THE EARLY HISTORY OF CHLORINE aiembic Clnb IRcpttnts, ^^mimsmEw- aiftnfitt €lab Eeprints — 0o. 13. THE EARLY HISTORY OF CHLORINE. Papers by CARL WILHELM SCHEELE (I774). C. L. BERTHOLLET (1785). GUYTON DE MORVEAU (1787). J. L. GAY-LUSSAC and L. J. THENARD. (1809). EDINBURGH : Published by THE ALEMBIC CLUB. Edi7ibiirs,h Agent: WILLIAM F. CLAY, 18 Teviot Place. Londoji Agents: SIMPKIN, MARSHALL, HAMILTON, KENT, & CO. LTD. 1905. ^/§/. ^-^A 1 O'NEILL UBHARY BOSTON COLLEG PREFACE. THE history of chlorine forms one of the most interesting and important chapters in the whole of chemistry, and this collection of papers is issued in order that students may have access to all the important early work on the subject. The volume containing Davy's researches (Reprint No. 9) may be taken as a continuation of the present one. The first paper contains Scheele's description of the discovery of chlorine, made accidentally when he was investigating the properties of "Brunsten" (black oxide of manganese). It is interesting to note, not only his clear and wonderfully correct views as to the nature of the substance, but also the very full description of it which he gives in a small space. In marked contrast to the preceding one is the long paper by Berthollet, in which, carried away by his zeal for Lavoisier's doctrines, he propounds the view that chlorine is the higher oxide of an as yet unknown radical. This view, although founded so loosely, obtained general adoption, and became so firmly rooted that it was only given up after one of the fiercest controversies connected with the science. The extract from de Morveau's Memoir is reprinted simply to shew clearly the position of chemists at that time. Although not directly connected with the matter 4 Pi'eface. in hand, it is perhaps permissible to call the attention of any chemists who use the expression "radicle" to the historical authority for " radical " contained in the second paragraph of the extract. The extracts from Gay-Lussac and Thenard bring us to the time of Davy. These three investigators were simultaneously engaged in investigating the properties of chlorine and hydrochloric acid, and endeavouring to isolate the radical. Before long, Davy concluded that chlorine contained no oxygen, but was itself an element ; this view was not adopted by his rivals till considerably later. Nevertheless, it is sometimes claimed that Gay- Lussac and Thenard first established the elementary nature of chlorine. This claim is apparently founded on the statement at the end of the paper now reprinted (p. 48). That it is not justified is clearly shewn by the extract from their " Physico-chemical Researches " given at the end of the present volume. As in the other translations of the Alembic Club Reprints, the endeavour has been to give a fairly accurate reproduction of the author's language rather than an elegant versioa H. M. ON MANGANESE And its Properties. By Carl Wilhelm Scheele.* * * * * ♦ Behaviour of Manganese with common Marine Acid, 6. {a) One ounce of pure spiritus salts was poured on half an ounce of finely-ground manganese. After this mixture had stood one hour in the cold, the acid had assumed a dark brown colour. Part of this solution was poured into a bottle, which was left open in a warm place. The solution gave off a smell like warm aqua regis^ and after a quarter of an hour it was clear and colourless as water, and the smell was gone, {b) The remainder of the brown mixture was set to digest, in order to see whether the marine acid would saturate itself with man- ganese. As soon as the mixture became warm, its smell of aqua regis became considerably augmented, and an effervescence also arose, which continued till the follow- ing day, when the acid was found to be saturated. On the residue which it had been unable to dissolve, there was again poured one ounce of spiritus salis, where- upon all the above-mentioned phenomena occurred, and the manganese became completely dissolved, except a little siliceous earth. 23. The sixth paragraph shews the behaviour of man- ganese with marine acid. In this case it is not so easy * [Translated from "Om Brunsten, eller Magnesia, och dess Egen- skaper,"Kong. Vetenskaps Academiens Handlingar, xxxv., pp. 89, 93, 94, 105-110. Stockholm, 1774.] 6 Scheele, to understand at first whence the manganese has obtained its phlogiston ; nothing combustible is added here, and nevertheless the complete dissolution of the manganese can be effected without heat. In fact, there occurs here a phenomenon which proves that phlogiston is certainly present in marine acid — a property which one would have attributed to nitrous acid, since chemists, subse- quent to Stahl, have believed that this principle is required in considerable quantity as one of its constit- uents. That, however, we may now reverse and attri- bute to marine acid. When marine acid stood over manganese in the cold it acquired a dark reddish brown colour (§ 6, a). As man- ganese does not give any colourless solution without uniting with phlogiston, it follows that marine acid can dissolve it without this principle. But such a solution has a blue or a red colour (§ 14, No. 4). The colour is here more brown than red, the reason being that the very finest portions of the manganese, which do not sink so easily, swim in the red solution ; for without these fine particles the solution is red, and red mixed with black makes brown. The manganese has here attached itself so loosely to acidum salis that water can precipitate it, and this precipitate behaves like ordinary manganese. When, now, the mixture of manganese and spiritus salts was set to digest, there arose an effervescence and smell of aqua regis (§ 6, b). In order clearly to apprehend this novelty I took a retort containing a mixture of manganese and acidum salis. In front of the neck I bound a bladder emptied of air,* and set the retort in hot sand. The bladder became distended by the effervescence in the retort. When the acid no longer effervesced, which was an indication of its saturation, I removed the bladder, and [* Compare Alembic Club Reprint, No. 8, § 30.] On Manganese^ and its Properties, 7 j .,^/ '^ found that this air had coloured it yellow, as if by aqua fortts, but did not contain any trace of aer fixus ; it had, however, a quite characteristically suffocating smell, which was most oppressive to the lungs. It resembled the smell of warm aqua regis. The solution in the retort was clear, inclining to yellow, which last mentioned colour was caused by its containing iron. If one wishes to be convinced that this dissolved manganese contains phlogiston, let him precipitate the solution with alkali tartaric edulcorate the precipitate, and then proceed therewith as is described in § 15, «, ^, c. But whence has this manganese obtained phlogiston ? From acidum salis. Here we cannot have recourse to heat, because the solution becomes clear without it, only it must stand several hours in the open air. What happens to the solution is as follows : The manganese is first attracted by the marine acid, whence a brown solution arises. By the help of the acid this dissolved manganese acquires a strong attraction for phlogiston (§ 14, No. 2), and actually draws it to itself from the particles of acid with which it is united. This part of the acid, which has thus lost one of its constituents and is only very loosely united to the now more phlogisticated manganese, is driven out from its earth by the remaining marine acid which has not yet suffered any decomposition, and appears then, with effervescence, as a highly elastic air, or similar fluid ; the brown colour has then disappeared and a water-clear solution resulted. 