NRLF 
 
 aa? 
 
 JLEMENTARY NATURE 
 
 OF 
 
 CHLORINE 
 
 PAPERS BY 
 HUMPHRY DAVY 
 
 (1809-1818), 
 
 alembic Club IReprints, 
 No, 9, 
 
/ 
 
 LIBRARY 
 
 I UNIVERSITY Of 
 \CALIfORWIA 
 
glemftit Clufi Keprintg fto. .9, 
 
 THE 
 
 ELEMENTARY NATURE 
 
 OF 
 
 CHLORINE. 
 
 PAPERS BY 
 
 HUMPHRY DAVY 
 (1809-1818). 
 
 PUBLISHED BY THE ALEMBIC CLUB. 
 
 Edinburgh Agent: 
 WILLIAM F. CLAY, 18 TEVIOT PLACE. 
 
 London Agents : 
 SIMPKIN, MARSHALL, HAMILTON, KENT & CO., LTD. 
 
 1902, 
 
OP 
 
 PREFACE. 
 
 THIS reprint contains the important contributions 
 of Humphry Davy on the properties and nature 
 of " muriatic acid " and " oxymuriatic acid," which led 
 to the re-adoption of Scheele's view of the relation in 
 which these bodies stand to each other as against 
 that advanced by Berthollet It has been considered 
 advisable to include the early Papers on muriatic acid, so 
 as to shew more clearly the change which took place in 
 Davy's views, and the causes which led to it. That 
 oxymuriatic acid might be a simple body seems to have 
 been first suggested by Gay Lussac and Thenard, in 1809, 
 but they themselves rejected this view at the time, and 
 it was left for Davy to show its correctness. The dis- 
 cussion which these Papers aroused, known as the 
 " Chlorine Controversy," was contributed to by Humphry 
 Davy only to a slight extent, his brother, Dr. John Davy, 
 taking the chief part in defending the theory. 
 
 In collecting Davy's contributions to any one subject 
 it is difficult to give all that is wanted without giving un- 
 necessary matter as well, since many of the larger Papers 
 deal with more than one subject. This is especially the 
 case with the Bakerian Lectures. In the present case 
 nothing has been omitted from any Paper unless it was 
 without direct bearing upon the subject of the reprint. 
 
 All excisions are indicated by asterisks. 
 
 H. M. 
 
 A List of the various Papers will be found on page 78. 
 
 149 
 
The Bakerian Lecture. An Account of some 
 new analytical Researches on the Nature of 
 certain Bodies, particularly the Alkalies, 
 Phosphorus, Sulphur, Carbonaceous Matter, 
 and the Acids hitherto undecompounded ; 
 with some general Observations on Chemical 
 Theory. * 
 
 Read December 15, 1808. 
 
 7. Introduction. 
 
 IN the following pages, I shall do myself the honour 
 of laying before the Royal Society, an account of 
 the. results of the different experiments, made with 
 the hopes of extending our knowledge of the principles of 
 bodies by the new powers and methods arising from the 
 applications of electricity to chemistry, some of which 
 have been long in progress, and others of which have 
 been instituted since their last session. 
 
 The objects which have principally occupied my 
 attention, are the elementary matter of ammonia, the 
 nature of phosphorus, sulphur, charcoal, and the diamond, 
 and the constituents of the boracic, fluoric, and muriatic 
 acids. 
 
 Amongst the numerous processes of decomposition, 
 which I have attempted, many have been successful ; and 
 from those which have failed, some new phenomena have 
 
 * [From "Philosophical Transactions" for 1809, vol. 99, pp. 
 39-104. Part reprinted, pp. 39, 40, 91-103.] 
 
6 Davy. 
 
 usually resulted which may possibly serve as guides in 
 future inquiries. On this account, I shall keep back 
 no part of the investigation, and I shall trust to the 
 candour of the Society for an excuse for its imper- 
 fection. 
 
 The more approaches are made in chemical inquiries 
 towards the refined analysis of bodies, the greater are the 
 obstacles which present themselves, and the less perfect 
 the results. 
 
 All the difficulties which occur in analysing a body, 
 are direct proofs of the energy of attraction of its con- 
 stituent parts. In the play of affinities with respect to 
 secondary compounds even, it rarely occurs that any 
 perfectly pure or unmixed substance is obtained ; and 
 the principle applies still more strongly to primary com- 
 binations. 
 
 The first methods of experimenting on new objects 
 likewise are necessarily imperfect ; novel instruments are 
 demanded, the use of which is only gradually acquired, 
 and a number of experiments of the same kind must be 
 made, before one is obtained from which correct data for 
 conclusions can be drawn. 
 
 8. Analytical Experiments on Muriatic Acid. 
 
 I have made a greater number of experiments upon 
 this substance, than upon any of the other subjects of 
 research that have been mentioned ; it will be impossible 
 to give any more than a general view of them within the 
 limits of the Bakerian lecture. 
 
 Researches carried on some years ago, and which are 
 detailed in the Journals of the Royal Institution, shewed 
 that there were little hopes of decomposing muriatic acid, 
 
Elementary Nature of Chlorine. 7 
 
 in its common form, by VOLTAIC electricity. When 
 aqueous solution of muriatic acid is acted upon, the 
 water alone is decomposed ; and the VOLTAIC electriza- 
 tion of the gas affords no indications of its decom- 
 position ; and merely seems to shew, that this elastic 
 fluid contains much more water than has been usually 
 suspected. 
 
 I have already laid before the Society, an account of 
 some experiments made on the action of potassium on 
 muriatic acid. I have since carried on the same pro- 
 cesses on a larger scale, but with precisely similar 
 results. 
 
 When potassium is introduced into muriatic acid gas, 
 procured from muriate of ammonia and concentrated 
 sulphuric acid, and freed from as much moisture as 
 muriate of lime is capable of attracting from it, it 
 immediately becomes covered with a white crust, it heats 
 spontaneously, and by the assistance of a lamp, acquires 
 in some parts the temperature of ignition, but does not 
 inflame. When the potassium and the gas are in proper 
 proportions, they both entirely disappear ; a white salt 
 is formed, and a quantity of pure hydrogene gas evolved, 
 which equals about one third of the original volume 
 of the gas. 
 
 By eight grains of potassium employed in this way, I 
 effected the absorption of nearly twenty two cubical 
 inches of muriatic acid gas ; and the quantity of hydro- 
 gene gas produced was equal to more than eight cubical 
 inches. 
 
 The correspondence between the quantity of hydrogene 
 generated in cases of this kind, and by the action of 
 potassium upon water, combined with the effects of 
 ignited charcoal upon muriatic acid gas, by which a 
 quantity of inflammable gas is produced equal to more 
 than one third of its volume ; seemed to shew, that the 
 
8 Davy. 
 
 phenomena merely depended upon moisture combined 
 with the muriatic acid gas.* 
 
 To determine this point with more certainty however, 
 and to ascertain whether or no the appearance of the 
 hydrogene was wholly unconnected with the decom- 
 position of the acid, I made two comparative experiments 
 on the quantity of muriate of silver, furnished by two 
 equal quantities of muriatic acid, one of which had been 
 converted into muriate of potash by the action of 
 potassium, and the other of which had been absorbed by 
 water ; every care was taken to avoid sources of error ; 
 and it was found that there was no notable difference in 
 the weight of the results. 
 
 There was no proof then, that the muriatic acid had 
 been decompounded in these experiments ; and there 
 was every reason to consider it as containing in its 
 common aeriform state, at least one third of its weight of 
 water ; and this conclusion we shall find warranted by 
 facts, which are immediately to follow. 
 
 I now made a number of experiments, with the hopes 
 of obtaining the muriatic acid free from water. 
 
 I first heated to whiteness, in a well luted porcelain 
 retort, a mixture of dry sulphate of iron, and muriate of 
 lime which had been previously ignited ; but a few cubic 
 inches of gas only, were obtained, though the mixture 
 was in the quantity of several ounces ; and this gas 
 contained sulphureous acid. I heated dry muriate of 
 lime, mixed both with phosphoric glass and dry boracic 
 
 * When the VOLTAIC spark is taken continuously, by means of 
 points of charcoal in muriatic acid gas over mercury, muriate of 
 mercury is rapidly formed, a volume of inflammable gas, equal to one 
 third of the original volume of the muriatic acid gas appears. The 
 acid gas enters into combination with the oxide of mercury, so that 
 water enough is present in the experiment to form oxide sufficient to 
 absorb the whole of the acid. 
 
Elementary Nature of Chlorine. 9 
 
 acid, in tubes of porcelain, and of iron, and employed 
 the blast of an excellent forge ; but by neither of these 
 methods was any gas obtained, though when a little 
 moisture was added to the mixtures, muriatic acid was 
 develloped in such quantities, as almost to produce 
 explosions. 
 
 The fuming muriate of tin, the liquor of Libavius^ is 
 known to contain dry muriatic acid. I attempted to 
 separate the acid from this substance, by distilling it with 
 sulphur and with phosphorus ; but without success. I 
 obtained only triple compounds, in physical characters, 
 something like the solutions of phosphorus, and sulphur 
 in oil, which were non-conductors of electricity, which 
 did not redden dry litmus paper, and which evolved 
 muriatic acid gas with great violence, heat, and ebullition 
 on the contact of water. 
 
 I distilled mixtures of corrosive sublimate and sulphur, 
 and of calomel and sulphur ; when these were used in 
 their common states, muriatic acid gas was evolved ; but 
 when they were dried by a gentle heat, the quantity was 
 exceedingly diminished, and the little gas that was 
 generated gave hydrogene by the action of potassium. 
 During the distillation of corrosive sublimate and sulphur, 
 a very small quantity of a limpid fluid passed over. 
 When examined by transmitted light, it appeared yellowish 
 green. It emitted fumes of muriatic acid, did not redden 
 dry litmus paper, and deposited sulphur by the action 
 of water. I am inclined to consider it as a modifica- 
 tion of the substance discovered by Dr. THOMSON, in 
 his experiments on the action of oxymuriatic acid on 
 sulphur. 
 
 M. M. GAY LUSSAC and THENARD* have mentioned, 
 that they endeavoured to procure dry muriatic acid by 
 distilling a mixture of calomel and phosphorus, and that 
 * The Moniteur before quoted [May 27, 1808]. 
 
io Davy. 
 
 they obtained a fluid which they consider as a compound 
 of muriatic acid, phosphorus, and oxygene. In dis 
 tilling corrosive sublimate with phosphorus, I had a 
 similar result, and I obtained the substance in much 
 larger quantities, than by the distillation of phosphorus 
 with calomel. 
 
 As oxy muriatic acid is slightly soluble in water, there 
 was reason to suppose, reciprocally that water must be 
 slightly soluble in this gas ; I endeavoured therefore to 
 procure dry muriatic acid, by absorbing the oxygene 
 from oxy muriatic acid gas by substances, which when 
 oxygenated, produced compounds possessing a strong 
 affinity for water. Phosphorus, it is well known, burns 
 in oxymuriatic acid gas ; though the results of this com- 
 bustion, I believe, have never been minutely examined, 
 With the hopes of procuring muriatic acid gas, free from 
 moisture, I made the experiment. I introduced phos- 
 phorus into a receiver having a stop-cock, which had 
 been exhausted, and admitted oxymuriatic acid gas. As 
 soon as the retort was full, the phosphorus entered into 
 combustion, throwing forth pale white flames. A white 
 sublimate collected in the top of the retort, and a fluid 
 as limpid as water, trickled down the sides of the neck. 
 The gas seemed to be entirely absorbed, for when the 
 stop-cock was opened, a fresh quantity of oxymuriatic 
 acid, nearly as much as would have filled the retort, 
 entered. 
 
 The same phenomenon of inflammation again took 
 place, with similar results. Oxymuriatic acid gas was 
 admitted till the whole of the phosphorus was consumed. 
 
 Minute experiments proved, that no gaseous muriatic 
 acid had been evolved in this operation, and the muriatic 
 acid was consequently to be looked for either in the 
 white sublimate, or in the fluid which had formed in the 
 neck of the retort. 
 
Elementary Nature of Chlorine. 1 1 
 
 The sublimate was in large portions, the fluid only in 
 the quantity of a few drops. I collected by different 
 processes, sufficient of both for examination. 
 
 The sublimate emitted fumes of muriatic acid when 
 exposed to air. When brought in contact with water, it 
 evolved muriatic acid gas, and left phosphoric acid, and 
 muriatic acid, dissolved in the water. It was a non- 
 conductor of electricity, and did not burn when heated ; 
 but sublimed when its temperature was about that of 
 boiling water, leaving not the slightest residuum. I am 
 inclined to regard it as a combination of phosphoric, and 
 muriatic acid in their dry states. 
 
 The fluid was of a pale greenish yellow tint, and very 
 limpid ; when exposed to air, it rapidly disappeared, 
 emitting dense white fumes which had a strong smell 
 differing a little from that of muriatic acid. 
 
 It reddened litmus paper in its common state, but had 
 no effect upon litmus paper which had been well dried, 
 and which was immediately dipped into it. It was a non- 
 conductor of electricity. It heated when mixed with 
 water, and evolved muriatic acid gas. I consider it as a 
 compound of phosphorous acid, and muriatic acid, both 
 free from water.* 
 
 Having failed in obtaining uncombined muriatic acid 
 in this way, I performed a similar process with sulphur, 
 but I was unable to cause it to inflame in oxymuriatic 
 acid gas. When it was heated in it, it produced an 
 orange coloured liquid, and yellow fumes passed into the 
 neck of the retort, which condensed into a greenish yellow 
 
 * I attempted to obtain dry muriatic acid likewise from the phos- 
 phuretted muriatic acid of M. M. GAY LUSSAC and THENARD, by 
 distilling it in retorts containing oxygene gas, and oxymuriatic acid 
 gas. In the first case, the retort was shattered by the combustion 
 of the phosphorus, with a violent explosion. In the second, com- 
 pounds, similar to those described above, were formed. 
 
12 Davy. 
 
 fluid. By repeatedly passing oxy muriatic acid through 
 this fluid, and distilling it several times in the gas, I 
 rendered it of a bright olive colour, and in this case it 
 seemed to be a compound of dry sulphuric, and muriatic 
 acid, holding in solution a very little sulphur. When it 
 was heated in contact with sulphur, it rapidly dissolved it, 
 and then became of a bright red colour, and when 
 saturated with sulphur, of a pale golden colour.* No 
 permanent aeriform fluid was evolved in any of these 
 operations, and no muriatic gas appeared, unless moisture 
 was introduced. 
 
 As there seemed little chance of procuring uncombined 
 muriatic acid, it was desirable to ascertain what would be 
 the effects of potassium upon it in these singular com- 
 pounds. 
 
 When potassium was introduced into the fluid, gene- 
 rated by the action of phosphorus on corrosive sublimate, 
 at first it slightly effervesced, from the action of the 
 liquid on the moist crust of potash surrounding it ; but 
 the metal soon appeared perfectly splendid, and swim- 
 ming on the surface. I attempted to fuse it by heating 
 the fluid, but it entered into ebullition at a temperature 
 below that of the fusion of the potassium ; indeed the 
 mere heat of the hand was sufficient for the effect, On 
 examining the potassium, I found that it was combined 
 at the surface with phosphorus, and gave phosphuretted 
 hydrogene by its operation upon water. 
 
 I endeavoured, by repeatedly distilling the fluid from 
 potassium in a close vessel, to free it from phosphorus, 
 and in this way I succeeded in depriving it of a consider- 
 able quantity of this substance. 
 
 I introduced ten or twelve drops of the liquid, which 
 
 * All these substances seem to be of the same nature as the 
 singular compound, the sulphuretted muriatic acid, discovered by 
 Dr. THOMSON, noticed in page 9. 
 
Elementary Nature of Chlorine. 1 3 
 
 had been thus treated, into a small plate glass retort, 
 containing six grains of potassium ; the retort was ex- 
 hausted after having been twice filled with hydrogene, 
 the liquid was made to boil, and the retort kept warm 
 till the whole had disappeared as elastic vapour. The 
 potassium was then heated by the point of a spirit lamp ; 
 it had scarcely melted, when it burst into a most brilliant 
 flame, as splendid as that of phosphorus in oxygene gas, 
 and the retort was destroyed by the rapidity of combustion. 
 
 In other trials made upon smaller quantities after 
 various failures, I was at last able to obtain the results ; 
 there was no proof of the evolution of any permanent 
 elastic fluid during the operation. A solid mass remained 
 of a greenish colour at the surface, but dark gray in the 
 interior. It was extremely inflammable, and often burnt 
 spontaneously when exposed to air ; when thrown upon 
 water, it produced a violent explosion, with a smell like 
 that of phosphuretted hydrogene. In the residuum of 
 its combustion there was found muriate of potash, and 
 phosphate of potash, 
 
 I endeavoured to perform this experiment in an iron 
 tube, hoping that if the muriatic acid was decomposed in 
 the process, its inflammable element, potassium and 
 phosphorus ; might be separated from each other by a 
 high degree of heat ; but in the first part of the operation 
 the action was so intense, as to produce a destruction of 
 the apparatus, and the stop-cock was separated from the 
 tube with a loud detonation. 
 
