Mr. Murray's illustration from the com and muriatic acid. of the two gasses employed-nothing ponderable escapes; muriatic acid gas consequently is not inferred, but is im mediately perceived to be, a compound of oximuriatic gas and hidrogen, and all other cases are analogous. Mr. Murray, to convince me of the errour of which he conceived me guilty, respecting the nature of Mr. Davy's bination of ox- theory, has recourse to particular instances to illustrate his ide of mercury argument. He says: "I combine oxide of mercury and muriatic acid, and form calomel, I conclude therefore, that calomel is a compound of oxide of mercury and muriatic acid. I combine muriatic acid and potash, and by dissi pation of the water I obtain a solid product, which I consider as a compound of the muriatic acid and potash, and I perceive in these conclusions no supposition, but a simple expression of facts." If Mr. Murray can combine oxide of mercury and muriatic acid, and form calomel, I have no objection to his conclusions; if the above is a simple expressio.. of facts, the theory which expresses those facts must be correct. But I have not been able to witness such facts. I have found, that, when muriatic acid gas is admitted into an exhausted retort, containing red precipitate, corrosive sublimate, and not calomel, is formed; that water in plenty is simultaneously produced; and that much heat is generated, sufficient indeed, when the experiment is made on a pretty large scale, to revive some mercury by the expulsion of its oxigen. Mr. Murray, not attending to all the phenomena, has formed a false theory. Stahl, finding sulphur produced by heating charcoal with sulphuric acid, asserted, that sulphur is a compound of sulphuric acid and phlogiston; aud Mr. Murray, knowing that different me tallic compounds may be procured by treating different oxides with muriatic acid, asserts, that these compounds consist of muriatic acid and metallic oxides. In Stahl's famous experiment, carbonic acid gas, not being then discovered, escaped his notice; but the same cannot be said of water, which Mr. Murray has thus neglected. The preceding illustration of Mr. Murray at once demonstrates the real difference between Mr. Davy's theory and the old hypothesis; and that the former is, as I have represented it, a simple simple expression of facts, and the latter a series of sup positions. I shall studiously avoid discussion in the remaining part of this paper: it is my intention to confine myself to facts, which speak for themselves, and are the only legitimate supports of a theory. Mr. Murray asserts, that Mr. Davy is obliged to sup- Water produced when pose, that water is produced in the common mode of mak- oxide of maning oximuriatic gas from muriatic acid, by means of the ganese is heated in muriatic black oxide of manganese. Mr. Davy has ascertained the acid gas. fact, that oximuriatic gas and water are produced, when black oxide of manganese is heated in muriatic acid gas. Mr. Murray imagines a great intricacy in some parts of Mr. Davy's Mr. Davy's theory, which does not really belong to it; for theory more simple, than theory, being an expression of. facts, must be as simple as Mr. Munay the facts themselves. Mr. Murray, for instance, conceives, supposes. that, in the solution of muriate of potash in water, water is decomposed; and that it is recomposed at the moment of its expulsion by heat. These are conjectures. In Mr. Davy's theory, fused muriate of potash, I conceive, is a compound of oximuriatic acid and potassium; and the solution of muriate of potash is a compound of oximuriatic acid, potassium, oxigen, and hidrogen. The mutual decomposition of nitrate of mercury and common salt is another supposed complicated instance pointed out by Mr. Murray. It is this gentleman who imagines the changes complicated. The facts are merely these: sodium surrenders its oximuriatic acid to the mercury, and receives in return its oxigen and nitric acid, and thus calomel and nitrate of soda are very simply formed. Things not accounted for not always anoma Mr. Murray seems to consider every thing anomalous, that is not accounted for; thus the want of action between charcoal and oximuriatic gas is in his opinion an anomaly lous. in Mr. Davy's theory. Can Mr. Murray account for the want of action between charcoal and nitrogen, and between the metals and nitrogen? and, if he cannot, does he consequently consider these facts anomalous? Mr. Murray doubts what I have alleged to be fact; viz. Mercury dethat the composition of muriatic acid gas is uniformly the composes mu riatic acid gas same. I do not pretend to account for the results of Dr. and forms caHenry's lomel. Carburetted hidrogen and oximuriatic gas do not form Henry's experiments, on which he rests his doubts. I have observed, that, when muriatic acid gas is left in a 'jar over mercury, the acid will slowly disappear, calomel will be formed, and at length nothing but hidrogen will remain. I have stated in my first paper the general result, that carbonic acid is not formed, when dried carburetted hidrogen is detonated over recently boiled me c. ry with an excarbonic acid, cess of oximuriatic gas. Mr. Murray wishes to know how I ascertained this fact.