24. This marine acid, deprived of phlogiston as one of its constituents, unites with water in very small quan- tity; and gives the water a slightly acid taste; but as soon as it comes in contact with a combustible matter it becomes again a proper marine acid. In order to investigate the properties of this air it is best to put it to the test in the elastic state. Ordinary marine acid 8 Scheele, is mixed with finely-ground manganese, in any chosen quantity, in a glass retort which is placed on warm sand ; small bottles which hold about twelve ounces of water are employed as receivers; about two drachms of water are put into each bottle, and the joints are not luted except by means of grey paper wrapped round the neck of the retort, and on this the bottle is fixed. When a bottle has remained a quarter of an hour or more, it is found, according to the quantity of the elastic acid in the receiver, that the air in it assumes a yellow colour ; the bottle is then removed from the retort. If the paper luting has held tight, a part of the air escapes with force; a previously fitted cork is then immediately inserted into the bottle, and another bottle is fixed to the neck of the retort in its stead. In this way several bottles can be partly filled with dephlogisticated marine acid. It is to be noted that the retort must be placed in such a posidon that in case drops should rise into the neck they can flow back, The water in the bottles serves this purpose, that, should any vapour of muricitic acid pass over, it may have this water to which it may betake itself. I take more than one bottle so that it is not necessary for me to start a new distillation for each experiment that I make. It is not advantageous to fill large globes, as a good deal of the acid escapes into the air every time they are opened. 25. Whatever was experimented with in this dephlo- gisticated marine acid was hung on a glass tube which I fastened into the cork, {ti) The corks in the bottles became yellow, as from aqua fortiSy and during the distil- lation the luting was likewise attacked, {b) Blue litmus paper became almost white ; all vegetable flowers — red, blue, and yellow — became white in a short time; the same thing also occurred with green plants. In the meantime the water in the bottle became changed to a On Manganese, and its Properties. g weak and pure marine acid, (c) The former colours of these flowers, as well as those of the green plants, could not be restored either by alkalies or by acids, (d) Ex- pressed oils and animal fats, when they hung as drops on the glass tube or were rubbed on it, became in a short time tough like turpentine, (e) Cinnabar became white on the surface, and when the piece was washed in water a pure mercurius sublimatus solution was obtained, but the sulphur was not altered. {f) Iron vitriol be- came red, and deliquesced. Copper and zinc vitriols were unaltered, {g) Iron filings were put into the same bottle and they dissolved. This solution was evaporated ad siccum and distilled with addition of oil of vitriol, when a pure marine acid, which did not dissolve gold, again passed over, {k) All metals were attacked, and with gold it is noteworthy that its solution in this dephlo- gisticated marine acid forms with alkali volatile an aurum fulminans. (i) When spiritus salis ammoniaci, prepared with lime, hung in drops on the tube, there arose a white cloud, and a quantity of air bubbles escaped from the drops, which gave off a smoke when they burst asunder, {k) Alkali fixum was changed into sal commune which decrepitated on charcoal, but did not detonate. (/) Arsenic deliquesced in these vapours : {in) Insects immediately died in them ; {n) and fire was immediately extinguished by them. 26. This proves sufficiently the great attraction which dephlogisticated marine acid has for the combustible."^ It is possible that Stahl obtained such a dephlogisticated marine acid by means of iron, as he concludes from the yellow colour on the cork, and imagined that the marine acid was changed into nitrous acid. If a mixture of *["Den brenbara" might be translated "phlogiston;" but Scheele also uses the latter word, so the literal translation is adopted here.] lO Scheele on Manganese, and its Properties, manganese, spiritus salts, or spiritus vitrioli, and alcohol vini is digested several days in a well-closed flask, and thereafter gently distilled, there arises no effervescence, but spiritus vini passes over ; it has, however, and this is noteworthy, a strong smell of aetJier nitri. The residue in the retort has lost its acid, and is saturated with man- ganese. If metals, sugar, turpentine, or linseed oil are added to a mixture of ground manganese and marine acid there arises no dephlogisticated marine acid; for here there is sufficient combustible present with which this elastic acid can combine. With mercury it is note- worthy that a good deal of it also goes into the solu- tion, from which it can be obtained by crystallisation, and behaves like corrosive sublimate. If leaves of pure gold are put into a mixture of ground manganese and pure acidum salis, it is found afterwards that this solu- tion contains gold, as well as manganese, dissolved. MEMOIR On Dephlogisticated Marine Acid, By M. Berthollet.* The important experiments by which the nature of water had just been determined, and the happy appUca- tion which M. de la Place had made of them to the production of inflammable gas by the dissolution of metals, threw great light on the whole of chemistry ; phlo- giston, that principle which Stahl had ingeniously imagined in order to account for a large number of phenomena, and by means of which there was really established between them a connection which has served for a long time to guide chemists in their researches, appeared to me to have at last become a useless hypothesis, whereupon I believed it incumbent on me to subject dephlogisticated marine acid to new experiments, as its properties might destroy or confirm the opinion I had adopted. These experiments were the subject of a memoir which I read at the public meeting of 6th April 1785. I shall now enter into greater detail, add some new observations, and reply to some objections which have since then been made to the theory which I had established. Scheele, when investigating the effects which different acids produced on manganese, observed that muriatic acid produced an eff'ervescence with it, and that there * [Translated fiom "Memoires de I'Academie Royalc " for the year 1785. Pp. 276-295. Paris, 1788.] 