 I heated potassium in the vapour of the compound of 
 muriatic and phosphoric acid; but in this case, the 
 inflammation was still more intense, and in all the 
 experiments that I have hitherto tried, the glass vessels 
 have been either fused or broken ; the solid residuum 
 has however appeared to be of the same kind as that I 
 have just described. 
 
14 Davy. 
 
 The results of the operation of the sulphuretted com- 
 pounds containing muriatic acid free from water upon 
 potassium, are still more extraordinary than those of the 
 phosphuretted compounds. 
 
 When a piece of potassium is introduced into the sub- 
 stance that distils over during the action of heated 
 sulphur upon oxymuriatic acid, it at first produces a 
 slight effervescence, and if the volume of the potassium 
 considerably exceeds that of the liquid, it soon explodes 
 with a violent report, and a most intense light. 
 
 I have endeavoured to collect the results of this 
 operation, by causing the explosion to take place in large 
 exhausted plate glass retorts ; but, except in a case in 
 which I used only about a quarter of a grain, I never 
 succeeded. Generally the retort, though connected with 
 the air pump at the time, was broken into atoms ; and 
 the explosion produced by a grain of potassium, and an 
 equal quantity of the fluid, has appeared to me consider- 
 ably louder than that of a musket. 
 
 In the case in which I succeeded in exploding a 
 quarter of a grain, it was not possible for me to ascertain 
 if any gaseous matter was evolved ; but a solid compound 
 was formed of a very deep gray tint, which burnt, throw- 
 ing off bright scintillations, when gently heated, which 
 inflamed when touched with water, and gave most 
 brilliant sparks, like those thrown off by iron in oxygene 
 gas. 
 
 Its properties certainly differed from those of any 
 compound of sulphur and potassium that I have seen : 
 whether it contains the muriatic basis must however be 
 still a matter of inquiry. 
 
 There is, however, much reason for supposing, that in 
 the singular phenomena of inflammation and detonation 
 that have been described, the muriatic acid cannot be 
 entirely passive : and it does not seem unfair to infer, 
 
Elementary Nature of Chlorine. 1 5 
 
 that the transfer of its oxygene and the production of a 
 novel substance, are connected with such effects, and 
 that the highly inflammable nature of the new compounds, 
 partly depends upon this circumstance. I am still pur- 
 suing the inquiry, and I shall not fail immediately to 
 communicate to the Society, such results as may appear 
 to me worthy of their attention. 
 
 p. Some general Observations, with Experiments. 
 
 The experiments that I have detailed on the acids, offer 
 some new views with respect to the nature of acidity. 
 That a compound of muriatic acid with oxide of tin or 
 phosphorus should not redden vegetable blues, might be 
 ascribed to a species of neutralization, by the oxide or 
 inflammable body ; but the same reasoning will not apply 
 to the dry compounds which contain acid matter only, 
 and which are precisely similar as to this quality. Let a 
 piece of dry and warm litmus paper be moistened with the 
 compound of muriatic and phosphorous acid, it perfectly 
 retains its colour. Let it then be placed upon a piece of 
 moistened litmus paper, it instantly becomes of a bright 
 red, heats and devellopes muriatic acid gas. 
 
 All the fluid acids that contain water are excellent con- 
 ductors of electricity, in the class called that of imperfect 
 conductors; but the compounds to which I have just 
 alluded, are non-conductors in the same degree as oils, 
 with which they are perfectly miscible. When I first 
 examined muriatic acid, in its combinations free from 
 moisture, I had great hopes of decomposing them by 
 electricity; but there was no action without contact of 
 the wires, and the spark seemed to separate no one of 
 their constituents, but only to render them gaseous. The 
 circumstance likewise applies to the boracic acid, which 
 
1 6 Davy. 
 
 is a good conductor as long as it contains water ; but 
 which, when freed from water and made fluid by heat, is 
 then a non-conductor. 
 
 The alkalies and the earthy compounds, and the 
 oxides, as dry as we can obtain them, though non-con- 
 ductors when solid, are, on the contrary, all conductors 
 when rendered fluid by heat. 
 
 When muriatic acid, existing in combination with 
 phosphorous or phosphoric acid, is rendered gaseous by 
 the action of water, the quantity of this fluid that dis- 
 appears, at least equals from one third to two fifths of the 
 weight of the acid gas produced; a circumstance that 
 agrees with the indications given by the action of 
 potassium.* 
 
 I attempted to procure a compound of dry muriatic 
 and carbonic acids, hoping that it might be gaseous, and 
 that the two acids might be decomposable at the same 
 time by potassium. The process that I employed was by 
 passing corrosive sublimate in vapour through charcoal 
 ignited to whiteness ; but I obtained a very small quantity 
 of gas, which seemed to be a mixture of common muriatic 
 acid gas and carbonic acid gas ; a very minute portion 
 of running mercury only was obtained, by a long continua- 
 tion of the process ; and the slight decomposition that 
 did take place, I am inclined to attribute to the pro- 
 duction of water, by the action of the hydrogene of the 
 charcoal upon the oxygene of the oxide of mercury.t 
 
 * Page 13. 
 
 t These facts and the other facts of the same kind, explain the 
 difficulty of the decomposition of the metallic muriates in common 
 processes of metallurgy. They likewise explain other phenomena 
 in the agencies of muriatic salts. In all cases when a muriatic salt 
 is decomposed by an acid, and muriatic acid gas set free, there 
 appears to be a double affinity, that of the acid for the basis, and of 
 the muriatic acid for water ; pure muriatic acid does not seem 
 capable of being displaced by any other acid. 
 
Elementary Nature of Chlorine. 1 7 
 
 In mixing muriatic acid gas with carbonic acid, or 
 oxygene, or hydrogene, the gases being in their common 
 states, as to moisture, there was always a cloudiness pro- 
 duced ; doubtless owing to the attraction of their water 
 to form liquid muriatic acid. 
 
 On fluoric acid gas no such effect was occasioned. 
 This fact, at first view, might be supposed to shew, that 
 the hydrogene evolved by the action of potassium upon 
 fluoric acid gas, is owing to water in actual combination 
 with it, like that in muriatic acid gas, and which may be 
 essential to its elastic state ; but it is more probable, from 
 the smallness of the quantity, and from the difference of 
 the quantity in different cases, that the moisture is merely 
 in that state of diffusion or solution in which it exists in 
 gases in general, though from the disposition of water to 
 be deposited in this acid gas in the form of an acid 
 solution, it must be either less in quantity, or in a less 
 free state, so as to require for its exhibition much more 
 delicate hygrometrical tests. 
 
1 8 Davy. 
 
 New analytical Researches on the Nature of 
 certain Bodies, being an Appendix to the 
 Bakerian Lecture for i8o8.*t 
 
 # * * * * 
 
 IV, Further Inquiries respecting muriatic Acid. 
 
 The experiments on muriatic acid, which I have 
 already had the honour of laying before the Society, 
 shew that the ideas which had been formerly entertained 
 respecting the difference between the muriatic acid and 
 the oxymuriatic acid are not correct. They prove that 
 muriatic acid gas is a compound of a substance, which as 
 yet has never been procured in an uncombined state, and 
 from one third to one-fourth of water, and that oxymuriatic 
 acid is composed of the same substance, (free from water) 
 united to oxygene. They likewise prove, that when 
 bodies are oxydated in muriatic acid gas, it is by a 
 decomposition of the water contained in that substance, 
 and when they are oxydated in oxymuriatic acid, it is by 
 combination with the oxygene in that body, and in both 
 cases there is always a union of the peculiar unknown 
 substance, the dry muriatic acid with the oxydated body. 
 
 * The account of the principal facts respecting the action of 
 potassium on ammonia, in this communication, were read before 
 the Royal Society, February 2, 1809. The paper was ordered to be 
 printed March 16, 1809. At that time, having stated to the Council 
 that I had since made some new experiments on this matter, and on 
 the subjects discussed in the Bakerian Lecture for 1808, I received 
 permission to add them to the detail of the former observations for 
 publication. 
 
 t [From " Philosophical Transactions" for 1809, vol. 99, pp 450- 
 470. Part reprinted, pp. 468-470.] 
 
Elementary Natiire of Chlorine. 19 
 
 Of all known substances belonging to the class of acids, 
 the dry muriatic acid is that which seems to possess the 
 strongest and most extensive powers of combination. It 
 unites with all acid matters that have been experimented 
 upon, except carbonic acid, and with all oxides (including 
 water), and all inflammable substances that have been 
 tried, except those which appear to be elementary, car- 
 bonaceous matter and the metals ; and should its basis 
 ever be separated in the pure form, it will probably be 
 one of the most powerful agents in chemistry. 
 
 I have lately made several new attempts to procure 
 uncombined dry muriatic acid ; but they have been all 
 unsuccessful. 
 
 I heated intensely, in an iron tube, silex in a very 
 minute state of division, and muriate of -soda that had 
 been fused ; but there was not the smallest quantity of 
 gas evolved. In this case, the silex had been ignited to 
 whiteness before it was used ; but when silex in its 
 common state was employed, or when aqueous vapour 
 was passed over a mixture of dry silex and dry salt in a 
 porcelain tube, muriatic acid gas was developed with 
 great rapidity. 
 
 I have stated page 79, that a sublimate is formed by 
 the combustion of the olive-coloured oxide of boracium 
 in oxymuriatic acid. On the idea that this might be 
 boracic acid, and that dry muriatic acid might be 
 separated in the process, I examined the circumstances 
 of the experiment ; but I found the sublimate to be a 
 compound of boracic and muriatic acid, similar to the 
 compound of muriatic and phosphoric acid. 
 
 I heated freshly sublimed muriate of ammonia with 
 potassium ; when the quantities were equal, as much 
 hydrogene gas was developed as is generated by the 
 action of water on potassium ; much ammonia was 
 evolved, and muriate of potash formed ; when the 
 
2O Davy. 
 
 potassium was to the muriate as 4 to i, less hydrogen 
 appeared, and a triple compound of muriatic acid, 
 ammonia, and potassium, or its protoxide was formed, 
 which was of a dark gray colour, and gave ammonia and 
 muriate of potash by the action of water. There was 
 not the slightest indications of the decomposition of the 
 acid in the experiment. The process, in which this 
 decomposition may be most reasonably conceived to 
 take place, is in the combustion of potassium in the 
 phosphuretted muriatic acid, deprived by simple distilla- 
 tion with potassium of as much phosphorus as possible. 
 I am preparing an apparatus for performing this experi- 
 ment, in a manner which, I hope, will lead to distinct 
 conclusions. 
 
 The Bakerian Le^ire for 1 809. 
 
 Read November 16, 1809. 
 
 V. Some Considerations of Theory illustrated by 
 
 new Facts* 
 
 # # * * # 
 
 Muriatic acid gas, as I have shewn, and as is further 
 
 proved by the researches of MM. GAY LUSSAC and 
 
 THENARD, is a compound of a body unknown in a 
 
 separate state, and water. The water, I believe, cannot 
 
 be decompounded, unless a new combination is formed ; 
 
 thus it is not changed by charcoal ignited in the gas by 
 
 * [From "Philosophical Transactions" for 1810, vol. 100, p. 67.] 
 
Elementary Nature of Chlorine. 2 1 
 
 VOLTAIC electricity ; but it is decompounded by all the 
 metals ; and in these cases hydrogene is elicited, in a 
 manner similar to that in which one metal is precipitated 
 by another ; the oxygene being found in the new com- 
 pound. This at first view, might be supposed in favour 
 of the idea, that hydrogene is a simple substance ; but 
 the same reasoning may be applied to a protoxide as to a 
 metal ; and in the case of the nitromuriatic acid, when 
 the nitrous acid is decomposed to assist in the formation 
 of a metallic muriate, the body disengaged (nitrous gas,) 
 is known to be in a high state of oxygenation. 
 
 Researches on the oxynmriatic Acid, its Nature 
 and Combinations ; and on the Elements of 
 the muriatic Acid. With some Experiments 
 on Sulphur and Phosphorus, made in the 
 Laboratory of the Royal Instititiion* t 
 
 Read July 12, 1810, 
 
 illustrious discoverer of the oxymuriatic acid 
 considered it as muriatic acid freed from hydro- 
 gene,^ and the common muriatic acid as a com- 
 pound of hydrogene and oxymuriatic acid ; and on this 
 
 * Communicated to the Royal Society at the request of the 
 Managers of the Royal Institution. 
 
 t [From "Philosophical Transactions" for 1810, vol. 100, pp. 
 231-257. Pp. 251-257 are not reprinted.] 
 
 % Mem. Acad. Stockholm for 1774, p. 94. 
 
22 Davy. 
 
 theory he denominated oxymuriatic acid dephlogisticated 
 muriatic acid. 
 
 M. BERTHOLLET,* a few years after the discovery of 
 SCHEELE, made a number of important and curious ex- 
 periments on this body ; from which he concluded, that 
 it was composed of muriatic acid gas and oxygene ; and 
 this idea for nearly twenty years has been almost universally 
 adopted. 
 
 Dr. HENRY, in an elaborate series of experiments, made 
 with the view of decomposing muriatic acid gas, ascer- 
 tained that hydrogene was produced from it, by electri- 
 city ; and he attributed the phenomenon to water con- 
 tained in the gas.f 
 
 In the Bakerian lecture for 1808, I have given an 
 account of the action of potassium upon muriatic acid 
 gas, by which more than one-third of its volume of 
 hydrogene is produced ; and I have stated, that muri- 
 atic acid can in no instance be procured from oxy- 
 muriatic acid, or from dry muriates, unless water or its 
 elements be present. 
 
 In the second volume of the Memoires d'Arcueil, 
 M. M. GAY LUSSAC and THENARD have detailed an 
 extensive series of facts upon muriatic acid, and oxy- 
 muriatic acid. Some of their experiments are similar 
 to those I have detailed in the paper just referred to; 
 others are peculiarly their own, and of a very curious 
 kind : their general conclusion is, that muriatic acid gas 
 contains about one quarter of its weight of water ; and 
 that oxymuriatic acid is not decomposable by any 
 substances but hydrogene, or such as can form triple 
 combinations with it. 
 
 One of the most singular facts that I have observed 
 on this subject, and which I have before referred to, is, 
 
 * Journal de Physique, 1785, p. 325. 
 t Phil. Trans, for 1800, p. 191. 
 
Elementary Nature of Chlorine. 23 
 
 that charcoal, even when ignited to whiteness in oxy- 
 muriatic or muriatic acid gases, by the VOLTAIC battery, 
 effects no change in them ; if it has been previously 
 freed from hydrogene and moisture by intense ignition 
 in vacuo. 
 
 This experiment, which I have several times repeated 
 led me to doubt of the existence of oxygene in that sub- 
 stance, which has been supposed to contain it above all 
 others in a loose and active state ; and to make a more 
 rigorous investigation than had been hitherto attempted 
 for its detection. 
 
 If oxymuriatic acid gas be introduced into a vessel 
 exhausted of air, containing tin; and the tin be gently 
 heated, and the gas in sufficient quantity, the tin and 
 the gas disappear, and a limpid fluid, precisely the 
 same as Libavius's liquor is formed; it occured to 
 me, that if this substance is a combination of muriatic 
 acid and oxide of tin, oxide of tin ought to be separated 
 from it by means of ammonia. I admitted ammoniacal 
 gas over mercury to a small quantity of the liquor of 
 Libavius; it was absorbed with great heat, and no gas 
 was generated ; a solid result was obtained, which was 
 of a dull white colour; some of it was heated, to ascer- 
 tain if it contained oxide of tin ; but the whole volatil- 
 ized, producing dense pungent fumes. 
 
 Another experiment of the same kind, made with great 
 care, and in which the ammonia was used in great excess, 
 proved that the liquor of Libavius cannot be decom- 
 pounded by ammonia ; but that it forms a new combina- 
 tion with this substance. 
 
 I have described, on a former occasion, the nature of 
 the operation of phosphorus on oxymuriatic acid, and I 
 have stated that two compounds, one fluid, and the other 
 solid, are formed in the process of combustion, of which 
 the first, on the generally received theory of the nature of 
 
24 Davy, 
 
 oxymuriatic acid, must be considered as a compound of 
 muriatic acid and phosphorous acid, and the other oi 
 muriatic acid and phosphoric acid. It occured to me, 
 that if the acids of phosphorus really existed in these 
 combinations, it would not be difficult to obtain them, 
 and thus to gain proofs of the existence of oxygene in 
 oxymuriatic acid. 
 
 I made a considerable quantity of the solid compound 
 of oxymuriatic acid and phosphorus by combustion, and 
 saturated it with ammonia, by heating it in a proper 
 receiver filled with ammoniacal gas, on which it acted 
 with great energy, producing much heat; and they 
 formed a white opaque powder. Supposing that this 
 substance was composed of the dry muriates and phos- 
 phates of ammonia; as muriate of ammonia is very 
 volatile, and as ammonia is driven off from phosphoric 
 acid, by a heat below redness, I conceived that by 
 igniting the product obtained, I should procure phos- 
 phoric acid ; I therefore introduced some of the powder 
 into a tube of green glass, and heated it to redness, out 
 of the contact of air by a spirit lamp ; but found, to 
 my great surprise, that it was not at all volatile nor 
 decomposable at this degree of heat, and that it gave off 
 no gaseous matter. 
 
