292 Preparation and Habitudes of the Oxygenated Muriat of Potash. alkali was employed. A given quantity of the ftrong folution of potash appeared to produce more of this falt than the fame quantity of a folution of pearlash of the fame specific gravity. very The remaining lixivium, on evaporation, did not yield this falt, though a muriat of potafh was formed, that appeared to be confiderably oxygenated: fince, with the addition of the fulphuric or muriatic acid, it became a very powerful destroyer of vegetable colours; it would not detonate with fulphur, or inflame combustible fubitances, with acids; it was foluble in water, much more fo than the muriat firft formed from the fame alkali. may here remark, that I think the French chemists were right in calling the first salt the hyperoxygenated muriat, as the falt last mentioned is certainly oxygenated in fome degree however, in the following experiments I fhall ufe the term oxygenated muriat, when fpeaking of the falt formed during the distillation, and on cooling the lixivium after being faturated with the gas. I Experiment I. One part of the oxygenated muriat of potash required about feventeen parts of water at the temperature of 60°, to diffolve it; whilft five parts of boiling water diffolved two of the falt. Repeated folutions did not appear to injure, but rather to increase, its detonating property. The crystals became much whiter; and a quantity of the earthy matter before mentioned was feparated at every fresh crystallization. Experiment II. A quantity of this falt was put into a bottle, and placed in a fituation much exposed to the light: after being kept there more than twelve months, it did not appear to have lost any part of its detonating property. This fact is contrary to Chaptal's affertion, that the mere impreffion of light is fufficient to decompose it *. Experiment III. Water faturated with this falt was expofed to the light for feveral months, without appearing to be at all changed. It was put into a bottle with a ground. ftopper and tube, to which an apparatus was adapted to receive any gas that might come: over; but no gas whatever was difengaged. Experiment IV. Sixty grains of falt were fufed by the heat of a lamp in a bottle with a ground ftopper and tube. After having been kept in a fluid ftate for about half an hour, I found that it had loft two grains in weight, and that a fmall quantity of air was given out, which proved to be oxygenous by the test of nitrous gas. The falt which had been melted would still detonate with fulphur, &c. The lofs of weight was, I am inclined to think, chiefly owing to the escape of the water of cryftallization; for the falt when cool had lost its transparency. Experiment V. From forty grains of the falt in an earthen retort, I procured by the application of heat about thirty-fix cubic inches of oxygenous gas; the evolution of which was very rapid, and commenced as foon as the retort became flightly red. Forty grains expofed in a crucible to a strong red heat appeared, from the mean of two experiments, to have loft about feventeen grains in weight. The remaining muriat, being afterwards thrown into the fulphuric acid, produced a very ftrong fmell of oxygenated muriatic acid; from which I inferred that the whole of the oxygen had not been expelled by the heat; whence the oxygenated muriat of potash may, I think, be ftated to contain about half its weight of oxygen in a concrete ftate. Elements of Chemistry, i. 250. Experiment Experiments with the Oxygenated Muriat of Potash. 293. Experiment VI. Strong nitrous acid difengaged the oxygenated muriatic acid from this falt. During the solution of two or three grains of the oxygenated muriat in this acid, a grain or two of phosphorus was dropped into the glafs containing the mixture; when a number of vivid flashes appeared in the liquor, darting forth at intervals for a confiderable time. This is one of the most ftriking experiments I ever faw; but a little caution is neceffary in performing it, the phosphorus being sometimes thrown out of the mixture *. Experiment VII. The muriatic acid diffolved this falt, a great deal of the oxygenated acid being given out. A few grair of the falt added to an ounce of the acid rendered it a very powerful deftroyer of vegetable colours. This mixture may probably be used with advantage in taking stains of ink, &c. out of linen or cotton. Phosphorus added to this acid along with the falt did not produce the fame effect as with the nitrous acid; no light appearing, as in the last experiment. Experiment VIII. On putting a little of the falt into the fulphuric acid, a violent crackling, or a great number of small explosions, took place, and a very strong smell of nitrous gas was produced; the mixture at the fame time affuming an orange colour, which difappeared after it had stood a fhort time. A very small piece of phosphorus having been dropped on about two grains of the salt (previously thrown into the acid), an explosion immediately took place, which blew out a great part of the mixture upon my hand; an accident that might have proved serious if I had not had water near me. Experiment IX. Finding a great quantity of gas to be difengaged from this falt by the fulphuric acid, which had a very strong smell of nitrous gas, I put forty grains of the falt into a glass retort, and poured upon it nearly an equal weight of fulphuric acid diluted with water. With the heat of a lamp the gas began to come over very rapidly, and was received in a glass jar placed in a bason of water. A confiderable portion of it appeared to be absorbed by the water, which acquired a yellowish colour. This colour difappeared on standing a few days, and a brown matter was depofited, which being carefully collected and dried weighed one grain, and appeared to be manganese; for a little of