12 Bertholiet. was disengaged a vapour similar to that from hot aqua regia. He says, " The manganese is first attracted by the muriatic acid, thereafter it acquires, by means of the acid, a stronger affinity for phlogiston, and then it abstracts the latter from the particles of the acid with which it has not itself combined. This portion, thus deprived of one of its constituent parts and feebly united to the phlogisti- cated manganese, is sublimed by the rest of the acid which is still undecomposed, and manifests itself, with effervescence, as a very elastic air or as a fluid resem- bling air. Muriatic acid deprived of phlogiston, which is one of its constituent parts, only unites with water in very small quantity and does not render it strongly acid, but as soon as it meets with a phlogisticated substance it becomes again a true muriatic acid. It is in its elastic state that the qualities of this air are best shewn." He thereafter describes how this vapour ought to be collected in small flasks which are adapted to the neck of the retort, and in which a little water has been placed. Bergman adopted Scheele's view; with him he regards manganese as a substance very avid of phlogiston, and believes that it removes this principle from the marine acid, which thereby acquires the properties characterising the gas of dephlogisticated marine acid, and that this gas acts upon substances which contain phlogiston by remov- ing this principle from them. It is to these two illustrious chemists that we owed the chief and almost the only ideas which we had about dephlogisticated marine acid when I turned my attention to it. I commenced by assuring myself that dephlogisticated marine acid, in the form of gas, combined with water more easily and more abundantly than acid of chalk. After that, I tried to saturate water with it in the least embarrassing manner and without exposing myself to Memoir on Dephlogisticated Marine Acid. 13 breathing it, for it is suffocating. Scheele in his experi- ments employed one part of manganese to two of marine acid; but I have found that one part of manganese to four parts of fuming marine acid, or to six of ordinary marine acid, is sufficient, and even that in these propor- tions there is a fairly considerable portion of manganese which is not attacked by the marine acid. I pour the marine acid on the pulverised manganese contained in a tubulated retort to which I have previously adapted an empty bottle, and, successively, in the manner of M. WouLF, three other bottles almost filled with water; the last bottle communicates by a tube with a vessel which is filled with water, and on which, when the air of the apparatus is expelled and the smell of dephlogisticated marine acid begins to be perceptible, I invert a large bottle likewise full of water. If I employ fuming marine acid the gas begins to come off in abundance without the necessity of applying heat to the retort, but if the marine acid is of only medium strength I put a slight fire below the retort from the commencement, and augment it gradually until the liquid enters into ebullition ; shortly after the ebullition has commenced, the operation comes to an end ; its termina- tion is announced by the drops of marine acid which fall from the beak of the retort into the first bottle. As absorption proceeds, the water assumes a greenish yellow colour, and when it approaches saturation the gas assumes a concrete form; in this state it gradually descends to the bottom of the liquid in small yellowish flakes, so that its specific gravity is a little greater than that of the saturated water; but, to obtain it in this form, it is necessary that the temperature of the place where the experiment is performed should not be too far from the freezing point, and further, the bottles should be surrounded by pounded ice, or, if they are relatively 14 BertholleU too large, it may even be necessary to saturate the liquid by a second operation. Each ounce of marine acid employed suffices to saturate about a pint of water. In a second operation the water contained in the inverted bottle, which has absorbed that portion of the gas which could not enter into combination in the bottles of the apparatus, may be employed for filling these; by this means there is no loss of the gas, and breathing it is avoided. The concrete form of dephlogisticated marine acid resumes the gaseous state when it is exposed to a feeble degree of heat \ if the hand is placed upon the bottom of the bottle which contains it, it is seen to resolve itself into bubbles which rise to the surface ; hence it is difficult to preserve it in closed vessels ; a part, however, dissolves again in the liquid. It is chiefly in the liquid state that I have examined dephlogisticated marine acid ; to determine its specific gravity I decanted the liquid from the concrete part, the thermometer being at 5 degrees above zero, and I found it to be 1003. It has a harsh taste which does not resemble that of the acids. Scheele and Bergman have observed that it destroyed vegetable colours; and it produced this effect, which I shall analyse further on, more or less promptly without any red tint becoming perceptible. A property which specially merits attention is that it does not cause an effervescence with solution of fixed alkali even when the latter is saturated with fixed air. The fixed alkalies, nevertheless, contract an affinity, and combine with it ; for they cause it to lose its colour and a great part of its odour, as lime also does. If, after having added the alkali, acetous acid is poured into it, an effervescence is seen to be immediately produced, as if the alkali were simply dissolved in the water, and the odour regains all its sharpness. The calcareous earth, when it is in the effervescent state, Memoir on Dephlogisticated Marine Acid. 15 has also the property of combining with dephlogisticated marine acid, and dissolves in it in fairly considerable quantity ; it is precipitated from it by all the alkalies, and even by lime water; which proves that lime combines with this liquid more strongly than effervescent calcareous earth does. We can therefore, as it seems to me, regard dephlogis- ticated marine acid as almost entirely deprived of acidity. ScHEELE and Bergman were unable to recognise this essential property, as in the process which they employed the water of the vessels in which they received the gas could contain only a very small portion of dephlogisticated marine acid, mixed with a portion of marine acid which always passes over in the distillation; in my apparatus this portion of marine acid is retained in the first bottle, which I leave empty, and which it is well to surround with ice or cold water. When the operation is not made with sufficient care a little marine acid passes even into the first bottle which is filled with water ; this accident can be easily recognised by pouring into the liquid some solution of effervescing fixed alkali j if any bubbles are seen to be disengaged this is a proof that it contains some marine acid, for it should not produce any effervescence. In a retort at the pneumato-chemical apparatus, I boiled a mixture of mineral alkali and dephlogisticated marine acid ; much gas was disengaged, of which a great