 The circumstance that a substance composed princi- 
 pally of oxymuriatic acid, and ammonia, should resist 
 decomposition or change at so high a temperature, 
 induced me to pay particular attention to the properties 
 of this new body. 
 
 It had no taste nor smell ; it did not seem to be 
 soluble, nor did it undergo any perceptible change when 
 digested in boiling water : it did not appear to be 
 acted upon by sulphuric, muriatic, or nitric acids, nor 
 by a strong lixivium of potash. The only processes by 
 which it seemed susceptible of decomposition were by 
 
Elementary Nature of Chlorine. 25 
 
 combustion, or the action of ignited hydrat of potash. 
 When brought into the flame of a spirit lamp and made 
 red-hot, it gave feeble indications of inflammation, and 
 tinged the flame of a yellow colour, and left a fixed acid, 
 having the properties of phosphoric acid. When acted 
 on by red-hot hydrat of potash, it emitted a smell of 
 ammonia, burnt where it was in contact with air, and 
 appeared to dissolve in the alkali. The potash which 
 had been so acted upon gave muriatic acid, by the addi- 
 tion of sulphuric acid. 
 
 I heated some of the powder to whiteness, in a 
 tube of platina; but it did not appear to alter; and 
 after ignition gave ammonia by the action of fused 
 hydrat of potash. 
 
 I caused ammonia, made as dry as possible, to act on 
 the phosphuretted liquor of M. M. GAY LUSSAC and 
 THENARD ; and on the sulphuretted muriatic liquor of 
 Dr. THOMSON ; but no decomposition took place ; nor 
 was any muriate of ammonia formed when proper pre- 
 cautions were taken to exclude moisture. The results 
 were new combinations ; that from the phosphoretted 
 liquor, was a white solid, from which a part of the 
 phosphorus was separated by heat ; but which seemed no 
 further decomposable, even by ignition. That from the 
 sulphuretted liquor was likewise solid, and had various 
 shades of colour, from a bright purple to a golden yellow, 
 according as it was more or less saturated with ammonia; 
 but as these compounds did not present the same uniform 
 and interesting properties, as that from the phosphoric 
 sublimate, I did not examine them minutely : I con- 
 tented myself by ascertaining that no substance known 
 to contain oxygene could be procured from oxymuriatic 
 acid, in this mode of operation. 
 
 It has been said, and taken for granted by many 
 chemists, that when oxymuriatic acid and ammonia acl 
 
26 Davy. 
 
 upon each other, water is formed ; I have several times 
 made the experiment, and I am convinced that this is not 
 the case. When about 15 or 16 parts of oxymuriatic 
 acid gas are mixed with from 40 to 45 parts of ammoniacal 
 gas, there is a condensation of nearly the whole of the 
 acid and alkaline gasses, and from 5 to 6 parts of nitrogene 
 are produced ; and the result is dry muriate of ammonia. 
 
 Mr. CRUIKSHANK has shown that oxymuriatic acid 
 and hydrogene, when mixed in proportions nearly equal, 
 produce a matter almost entirely condensible by water ; 
 and M. M. GAY LUSSAC and THENARD, have stated that 
 this matter is common muriatic acid gas, and that no 
 water is deposited in the operation. I have made a 
 number of experiments on the action of oxymuriatic acid 
 gas and hydrogene. When these bodies were mixed in 
 equal volumes over water, and introduced into an ex- 
 hausted vessel and fired by the electric spark, there was 
 always a deposition of a slight vapour, and a conden- 
 sation of from T ^ to ^5- of the volume; but the gas 
 remaining was muriatic acid gas. I have attempted to 
 make the experiment in a manner still more refined, 
 by drying the oxymuriatic acid and the hydrogene by 
 introducing them into vessels containing muriate of lime, 
 and by suffering them to combine at common tempera- 
 tures ; but I have never been able to avoid a slight con- 
 densation ; though in proportion as the gasses were free 
 from oxygene or water, this condensation diminished. 
 
 I mixed together sulphuretted hydrogene in a high 
 degree of purity and oxymuriatic acid gas both dried, in 
 equal volumes : in this instance the condensation was 
 not j^ ; sulphur, which seemed to contain a little oxy- 
 muriatic acid, was formed on the sides of the vessel : 
 no vapour was deposited ; and the residual gas con- 
 tained about ^ of muriatic acid gas, and the remainder 
 was inflammable. 
 
Elementary Nature of Chlorine. 27 
 
 M. M. GAY LUSSAC and THENARD have proved by a 
 copious collection of instances, that in the usual cases 
 where oxygene is procured from oxymuriatic acid, water 
 is always present, and muriatic acid gas is formed; now, as it 
 is shewn that oxymuriatic acid gas is converted into 
 muriatic acid gas, by combining with hydrogene, it is 
 scarcely possible to avoid the conclusion, that the oxy- 
 gene is derived from the decomposition of water, and, 
 consequently, that the idea of the existence of water in 
 muriatic acid gas, is hypothetical, depending upon an 
 assumption which has not yet been proved the existence 
 of oxygene in oxymuriatic acid gas. 
 
 M. M. GAY LUSSAC and THENARD indeed have stated 
 an experiment, which they consider as proving that 
 muriatic acid gas contains one quarter of its weight 
 of combined water. They passed this gas over litharge, 
 and obtained so much water; but it is obvious that in 
 this case they formed the same compound as that pro- 
 duced by the action of oxymuriatic acid on lead; and 
 in this process the muriatic acid must loose its 
 hydrogene, and the lead its oxygene; which of course 
 would form water ; these able chemists, indeed, from the 
 conclusion of their memoir, seem aware, that such an 
 explanation may be given, for they say that the oxy- 
 muriatic acid may be considered as a simple body. 
 
 I have repeated those experiments which led me first 
 to suspect the existence of combined water in muriatic 
 acid, with considerable care ; I find that, when mercury 
 is made to act upon i in volume of- muriatic acid gas, 
 by VOLTAIC electricity, all the acid disappears, calomel is 
 formed, and about .5 of hydrogene evolved. 
 
 With potassium, in experiments made over very dry 
 mercury, the quantity of hydrogene is always from 9 to n, 
 the volume of the muriatic acid gas used being 20. 
 
 And in some experiments made very carefully by my 
 
28 Davy. 
 
 brother Mr. JOHN DAVY, on the decomposition of muriatic 
 acid gas, by heated tin and zinc, hydrogene equal to about 
 half its volume was disengaged, and metallic muriates, the 
 same as those produced by the combustion of tin and 
 zinc in oxymuriatic gas. resulted. 
 
 It is evident from this series of observations, that 
 SCHEELE'S view, (though obscured by terms derived from 
 a vague and unfounded general theory,) of the nature of 
 the oxymuriatic and muriatic acids, may be considered as 
 an expression of facts ; whilst the view adopted by the 
 French school of chemistry, and which, till it is minutely 
 examined, appears so beautiful and satisfactory, rests in 
 the present state of our knowledge, upon hypothetical 
 grounds. 
 
 When oxymuriatic acid is acted upon by nearly an 
 equal volume of hydrogene, a combination takes place 
 between them, and muriatic acid gas results. When 
 muriatic acid gas is acted on by mercury, or any other 
 metal, the oxymuriatic acid is attracted from the hydro- 
 gene, by the stronger affinity of the metal ; and an 
 oxymuriate, exactly similar to that formed by combustion, 
 is produced. 
 
 The action of water upon those compounds, which have 
 been usually considered as muriates, or as dry muriates, 
 but which are properly combinations of oxymuriatic acid 
 with inflammable bases, may be easily explained, accord- 
 ing to these views of the subject. When water is added 
 in certain quantities to Libavius's liquor, a solid crystal- 
 lized mass is obtained, from which oxide of tin and 
 muriate of ammonia can be procured by ammonia. In 
 this case, oxygene may be conceived to be supplied to 
 the tin, and hydrogene to the oxymuriatic acid. 
 
 The compound formed by burning phosphorus in 
 oxymuriatic acid, is in a similar relation to water : if 
 that substance be added to it, it is resolved into two 
 
Elementary Nature of Chlorine. 29 
 
 powerful acids; oxygene, it may be supposed, is fur- 
 nished to the phosphorus to form phosphoric acid, hydro- 
 gene to the oxy muriatic acid to form common muriatic 
 acid gas. 
 
 None of the combinations of the oxymuriatic acid 
 with inflammable bodies, can be decomposed by dry 
 acids ; and this seems to be the test which distinguishes 
 the oxymuriatic combinations from the muriates, though 
 they have hitherto been confounded together. Muriate 
 of potash for instance, if M. BERTHOLLET'S estimation 
 of its composition, approaches towards accuracy, when 
 ignited, is a compound of oxymuriatic acid with potas- 
 sium ; muriate of ammonia, is a compound of muriatic 
 acid gas and ammonia j and when acted on by potas- 
 sium, it is decompounded ; the oxymuriatic acid may be 
 conceived to combine with the potassium to form 
 muriate of potash, and the ammonia and hydrogene are 
 set free. 
 
 The vivid combustion of bodies in oxymuriatic acid 
 gas, at first view, appears a reason why oxygene should 
 be admitted in it ; but heat and light are merely results 
 of the intense agency of combination. Sulphur and 
 metals, alkaline earths and acids become ignited during 
 their mutual agency ; and such an effect might be ex- 
 pected in an operation [so rapid, as that of oxymuriatic 
 acid upon metals and inflammable bodies. 
 
 It may be said, that a strong argument in favour of the 
 hypothesis, that oxymuriatic acid consists of an acid basis 
 united to oxygene, exists in the general analogy of the 
 compounds of oxymuriatic acid and metals, to the common 
 neutral salts ; but this analogy when strictly investigated, 
 will be found to very indistinct, and even allowing it, it 
 may be applied with as much force to support an opposite 
 doctrine, namely, that the neutral salts are compounds of 
 bases with water ; and the metals of bases with hydrogene ; 
 
30 Davy. 
 
 and that in the case of the action of oxymuriatic acid and 
 metals, the metal furnishes hydrogene to form muriatic 
 acid, and a basis to produce the neutral combination. 
 
 That the quantity of hydrogene evolved during the 
 decomposition of muriatic acid gas by metals, is the 
 same that would be produced during the decomposi- 
 tion of water by the same bodies, appears, at first view, 
 an evidence in favour of the existence of water in 
 muriatic acid gas ; but as there is only one known com- 
 bination of hydrogene with oxymuriatic acid, one quan- 
 tity must always be separated. Hydrogene is disengaged 
 from its oxymuriatic combination, by a metal, in the 
 same manner as one metal is disengaged by another, 
 from similar combinations ; and of all inflammable bodies 
 that form compounds of this kind, except perhaps phos- 
 phorus and sulphur, hydrogene is that which seems to 
 adhere to oxymuriatic acid with the least force. 
 
 I have caused strong explosions from an electrical jar, 
 to pass through oxymuriatic gas, by means of points 
 of platina, for several hours in succession ; but it seemed 
 not to undergo the slightest change. 
 
 I electrized the oxymuriates of phosphorus and sul- 
 phur for some hours, by the power of the VOLTAIC 
 apparatus of 1000 double plates; no gas separated, 
 but a minute quantity of hydrogene, which I am inclined 
 to attribute to the presence of moisture in the appa- 
 ratus employed; for I once obtained hydrogene from 
 Libavius's liquor by a similar operation ; but I have 
 ascertained, that this was owing to the decomposition of 
 water, adhering to the mercury; and in some late 
 experiments made with 2000 double plates, in which the 
 discharge was from platina wires, and in which the 
 mercury used for confining the liquor was carefully 
 boiled, there was no production of any permanent elastic 
 matter. 
 
Elementary Nature of Chlorine. 31 
 
 As there are no experimental evidences of the exist- 
 ence of oxygene in oxymuriatic acid gas, a natural 
 question arises, concerning the nature of these com- 
 pounds, in which the muriatic acid has been supposed 
 to exist, combined with much more oxygene than 
 oxymuriatic acid, in the state in which it has been named 
 by Mr CHENEVIX, hyperoxygenized muriatic acid. 
 
 Can the oxymuriatic acid combine either with oxygene 
 or hydrogene, and form with each of them an acid com- 
 pound ; of which that with hydrogene has the strongest, 
 and that with oxygene the weakest affinity for bases ? for 
 the able chemist to whom I have just referred, conceives 
 that hyperoxymuriates are decomposed by muriatic 
 acid. Or, is hyperoxymuriatic acid the basis of all this 
 class of bodies, the most simple form of this species of 
 matter ? 
 
 The phenomena of the composition and decomposi- 
 tion of the hyperoxymuriates, may be explained on either 
 of these suppositions ; but they are mere suppositions un- 
 supported by experiment. 
 
 I have endeavoured to obtain the neutralizing acid, 
 which has been imagined to be hyperoxygenised, from 
 hyperoxymuriate of potash, by various modes, but uni- 
 formly without success. By distilling the salt with dry 
 boracic acid, though a little oxymuriatic acid is generated, 
 yet oxygene is the chief gaseous product, and a muriate 
 of potash not decomposable is produced. 
 
 The distillation of the orange coloured fluid, produced 
 by dissolving hyperoxymuriate of potash in sulphuric acid, 
 affords only oxygene in great excess, and oxymuriatic 
 acid. 
 
 When solutions of muriates, or muriatic acid are 
 electrized in the VOLTAIC circuit, oxymuriatic acid is 
 evolved at the positive surface, and hydrogene at the 
 negative surface. When a solution of oxymuriatic acid in 
 
32 Davy. 
 
 water is electrized, oxymuriatic acid and oxygene appear* 
 at the positive surface, and hydrogene at the negative 
 surface, facts which are certainly unfavourable to the idea 
 of the existence of hyperoxygenised muriatic acid, 
 whether it be imagined a compound of oxymuriatic 
 acid with oxygene, or the basis of oxymuriatic acid. 
 
 If the facts respecting the hyperoxymuriate of potash, 
 indeed, be closely reasoned upon, it must be regarded as 
 nothing more than as a triple compound of oxymuriatic 
 acid, potassium, and oxygene. We have no right to 
 assume the existence of any peculiar acid in it, or of a 
 considerable portion of combined water ; and it is per- 
 haps more conformable to the analogy of chemistry, to 
 suppose the large quantity of oxygene combined with 
 the potassium, which we know has an intense affinity 
 for oxygene, and which, from some experiments, I am 
 inclined to believe, is capable of combining directly with 
 more oxygene than exists in potash, than with the oxy- 
 muriatic acid, which, as far as is known, has no affinity 
 for that substance. 
 
 It is generally supposed that a mixture of oxymuriatic 
 acid and hyperoxymuriatic acid is disengaged when 
 hyperoxymuriate of potash is decomposed by common 
 muriatic acid ; f but I am satisfied, from several trials, 
 that the gas procured in this way, when not mixed with 
 
 * The quantity of oxymuriatic acid in the aqueous solution, is so 
 small, that the principal products must be referred to the decom- 
 position of water. This happens in other instances ; the water only 
 is decomposed in dilute solutions of nitric and sulphuric acids. 
 
 t If hyperoxymuriate of potash be decomposed by nitric or 
 sulphuric acid, it affords oxymuriatic acid and oxygene. If it be 
 acted upon by muriatic acid, it affords a large quantity of oxy- 
 muriatic acid gas' only. In this last case, the phenomenon seems 
 merely to depend upon the decomposition of the muriatic acid gas, 
 by the oxygene, loosely combined in the salt. 
 
Elementary Nature of Chlorine. 33 
 
 oxygene, unites to the same quantity of hydrogene/* as 
 common oxymurialic acid gas from manganese; and I 
 find, by a careful examination, that the gas disengaged 
 during the solution of platina, in a mixture of nitric and 
 muriatic acids, which has been regarded as hyperoxy- 
 munatic acid, but which I stated some years ago to 
 possess the properties of oxy muriatic acid gas,t is 
 actually that body, owing its peculiar colour to a small 
 quantity of nitromuriatic vapour suspended in it, and 
 from which it is easily freed by washing. 
 
 Few substances, perhaps, have less claim to be con- 
 sidered as acid, than oxymuriatic acid. As yet we have 
 no right to say that it has been decompounded ; and as 
 its tendency of combination is with pure inflammable 
 matters, it may possibly belong to the same class of 
 bodies as oxygene. 
 
 May it not in fact be a peculiar acidifying and dis 
 solving principle, forming compounds with combustible 
 bodies, analogous to acids containing oxygene, or oxides. 
 in their properties and powers of combination ; but 
 differing from them, in being for the most part, decom- 
 
 * This likewise appears from Mr. CRUICKSHANK'S experiments. 
 See Nicholson's Journal, Vol. V. 4.10. p. 206. 
 
 *t* The platina, I find by several experiments, made with great 
 care, has no share in producing the evolution of this gas. It is 
 formed during the production of aqua regia. The hydrogene of the 
 muriatic acid attracts oxygene from the nitric acid, Oxymuriatic 
 acid gas is set free, and nitrous gas remains in the solution, and 
 gives it a deep red colour. Nitrous acid and muriatic acid produce 
 no oxymuriatic acid gas. Platina, during its solution in perfectly 
 formed aqua regia, gives only nitrous gas and nitrous vapour ; and I 
 find, that rather more oxymuriatic acid gas is produced, by heating 
 together equal quantities of nitric acid of 1.45, and muriatic acid of 
 1.18, when they are not in contact with platina, than when exposed 
 to that metal. The oxymuriatic acid gas, produced from muriatic 
 acid by nitric acid, I find combines with about an equal volume of 
 hydrogene by detonation. 
 
