders Station Meter Governor Distribution Mains Gas Mathematics, or Formulae for the Distribution of Gas, by Lewis Thompson, Esq. Services Consumers' Meters Regulators Burners Fittings Photometer Carburization of Gas Air Gas and Water Gas Composition of Coal Gas, by Lewis Thompson, Esq. Analyses of Gas Influence of Atmospheric Pressure and Temperature on Gas Residual Products Appendix Description of Retort Settings, Buildings, etc., etc. The New Formula for Mean Velocity of Discharge of Rivers and Canals. . By W. R. KUTTER. Translated from articles in the ' Cultur-Ingenieur,' by Lowis D'A. JACKSON, AssOc. Inst. C.E. 8vo, cloth, I2J. 6