part was fixed air, and the other part at first atmospheric air and then air purer than this, but the last portions were hardly anything but fixed air. With lime there is no fixed air disengaged, but atmospheric air which gradually approaches to vital air, and finally a little very pure vital air. The fixed air of the first experiment is thus furnished by the alkali, as it is in the effervescences, the atmospheric air is due to the space which I left empty in the apparatus, and the vital air to the dephlogisticated marine acid. l6 Berthollet. The salt which is found in the retort is similar to sea salt, which explains the observation of Scheele and Bergman as to the identity of the neutral salts formed by dephlo- gisticated marine acid with those of ordinary marine acid. They were obliged to suppose that the alkalies imparted some phlogiston to the dephlogisticated marine acid and that too without themselves suffering any alteration in their properties by this loss. I calcined some manganese at a strong heat in a pneumato-chemical apparatus. I extracted from it, as had already been observed, a large quantity of vital air ; it lost an eighth of its weight. In this state I treated it with marine acid and obtained from it a much smaller quantity of dephlogisticated marine acid. It is therefore to the vital air of the manganese, which combines with the marine acid, that the formation of the dephlogisticated marine acid is due. I ought to state that this theory was presented and announced some time ago by M. Lavoisier, and that M. de Fourcroy has made use of it in his Elements of Chemistry and Natural History to explain the properties of dephlogisticated marine acid such as they were then known. The experiments which I have just described have not appeared sufficiently conclusive to some chemists ; I shall take from the first part of the learned Dictionary of Chemistry, which M. de Morveau has just published, the reasons which can be adduced to prove the necessity of phlogiston in the explanation of the properties of dephlogisticated marine acid. I reduce to three the objections of this celebrated chemist: i.° marine acid does not combine with vital air in the elastic state, how could it remove it from a substance by a simple affinity ? 2.° when dephlogisticated marine acid combines with the alkalies, the earths, or the metals, there is nothing to prove that it does not receive phlogiston or inflammable Memoir on Dephlogisticated Marine Acid. if gas from them in exchange ; for this fluids according to M. DE MoRVEAU, is nothing but phlogistofi itself brought into the state of gas by the matter of heat ; 3.° the differences which manganese presents in the states of regulus, of white calx, and of black calx, and the effects which it produces when it is treated before the blow-pipe or when it is mixed with other substances can only be explained by means of phlogiston. But, i.° the elastic state of a fluid is an obstacle to combination, whatever may be the cause which holds the parts of the fluid in expansion; this is a general fact, for the explanation of which phlogiston is of no service, for, at a low temperature, vital air cannot combine with inflammable gas in the elastic state, although, according to M. DE MoRVEAU, inflammable gas is nothing but phlogiston, and vital air has a great affinity for it. If, then, we do not go back to the cause of the elasticity of fluids, the difficulty is no less great in following the opinion of M. de Morveau; but if we regard vital air as a compound of the principle of light or of heat with a base, as experiments prove, there remains much less obscurity for those who reject the theory of phlogiston. In fact, a substance must be in a state to overcome the affinity which the principle of light has for the base of vital air, in order to expel the former, and form with the latter a new compound ; but marine acid has a very feeble affinity for vital air, it cannot combine with it except by compound affinities, and easily gives it up to all substances with which this principle has any affinity. There will be found at the end of this memoir explanations regarding the third objection. 2.° I saturated distilled water with dephlogisticated marine acid, but although I repeated the operation three times, and the bottle was well surrounded with ice, I could not obtain any in the concrete form, because the B 1 8 Berthollet thermometer was at i8 degrees. With this liquid I filled a bottle communicating by means of a tube with a pneumato-chemical apparatus \ this bottle with the tube, which was itself filled with the liquid, was of the capacity of 5 1. 1 cubic inches; I exposed it to sunlight; I soon saw a large quantity of small bubbles become disengaged, which, on being collected in a bottle filled with water, formed at the end of several days a volume of air of 15.27 cubic inches, the thermometer being at 17 degrees. The dephlogisticated marine acid lost its colour gradually ; in this state the liquid no longer destroys blue vegetable colours but reddens them strongly, like ordinary marine acid ; it produces an effervescence with fixed alkalies ; it retains an odour of dephlogisticated marine acid which is scarcely perceptible; in fine, it is reduced almost entirely to ordinary marine acid. To determine the quantity of this acid which was present in the liquid, I precipitated it by a solution of silver, and, with the same solution, I also precipitated 500 grains of marine acid, of which the specific gravity was to that of distilled water as 1 141 is to 1000, and which I had diluted with distilled water. The two precipitates were dried equally; the 500 grains of marine acid gave 7 gros 43 grains of muriate of silver, and the dephlogis- ticated marine acid gave 5 gros 23 grains, so that, neglecting the volume of liquid which was put into the tube, 50.45 cubic inches of dephlogisticated marine acid contained 350.09 grains of marine acid of a specific gravity equal to that of the 500 grains employed, which comes to about 7 grains per cubic inch of liquid. The air which was disengaged from the dephlogisticated marine acid having been put over a solution of liver of sulphur, was absorbed, leaving a residue of one cubic inch, so that it consisted of vital air, which contained one- fifteenth of mephitic air, the latter being without doubt due Memoir on Dephlogisticated Marine Acid. 19 to some atmospheric air which would be disengaged both from the water and from the apparatus which I employed. I do not deduct its volume, however, because there remained a small portion of dephlogisticated marine acid which had resisted decomposition, and because the water was impregnated with vital air, so much so, that on agitating it, bubbles escaped from it ; there would rather be a small addition to make. Accordingly 51,1 cubic inches of liquid contained 15.27 cubic inches of vital air, at the temperature of 17 degrees, which makes about 0.299 cubic inch of vital air per cubic inch of liquid; but I need not state that in these calculations I do not profess to give anything but approximations. In an experiment made with dephlogisticated marine acid which had been