 C 
 
34 Davy. 
 
 posable by water ? On this idea muriatic acid may be 
 considered as having hydrogene for its basis, and oxy- 
 muriatic acid for its acidifying principle. And the 
 phosphoric sublimate as having phosphorus for its basis, 
 and oxymuriatic acid for its acidifying matter. And 
 Libavius's liquor, and the compounds of arsenic with 
 oxymuriatic acid, may be regarded as analogous bodies. 
 The combinations of oxymuriatic acid with lead, silver, 
 mercury, potassium, and sodium, in this view would be 
 .considered as a class of bodies related more to oxides 
 than acids, in their powers of attraction. 
 
 It is needless to take up the time of this learned 
 Society by dwelling upon the imperfection of the modern 
 nomenclature of these substances. It is in many cases 
 connected with false ideas of their nature and com- 
 position, and in a more advanced state of the enquiry, 
 it will be necessary for the progress of science, that it 
 should undergo material alterations. 
 
 It is extremely probable that there are many combin- 
 ations of the oxymuriatic acid with inflammable bodies 
 which have not been yet investigated. With phosphorus 
 it seems capable of combining in at least three pro- 
 portions ; the phosphuretted muriatic acid of GAY 
 LUSSAC and THENARD is the compound containing 
 the maximum ot phosphorus. The chrystalline phos- 
 phoric sublimate, and the liquor formed by the com- 
 bustion of phosphorus in oxymuriatic acid gas, disengage 
 no phosphorus by the action of water ; the sublimate, as I 
 have already mentioned,, affords phosphoric and muriatic 
 acid ; and the liquid, I believe only phosphorous acid 
 and muriatic acid. 
 
 The sublimate from the boracic basis gives, I believe, 
 only boracic and muriatic acid, and may be regarded as 
 boracium acidified by oxymuriatic acid. 
 
 It is evident, that whenever an oxymuratic combination 
 
Elementary Nature of Chlorine. 35 
 
 is decomposed by water, the oxide or acid or alkali or 
 oxidated body formed must be in the same proportion as 
 the muriatic acid gas, as the oxygene and hydrogene 
 must bear the same relation to each other ; and experi- 
 ments upon these compounds will probably afford simple 
 modes of ascertaining the proportions of the elements, in 
 the different oxides, acids, and alkaline earths. 
 
 If, according to the ingenious idea of Mr. DALTON, 
 hydrogene be considered as i in weight, in the proportion 
 it exists in water, then oxygene will be nearly 7.5 ; and 
 assuming that potash is composed of i proportion of 
 oxygene, and i of potassium, then potash will be 48, 
 and potassium* about 40.5 ; and from an experiment 
 which I have detailed in the last Bakerian lecture, on the 
 combustion of potassium in muriatic acid gas, oxy- 
 muriatic acid will be represented by 32.9, and muriatic 
 acid gas, of course, by 33.9 ; and this estimation agrees 
 with the specific gravity of oxymuriatic acid gas, and 
 muriatic acid gas. From my experiments, 100 cubical 
 inches of oxymuriatic acid gas weigh, the reductions 
 being made for the mean temperature and pressure, 74.5 
 grains ; whereas by estimation they should weigh 74.6. 
 Muriatic acid gas I find weighs, under like circumstances, 
 in the quantity of 100 cubic inches, 39 grains ; by 
 estimation it should weigh 38.4 grains. 
 
 It is easy from these data, knowing the composition of 
 any dry muriate, to ascertain the quantity of oxide or of 
 acid it would furnish by the action of water, and con- 
 sequently the quantity of oxygene with which the in- 
 flammable matter will combine, f 
 
 In considering the dry muriates, as compounds of 
 oxymuriatic acid and inflammable bodies; the argu- 
 ment that I have used in the last Bakerian lecture, to 
 
 * Supposing potash to contain nearly 15.6 per cent, of oxygene. 
 t [Note not reprinted.] 
 
36 Davy. 
 
 shew that potassium does not form hydrate of potash 
 by combustion, is considerably strengthened ; for from 
 the quantity of oxymuriatic acid the metal requires to 
 produce a muriate, it seems to be shewn that it is the 
 simplest known form of the alkaline matter. This I 
 think approaches to an experimentum crucis. Potash 
 made by alcohol, and that has been heated to redness, 
 appears to be an hydrat of potash, whilst the potash 
 formed by the combustion of potassium must be con- 
 sidered as a pure metallic oxide, which requires about 
 19 per cent, of water to convert into a hydrat. 
 
 Amongst all the known combustible bodies, char- 
 coal is the only one which does not combine directly 
 with oxymuriatic acid gas ; and yet there is reason for 
 believing that this combination may be formed by the 
 intermedium of hydrogene. I am inclined to consider 
 the oily substance produced by the action of oxy- 
 muriatic acid gas, and olefiant gas, as a ternary com- 
 pound of these bodies ; for they combine nearly in 
 equal volumes; and I find that, by the action of 
 potassium upon the oil so produced, muriate of potash 
 is formed, and gaseous matter, which I have not yet 
 been able to collect in sufficient quantity to decide 
 upon its nature, is formed. Artificial camphor, and 
 muriatic ether, as is probable from the ingenious 
 experiments of M. GEHLEN and M. THENARD, must be 
 combinations of a similar kind, one probably with more 
 hydrogene, and the other with more carbon. 
 
 One of the greatest problems in oeconomical chemistry, 
 is the decomposition of the muriates of soda and potash. 
 The solution of this problem will, perhaps, be facilitated 
 by these new views. The affinity of potassium and 
 sodium for oxymuriatic acid, is very strong ; but so like- 
 wise is their attraction for oxygene, and the affinity of 
 their oxides for water. The affinities of oxymuriatic 
 
Elementary Nature of Chlorine. 37 
 
 acid gas for hydrogene, and of muriatic acid gas for 
 water, are likewise of a powerful kind. Water, therefore, 
 should be present in all cases, when it is intended to 
 attempt to produce alkali. It is not difficult after these 
 views to explain the decomposition of common salt, by 
 aluminous or silicious substances, which, as it has been 
 long known, act only when they contain water. In 
 these cases the sodium may be conceived to combine 
 with the oxygene of the water and with the earth, to form 
 a vitreous compound ; and the oxymuriatic acid to unite 
 with the hydrogene of the water, forming muriatic acid 
 gas. 
 
 It is also easy, according to these new ideas, to explain 
 the decomposition of salt by moistened litharge, the 
 theory of which has so much perplexed the most acute 
 chemists. It may be conceived to be an instance of 
 compound affinity : the oxymuriatic acid is attracted by 
 the lead, and the sodium combines with the oxygene of 
 the litharge and with water to form hydrat of soda, which 
 gradually attracts carbonic acid from the air. 
 
 As iron has a strong affinity for oxymuriatic acid, I 
 attempted, to procure soda by passing steam over a 
 mixture of iron filings, and muriate of soda intensely 
 heated : and in this way, I succeeded in decomposing 
 some of the salt : hydrogene came over ; a little hydrate 
 of soda was formed ; and muriate of iron was produced. 
 
 It does not seem improbable, supposing the views 
 that have been developed accurate, that by complex 
 affinities, even potassium and sodium in their metallic 
 form, may be procured from their oxymuriatic combina- 
 tions : for this purpose the oxymuriatic acid should be 
 attracted by one substance, and the alkaline metals by 
 another; and such bodies should be selected for the 
 experiment, as would produce compounds differing con- 
 siderably in degree of volatility. 
 
38 Davy. 
 
 I cannot conclude the subject of the application of 
 these doctrines, without asking permission to direct the 
 attention of the Society, to some of the theoretical rela- 
 tions of the facts noticed in the preceding pages. 
 
 That a body principally composed of oxymuriatic acid 
 and ammonia, two substances which have been generally 
 conceived incapable of existing together, should be so 
 difficult of decomposition, as to be scarcely affected 
 by any of the agents of chemistry, is a phaenomenon 
 of a perfectly new kind. Three bodies, two of which 
 are permanent gases, and the other of which is con 
 siderably volatile, form in this instance, a substance 
 neither fusible nor volatile, at a white heat. It could 
 not have been expected that ammonia would remain 
 fixed at such a temperature ; but that it should remain 
 fixed in combination with oxymuriatic acid, would 
 have appeared incredible, according to all the existing 
 analogies of chemistry. The experiments on which 
 these conclusions are founded, are, however, uniform 
 in their results : and it is easy to repeat them. They 
 seem to shew, that the common chemical proposi- 
 tion, that complexity of composition is uniformly con- 
 nected with facility of decomposition, is not well founded. 
 The compound of oxymuriatic acid, phosphorus, and 
 ammonia, resembles an oxide, such as silex, or that of 
 columbium in its general chemical characters, and is as 
 refractory when treated by common re-agents ; and 
 except by the effects of combustion, or the agency of 
 fused potash, its nature could not be detected by any 
 of the usual methods of analysis. Is it not likely, 
 reasoning from these circumstances, that many of the 
 substances, now supposed to be elementary, may be 
 reduced into simpler forms of matter ? And that an 
 intense attraction, and an equilibrium of attraction, may 
 give to a compound, containing several constituents, 
 
Elementary Nature of Chlorine. 39 
 
 that refractory character, which is generally attributed to 
 unity of constitution, or to the homogeneous nature of its 
 parts ? 
 
 Besides the compound of the phosphoric sublimate 
 and ammonia, and the other analogous compounds which 
 have been referred to, it is probable that other com- 
 pounds of like nature may be formed of the oxides, 
 alkalies, and earths, with the oxymuriatic combinations, 
 or of the oxymuriatic compounds with each other ; and 
 should this be the case, the more refined analogies 
 of chemical philosophy will be extended by these new, 
 and as it would seem at first view, contradictory facts. 
 For if, as I have said, oxymuriatic acid gas be referred 
 to the same class of bodies as oxygene gas, then, as 
 oxygene is not an acid, but forms acids by combining 
 with certain inflammable bodies, so oxymuriatic acid, 
 by uniting to similar substances, may be conceived 
 to form either acids, which is the case when it com- 
 bines with hydrogene, or compounds like acids or 
 oxides, capable of forming neutral combinations, as in 
 the instances of the oxymuriates of phosphorus and tin. 
 
 Like oxygene, oxymuriatic acid is attracted by the 
 positive surface in VOLTAIC combinations ; and on the 
 hypothesis of the connection of chemical attraction with 
 electrical powers, all its energies of combination cor- 
 respond with those of a body supposed to be negative in 
 a high degree. 
 
 And in most of its compounds, except those contain- 
 ing the alkaline metals, which may be conceived in the 
 highest degree positive, and the metals with which it 
 forms insoluble compounds, it seems still to retain its 
 negative character. 
 
 * * * * * 
 
4O Davy. 
 
 The Bakerian Lecture. On some of tke Com- 
 binations of Oxy muriatic Gas and Oxygene, 
 and on the chemical Relations of these 
 Principles, to inflammable Bodies*' 
 
 Read November 15, 1 8 1 o. 
 
 /. Introduction. 
 
 IN the last communication which I had the honour of 
 presenting to the Royal Society, I stated a number 
 of facts, which inclined me to believe, that the 
 body improperly called in the modern nomenclature of 
 chemistry, oxymuriatic acid gas, has not as yet been 
 decompounded ; but that it is a peculiar substance, 
 elementary as far as our knowledge extends, and 
 analogous in many of its properties to oxygene gas. 
 
 My objects in the present Lecture, are to detail a 
 number of experiments which I have made for the purpose 
 of illustrating more fully the nature, properties, and 
 combinations of this substance, and its attractions for 
 inflammable bodies, as compared with those of oxygene ; 
 and likewise to present some general views and conclu- 
 sions concerning the chemical powers of different species 
 of matter, and the proportions in which they enter into 
 union. 
 
 I have been almost constantly employed, since the 
 last session of the Society, upon these researches, yet 
 this time has not been sufficient to enable me to approach 
 
 * [From "Philosophical Transactions" for 1811, vol. 101, pp. 
 i-3. I2 -35] 
 
Elementary Nature of Chlorine. 41 
 
 to any thing complete in the investigation. But on 
 subjects, important both in their connexion with the 
 higher departments of chemical philosophy, and with the 
 oeconomical applications of chemistry, I trust that even 
 these imperfect labours will not be wholly unacceptable. 
 
 2. On the Combinations of Oxymuriatic Gas and 
 Oxygene with the Metals from. -the fixed Alkalies. 
 
 The intensity of the attraction of potassium for oxy- 
 muriatic gas, is shewn by its spontaneous inflammation 
 in that substance, and by the vividness of the combus- 
 tion. I satisfied myself, by various minute experiments, 
 that no water is separated in this operation, and that the 
 proportions of the compound are such that one grain of 
 potassium absorbs about i.i cubical inch of oxy muriatic 
 gas at the mean temperature and pressure, and that they 
 form a neutral compound, which undergoes no change by 
 fusion. I used, in the experiments from which these 
 conclusions are drawn, a tray of platina for receiving the 
 potassium ; the metal was heated in an exhausted vessel, 
 to decompose any water absorbed by the crust of potash, 
 which forms upon the potassium during its exposure to 
 the atmosphere, and the gas was freed from vapour by 
 muriate of lime. Large masses of potassium cannot be 
 made to inflame, without heat in oxymuriatic gas. In all 
 experiments in which I fused the potassium upon glass, 
 the retorts broke in pieces in consequence of the violence 
 of the combustion, and even in two instances when I used 
 the tray of platina. If oxymuriatic gas be used, not 
 freed from vapour, or if the potassium has been previously 
 exposed to the air, a little moisture always separates 
 during the process of combustion. When pure potassium, 
 and pure oxymuriatic gas are used, the result, as I have 
 
42 Davy. 
 
 stated, is a mere binary compound, the same as muriate of 
 potash, that has undergone ignition. 
 
 The combustion of potassium and sodium in oxygene 
 gas, is much less vivid than in oxymuriatic gas. From 
 this phenomenon, and from some others, I was inclined 
 to believe that the attraction of these metals for oxygene 
 is feebler, than their attraction for oxymuriatic gas. I 
 made several experiments, which proved that this is the 
 fact ; but before I enter upon a detail of them, it will be 
 necessary to discuss more fully than I have yet attempted, 
 the nature of the combinations of potassium and sodium 
 with oxygene, and of potash and soda with water. 
 
 I shall now resume the detail of the experiments that 
 I have made, on the relative attractions of oxymuriatic gas 
 and oxygene, for the metals of the fixed alkalies. I burnt 
 a grain of potassium in oxygene gas, in a retort of green 
 glass, furnished with a stop-cock, and heated the oxide 
 formed, to redness, to convert it into potash : half a cub- 
 ical inch of oxygene was absorbed. The retort was 
 exhausted, and very pure oxymuriatic gas admitted. The 
 colour of the potash instantly became white, and by a 
 gentle heat, the whole was converted into muriate of 
 potash : a cubical inch and \ of oxymuriatic gas were 
 absorbed, and exactly half a cubical inch of oxygene 
 generated. The barometer during this operation was at 
 30.3, the thermometer at 62 FAHRENHEIT. I made 
 several experiments of the same kind, but this is the only 
 one on which I can place entire dependence. When I 
 attempted to use larger quantities of potassium, the retort 
 usually broke during the cooling of the glass, and it was 
 not possible to gain any accurate results in employing 
 metallic trays. The potassium was spread into a thin 
 plate, and of course was much oxidated before its ad- 
 
Elementary Nature of Chlorine. 43 
 
 mission into the retort, which rendered the absorption of 
 oxygene a little less than it ought to have been. In the 
 process it was heated in vacuo before the combustion, to 
 decompose the water in the crust of potash ; for in cases 
 when this precaution was not taken, I found that hydrat 
 of potash sublimed, and lined the upper part of the retort, 
 and from this the oxymuriatic gas separated water as 
 well as oxygene. 
 
 The phenomenon of the separation of water from 
 hydrat of potash by oxymuriatic gas, was happily 
 exemplified in an experiment in which I introduced 
 oxymuriatic gas to the peroxide of potassium, formed in 
 a large retort, and in which the potassium had been 
 covered with a considerable crust of hydrat of potash. 
 The upper part of the retort and its neck contained a 
 white sublimate of hydrat, which had risen in combustion, 
 and which was perfectly opaque. As soon as the gas 
 was admitted, it instantly became transparent from the 
 evolution of water ; and on heating the glass in contact 
 with the sublimate, its opacity was restored, and water 
 driven off. 
 
 In various cases in which I heated dry potash, or 
 mixtures of potash and the peroxide, in oxymuriatic gas, 
 there was no separation of moisture, except when the gas 
 contained aqueous vapour ; and the oxygene evolved in 
 the process, when the heat was strongly raised, exactly 
 corresponded to that absorbed by the potassium. 
 