it, being put into the muriatic acid, fo far oxygenated it that it would deftroy the blue colour of a diluted folution of indigo in the fulphuric acid. The precipitate before mentioned, that was firft produced in the alkali employed, did not appear to have this effect. The quantity of this sediment that I had an opportunity of collecting was fo fmall, that I could not try many other experiments with it: indeed I did not always fucceed in procuring it; for I found that, unless the difengagement of the gas was very rapid, but little of it could be obtained. Experiment X. On two drams of the falt in a glass retort, I poured an equal weight of fulphuric acid diluted with a little water, and adapted the retort to Woulfe's apparatus. The heat of a lamp was applied; and prefently the gas began to escape, and was abforbed by the water in a confiderable quantity; to which it communicated a yellowish colour, and a liquid began to trickle down the neck of the retort into the receiver. This had continued but a short time before a violent explosion took place, which broke the retort and two of the receivers to pieces, together with feveral other glaffes which were on the table. This was feveral times repeated, but with more caution than before; and I always found, This curious experiment was first noticed by J. Collier, and was communicated by him to the Society fome time ago. VOL. II,- OCT. 1798. ૦૧ that 294 : Inflammation of combustible Bodies with that when the mixture acquired a certain degree of heat an explosion certainly took place, except the retort had a pretty wide neck, and the neck was fimply introduced into a re ceiver with a confiderable opening in it without any lute; or put into water, as in the last experiment; and even in this cafe I would not advife fo much of the falt to be ufed at one time as is here mentioned. The fmall quantity of acid I was able to collect in this way, by adapting a loose receiver, appeared to be a weak muriatic acid flightly oxygenated; it was of a dilute purple colour, which difappeared on its being expofed a fhort time to the Light a fmall piece of iron dropped into it caufed it to become transparent immediately. It was a matter of much furprise to me, to find fo ftrong a fmell of nitrous gas produced on decompofing this falt with fulphuric acid. Now, as nitrous gas consists of azot and oxygen, fuppofing this to be nitrous gas (for I do not affert it to be fo, though I fhould think the fmell in this inftance an almoft fufficient criterion), whence comes the azot? At first I thought it might come from a decompofition of the alkaline bafe of the falt; as fome chemifts have imagined the vegetable alkali to be compofed of lime and azot : in that cafe, I expected the refiduum would have been the fulphat of lime; but I found it to be chiefly fulphat of potash, with a little of the oxygenated muriat that remained undecompofed along with it. At prefent I fhail not hazard any opinion respecting the origin of this nitrous fmell; but hope fome experiments I am at prefent engaged with will, if I can find time to profecute them, throw fome light upon this fubject. II. On the Detonation and Inflammation of combustible Subftances with the Salt produced by Friction and the Acids. THE detonating properties of this falt were tried with various fubftances in the followingexperiments the different mixtures were intimately combined by gently rubbing them in a ftone-ware mortar: after this was done, one fmart stroke across the mixtures would cause the whole of some of them to explode at once, and others fucceffively by repeating the friction. The fulphuric acid inflamed moft of thefe mixtures of the falt with combustible. fubftances: the nitrous acid also had the fame effect with fome of them. Experiment I. with Phosphorus. Half a grain of this fubftance rubbed with the fame weight of the falt produced violent explosion with flame. I apprehended it would be dangerous to use much greater quantities, as the phosphorus is frequently thrown out with violence before it is confumed. The fulphuric acid inflamed this mixture, as I have before: ftated. Experiment II. with Charcoal. Two grains of falt with one of charcoal intimately mixed, and perfectly dry, produced by a smart ftroke a strong flame without much report. The fulphuric and nitrous acids inflamed this mixture, the latter with most rapidity. Experiment III. with Pit-coal. A grain of dry pit-coal rubbed with the fame quantity of the falt produced sparks and some small reports. With half the quantity of coal the reports were much louder. The fulphuric acid added to about twenty grains of the falt with ten of the coal, produced a bright red flame rifing up to a confiderable height. Experiment IV. with Sulphur. A grain of the falt rubbed with half a grain of fulphur produced a very loud report, attended with flame and aftrong fmell of fulphureous acid.. When the fulphur was reduced to a quarter of a grain, the explosion was not made at once as the Oxygenated Muriat of Petafb. 