obtained at a lower temperature, and which had been decanted from a concrete portion, I found that the Hquid contained about a quarter less of acid and of vital air ; so that dephlogisticated marine acid follows in its combination with water, a law different from that followed by the other elastic fluids which can combine with it, which unite with it in greater quantity the more the temperature approaches the freezing point : this arises from the tendency of dephlogisticated marine acid gas to take the concrete form by means of cold ; but this difference is limited within a very small compass, for as soon as the thermometer is some degrees above freezing point, dephlogisticated marine acid tends to separate from the water and resume the elastic state. Hence it appears that the best way to obtain this liquid very concentrated is to produce in it a fairly considerable quantity of concrete substance, and then to let this dissolve at a temperature approaching the loth degree of Reaumur's thermometer; it is also at about this degree of heat that we can obtain the greatest effects of the Hquid 20 Berthollet. on the substances which are submitted to its action ; and on applying heat this effect is diminished by the tendency towards the gaseous state which is commun- icated to the dephlogisticated marine acid. This con- sideration may also apply to various other chemical solutions, and serves to explain the interesting observa- tion of M. DE BuTiNi, who noticed that aerated water dissolved so much the more magnesia the colder it was. These experiments ought to dispel any doubts which might remain as to the nature of dephlogisticated marine acid j the latter is manifestly formed by the combination of vital air with marine acid, but in it the vital air is deprived of a part of the principle of elasticity, and adheres so feebly to the marine acid that the action of light suffices to disengage it promptly, light having more affinity for its base than marine acid has. There are, then, two con- ditions which dispose it to quit the marine acid in order to combine with substances with which it has affinity, and which render dephlogisticated marine acid proper to discover what are the properties which depend on combination with vital air, which could not have taken place except by more complicated or much slower means. It is vital air, then, which disguises the properties of dephlogisticated marine acid; it loses them as soon as that prmciple separates from it. Dephlogisticated marine acid dissolves iron and zinc without any gas being disengaged, and in the same manner as water dissolves salt; for that these metals should dissolve in an acid it is only necessary that they should unite with a portion of vital air, as M. Lavoisier has proved; and as dephlogisticated marine acid can furnish them with the portion of vital air necessary when it dissolves them, there is no decomposition of water and no inflammable air is produced. But, if one is inclined to suppose that light gives Memoir on Dephlogisticated Marine A cid. 2 1 phlogiston to the dephlogisticated marine acid which is exposed to it, let us see what are the consequences which would follow therefrom. Firstly, it would require that the light should give phlogiston to dephlogisticated marine acid without communicating any to vital air, with which, however, it is believed that it has a very great affinity ; secondly, as phlogiston is no other than inflammable gas, according to Messrs Kirwan, de Morveau, de la Metherie, and some other chemists, it must be supposed that light contains a large quantity of inflammable gas and that the sun every instant suffers an immense loss of matter. Will one say that iron and zinc contain inflammable gas which they give to dephlogisticated marine acid whilst they combine with its vital air? The difficulty remains unaltered, for light would have to be able to decompose dephlogisticated marine acid just the same. If now, physicists cannot admit that light gives inflammable gas, I say that it would be proved by the ex- periment of which I have just spoken that iron and zinc do not contain inflammable gas, even although the direct experiments which have been made on this subject should not be decisive. Finally, chemists agree that the metals are reduced to calces when they are dissolved by means of marine acid, and consequently that they are combined with vital air ; but it is not the marine acid which has been able to communicate the vital air to them, for it is not decomposed in these dissolutions ; it must necessarily be the water then which furnishes it to them, as it must be it which gives the inflammable gas, as M. de la Place has shewn : these truths lend a mutual support. When solution of mercurial nitre is poured into dephlogisticated marine acid no white precipitate is produced; but on evaporating the liquid, corrosive sub- limate is obtained from it. Similarly, if white precipitate is put into dephlogisticated marine acid it dissolves, the 22 Berthollet. odour and the colour of the dephlogisticated marine acid disappear, vegetable colours are no longer destroyed, and the marine acid is meanwhile in combination ; for, on adding to the liquid a little lime water, there is immedi ately formed a mercurial precipitate, which would not take place if a portion of marine acid were free. Hence it results that the difference between white precipitate and corrosive sublimate consists in this, that in the latter the mercury is combined with a greater quantity of vital air and marine acid. The manner in which dephlogisticated marine acid acts on mercury merits attention ; if some of this liquid is put on a certain quantity of mercury, the surface of the metal blackens, there is formed the calx of mercury known by the name of ethiopsper se^ and the liquid reddens blue paper, so that the metal begins by removing the vital air from the marine acid. If they are still left in contact the calx of mercury which has been formed takes up marine acid and becomes white, it passes into the state of combination known by the name of panacea, and the supernatant water does not contain either acid or mercurial salt ; if it be poured off and dephlogisticated marine acid anew added, there is at once formed a com- bination with the mercurial salt, which, according to the quantities of marine acid which it absorbs, takes successively the properties of mercurius dulcis and of white precipitate, and then, if the liquid is renewed, it dissolves and forms corrosive sublimate ; so that in this experiment the whole series of mercurial muriates is obtained, to which corresponds that of their causticity. ScHEELE announced that dephlogisticated marine acid had no action on sulphur, but M. de Morveau has ascertained that it changes it into vitriolic acid. When some is poured on a small portion of solution of hepar made with fixed alkali, there is no hepatic gas disengaged Memoir on Dephlogisticated Marine Acid. 23 and there is only very little precipitate formed; the odour of the dephlogisticated marine acid is dispelled, and veget- able colours are no longer destroyed; but though hepar acts on them like the alkalies, the