 When muriatic acid gas was introduced to potash 
 formed from the combustion of potassium, water was 
 instantly formed, and oxymuriate of potassium.* I have 
 made no accurate experiment on the proportions of 
 muriatic acid gas decomposed by potash, but I made a 
 very minute investigation, of the nature of the mutual 
 decomposition of this substance, and hydrat of potash. 
 * i.e. Muriate of potash. 
 
44 Davy. 
 
 Ten grains of hydrat of potash were heated to redness 
 in a tray of platina, which was carefully weighed ; it was 
 introduced into a retort which was exhausted of air, and 
 the retort was filled with muriatic acid gas. The hydrat 
 of potash was heated by a spirit lamp ; water instantly 
 separated in great abundance, and muriate of potash 
 formed. A strong heat was applied till the process was 
 completed, when the tray was taken out and weighed ; it 
 had gained 2\\ grains. A minute quantity of liquid 
 muriatic acid was added to the muriate to ensure a 
 complete neutralization, and the tray heated to redness : 
 there was no additional increase of weight. 
 
 In the few experiments which I have made on the 
 action of sodium and soda on oxymuriatic gas, the 
 phenomena appeared precisely analogous ; but sodium, 
 as might have been expected, absorbed nearly twice as 
 much oxymuriatic gas as potassium. 
 
 When common salt that has been ignited, is heated 
 with potassium, there is an immediate decomposition, 
 and by giving the mixture a red heat, pure sodium is 
 obtained ; and this process affords an easy mode, and 
 the one I have always lately adopted for procuring that 
 metal. No hydrogene is disengaged in this operation, 
 and two parts of potassium I find produces rather more 
 than one of sodium. 
 
 From the series of proportions that I have communi- 
 cated in my last paper, it is evident that i grain of 
 potassium ought to absorb 1.08 cubical inches of oxy- 
 muriatic acid; and that the potash formed from one 
 grain of potassium ought to decompose about 2.16 cubical 
 inches of muriatic acid gas ; and these estimations agree 
 very nearly with the result of experiments. 
 
 The estimation of the composition of soda, as deduced 
 from the experiments in the last Bakerian lecture, is 25.4 
 of oxygene to 74.6 of metal, and this would give the 
 
Elementary Nature of Chlorine. 45 
 
 number representing the proportion in which sodium 
 combines with bodies 22.;* from which it is evident, 
 that a grain of sodium ought to absorb nearly 2 cubical 
 inches of oxymuriatic gas, and that the same quantity 
 converted into soda, would decompose nearly four cubical 
 inches of muriatic gas. Muriate of soda ought on this 
 idea to contain one proportion of sodium, 22., and one of 
 oxymuriatic gas 32.9 ; and this estimation is very near 
 that which may be gained from Dr. MARCET'S analysis of 
 this substance. Hydrat of potash ought to consist of i 
 proportion of potash, represented by 48., and one of 
 water, represented by 8.5. This gives its composition as 
 15.1 of water, and 84.9 of potash. Hydrat of soda ought, 
 according to theory, to contain i proportion of soda 29.5, 
 and i of water 8.5, which will give in 100 parts 22.4 of 
 water ; and the experiments that I have detailed, conform 
 as well as can be expected with these conclusions. 
 
 The proportions of potash and soda indicated, in 
 different neutral combinations, by these estimations, will 
 be found to agree very nearly with those derived from 
 the most accurate analysis, particularly those of M. 
 BERTHOLLET ; or the differences are such as admit of 
 an easy explanation. 
 
 I stated in my last communication, the probability 
 that the oxygene in the hyperoxymuriate of potash was 
 in triple combination with the metal and oxymuriatic 
 gas ; the new facts respecting the peroxide confirm this 
 idea. Potassium, perfectly saturated with oxygene, would 
 probably contain six proportions ; for, according to Mr. 
 CHENEVIX'S analysis, which is confirmed by one made 
 in the Laboratory of the Royal Institution, by Mr. E. 
 DAVY, hyperoxymuriate of potash must consist of 40.5 
 potassium, 32.9 oxymuriatic gas, and 45 of oxygene. 
 
 I have mentioned, that by strongly heating the per- 
 * [Note not reprinted.] 
 
46 Davy. 
 
 oxide of potassium in oxymuriatic acid, all the oxygene 
 is expelled, and a mere combination of oxymuriatic gas 
 and potassium formed. I thought it possible, that at a 
 low temperature, a combination might be effected, and I 
 have reason to believe that this is the case. I made 
 a peroxide of potassium, by heating potassium with 
 about twice the quantity of nitre, and admitted oxy- 
 muriatic gas which was absorbed : some oxygene was 
 expelled on the fusion of the peroxide, but a salt 
 remained, which gave oxymuriatic gas, as well as muri- 
 atic acid, by the action of sulphuric acid. 
 
 It seems evident, that in the formation of the hyper- 
 oxymuriate of potash, one quantity of potash is decom- 
 posed by the attraction of oxymuriatic gas to form 
 muriate of potash ; but the oxygene, instead of being 
 set free in the nascent state, enters into combination 
 with another portion of potash, to form a peroxide, and 
 with oxymuriatic gas. 
 
 The proportions required for these changes may be 
 easily deduced from the data which have been stated in 
 the preceding pages. 5 proportions of potash, equal 
 to 240 grains, must be decomposed to form with an 
 equal number of proportions of oxymuriatic gas equal 
 to 164.5 grains, 5 proportions of muriate of potash 
 equal to 367 grains ; and 5 of oxygene equal to 37.5 
 grains, combined with one of potash, equal to 48, must 
 unite in triple union with one of oxymuriatic gas equal to 
 32.9, to form one proportion, equal to 118.4 grains of 
 hyperoxymuriate of potash. 
 
 ?. On the Combinations of the Metals of the Earths, 
 with Oxygene and Oxymuriatic Gas. 
 
 The muriates of baryta, lime, and strontia, after being 
 a long time in a white heat, are not decomposable by any 
 
Elementary Nature of Chlorine. 47 
 
 simple attractions : thus, they are not altered by dry boracic 
 acid, though, when water is added to them, they readily 
 afford muriatic acid and their peculiar earths. 
 
 From this circumstance, I was induced to believe that 
 these three compounds consist merely of the peculiar 
 metallic bases, which I have named barium, strontium, and 
 calcium, and oxymuriatic gas ; and such experiments as 
 I have been able to make, confirm the conclusion. 
 
 When baryta, strontia, or lime, is heated in oxymuriatic 
 gas to redness, a body precisely the same as a dry muriate 
 is formed, and oxygene is expelled from the earth. I 
 have never been able to effect so complete a decom- 
 position of these earths by oxymuriatic gas, as to ascertain 
 the quantity of oxygene produced from a given quantity 
 of earth. But in three experiments made with great care 
 I found that one of oxygene was evolved for every two in 
 volume of oxymuriatic gas absorbed. 
 
 I have not yet trid the experiment of acting upon 
 oxymuriatic gas by the bases of the alkaline earths ; but 
 I have not the least doubt that these bodies would 
 combine directly with that substance, and form dry 
 muriates. 
 
 In the last experiments that I made on the metalliza- 
 tion of the earths by amalgamation, I paid particular 
 attention to the state of the products formed, by exposing 
 the residuum of amalgams to the air. I found that baryta 
 formed in this way was not fusible at an intense white 
 heat, and that strontia and lime so formed gave off no 
 water when ignited. Baryta made from chrystals of the 
 earth, as M. BERTHOLLET has shewn, is a fusible hydrat, 
 and I found that this earth gave moisture when decom- 
 posed by oxymuriatic gas ; and the lime, in hydrat ot 
 lime, was much more rapidly decomposed by oxymuriatic 
 gas than quicklime, its oxygene being rapidly expelled 
 with the water. 
 
48 Davy. 
 
 Some dry quicklime was heated in a retort, filled with 
 muriatic acid gas ; water was instantly formed in great 
 abundance, and it can hardly be doubted, that this arose 
 from the hydrogene of the acid combining with the 
 oxygene of the lime. 
 
 As potassium so readily decomposes common salt, I 
 thought it might possibly decompose muriate of lime, 
 and thus afford easy means of procuring calcium. The 
 rapidity with which muriate of lime absorbs water, and 
 the difficulty of freeing it even by a white heat from the 
 last portions, rendered the circumstances of the experi- 
 ments unfavourable. I found, however, that by heating 
 potassium strongly, in contact with the salt, in a retort of 
 difficultly fusible glass, I obtained a dark coloured matter, 
 diffused through a vitreous mass, which effervesced 
 strongly with water. The potassium had all disappeared, 
 and the retort had received a heat at which potassium 
 entirely volatilizes. I had similar results with muriate of 
 strontia, and (though less distinct, more potassium 
 distilling off unaltered) with muriate of baryta. Either 
 the bases of the earths were wholly or partially deprived 
 of oxymuriatic gas in these processes, or the potassium 
 had entered into triple combination with the muriates. 
 I hope on a future occasion to be able to decide this 
 point. 
 
 Combinations of muriatic acid gas with magnesia, 
 alumine and silex, are all decomposed by heat, the acid 
 being driven off, and the earth remaining free. I con- 
 jectured from this circumstance," that oxymuriatic gas 
 would not expel oxygene from these earths, and the 
 suspicion was confirmed by experiments. I heated 
 magnesia, alumine, and silex to redness in oxymuriatic 
 gas, but no change took place. 
 
 M. M. GAY LTJSSAC and THENARD have shewn that 
 baryta is capable of absorbing oxygene; and it seems 
 
Elementary Nature of Chlorine. 49 
 
 likely, (as according to Mr. CHENEVIX'S experiments, 
 most of the earths are capable of becoming hyperoxy- 
 muriates) that peroxides of their bases must exist. 
 
 I endeavoured to combine lime with more oxygene, 
 by heating it in hyperoxymuriate of potash, but without 
 success, at least after this process it gave off no oxygene 
 in combining with water. The salt, called oxymuriate 
 of lime, made for the use of the bleachers, I found gave 
 off oxygene by heat, and formed muriate of lime. 
 
 From the proportions which I have given in the last 
 Bakerian lecture, but which were calculated from the 
 analyses of sulphates, it follows that if the muriates of 
 baryta, strontia, and lime, be regarded as containing one 
 proportion of oxymuriatic gas, and one of metal, then 
 they would consist of 71 * barium, 46 strontium, and 21 
 calcium, to 32.9 of oxymuriatic gas. 
 
 To determine how far these numbers are accurate, 50 
 grains of each of these muriates that had been heated 
 to whiteness were decomposed by nitrate of silver, the 
 precipitate was collected, washed, heated, and weighed. 
 
 The muriate of baryta, treated in this way, afforded 68 
 grains of horn-silver. 
 
 The muriate of strontia 85 grains. 
 
 The muriate of lime 125 grains. 
 
 From experiments to be detailed in the next section, 
 it appears that horn-silver consists of 12 of silver to 3.9 
 of oxymuriatic gas, and consequently that barium should 
 be represented by 65.1, strontium by 46.1, and calcium 
 by 20.8. 
 
 * If Mr. JAMES THOMPSON'S analysis of sulphate of barytes be 
 made the basis of calculation, sulphuric acid being estimated as 36, 
 then the number representing barium will be about 65.5 
 
5O Davy. 
 
 4.. On the Combinations of the Common Metals, with 
 Oxygene and Oxymuriatic Gas. 
 
 In the limits which it is usual to adopt in this lecture, 
 it will not be possible for me to give more than an out- 
 line of the numerous experiments that I have made on 
 the combinations of oxymuriatic gas with metals ; I must 
 confine myself to a general statement of the mode of 
 operating, and the results. I used in all cases small 
 retorts of green glass, containing from 3 to 6 cubical 
 inches, furnished with stopcocks. The metallic sub- 
 stances were introduced, the retort exhausted and filled 
 with the gas to be acted upon, heat was applied by 
 means of a spirit lamp, and after cooling, the results 
 were examined, and the residual gas analysed, 
 
 All the metals that I tried, except silver, lead, nickel, 
 cobalt, and gold, when heated, burnt in the oxymuriatic 
 gas, and the volatile metals with flame. Arsenic, anti- 
 mony, tellurium and zinc with a white flame, mercury 
 with a red flame. Tin became ignited to whiteness, and 
 iron and copper to redness ; tungsten and manganese to 
 dull redness ; platina was scarcely acted upon at the heat 
 of fusion of the glass. 
 
 The product from arsenic was butter of arsenic ; a 
 dense, limpid, highly volatile fluid, a non-conductor of 
 electricity, and of high specific gravity, and which when 
 decomposed by water, gave oxide of arsenic and muriatic 
 acid. That from antimony, was butter of antimony, an 
 easily fusible and volatile solid of the colour of horn- 
 silver, of great density, crystallizing on cooling in 
 hexahedral plates, and giving, by its decomposition by 
 water, white oxide. 
 
 The product from tellurium, in its sensible qualities 
 
Elementary Nature of Chlorine. 5 1 
 
 resembled that from antimony, and gave when acted on 
 by water white oxide. 
 
 The product from mercury was corrosive sublimate. 
 That from zinc was similar in colour to that from antimony, 
 but was much less volatile. 
 
 The combination of oxymuriatic gas and iron, was of a 
 bright brown ; but having a lustre approaching to the 
 metallic, and was iridescent like the Elba iron ore. It 
 volatilized at a moderate heat, filling the vessel with 
 beautiful minute crystals of extraordinary splendour, 
 and collecting in brilliant plates, the form of which I 
 could not determine. When acted on by water, it gave 
 red muriate of iron. 
 
 Copper formed a bright red brown substance, fusible 
 at a heat below redness, and becoming crystalline and 
 semi-transparent on cooling, and which gave a green 
 fluid, and a green precipitate by the action of water.* 
 
 The substance from manganese was not volatile at a 
 dull red heat ; It was of a deep brown colour, and by the 
 action of water became of a brighter brown : a muriate 
 of manganese, which did not redden litmus remained in 
 solution ; and an insoluble matter remained of a chocolate 
 colour.t 
 
 * It is worth enquiry, whether the precipitate from oxymuriate of 
 copper by water is not a hydrated submuriate, analogous in its com- 
 position to the crystalized muriate of Peru. This last I find affords 
 muriatic acid and water by heat. 
 
 The resin of copper discovered by BOYLE, formed by heating 
 copper with corrosive sublimate, probably contains only I propor- 
 tion of oxymuriatic gas, whilst that above referred to must 
 contain 2. 
 
 + When muriate of manganese is made by solution of its oxide in 
 muriatic acid, a neutral combination is obtained, but this is decom- 
 posed by heat ; muriatic gas flies oft, and brown oxide of manganese 
 remains. In this respect manganese appears as a link between the 
 ancient metals and the newly discovered ones. Its muriate is de- 
 
52 Davy. 
 
 Tungsten afforded a deep orange sublimate, which, 
 when decomposed by water, afforded muriatic acid, and 
 the yellow oxide of tungsten. 
 
 Tin afforded LIBAVIUS'S liquor, which gave a muriate 
 by the action of water containing the oxide of tin, at the 
 maximum of oxidation. 
 
 Silver and lead produced horn-silver and horn-lead, 
 and bismuth, butter of bismuth. The absorption of 
 oxymuriatic gas was in the following proportions for two 
 grains of each of the metals : for arsenic 3.6 cubical 
 inches, for antimony 3.1, for tellurium 2.4, for mercury 
 1.05,* for zinc 3.2, for iron 5.8, for tin 4, for bismuth 
 1.5, for copper 3.4, for lead .9, for silver, the absorption 
 of volume was -$, and the increase of weight of the 
 silver was equivalent to $ of a grain, f 
 
 In acting upon metallic oxides by oxymuriatic gas, I 
 found that those of lead, silver, tin, copper, antimony, 
 bismuth, and tellurium, were decomposed in a heat 
 below redness, but the oxides of the volatile metals, 
 
 composed like that of magnesia ; and its oxide is the only one 
 amongst those long known, as far as my experiments have gone, 
 which neutralizes the acid energy of muriatic acid gas, so as to 
 prevent it in solution from affecting vegetable blues. 
 
 * The gas in these experiments was not freed from aqueous 
 vapour, and as stopcocks of brass were used, a little gas might have 
 been absorbed by the surface of this metal, so that the processes 
 offer only approximations to the composition of the oxymuriates. 
 The processes on lead, tellurium, iron, antimony, copper, tin, 
 mercury, and arsenic, were carried on in three successive days, 
 during which the height of the mercury in the barometer varied 
 from 30.26 inches to 30. 15, and the height of that in the thermometer 
 from 63.5 to 6 1 FAHRENHEIT. 
 
 The experiment on silver was made at the temperature of 52 
 FAHRENHEIT, and under a pressure equal to that of 29.9 inches. 
 
 t This agrees nearly with another experiment made by my 
 brother, Mr. JOHN DAVY, in which 12 grains of silver increased to 
 15.9 during their conversion into horn-silver. 
 
Elementary Nature of Chlorine. 53 
 
 more readily than those of the fixed ones. The oxides 
 of cobalt and nickel were scarcely acted upon at a dull 
 red heat. The red oxide of iron was not affected at a 
 strong red heat, whilst the black oxide was rapidly 
 decomposed at a much lower temperature; arsenical 
 acid underwent no change at the greatest heat that 
 could be given it in the glass retort, whilst the white 
 oxide readily decomposed. 
 