-I considered the precipitation of charcoal, and no cloudiness being produced on passing the residual gas through lime-water, sufficient evidences of this. Detonation of axide. Mr. Murray objects to the mode in which his experiment hidrogen, oxi- on the detonation of a mixture of hidrogen gas, oximuriatic muriatic gas, and carbonic gas, and carbonic oxide, was repeated, and is not satisfied with the results which are in opposition to his own. I have assisted my brother in again making this experiment; Mr. Hatchett and Mr. Brande were present. A mixture, consisting of 14-6 measures of oximuriatic gas, of 4 measures of hidrogen gas, and of 10 measures of gaseous oxide of carbon, was inflamed by an electric spark over recently boiled mercury; a condensation of half a measure only was produced by the explosion. Pure ammoniacal gas was added in excess, and, after the admission of water, there remained 13 measures of unabsorbable gas. Eight measures of oxigen being introduced, the mixture was inflamed; there was a diminution equal to 4 measures, and 8 measures of the residue were absorbed by a strong solution of potash *. $ measures of residual carbonic oxide; and, when the common air present is taken into account, with the difficulty The oximuriatic gas was procured from a mixture of common salt, black oxide of manganese, and diluted sulphuric acid; the 14. measures employed were found by a comparative trial to be contaminated by 2 measures of common air. The other two gasses had been previously dried by potash. 11.5 measures of the carbonic oxide, detonated with 165 of oxigen, were immediately diminished to 19; and by agitation with a strong solution of potash, there was a farther diminution produced equal to 11 measures, of of effecting the entire exclusion of moisture, no result more satisfactorily conclusive, that no carbonic acid was formed, could be expected: and we obtained a similar result in another experiment, in which we employed a strong solution of potash instead of ammoniacal gas, for absorbing the acid gas formed. I mentioned in a note to my former paper the discovery Compound of made by Mr. Davy of a gaseous compound of oximuriatic oximuriatic gas and origen. gas and oxigen. I stated the method of procuring it, and the property which it has of converting carbonic oxide into carbonic acid, Mr. Murray appears to think very lightly of this compound. But I can assure this gentleman, "notwithstanding it is pro-ured (as he justly remarks) from the same materials as oximuriatic gas, and by a process apparently not much different from that which is usually employed," that Mr. Davy has found it to possess Its singular very different properties. Copper leaf, arsenic, and the properties. common metals, for instance, which instantly inflame in oximuriatic gas, remain untarnished in this gas. And, what is extraordinary, it is origen in union which prevents the combustion of the metals from taking place; for when the combination is broken by nitrous gas, or a gentle heat, the oximuriatic gas, set free, acts as usual. The decompo sition too of this gas by heat is so rapid, that it produces a loud explosion; and, if the quantity is large, a dangerous one: and it is a very singular circunstance, that it is attended with the evolution of heat, and even of light, notwithstanding there is a very considerable increase of volume. Mr. Murray may have remarked the difference of colour between common oximuriatic gas and the gas from oximuriate of potash; it is owing to an admixture of the newly discovered gas. When this gentleman learns, that the pure gas contains about half its volume of oxigen, he will probably no longer doubt, that it may be able to convert carbonic oxide into carbonic acid; and since origen united to oximuriatic gas deprives the latter of all those properties, which it was supposed to owe to loosely combined oxigen, he will probably adopt the new idea, that oximuriatic gas is a simple body. But if on the contrary he should still prefer the old hypothesis the consequence is inevitable- he he must account for muriatic acid being a supporter of I am, Sir, with great respect, Your humble servant, London, March the 15th, 1811. J. DAVY. L Questions on the production of hyperoxi muriate of potash. VIL. An Attempt to answer the Queries proposed by F. D. in SIR, To Mr. NICHOLSON. A Correspondent, in your Journal for April, has in a He observes, that, "when the oximuriatic acid comes into contact with the oxide of potassium, we must suppose, that part of it from superior affinity displaces part of the oxigen, and combines with the potassium". He then proposes the following questions:-" How shall we in the first place account for this partial action? If a superior affinity exist between part of the oximuriatic acid and part of the potassium; how is it, that it does not subsist between the whole? How is it, that the whole oxigen of the potash is not set free, and the combination consist of muriate of potash Partial decom- only?" In answer to these questions; it may be observed, positions take that there are many phenomena in chemistry, where a partial place in chemistry. decomposition only takes place, as has been noticed and explained by Berthollet in his Chemical Statics. 7 |