mixture of which I have just spoken indicates only an acid, and the solution of heavy spar occasions an abundant precipitate. These phenomena shew that a part of the sulphur of the hepar is changed immediately into vitriolic acid by the dephlogisticated marine acid. I added water saturated with hepatic gas to dephlogisti- cated marine acid ; the colour and the odour of the latter were destroyed, no precipitate was formed, veget- able colours were not altered except as they are by an acid, a solution of lead was precipitated white, and the solution of heavy earth formed an abundant precipitate ; but if a little dephlogisticated marine acid is added to hepaticised water it becomes clouded and a little sulphur precipitates. In the first case the dephlogisticated marine acid and the hepatic gas are destroyed on the instant and entirely, if they are employed in the correct proportions ; the sulphur and the inflammable gas which holds it in solution are reduced by combination with the vital air, the first to vitriolic acid and the second to water : but in the second experiment the vital air combines at first with the inflammable gas, so that a portion of the sulphur is precipitated and can be changed into vitriolic acid only by the addition of a sufficient quantity of dephlogisti- cated marine acid. It is thus that a part of the sulphur is deposited in the combustion of hepatic gas. M. DE MoRVEAU says, that having mixed and agitated nitrous gas with dephlogisticated marine acid in the mercury apparatus, there was an absorption of about the fifteenth of the volume. He says also {page 255, Diet, de Chim.) that when this acid is in the state of liquid it does not absorb nitrous gas even when they are kept in 24 Berthollet. contact for a whole month {ibid., page 263). I will in the first place remark that, as both dephlogisticated marine acid and the nitrous acid which is formed attack mercury, this apparatus is not suitable for determining the action of dephlogisticated marine acid and nitrous gas, and I have observed that nitrous gas is really decomposed and changed into nitrous acid by dephlogisticated marine acid in the liquid form ; but it is mostly in the state of ga? that I have examined their reciprocal action. I mixed four measures of nitrous gas with two measures of dephlo- gisticated marine acid gas, a considerable redness was produced, and the mixture was reduced to 1.4 measure. By employing the calculation of M. Lavoisier, who fixes the ratio of nitrous gas to vital air, in the composition of nitrous acid, as 69 : 40, we may conclude that the two measures of dephlogisticated marine acid contained 1.507 of vital air, which would seem to indicate that this gas has a considerable specific gravity, to contain so much vital air. However, I have not confidence in this result, because nitrous gas dissolves easily in aqua regia, as I have shewn in my Memoir on aqua regia, and consequently a part of the nitrous gas could have been abstracted with- out having really combined with vital air. Four measures of nitrous gas, or 400 parts, were re- duced to 0.35 on passing into it much dephlogisticated marine acid gas, and then absorbing the excess by water. M. DE MoRVEAU adds {ibid., page 251) that dephlo- gisticated marine acid, after having been mixed and agitated with inflammable gas in different proportions, no longer destroyed colours, that it changed blue paper to red, that it had only a very feeble odour, and that there- after the inflammable gas was found detonating. Here again I have not been fortunate in obtaining the same results as this celebrated chemist on this subject ; I passed into a measured quantity of very pure inflamm- Memoir on Dephlogisticated Marine A cid. 2 5 able gas, several times in succession, an equal volume of dephlogisticated marine acid gas which did not contain atmospheric air ; I agitated the mixture each time over water; the absorption of the marine acid gas having been made, the volume of the inflammable gas was not found changed. I then examined this inflammable gas with Volta's eudiometer. It was not detonating ; I mixed it with vital air, and on detonation it destroyed quite as much as an equal quantity of the same gas which had not been agitated with dephlogisticated marine acid. As I have repeated this experiment several times, I am forced to believe that dephlogisticated marine acid has no action on inflammable gas when it is in the gaseous state, just as vital air in the elastic state has none on marine acid I assured myself of this latter fact by a direct experiment, though it is sufficiently convincing to observe that marine acid does not at all assume the properties of dephlo- gisticated marine acid when it is left exposed to atmos- pheric air, of which about a quarter is vital air. Bergman affirms that phosphorus is decomposed by the gas of dephlogisticated marine acid. M. de MoRVEAU and M. Angulo, on the contrary, have made several experiments by which they claim to prove that phosphorus has no action on dephlogisticated marine acid. I observed, like them, that phosphorus had no action on dephlogisticated marine acid in the cold, and if heat is employed without light, the dephlogisticated marine acid is disengaged in the form of gas, without suffering decomposition ; but if a morsel of phosphorus is put into dephlogisticated marine acid and exposed to light, the colour of the acid is dissipated, its odour disappears, the liquid reddens blue vegetable colours, and lime water precipitates calcareous phosphate from it ; so that phos- phorus combines with the vital air of dephlogisticated marine acid, and becomes phosphoric acid. 26 Berthollet Phosphorus, which is exposed to light in dephlo- gisticated muriatic acid, becomes white and opaque be- fore changing into phosphoric acid ; it appears that this state is due to a portion of vital air, which is insuflficient to give it the properties of an acid ; it is probably thus that phosphorus whitens on the surface when it is pre- served for a long time in water ; when it is entirely in this state it could be compared to sulphurous acid relatively to vitriolic acid, only that has not yet sufficient vital air to be sensibly acid. It is probably phosphorus thus com- bined with a portion of vital air which M. de Morveau has called the acidifiable base of phosphorus^ which he obtained by exposing phosphoric acid in a crucible to a considerable degree of heat \ for the portion of vital air which was least adherent to the acid, has been forced to dissipate itself, and there was bound to remain a com- bination of phosphorus and a little vital air, which is less combustible and less liable to be attacked by nitrous acid 1°, because the affinity of the phosphorus for vital air is already satisfied in part, 2°, because the heat which would be disengaged at the commencement, when the combination took place with the greatest force, cannot in this case aid that part of the combination which takes place only through a feeble affinity. It is thus that sulphur is immediately reduced to vitriolic acid if the combustion is vivid ; but that, if the combustion is slow, only sul- phurous acid is