 In cases where oxygene was given off, it was found 
 exactly the same in quantity as that which had been 
 absorbed by the metal. Thus 2 grains of red oxide of 
 mercury absorbed ^ of a cubical inch of oxymuriatic 
 gas, and afforded 0.45 of oxygene.* Two grains of 
 
 * I have made two analyses of corrosive sublimate and calomel, 
 with considerable care. I decomposed 100 grains of corrosive 
 sublimate, by 90 grains of hydrat of potash. This afforded 79.5 
 grains of orange coloured oxide of mercury, 40 grains of which 
 afforded 9.15 cubical inches of oxygene gas j the muriate of silver 
 formed from the 100 grains was 102.5. 
 
 100 grains of calomel, decomposed by 90 grains of potash, afforded 
 82 grains of olive coloured oxide of mercury, of which 40 grains 
 gave by decomposition by heat 4.8 cubical inches of oxygene. The 
 quantity of horn-silver formed from the 100 grains was 58.75 
 grains. 
 
 In the second analysis, the quantity of oxide obtained from 
 corrosive sublimate was 78.7 ; the quantity of muriate of silver 
 formed was 103.4 ; the oxide produced from calomel weighed 83 
 grains ; the horn- silver formed was 57^ grains. I am inclined to 
 put most confidence in the last analyses ; but the tenor of both is 
 to shew that the quantity of oxymuriatic gas in corrosive sublimate, 
 is exactly double that in calomel, and that the orange oxide contains 
 twice as much oxygene as the black, the mercury being considered 
 as the same in all. The olive colour of the oxide formed from 
 calomel, is owing to a slight admixture of orange oxide, formed by 
 the oxygene of the water used in precipitation ; the tint I find is 
 almost black, when a boiling solution of potash is used ; and trituration, 
 with a little orange oxide brings the tint to olive. It has been 
 stated, that the olive oxide thrown down from calomel by potash is 
 
54 Davy. 
 
 dark olive oxide from calomel decomposed by potash, 
 absorbed about $ of oxymuriatic gas, and afforded T Vo- of 
 oxygene, and corrosive sublimate was produced in both 
 cases. 
 
 In the decomposition of the white oxide of zinc, 
 oxygene was expelled exactly equal to half the volume 
 of the oxymuriatic acid absorbed. In the case of the 
 decomposition of the black oxide of iron, and the white 
 oxide of arsenic, the changes that occurred were of a 
 very beautiful kind ; no oxygene was given off in either 
 case, but butter of arsenic, and arsenical acid formed in 
 one instance, and the ferruginous sublimate, and red 
 oxide of iron in the other. 
 
 Two grains of white oxide of arsenic absorbed 0.8 of 
 oxymuriatic gas.* 
 
 I doubt not that the same phenomena will be found to 
 occur in other instances, in which the metal has com- 
 paratively a slight attraction only for oxymuriatic gas, 
 and when it is susceptible of different degrees of oxy- 
 dation, and in which the peroxide is used. 
 
 The only instance in which I tried to decompose a 
 common metallic oxide, by muriatic acid, was in that of 
 the fawn coloured oxide of tin ; a compound of water 
 and LIBAVIUS'S liquor separated. 
 
 a submuriate ; but I have never been able to find a vestige of 
 muriatic acid in it when well washed. It is not easy to obtain 
 perfect precision in analyses of the oxides of mercury ; water adheres 
 to the oxides, which cannot be entirely driven off without the 
 expulsion of some oxygene. In all my experiments, though the 
 oxides had been heated to a temperature above 212, a little dew 
 collected in the neck of the retort, so that the 40 grains must have 
 been over-rated. 
 
 * A singular instance of the tendency of the oxide of arsenic to 
 become arsenical acid, occurs in its action on fused hydrat of 
 potash, the water in the hydrat is rapidly decomposed, and 
 arseniuretted hydrogene evolved, and arseniate of potash formed. 
 
Elementary Nature of Chlorine. 5 5 
 
 From the proportions which may be gained in con- 
 sidering the volumes of oxymuriatic gas absorbed by the 
 different metals, in their relations to the quantity of 
 oxygene which would be required to convert them into 
 oxides, it would appear, that in the experiments to which 
 I have referred, either one, two, or three proportions of 
 oxymuriatic gas combine with one of metal, and con- 
 sequently, from the composition of the muriates, it will be 
 easy to obtain the numbers representing the proportions 
 in which these metals may be conceived to enter into 
 other compounds.* 
 
 5. General Conclusions and Observations, illustrated 
 by Experiments. 
 
 All the conclusions which I ventured to draw in my 
 last communication to the Society, will, I trust, be 
 found to be confirmed by the whole series of these new 
 enquiries. 
 
 Oxymuriatic gas combines with inflammable bodies, 
 to form simple binary compounds; and in these cases, 
 when it acts upon oxides, it either produces the expul- 
 sion of their oxygene, or causes it to enter into new 
 combinations. 
 
 If it be said that the oxygene arises from the decom- 
 position of the oxymuriatic gas, and not from the oxides, 
 it may be asked, why it is always the quantity contained 
 in the oxide ; and why in some cases, as those of the 
 
 * From the experiments detailed in the note in the preceding 
 pages, it would appear that the number representing the proportion 
 in which mercury combines must be about 200. That of silver, as 
 would appear from the results, page 52, about 100. The numbers 
 of other metals may be learnt from the data in the same page, but 
 from what has been stated, these data cannot be considered as very 
 correct. 
 
56 Davy. 
 
 peroxides of potassium and sodium, it bears no relation 
 to the quantity of gas ? 
 
 If there existed any acid matter in oxymuriatic gas, 
 combined with oxygene, it ought to be exhibited in 
 the fluid compound of one proportion of phosphorus, 
 and two of oxymuriatic gas ; for this, on such an 
 assumption, should consist of muriatic acid (on the old 
 hypothesis, free from water) and phosphorous acid ; but 
 this substance has no effect on litmus paper, and does 
 not act under common circumstances, on fixed alkaline 
 bases, such as dry lime or magnesia. Oxymuriatic gas, 
 like oxygene, must be combined in large quantity with 
 peculiar inflammable matter, to form acid matter. In its 
 union with hydrogene, it instantly reddens the driest 
 litmus paper, though a gaseous body. Contrary to acids, 
 it expels oxygene from protoxides, and combines with 
 peroxides. 
 
 When potassium is burnt in oxymuriatic gas, a dry 
 compound is obtained. If potassium combined with 
 oxygene is employed, the whole of the oxygene is 
 expelled, and the same compound formed. It is contrary 
 to sound logic to say, that this exact quantity of oxygene 
 is given off from a body not known to be compound, 
 when we are certain of its existence in another ; and all 
 the cases are parallel. 
 
 An argument in favour of the existence of oxygene in 
 oxymuriatic gas, may be derived by some persons from 
 the circumstances of its formation, by the action of 
 muriatic acid on peroxides, or on hyperoxymuriate of 
 potash ; but a minute investigation of the subject will, I 
 doubt not, shew that the phenomena of this action are 
 entirely consistent with the views I have brought forward. 
 By heating muriatic acid gas in contact with dry peroxide 
 of manganese, water I found was rapidly formed, and 
 oxymuriatic gas produced, and the peroxide rendered 
 
Elementary Nature of Chlorine. S7 
 
 brown. Now as muriatic acid gas is known to consist of 
 oxymuriatic gas and hydrogene, there is no simple 
 explanation of the result, except by saying that the 
 hydrogene of the muriatic acid, combined with oxygene 
 from the peroxide to produce water. 
 
 SCHEELE explained the bleaching powers of the oxymuri- 
 atic gas, by supposing that it destroyed colours by com- 
 bining with phlogiston. BERTHOLLET considered it as 
 acting by supplying oxygene. I have made an experiment, 
 which seems to prove that the pure gas is incapable of 
 altering vegetable colours, and that its operation in 
 bleaching depends entirely upon its property of decom- 
 posing water, and liberating its oxygene. 
 
 I filled a glass globe containing dry powdered muriate 
 of lime, with oxymuriatic gas. I introduced some dry 
 paper tinged with litmus that had been just heated, into 
 another globe containing dry muriate of lime ; after some 
 time this globe was exhausted, and then connected with 
 the globe containing the oxymuriatic gas, and by an 
 appropriate set of stopcocks, the paper was exposed to 
 the action of the gas. No change of colour took place, 
 and after two days there was scarcely a perceptible 
 alteration. 
 
 Some similar paper dried, introduced into gas that had 
 not been exposed to muriate of lime, was instantly 
 rendered white.* 
 
 Paper that had not been previously dried, brought in 
 contact with dried gas, underwent the same change, but 
 more slowly. 
 
 The hyperoxymuriates seem to owe theii bleaching 
 powers entirely to their loosely combined oxygene ; there 
 
 * The last experiments were made in the laboratory of the 
 Dublin Society ; most ot the preceding ones in the laboratory of 
 the Royal Institution ; and I have been permitted to refer to them 
 by the Managers of that useful public establishment. 
 
58 Davy. 
 
 is a strong tendency in the metal of those in common 
 use, to form simple combinations with oxymuriatic gas, 
 and the oxygene is easily expelled or attracted from 
 them. 
 
 It is generally stated in chemical books, that oxy- 
 muriatic gas is capable of being condensed and crystallized 
 at a low temperature ; I have found by several experi- 
 ments that this is not the case. The solution of 
 oxymuriatic gas in water freezes more readily than pure 
 water, but the pure gas dried by muriate of lime under- 
 goes no change whatever, at a temperature of 40 below 
 o of FAHRENHEIT. The mistake seems to have arisen 
 from the exposure of the gas to cold in bottles containing 
 moisture. 
 
 I attempted to decompose boracic and phosphoric 
 acids by oxymuriatic gas, but without success ; from 
 which it seems probable that the attractions of boracium 
 and phosphorus for oxygene are stronger than for oxy- 
 muriatic gas. And from the experiments I have already 
 detailed, iron and arsenic are analogous in this respect, 
 and probably some other metals. 
 
 Potassium, sodium, calcium, strontium, barium, zinc, 
 mercury, tin, lead, and probably silver, antimony, and 
 gold seem to have a stronger attraction for oxymuriatic 
 gas than for oxygene. 
 
 I have as yet been able to make very few experi- 
 ments on the combinations of the oxymuriatic com- 
 pounds with each other, or with oxides. The liquor 
 from arsenic, and that from tin, mix, producing an 
 increase of temperature ; and the phosphuretted, and 
 the sulphuretted liquors unite with each other, and with 
 the liquor of LIBAVIUS, but without any remarkable 
 phenomena. 
 
 I heated lime gently in a green glass tube, and passed 
 the phosphoric sublimate, the saturated oxymuriate of 
 
Elementary Nature of Chlorine. 59 
 
 phosphorus through it, in vapour ; there was a violent 
 action with the production of heat and light, and a gray 
 fused mass was formed, which afforded by the action 
 of water, muriate and phosphate of lime. 
 
 I introduced some vapour from the heated phosphoric 
 sublimate, into an exhausted retort containing dry paper 
 tinged with litmus : the colour slowly changed to pale 
 red. This fact seems in favour of the idea that the 
 substance is an acid; but as some minute quantity of 
 aqueous vapour might have been present in the receiver, 
 the experiment cannot be regarded as decisive : the 
 strength of its attraction for ammonia, is perhaps like- 
 wise in favour of this opinion. All the oxymuriates that 
 I have tried, indeed form triple compounds with this 
 alkali ; but phosphorus is expelled by a gentle heat from 
 the other compounds of oxymuriatic gas and phos- 
 phorus with ammonia, and the substance remaining in 
 combination is the phosphoric sublimate. 
 
 6. Some Reflections on the Nomenclature of the 
 Oxymuriatic Compounds. 
 
 To call a body which is not known to contain 
 oxygene, and which cannot contain muriatic acid, oxy- 
 muriatic acid, is contrary to the principles of that 
 nomenclature in which it is adopted ; and an alteration 
 of it seems necessary to assist the progress of discus- 
 sion, and to diffuse just ideas on the subject. If the 
 great discoverer of this substance had signified it by any 
 simple name, it would have been proper to have recurred 
 to it ; but, dephlogisticated marine acid is a term which 
 can hardly be adopted in the present advanced sera of 
 the science. 
 
 After consulting some of the most eminent chemical 
 
60 Davy. 
 
 philosophers in this country, it has been judged most 
 proper to suggest a name founded upon one of its obvious 
 and characteristic properties its colour, and to call it 
 Chlorine^ or Chloric gas.* 
 
 Should it hereafter be discovered to be compound, 
 and even to contain oxygene, this name can imply no 
 error, and cannot necessarily require a change. 
 
 Most of the salts which have been called muriates, are 
 not known to contain any muriatic acid', or any oxygene. 
 Thus LIBAVIUS'S liquor, though converted into a muriate 
 by water, contains only tin and oxymuriatic gas, and horn- 
 silver seems incapable of being converted into a true muriate. 
 
 I venture to propose for the compounds of oxy- 
 muriatic gas and inflammable matter, the name of their 
 bases, with the termination ane. Thus argentane may 
 signify horn-silver; stannane, LIBAVIUS'S liquor; anti- 
 monane, butter of antimony ; sulphurane, Dr. THOMSON'S 
 sulphuretted liquor ; and so on for the rest. 
 
 In cases when the proportion is one quantity of oxy- 
 muriatic gas, and one of inflammable matter, this 
 nomenclature will be competent to express the class to 
 which the body belongs, and its constitution. In cases 
 when two or more proportions of inflammable matter, 
 combine with one of gas ; or two or more of gas, with one 
 of inflammable matter, it may be convenient to signify 
 the proportions by affixing vowels before the name, when 
 the inflammable matter predominates, and after the name, 
 when the gas is in excess ; and in the order of the 
 alphabet, a signifying two, e three, / four, and so on. 
 
 The name muriatic acid, as applied to the compound 
 of hydrogene and oxymuriatic gas, there seems to be no 
 reason for altering. And the compounds of this body 
 with oxides should be characterised in the usual manner, 
 and as the other -neutral salts. 
 
 * From /Vcoos. 
 
Elementary Nature of Chlorine. . 6 1 
 
 Thus muriate of ammonia and muriate of magnesia, 
 are perfectly correct expressions. 
 
 I shall not dwell any longer at present upon this 
 subject. What I have advanced, I advance merely as 
 suggestion, and principally, for the purpose of calling the 
 attention of philosophers to it.* As chemistry improves, 
 many other alterations will be necessary ; and it is to be 
 
 * It may be conceived that a name may be found for the 
 oxymuriatic gas in some modification of its present appellation 
 which may harmonize with the new views, and which may yet 
 signify its relation to the muriatic acid, such as demuriatic gas, or 
 oxymuric gas ; but in this case it would be necessary to call the 
 muriatic acid hydrogenated muriatic acid, or hydromuriatic acid ; 
 and the salts which contain it hydrogenated muriates or hydro- 
 muriates ; and on such a plan, the compounds of oxymuriatic gas 
 must be called demuriates or oxymuriates, which I conceive would 
 create more complexity and difficulty in unfolding just ideas on this 
 department of chemical knowledge than the methods which I have 
 ventured to propose. It may however be right, considering the 
 infant state of the investigation, to suspend, for a time, the adoption 
 of any new terms for these compounds. It is possible that oxy- 
 muriatic gas may be compound, and that this body and oxygene 
 may contain some common principle ; but at present we have no 
 more right to say that oxymuriatic gas contains oxygene than to say 
 that tin contains hydrogene ; and names should express things and 
 not opinions ; and till a body is decompounded, it should be 
 considered as simple. 
 
 In the last umber of Mr. NICHOLSON'S Journal, which appeared 
 February ist, whilst this sheet was correcting for the press, I have 
 seen an ingenious paper, by Mr. MURRAY, of Edinburgh, in which 
 he has attempted to shew, that oxymuriatic gas contains oxygene. 
 His methods are, by detonating oxymuriatic gas in excess, with a 
 mixture of hydrogene, and gaseous oxide of carbone, when he 
 supposes carbonic acid is formed ; and by mixing oxymuriatic gas in 
 excess, with sulphuretted hydrogene, when he supposes sulphuric 
 acid, or sulphureous acid is formed. In some experiments, in which 
 my brother, Mr. JOHN DAVY, was so good as to co-operate, made 
 over boiled mercury, we found, that 7 parts of hydrogene, 8 parts 
 of gaseous oxide of carbone, and 20 parts of oxymuriatic gas, 
 exploded by the electric spark, diminished to about 30 measures ; 
 
62 Davy. 
 
 hoped that whenever they take place, they will be made 
 independent of all speculative views, and that new names 
 will be derived from some simple and invariable property, 
 and that mere arbitrary designations will be employed, to 
 signify the class to which compounds or simple bodies 
 belong. 
 
 and calomel was formed on the sides of the tube. On adding dry 
 ammonia in excess, and exposing the remainder to water, a gas 
 remained which equalled more than 9 measures, and which was 
 gaseous oxide of carbone, with no more impurity than might be 
 expected from the air in the gasses, and the nitrogene expelled 
 from the ammonia ; so that the oxygene in Mr. MURRAY'S carbonic 
 acid, it seems, was obtained from water, or from the carbonic oxide. 
 Sulphuretted hydrogene, added over dry mercury, to oxymuriatic 
 gas in excess, inflamed in two or three experiments ; muriatic acid 
 gas containing the vapour of oxymuriate of sulphur, was formed, 
 which, when neutralized by ammonia, gave muriate of ammonia, 
 and a combination of ammonia, and oxymuriate of sulphur. 
 