295 as before, but fucceffively. When the proportion of fulphur was increafed to three fourths Experiment V. with Sulphuret of Potafb. One grain of the falt rubbed with the fame weight of this fubftance produced a very loud explofion with flame. With half a grain of the fulphuret I thought the report fully as violent. A little of these mixtures melted over the fire had not the effect of the fulminating powder made with nitre. It only emitted a flash without any report, nor was 1 able to produce a fulminating mixture by varying the proportions of the falt, alkali and fulphur. The fulphuric or nitrous acids dropped on this mixture gave a very strong bright flame. Experiment VI. with Sulphuret of Mercury. (Cinnabar.) Equal parts of this fubftance A change of and of the falt detonated fucceffively by friction, a grain of each being used. proportion appeared to weaken the detonating property of the mixture. The fulphuric acid inflamed this mixture, but not fo rapidly as in the last experiment. The nitrous acid. did not inflame it. Experiment VII. with Sulphuret of Arfenic. (Orpiment.) A grain or two of the falt rubbed with an equal weight of this substance produced little more than a flash; but a grain of the falt with half a grain of the fulphuret gave a strong report, though very little friction was ufed. Reducing the quantity of fulphuret to a quarter of a grain, the explosions were weak and fucceffive. A larger quantity of this mixture than is mentioned above makes a report which is very unpleasant, with confiderable flame. I was greatly surprised, the first time I made the experiment with two or three grains of the salt and a portion of the fulphuret, by their exploding in a most violent manner, though a very flight friction had been ufed. The fulphuric or nitrous acids gave a very strong flame the moment they were dropped upon this mixture. Experiment VIII. with Cotton-wool. A fmall quantity of very dry cotton-wool was rubbed with a little of the falt; no detonation took place. The wool was afterwards dropped into the fulphuric acid, and took fire immediately; but the nitrous acid would not inflame it. Experiment IX. with Loaf-fugar. One grain of this fubftance rubbed with two of the falt number of fucceffive reports. The fulphuric or nitrous acids dropped on this gave mixture inftantly produced a strong flame afcending to a confiderable height. Experiment X. with fixed and effential Oils. A few drops of spermaceti oil rubbed with a grain or two of the falt produced a number of loud reports. The fulphuric acid inflamed this mixture; the nitrous acid did not. Olive oil, the effential oils of rosemary, juniper, cloves, carraway, anifeed, cinnamon, nutmeg, amber, mint, and effence of lemon, were rubbed with the falt: all of them detonated fucceffively, and fuch of the mixtures as were tried took fire with the fulphuric acid. Experiment XI. with Spirit of Turpentine. A few drops of fpirit of turpentine rubbed with a little of the falt detonated in much the fame manner as the substances used in the last experiment. The fulphuric acid dropped on this mixture produced a strong flame, with a cloud of very black smoke. Experiment XII. with Camphor. A little of this fubftance on being rubbed with a graiu of 296 Inflammation, &c. with Oxygenated Muriat of Potafb. of the falt produced a number of fucceffive detonations. The fulphuric acid produced flame with fome explosions. Experiment XIII. with Rofin. One part of this fubftance with two parts of the falt detonated fucceffively when well rubbed together. The fulphuric acid inflamed this mixture, but the nitrous acid did not. Experiment XIV. with Gum-Arabic. The detonations were very flight. It was mixed with twice its weight of the falt. The fulphuric acid fet fire to the mixture, but the ni trous acid would not. Experiment XV. with Pruffian Blue. No detonations whatever were produced by friction, nor did the acids inflame a mixture of this fubftance with the falt*. Experiment XVI. with Indigo. Half a grain of fine Spanish indigo rubbed with a grain of the falt detonated fucceffively, like the mixture with rofin or gum. The fulphuric acid inflamed this mixture, but the nitrous acid did not. Experiment XVII. with Ether. A few drops of ether on about two grains of the falt rubbed to a very fine powder produced no detonation by friction. The fulphuric or nitrous acids poured fuddenly upon it produced flame. Experiment XVIII. with Iron-filings. These alone rubbed with the falt produced no detonation by fimple friction; but two grains of the falt, one grain of iron-filings, and half a grain of fulphur, being well rubbed together, about a quarter of a grain of this mixture exploded violently with friction. The fulphuric acid added caused a few sparks to appear; but the nitrous acid did not produce any. Varying the above proportions did not appear to improve the detonating property of the mixture. Experiment XIX. with Aurum Mufivum. Equal parts of this fubftance and of the falt detonated ftrongly with flame, on being rubbed together in an iron mortar a very flight friction was neceffary. The fulphuric acid gave a small flame, but with the nitrous I could not procure any. From the foregoing experiments I think we may venture to conclude, that the oxygenated muriat of potash is equally harmless as common nitre; except it be brought into an intimate union with fomething that has a greater affinity with one of its constituent parts, than exifts between those parts when combined in the salt, and that fome combustible fubftance be prefent: but its oxygen being fo easily disengaged renders a little caution neceffary; and as the fulphuric or nitrous acids feem fo readily to inflame many of the mixtures, I would not advise any person to make more of them than is neceffary for immediate experiment. This precaution may prevent any unpleasant circumftance from accidental mixture with the acids, which appear to difengage a great part of the oxygen almost instantaneously. I fhall not fay much about the theory of thefe detonations, none of the foregoing experi ments having been so carefully conducted as to determine accurately what changes took place; yet I think we may attempt to explain fome of them in the following manner: With phosphorus the oxygen seems to combine, and form phosphoreous acid gas, or phosphoric acid; with fulphur, the fulphureous acid gas, or fulphuric acid, according to the rapidity of Chaptal (Elements of Chemistry, vol. ii. page 377,) says, "Pruffian blue takes fire more eafily than fulphur, and detonates ftrongly with the oxygenated muriat of potash. (Quære, Did he not make use of indigo There?). the |