formed, which then assumes the state of vitriolic acid with some difficulty. It is probable that ordinary phosphoric glass similarily retains a greater or less quantity of vital air. Chemists in general have belie i^ed that all the colours of bodies are due to the same principle diversely modi- fied and combined in different proportions. Bergman in particular has attributed them to phlogiston (Mem. sur I'indigo) and he has claimed to prove by ingeni- Memoir on Dephlogisticated Marine Acid. 27 ous experiments that the different proportions of this principle cause the variations of colours : thus nitrous acid, which, according to him, is yellow when it has an excess of phlogiston, becomes green if water is added to it, and then blue on further diluting it. The different proportions of vital air which it is here necessary to substitute for phlogiston have a great influence on colours, as the following experiments go to prove; nevertheless nothing in general can be concluded with regard to it, for vital air gives a yellow colour to marine acid, whilst if the proportion in nitrous acid be diminished, this like- wise becomes coloured yellow; for it is by driving off vital air that this acid is coloured by light, as I have assured myself by experiments which I have described elsewhere {^Journal de physique). The calces of iron, as may be seen in Kirwan's Elements of Mineralogy, and may be verified by exposing to the air a precipitate obtained from martial vitriol by fixed alkali, pass through the following gradations accord- ing as they are, as he says, more or less dephlogisticated ; blue, green, brown, red, yellow, whitish. If concentrated dephlogisticated marine acid is used to dissolve iron, it gives with alkali a pale yellow precipitate ; if, on the contrary, the same acid diluted with water is put on the metal it takes a blue colour, and the part which dissolves gives with alkali a blue precipitate, which soon passes to green, brown, red, and finally to a bright yellow, accord- ing as more dephlogisticated marine acid is added to it ; so that the colours depend only on the quantity of vital air which unites with the iron, and it is now known that martial ethiops only differs from the other calces of iron in that it contains less vital air. If a solution of copper is precipitated by means of volatile alkali, dephlogisticated marine acid promptly gives to the blue precipitate which has formed, a green colour 28 Berthollet. similar to that which it would take if it was left a long time exposed to air. Not only does dephlogisticated marine acid destroy vegetable colours, so that alkali cannot restore them, but this effect equally takes place even when a quantity of alkali proper for the saturation of the disguised marine acid is put into the liquid. Among the vegetable colours that of violet syrup is destroyed instantly, likewise that of litmus ; but with this latter there remains a yellow tint which resists for some time the action of the liquid ; the same thing takes place with the colouring part of Pernambuco wood, and especially with that of madder. Dephlogisticated marine acid loses its properties by acting on the colouring matters, and it resumes those of marine acid, so that the colouring matters combine with the vital air and remove it from the marine acid ; they thereby become soluble, but some only by means of the acid so that they can be precipitated by an alkali ; others, on the contrary, are soluble in water and are not precipitated by alkali. The green parts of plants are sometimes reduced to white by dephlogisticated marine acid, at other times to yellow ; sometimes they take a reddish colour, in fact they undergo quickly changes perfectly analogous to those which air produces on them naturally ; the leaves of evergreen trees resist for a long time the action of de- phlogisticated marine acid, and finally take in it only the yellow tint which the air can give them. The alterations which air produces on colours depend then principally on the vital air combining with them more or less easily, and in quantity more or less consider- able; and dephlogisticated marine acid can shew in a few moments the effects which air would only produce in a long space of time : thus, whilst it destroys in a moment the greater number of vegetable colours, to destroy the Memoir on Dephlogisticated Marine Acid. 29 colour of indigo it requires to act during several days, and a considerable quantity of it is necessary. I shall avail myself of this means of analysis with much more detail to determine the properties of colouring matters which are employed in dyeing, and endeavour to make of the properties of dephlogisticated marine acid some applica- tions useful to the arts. The action of this liquid appeared to me suitable to give us information as to what happens when plants deprived of light become sickly and whiten, and to explain why plants exposed to the sun give vital air, according to the beautiful observation of M. Ingenhouz, and why there is no elastic fluid disengaged when they are in the shade, as M. Senebier has proved. The oil which enters into the composition of vegetable matters certainly contains much of the inflammable gas obtainable from water, so that it is very probable that water is decomposed in vegetation, that the vital air which it contained is in part exhaled if the light favours its disengagement, as it does for de- phlogisticated marine acid and for nitrous acid, whereas without the aid of this affinity it cannot assume the elastic state j then it combines with the colouring matters if there are any formed, and the plants become white ; but when the decomposition of the water is not favoured by light it takes place probably to a much less extent, vegetation languishes, the plants have much less oily and resinous matter, and thereby are even deprived of colouring matters : M. Senebier also observed that the sickly plants were less inflammable. This theory can be applied to a great number of the phenomena of vegetation {Journal de phys. Aout lySd). But dephlogisticated marine acid, which destroys all vegetable colours more or less easily, acts in a different manner on animal colours ; it gives a yellow colour to silk and wool, which are white, and we know that nitrous acid 30 BertholleU produces a similar effect. It appears then that vital air has the property of combining with animal substances, and turning them yellow by this combination. I have not spoken in this memoir of the phenomena which volatile alkali presents with dephlogisticated marine acid, because I have detailed them in the analysis of volatile alkali ; I will simply remark that when caustic volatile alkali is poured on dephlogisticated marine acid it entirely destroys the colour without producing any precipitate; and if a drop of solution of manganese is added to it a slight blackish precipitate is at once perceived. After the explanations which I have just given I believe that it will suffice to indicate the replies that might be made to some of the difficulties which the learned chemist of Dijon believed could be solved only on the supposition of phlogiston. Manganese treated with fire