 When a mixture of oxymuriatic gas in excess, and sulphuretted 
 hydrogene, was suffered to pass into the atmosphere, the smell was 
 that of oxymuriate of sulphur ; there was not the slightest indica- 
 tion of the presence of any sulphuric or sulphureous acid. If 
 Mr. MURRAY had used ammonia, instead of water, for analyzing his 
 results, I do not think he would have concluded, that oxymuriatic 
 gas is capable of decomposition by such methods. 
 
 I shall not, at present, enter upon a detail of other experiments 
 which I have made on this subject, in co-operation with my brother, 
 as it is his intention to refer to them, in an answer to Mr. MURRAY'S 
 paper. 
 
 I shall conclude, by saying, that this ingenious chemist, has 
 mistaken my views, in supposing them hypothetical ; I merely state 
 what I have seen, and what I have found. There may be oxygene 
 in oxymuriatic gas ; but I can find none. I repeated Mr. MURRAY'S 
 experiments with great interest ; and their results, when water is 
 excluded, entirely confirm all my ideas on the subject, and afford no 
 support to the hypothetical ideas, which he has laboured so zealously 
 to defend. 
 
Elementary Nature of Chlorine. 63 
 
 On a Combination of Oxymuriatic Gas and 
 Oxygene Gas* 
 
 Read February 21, 1 8 1 1 . 
 
 1 SHALL beg permission to lay before the Society the 
 account of some experiments on a compound of 
 oxymuriatic gas and oxygene gas, which, I trust, will 
 be found to illustrate an interesting branch of chemical 
 enquiry, and which offer some extraordinary and novel 
 results. 
 
 I was led to make these experiments in consequence 
 of the difference between the properties of oxymuriatic 
 gas prepared in different modes ; it would occupy a great 
 length of time to state the whole progress of this in- 
 vestigation. It will, I conceive, be more interesting that 
 I should immediately refer to the facts ; most of which 
 have been witnessed by Members of this Body, belonging 
 to the Committee of Chemistry of the Royal Institution. 
 
 The oxymuriatic gas prepared from manganese, either 
 by mixing it with a muriate and acting upon it by sulphuric 
 acid, or by mixing it with muriatic acid, is when the 
 oxide of manganese is pure, and, whether collected over 
 water or mercury, uniform in its properties ; its colour is 
 a pale yellowish green ; water takes up about twice its 
 volume ; and scarcely gains any colour ; the metals burn 
 in it readily ; it combines with hydrogene without any 
 deposition of moisture : it does not act on nitrous gas 
 or muriatic acid, or carbonic oxide, or sulphureous gasses, 
 
 * [From "Philosophical Transactions" for 1811 vol. 101, pp. 
 155-162.] 
 
64 Davy. 
 
 when they have been carefully dried. It is the substance 
 which I employed in all the experiments on the com- 
 binations of oxymuriatic gas described in my last two 
 papers. 
 
 The gas produced by the action of muriatic acid on 
 the salts which have been called hyperoxymuriates, on 
 the contrary, differs very much in its properties, accord- 
 ing as the manner in which it is prepared and collected 
 is different. 
 
 When much acid is employed to a small quantity of 
 salt, and the gas is collected over water, the water becomes 
 tinged of a lemon colour ; but the gas collected is the 
 same as that procured from manganese. 
 
 When the gas is collected over mercury, and is pro- 
 cured^ from a weak acid, and from a great excess of salt 
 by a low heat, its colour is a dense tint of brilliant yellow 
 green, and it possesses properties entirely different from 
 the gas collected over water. 
 
 It sometimes explodes during the time of its transfer 
 from one vessel to another, producing heat and light, with 
 an expansion of volume ; and it may be always made to 
 explode by a very gentle heat, often by that of the hand.* 
 
 It is a compound of oxymuriatic gas and oxygene, 
 mixed with some oxymuriatic gas. This is proved by the 
 results of its spontaneous explosion. It gives off, in 
 
 * My brother, Mr. J. DAVY, from whom I receive constant and 
 able assistance in all my chemical enquiries, had several times 
 observed explosions, in transferring the gas from hyperoxymuriate 
 of potash, over mercury, and he was inclined to attribute the 
 phenomenon to the combustion of a thin film of mercury, in contact 
 with a globule of gas. I several times endeavoured to produce the 
 effect, but without success, till an acid was employed for the prepara- 
 tion of the gas, so diluted as not to afford it without the assistance 
 of heat. The change of colour and expansion of volume, when the 
 effect took place, immediately convinced me, that it was owing to a 
 decomposition of the gas. 
 
Elementary Nature of Chlorine. 65 
 
 this process, from \ to f its volume of oxygene, loses its 
 vivid colour, and becomes common oxymuriatic gas. 
 
 I attempted to obtain the explosive gas in a pure form, 
 by applying heat to a solution of it in water ; but in this 
 case, there was a partial decomposition ; and some oxy- 
 gene was disengaged, and some oxymuriatic gas formed. 
 Finding that in the cases when it was most pure, it 
 scarcely acted upon mercury, I attempted to separate the 
 oxymuriatic gas with which it is mixed, by agitation in a 
 tube with this metal ; corrosive sublimate formed, and an 
 elastic fluid was obtained, which was almost entirely 
 absorbed by J of its volume of water. 
 
 This gas in its pure form is so easily decomposable 
 that it is dangerous to operate upon considerable 
 quantities. 
 
 In one set of experiments upon it, a jar of strong glass, 
 containing 40 cubical inches, exploded in my hands with 
 a loud report, producing light ; the vessel was broken, 
 and fragments of it were thrown to a considerable dis- 
 tance. 
 
 I analysed a portion of this gas, by causing it to explode 
 over mercury in a curved glass tube, by the heat of a 
 spirit lamp. 
 
 The oxymuriatic gas formed, was absorbed by water ; 
 the oxygene was found to be pure, by the test of nitrous 
 gas. 
 
 50 parts of the detonating gas, by decomposition, ex- 
 panded so as to become 60 parts. The oxygene, remain- 
 ing after the absorption of the oxymuriatic gas, was about 
 20 parts. Several other experiments were made, with 
 similar results. So that it may be inferred, that it con- 
 sists of 2 in volume of oxymuriatic gas, and i in volume 
 of oxygene ; and the oxygene in the gas is condensed 
 to half its volume. Circumstances conformable to the 
 laws of combination of gaseous fluids, so ably illustrated 
 
 
 
66 Davy. 
 
 by M. GAY LUSSAC, and to the theory of definite pro- 
 portions. 
 
 I have stated on a former occasion, that approximations 
 to the numbers representing the proportions in which 
 oxygene and oxymuriatic gas combine, are found in 7.5 
 and 32.9. And this compound gas contains nearly these 
 quantities.* 
 
 The smell of the pure explosive gas somewhat resembles 
 that of burnt sugar, mixed with the peculiar smell of 
 oxymuriatic gas. Water appeared to take up eight or ten 
 times its volume ; but the experiment was made over 
 mercury, which might occasion an error, though it did 
 not seem to act on the fluid. The water became of a 
 tint approaching to orange. 
 
 When the explosive gas was detonated with hydrogene, 
 equal to twice its volume, there was a great absorption, 
 to more than , and solution of muriatic acid was formed ; 
 when the explosive gas was in excess, oxygene was always 
 expelled, a fact demonstrating the stronger attraction of 
 hydrogene for oxymuriatic gas than for oxygene. 
 
 I have said that mercury has no action upon this gas 
 in its purest form at common temperatures. Copper and 
 antimony, which so readily burn in oxymuriatic gas, did 
 not act upon the explosive gas in the cold : and when 
 
 * In page 245 of the Phil. Trans, for i8io[p. 35], I have mentioned 
 that the specific gravity of oxymuriatic gas, is between 74 and 75 
 grains per 100 cubical inches, The gas that I weighed, was collected 
 over water and procured from hyperoxymuriate of potash, and at 
 that time I conceived, that this elastic fluid did not differ from the 
 oxymuriatic gas from manganese, except in being purer. It probably 
 contained some of the new gas ; for I find that the specific gravity 
 of pure oxymuriatic gas from manganese, and muriatic acid is to 
 that of common air, as 244 to 100. Taking this estimation, the 
 specific gravity of the new gas will be about 238, and the number 
 representing the proportion in which oxymuriatic gas combines, from 
 this estimation, will be rather higher than is stated above. 
 
Elementary Nature of Chlorine. 67 
 
 they were introduced into it, being heated, it was instantly 
 decomposed, and its oxygene set free ; and the metals 
 burnt in the oxymuriatic gas. 
 
 When sulphur was introduced into it, there was at first 
 no action, but an explosion soon took place : and the 
 peculiar smell of oxymuriate of sulphur was perceived. 
 
 Phosphorus produced a brilliant explosion, by contact 
 with it in the cold, and there was produced phosphoric 
 acid and solid oxymuriate of phosphorus. 
 
 Arsenic introduced into it did not inflame; the gas 
 was made to explode, when the metal burnt with great 
 brilliancy in the oxymuriatic gas. 
 
 Iron wire introduced into it did not burn, till it was 
 heated so as to produce an explosion, when it burnt with 
 a most brilliant light in the decomposed gas. 
 
 Charcoal introduced in it ignited, produced a brilliant 
 flash of light, and burnt with a dull red light, doubtless 
 owing to its action upon the oxygene mixed with the 
 oxymuriatic gas. 
 
 It produced dense red fumes when mixed with nitrous 
 gas, and there was an absorption of volume. 
 
 When it was mixed with muriatic acid gas, there was a 
 gradual diminution of volume. By the application of 
 heat the absorption was rapid, oxymuriatic gas was formed, 
 and a dew appeared on the sides of the vessel. 
 
 These experiments enable us to explain the contra- 
 dictory accounts that have been given by different authors 
 of the properties of oxymuriatic gas. 
 
 That the explosive compound has not been collected 
 before, is owing to the circumstance of water having been 
 used for receiving the products from hyperoxymuriate of 
 potash, and unless the water is highly saturated with the 
 explosive gas, nothing but oxymuriatic gas is obtained .; 
 or to the circumstance of too dense an acid having been 
 employed. 
 
68 Davy. 
 
 This substance produces the phenomena which Mr. 
 CHENEVIX, in his able paper on oxymuriatic acid, referred 
 to the hyperoxygenised muriatic acid ; and they prove 
 the truth of his ideas respecting the possible existence cf 
 a compound of oxymuriatic gas, and oxygene in a separate 
 state. 
 
 The explosions produced in attempts to procure the 
 products of hyperoxymuriate of potash by acids are 
 evidently owing to the decomposition of this new and 
 extraordinary substance. 
 
 All the conclusions which I have ventured to make 
 respecting the undecompounded nature of oxymuriatic 
 gas, are, I conceive, entirely confirmed by these new 
 facts. 
 
 If oxymuriatic gas contained oxygene, it is not easy to 
 conceive, why oxygene should be afforded by this new 
 compound to muriatic gas, which must already contain 
 oxygene in intimate union. Though on the idea of 
 muriatic acid being a compound of hydrogene and oxy- 
 muriatic gas, the phenomena are such as might be 
 expected. 
 
 If the power of bodies to burn in oxymuriatic gas 
 depended upon the presence of oxygene, they all ought 
 to burn with much more energy in the new compound ; 
 but copper and antimony, and mercury, and arsenic, and 
 iron, and sulphur have no action upon it, till it is de- 
 composed ; and they act then according to their relative 
 attractions on the oxygene, or on the oxymuriatic gas. 
 
 There is a simple experiment which illustrates this 
 idea ; Let a glass vessel containing brass foil be exhausted, 
 and the new gas admitted, no action will take place ; 
 throw in a little nitrous gas, a rapid decomposition occurs, 
 and the metal burns with great brilliancy. 
 
 Supposing oxygene and oxymuriatic gas to belong to 
 the same class of bodies ; the attraction between them 
 
Elementary Nature of Chlorine. 69 
 
 might be conceived very weak, as it is found to be, and 
 they are easily separated from each other, and made 
 repulsive by a very low degree of heat. 
 
 The most vivid effects of combustion known, are those 
 produced by the condensation of oxygene or oxymuriatic 
 gas ; but in this instance, a violent explosion with heat 
 and light are produced by their separation, and expansion. 
 a perfectly novel circumstance in chemical philosophy. 
 
 This compound destroys dry vegetable colours, but 
 first gives them a tint of red. This and its considerable 
 absorbability by water would incline one to adopt Mr. 
 CHENEVIX'S idea that it approaches to an acid in its 
 nature. It is probably combined with the peroxide of 
 potassium in the hyperoxymuriate. 
 
 That oxymuriatic gas and oxygene combine and separate 
 from each other with such peculiar phaenomena, appears 
 strongly in favour of the idea of their being distinct, 
 though analogous species of matter. It is certainly 
 possible to defend the hypothesis that oxymuriatic gas 
 consists of oxygene united to an unknown basis ; but 
 it would be possible likewise to defend the speculation 
 that it contains hydrogene. 
 
 Like oxygene it has not yet been decomposed ; and I 
 sometime ago made an experiment, which like most of 
 the others I have brought forward, is very adverse to the 
 idea of its containing oxygene. 
 
 I passed the solid oxymuriate of phosphorus in vapour, 
 and oxygene gas together through a green glass tube 
 heated to redness. 
 
 A decomposition took place, and phosphoric acid was 
 formed, and oxymuriatic gas was expelled. 
 
 Now, if oxygene existed in the oxymuriate of phos- 
 phorus, there is no reason why this change should take 
 place. On the idea of oxymuriatic gas being undecom- 
 pounded, it is easily explained. Oxygene is known to 
 
/O Davy. 
 
 have a stronger attraction for phosphorus than oxymuriatic 
 gas has, and consequently ought to expel it from this 
 combination. 
 
 As the new compound in its purest form is possessed 
 of a bright yellow green colour, it may be expedient to 
 designate it by a name expressive of this circumstance, 
 and its relation to oxymuriatic gas. As I have named 
 that elastic fluid Chlorine, so I venture to propose for 
 this substance the name Euchlorine, or Euchloric gas 
 from u and xAwpos. The point of Nomenclature I am not, 
 however, inclined to dwell upon. I shall be content to 
 adopt any name that may be considered as most 
 appropriate by the able chemical philosophers attached 
 to this Society. 
 
 %* In page 48, it is stated that magnesia is not decomposed by 
 oxymuriatic gas at a red heat. From some experiments of M. M. 
 GAY LUSSAC, and THENARD, Bullet, de la Societ. Phil. Mai, 1810, 
 it appears that oxygene is procured by passing oxymuriatic gas over 
 magnesia, at a high temperature, and that a muriate indecomposable 
 by heat is proved. They attribute the presence of this oxygene to 
 the decomposition of the acid, but according to all analogies, it must 
 arise from the decomposition of the earth. 
 
Elementary Nature of Chlorine. 71 
 
 An Account of some new Experiments on the 
 Jhtoric Compounds ; with some Observations 
 on other Objects of Chemical Inquiry.* 
 
 Read February 13, 1814. 
 
 I have made many new experiments with the hope 
 of decomposing chlorine, but they have been all un- 
 availing ; nor have I been able to gain the slightest 
 evidence of the existence of that oxygen which many 
 persons still assert to be one of its elements. 
 
 I kept sulphuret of lead for some time in fusion in 
 chlorine, the results were sulphurane (Dr. THOMSON'S 
 liquor) and plumbane (muriate of lead) ; not an atom of 
 sulphate of lead was formed in the experiment, though if 
 any oxygen had been present, this substance might have 
 been expected to have been produced. 
 
 I heated plumbane (muriate of lead) in sulphurous acid 
 gas, and likewise in carbonic acid gas, but no change was 
 produced ; now, if oxygen had existed either in chlorine, 
 or in its combination with lead, there is every reason to 
 believe, that the attractions of the substances concerned 
 in these experiments would have been such as to have 
 produced the insoluble and fixed salts of lead, the sul- 
 phate in the first case, and the carbonate in the 
 second. 
 
 I shall not enter into any discussion upon the experi- 
 
 * [From " Philosophical Transactions" for 1814, vol. 104, pp. 62- 
 73. Part reprinted, pp. 68-72]. 
 
72 Davy. 
 
 ments in which water is said to be produced by the action 
 of muriatic gas on ammonia : there is, I believe, no 
 enlightened and candid person, who has witnessed the 
 results of processes in which large quantities of muriate 
 of ammonia, made by the combination of the gases in 
 close vessels, have been distilled, without being satisfied, 
 that there is no more moisture present, than the minute 
 quantity which is known to exist in the compound vapours 
 diffused through ammoniacal and muriatic acid gases, 
 which cannot be considered either as essential to the 
 existence of the gases, or as chemically combined with 
 them.* 
 
 One of the first experiments that I made, with the hope 
 of detecting oxygen in chlorine, was by acting upon it by 
 ammonia, when I found that no water was formed, and 
 that the results were merely muriate of ammonia and 
 azote ;t and the driest muriate of ammonia, I find, when 
 heated with potassium, converts it into muriate of potassa, 
 which result would be impossible on the hypothesis of 
 oxymuriatic gas being a compound of oxygen, for, if 
 there was a separation of water during the formation of 
 the muriate, the same oxygen could not be supposed to 
 be detached in water, and yet likewise to remain so as to 
 form part of a neutral salt. 
 