gives a large quantity of vital air, it loses thereby a part of its black colour, remaining brown however; it cannot dissolve in an acid without losing part of its air, hence vitriolic acid disengages from it a large quantity of vital air on dis- solving it j but, with an acid which has little action on it, it is necessary to add a substance which acts, on its part, by its affinity for vital air ; such are sugar, gum, etc. If the acid which dissolves the manganese has itself affinity for the air, whilst one part unites with the manganese another part combines with the air which is disengaged from it, and it is this which takes place when marine acid is treated with this substance. Let us pause a moment to remark that it is not by a simple affinity that marine acid removes the vital air from the calx of manganese. It is only because a portion of this acid dissolves the manganese and drives from it the portion of vital air which is superfluous to the new com- pound, that the other portion can unite with this vital air Memoir on Dephlogisticated Marine Acid. 31 deprived in part of the principle of elasticity, as the acid has only a feeble affinity for it. The precipitate from solutions of manganese differs from manganese in colour and in properties, because it contains much less vital air, so that it cannot be used to make dephlogisticated marine acid, being deprived of that portion of vital air which could combine with the marine acid. The calx of manganese renders glass red when it is abundantly provided with vital air, this colour is dis- sipated when the less adherent part of the vital air com- bines with some carbonaceous body. The black calx loses its colour in the inner flame of the blowpipe, because fixed air is formed by the carbonaceous portion ; it resumes it again in the external flame because it suffers a new calcination. Lastly, the regulus of man- ganese gives inflammable gas with vitriolic acid and with marine acid, because having much affinity for vital air it has the property of decomposing water ; with nitrous acid it gives nitrous gas, and it detonates with nitre on account of its affinity for vital air, whereas the black calx cannot detonate because it is already saturated with this principle. MEMOIR On the development of the principles of the methodical Nomenclature, read at the Academy^ 2nd May 1787/' By M. DE MORVEAU. Muriatic acid, from the Latin muria, muriaticum^ had already taken the place of marine acid in the writings of some chemists ; but it is well known that as an acid it stands apart, as it can take up an excess of oxygen and in this state its acidity appears rather to diminish than to augment, this probably being caused by the oxygen retaining a greater quantity of caloric in the compound. Whatever might be the cause of this phenomenon there is no doubt that it required a denomination appropriate to this particular character which till the present has very improperly been designated in the name dephlogisticated marine acid. The expression oxygenated muriatic acid, oxygenated muriates, appeared to us the most simple and the most conform to the object which we had proposed to ourselves, namely, to express only well verified facts. It is by a close adherence to this rule that we have ^[Translated from "Methodede Nomenclature chimique, /r^/^j/ par MM. DE Morveau, Lavoisier, Berthollet, and de Four- CROY." Paris 1787. Pp. 45-7.] Morveau. 33 formed the names of all the other compounds of muriatic acid : corrosive sublimate then becomes corrosive mercurial muriate; calomel, mild mercurial muriate; the salt produced by the ordinary dissolution of tin in this acid, muriate of tin ; butter of tin, sublii7ied muriate of tin ; Libavius' Xio^ox ^fumijig muriate of tin ^ etc., etc. Analogy leads us to believe that muriatic acid has an acidifiable base, in the same way as carbonic, sulphuric, and phosphoric acids, which equally serves to give a proper and particular character to the product of its combination with oxygen : this substance we ought not to designate otherwise than by the expression muriatic radical or muriatic radical principle ; so as not to give a name to an unknown substance, and to restrict ourselves to the expression of the only property of it which we know, which is in fact to produce this acid. We have had the same circumspection with reference to all the acids of which our knowledge is no more advanced, and of which it is very possible that in the future the bases will be discovered amongst substances already named. ABSTRACT Of the Memoirs read at the National Institute, from the Jth Ma7%h 1808 to the 2yth Feb- ruary 1809."^^ By MM. Gay-Lussac and Thenard. * -jt * -5«- * In our sixth memoir (Institute, 9th January 1809) we endeavour to obtain fluoric acid perfectly pure in order to isolate its radical and re-compose the acid. These researches lead us to a great number of new results, of which some are very remarkable, and give rise to our eighth memoir, which was read on the 27 th February at the Institute, and has for its object the nature and com- parative properties of oxy-muriatic acid gas and muriatic acid. * * -x- * * Properties of the metal of potash. ■H- -x- ■«■ * * We have also examined the action of the metal of potash on muriatic gas. At the ordinary temperature this action is very slow; but as soon as the metal is fused there is combustion with disengagement of light, and there result muriate of potash and hydrogen gas : as the * [Translated from "Memoires de Physique et de Chimie, de la Societe d'Arcueil," tome ii. Paris, 1809. Pp. 295, 298, 307, 308, 320, 321, 339-358.] Abstract of Memoirs. 35 quantity of hydrogen collected in this experiment is precisely the same as that which the metal would give in contact with water, and as we know, from the experiments of MM. Henry and Berthollet that muriatic acid gas contains much water, we may believe that this hydrogen comes from the action of the water of the acid on the metal, and consequently we can from this conclude nothing as to the nature of the acid. In order to solve this question we would require to have muriatic acid free from water ; but this, as will be seen by what follows, we can get only by combining it with other bodies, which then prevent its decomposition : that is why, when we treat calomel or oxymuriatic acid gas with phosphorus, we get a liquor formed of oxygen, phosphorus, and muriatic acid, of which the principal characters are that it is strongly acid, devoid of colour, and very limpid ; that it becomes troubled in the course of some days j that on contact with the air it spontane- ously inflames absorbent paper which has been saturated with it ; that it brings about, suddenly and by itself, the combustion of the metal of potash; finally, that with red-hot iron it forms muriate and phosphide of iron, without the disengagement of any gas other than a little muriatic acid. On the properties of fluoric acid, and especially its action on the metal of potash. .... It is thus proved that this gas* cannot contain water in any form, neither in the hygrometric state nor combined. Ammonia gas is absolutely in the same case, * [Fluoric acid gas, e.