 If water had been really formed during the action of 
 chlorine on ammonia, the result would have been a most 
 important one : it would have proved either that chlorine 
 or azote was a compound, and contained oxygen, or that 
 both contained this substance ; but it would not have 
 proved the existence of oxygen in chlorine, till it had 
 
 * Dr. HENRY found it very difficult to free ammonia from the 
 aqueous vapour existing in it by hydrate of potassa, and probably 
 the hydrated muriatic vapour which I have detected in muriatic acid 
 gas, by a freezing mixture, is not decomposable by muriate of lime. 
 
 t Philosophical Transactions for 1810. [This Reprint, pp. 25-26.] 
 
Elementary Nature of Chlorine. 73 
 
 been shewn that the azote of the ammonia was unchanged 
 in the operation. 
 
 Some authors continue to write and speak with scepti- 
 cism on the subject, and demand stronger evidence of 
 chlorine being undecompounded. These evidences it is 
 impossible to give. It has resisted all attempts at decom- 
 position. In this respect, it agrees with gold, and silver, 
 and hydrogen, and oxygen. Persons may doubt, whether 
 these are elementary bodies ; but it is not philosophical 
 to doubt, whether they have not been resolved into other 
 forms of matter. 
 
 By the same mode of reasoning is that in which 
 oxygen is conceived to exist in chlorine , any other species 
 of matter might be supposed to form one of its constituent 
 parts ; and by multiplying words all the phenomena might 
 be satisfactorily explained. Thus in the simple view of 
 the formation of muriatic acid, it is said one volume of 
 chlorine combines with one of hydrogen, and they form 
 two volumes of muriatic acid gas. In the hypothesis of 
 chlorine containing oxygen, it is said, the oxygen of the 
 chlorine combines with the hydrogen to form water, and 
 this water unites to an unknown something, or dry 
 muriatic acid, to produce a gaseous body. If it were 
 asserted that chlorine contained azote, oxygen, and this 
 unknown body, then it might be said, that, in the action 
 of hydrogen on chlorine, the azote, the oxygen and the 
 chlorine, having all attractions for hydrogen, enter into 
 union with it, and form a quadruple compound. 
 
 Professor BERZELIUS has lately adduced some argu- 
 ments, which he conceives are in favour of chlorine being 
 a compound of oxygen from the laws of definite pro- 
 portions; but I cannot regard these arguments of my 
 learned and ingenious friend as possessing any weight. 
 By transferring the definite proportions of oxygen to the 
 metals, which he has given to chlorine, the explanation 
 
74 Davy. 
 
 becomes a simple expression of facts; and there is no 
 general canon with respect to the multiples of the pro- 
 portions in which different bodies combine. Thus azote 
 follows peculiar laws in combining with every different 
 body ; it combines with three volumes of hydrogen, with 
 half a volume of oxygen, with 1.2 and ij of the same 
 body, and with four volumes of chlorine. 
 
 The chemists in the middle of the last century had an 
 idea, that all inflammable bodies contained phlogiston or 
 hydrogen. It was the glory of LAVOISIER to lay the 
 foundations for a sound logic in chemistry, by shewing 
 that the existence of this principle, or of other principles, 
 should not be assumed where they could not be detected. 
 
 In all cases, in which bodies support combustion or 
 form acids, oxygen has been supposed by the greater 
 number of modern chemists to be present ; but as there 
 are many distinct species of inflammable bodies, so there 
 may be many distinct species of matter which combine 
 with them with so much energy, as to produce heat and 
 light ; and various bodies appear capable of forming acids ; 
 thus hydrogen enters into the composition of nearly as 
 many acids as oxygen, and three bodies, namely, sul- 
 phuretted hydrogen, muriatic acid, and fluoric acid which 
 contain hydrogen, are not known to contain oxygen. 
 The existence of oxygen in the atmosphere, and its action 
 in the economy of nature, and in the processes of the 
 arts, have necessarily caused it to occupy a great portion 
 of the attention of chemists, and, being of such import- 
 ance, and in constant operation, it is not extraordinary, 
 that a greater number of phenomena should be attributed 
 to it, than it really produces. 
 
 In the views that I have ventured to develope, neither 
 oxygen, chlorine, or fluorine, are asserted to be elements; 
 it is only asserted, that, as yet, they have not been 
 decomposed. 
 
Elementary Nature of Chlorine. 75 
 
 As the investigation of nature proceeds, it is not im- 
 probable, that other more subtile bodies belonging to this 
 class will be discovered, and perhaps some of the 
 characteristic differences of those substances, which ap- 
 parently give the same products by analysis, may depend 
 upon this circumstance. 
 
 * * * * * 
 
 On the fallacy of the experiments in which 
 water is said to have been formed by the 
 decomposition of Chlorine* 
 
 Read February 12, 1818. 
 
 SOME experiments have been lately communicated to 
 the Royal Society of Edinburgh, from which it has 
 been inferred, that water is formed during the action of 
 muriatic acid gas on certain metals, and consequently, 
 that chlorine is decomposed in this operation. 
 
 In repeating those experiments, I have ascertained, 
 that the water is derived from sources not suspected by 
 the authors, and that their conclusions are unfounded. 
 To take up the time of the Society by long experimental 
 details and theoretical speculations on such an occasion, 
 will be unnecessary ; I shall therefore only transiently 
 mention the sources of error, and demonstrate their 
 operation by two or three examples. 
 
 When muriatic acid gas is passed through flint glass 
 tubes heated to redness, a small quantity of water is 
 formed by the action of the gas on the oxide of lead in 
 
 *[From "Philosophical Transactions" for 1818, vol. 108, pp. 
 169-171.] 
 
76 Davy. 
 
 the glass, and a smaller quantity by its action on the 
 alkali of the glass, the process being one of double affinity, 
 the hydrogen of the muriatic acid unites to the oxygen of 
 the oxide, and the chlorine combines with the metals. 
 
 A copious dew was formed by passing muriatic acid 
 gas through flint glass tubes red hot, and a less copious 
 dew, by passing it through green glass tubes. In the 
 first instance, the glass became opaque, and gained a 
 pearly lustre, and a combination of chlorine and lead 
 sublimed from the hotter into the colder part of the tube. 
 In the second, the surface of the tube became slightly 
 opaque, but no sublimate was formed. 
 
 When fine clean iron wire was introduced into such 
 tubes, and made red hot, and muriatic acid gas passed 
 over it, no particular precautions being taken to free the 
 tubes from common air, much more water appeared ; but 
 this excess of water principally owed its existence to the 
 combination of hydrogen disengaged from the muriatic 
 acid gas by the iron with the oxygen of the common air. 
 I say, principally, because an inappreciable quantity must 
 have been deposited from the vapour of hydrated muriatic 
 acid in the muriatic acid gas. This was proved by filling 
 the whole apparatus with hydrogen in another experi- 
 ment, and generating the muriatic acid gas in a retort 
 filled with hydrogen, when the water produced was no 
 more than might have been expected from the action of 
 the muriatic acid gas on the oxide of lead and alkali in 
 the glass. I give the details. Above 21 grains of the 
 first combination of chlorine and iron were formed ; the 
 quantity of moisture collected by bibulous paper, and 
 which was a strong acid solution of the proto-muriate of 
 iron, amounted to less than half a grain, and of this not 
 more than two-thirds could have been water. Now, if 
 chlorine had been decomposed in this operation, the quan- 
 tity of water ought to have been at least ten times as great. 
 
Elementary Nature of Chlorine. 77 
 
 I have shown by numerous experiments, that in the 
 action of muriatic acid gas upon metals, hydrogen, equal 
 in bulk to half the volume of the gas, is produced ; it is 
 therefore evident, that if water had been generated by the 
 action of muriatic acid gas on metals, it must have been 
 the chlorine, or the metal, or both, that were decomposed. 
 As chlorine can be freed from much of its aqueous vapour 
 by dry muriate of lime, which is not the case with muriatic 
 acid gas, it offers a much more unexceptionable substance 
 for experiments of this kind. I passed 23 cubical inches 
 of chlorine slowly through dry muriate of lime into a flint 
 glass tube red hot, containing a green glass tube full 
 of iron wire ; the chlorine combined with this iron wire 
 with intense heat ; the bright sublimate formed was 
 passed through more iron wire heated to redness, so 
 as to form a considerable quantity of the first compound 
 of chlorine with iron, which, when examined, was found 
 exactly the same as that produced by the action of 
 muriatic acid gas on iron. All the products were heated 
 strongly, and the end of the glass tube kept very cool ; but 
 not the slightest appearance of moisture was perceptible. 
 
 In all these experiments I was assisted by Mr FARADAY 
 of the Royal Institution. 
 
 Muriate of ammonia is not altered by being passed 
 through porcelain or glass tubes heated to redness, but if 
 metals be present, it offers similar results to muriatic acid 
 gas. In one experiment, in which muriate of ammonia 
 recently sublimed was used, instead of muriatic acid gas, 
 the appearance of moisture was less than in the experi- 
 ment on muriatic acid gas, which has been just detailed, 
 and yet there was a considerable action on the oxide of 
 lead in the glass, not only by the muriatic acid, but like- 
 wise by the free hydrogen of the decomposed ammonia. 
 
78 
 
 LIST OF PAPERS Reprinted, wholly or in part, 
 in the present volume. 
 
 The Bakerian Lecture, An Account of some new 
 analytical Researches on the Nature of certain 
 Bodies, particitlarly the Alkalies, Phosphorus, 
 Stdphtir, Carbonaceous Matter, and the Acids 
 hitherto undecompounded ; with some general 
 Observations on Chemical Theory. 1 808, page 5 
 
 New analytical Researches on the Nature of certain 
 Bodies, being an Appendix to the Bakerian Lec- 
 ture for 1808. 1809, - page 1 8 
 
 The Bakerian Lecture for 1809. On some new 
 Electro-chemical Researches, on various objects, 
 particularly the Metallic Bodies, from the Alka- 
 lies, and Earths, and on some Combinations of 
 Hydrogene. 1 809, - - page 20 
 
 Researches on the oxymuriatic Acid, its Nature and 
 Combinations ; and on the Elements of the muri- 
 atic Acid. With some Experiments on Sulphur 
 and Phosphorus, made in the Laboratory of the 
 Royal Institution. 1 8 1 o, page 2 1 
 
 The Bakerian Lecture. On some of the Combinations 
 of Oxymuriatic Gas and Oxygene, and on the 
 chemical Relations of these Principles to inflam- 
 mable Bodies. 1810, - - page 40 
 
 On a Combination of Oxymuriatic Gas and Oxygene 
 Gas. 1811, - page 63 
 
 An Account of some new Experiments on the fluoric 
 Compounds; with some observations on other 
 Objects of Chemical Inquiry. 1814, page 7 1 
 
 On the fallacy of the experiments in which water is 
 said to have been fortned by the decomposition of 
 Chlorine. 1818, - - - - page 75 
 
ALEMBIC CLUB REPRINTS. 
 
 Crown Octavo. Cloth. Uniform. 
 May be purchased separately or in complete seta. 
 
 VOLUMES ALREADY PUBLISHED. 
 
 No. 1. EXPERIMENTS UPON MAGNESIA ALBA, Quick- 
 Lime and some other Alcaline Substances. By JOSEPH 
 BLACK, M.D. 1755. 48 pp. Price is. 6d. net. 
 
 No. 2.-FOUNDATIONS OF THE ATOMIC THEORY: 
 
 Comprising Papers and Extracts by JOHN DALTON, WILLIAM 
 HYDE WOLLASTON, M.D., and THOMAS THOMSON, M.D. 
 1802-1808. 48 pp. Price is. 6d. net. 
 
 No. 3. EXPERIMENTS ON AIR. Papers published in the 
 Philosophical Transactions. By the Hon. HENRY CAVENDISH, 
 F.R.S, 1784-1785. 52pp. Priceis.6d.net. 
 
 No. 4 FOUNDATIONS OF THE MOLECULAR THEORY : 
 
 Comprising Papers and Extracts by JOHN DALTON, JOSEPH 
 Louis GAY-LUSSAC, and AMEDEO AVOGADRO. 1808-1811. 
 52 pp. Price is. 6d. net. 
 
 No. 5.-EXTRACTS FROM MICROGRAPHIA. By R. 
 
 HOOKE, F.R.S. 1665. 52 pp. Price is. 6d. net. 
 
 No. 6. THE DECOMPOSITION OF THE ALKALIES AND 
 ALKALINE EARTHS. Papers published in the Philo- 
 sophical Transactions. By HUMPHRY DAVY, Sec. R.S. 1807- 
 1808. 52 pp. Price is. 6d. net. 
 
 No. 7.-THE DISCOVERY OF OXYGEN. Part I. Experi- 
 ments by JOSEPH PRIESTLEY, LL.D. 1775. 5^ pp. Price 
 is. 6d. net. 
 
 No. 8. THE DISCOVERY OF OXYGEN. Part II. Expert- 
 ments by CARL WILHELM SCHEELE. 1777. 46 pp. Price 
 is. 6d. net. 
 
 No. 9.-THE ELEMENTARY NATURE OF CHLORINE. 
 
 Papers published in the Philosophical Transactions. By 
 HUMPHRY DAVY, Sec. R.S. 1810-1818. 80 pp. Price 
 2s. net. 
 
 No. 10.-RESEARCHES ON THE ARSENIATES, PHOS- 
 phates, and Modifications of Phosphoric Acid. By 
 
 THOMAS GRAHAM. 1833. 46 pp. Price is. 6d. net. 
 
 No. 11. ESSAYS OF JEAN REY, Doctor of Medicine, On 
 an Enquiry into the Cause Wherefore Tin and Lead 
 Increase in Weight on Calcination. 1630. 54 pp. Price 
 is. 6d. net. 
 
ALEMBIC CLUB REPRINTS. 
 
 Crown Octavo. Cloth. Uniform. 
 May be purchased separately or in complete sets. 
 
 VOLUMES ALREADY PUBLISHED. 
 
 No. 12. -THE LIQUEFACTION OF GASES. - Papers by 
 
 MICHAEL FARADAY, F.R.S., 1823-1845. With an Appendix. 
 80 pp. Price 2s. net. 
 
 No. 13. THE EARLY HISTORY OF CHLORINE. Papers 
 by CARL WILHELM SCHEELE, 1774 ; C. L. BERTHOLLET, 1785 ; 
 
 GUYTON DE MORVEAU, 1787 ; JOSEPH LOUIS GAY-LUSSAC 
 
 and L. J. THENARD. 1809. 50 pp. Price is. 6d, net. 
 
 No. 14.-RESEARCHES ON THE MOLECULAR ASYM- 
 
 metry of Natural Organic Products. Lectures by Louis 
 PASTEUR. 1860. 46 pp. Price is. 6d. net. 
 
 No. 15. THE ELECTROLYSIS OF ORGANIC COM- 
 POUNDS. Papers by HERMANN KOLBE. 1845-1868. 
 16 pp. Price is. 6d. 
 
 Postageofanyoftheabouetoanypartofthe World, 2d. each extra. 
 
 In Preparation. 
 PAPERS ON ETHERIFICATION AND OTHER SUBJECTS. 
 
 By ALEXANDER W. WILLIAMSON, LL.D., F.R.S., etc. 
 
 Also Published by the Alembic Club : 
 
 LECTURES ON THE HISTORY OF THE DEVELOPMENT 
 of Chemistry since the time of Lavoisier. By Dr A. 
 LADENBURG, Professor of Chemistry in the University of 
 Breslau. Translated from the Second German Edition by 
 LEONARD DOBBIN, Ph.D. Cloth, 8vo, 373. Price 6s. 6d. 
 net ; by post, 6s. lod. 
 
 (Ebmbttrgh : 
 PUBLISHED BY THE ALEMBIC CLUB. 
 
 Edinburgh. Agent: 
 WILLIAM F. CLAY, 18 TEVIOT PLACE. 
 
 London Agents: 
 SIMPKIN, MARSHALL, HAMILTON, KENT & CO., LTD. 
 
RETURN CIRCULATION DEPARTMENT 
 TO* 202 Main Library 
 
 LOAN PERIOD 1 
 HOME USE 
 
 2 
 
 3 
 
 4 
 
 5 
 
 6 
 
 ALL BOOKS MAY BE RECALLED AFTER 7 DAYS 
 
 1 -month loans may be renewed by calling 642-3405 
 
 6-month loans may be recharged by bringing books to Circulation Desk 
 
 Renewals and recharges may be made 4 days prior to due date 
 
 DUE AS STAMPED BELOW 
 
 APR 2 2 1980 
 
 
 INTER-LIBRARY 
 
 
 LOAN 
 
 
 
 
 ja-c. em. W 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 | 
 
 
 FORM NO. DD6 60m 
 
 UNIVERSITY OF CALIFORNIA, BERKELEY 
 1 1 778 BERKELEY, CA 94720 
 
U.C. BERKELEY LIBRARIES 
 
 COOS240522