430 Reply to Mr. PhUllp/s An'tinadvsrsions. [Junk, 



simple form entirely changed. I have occasionally analyzed many 

 minerals in which arsenic made a prominent ingredient, and 

 these were first treated by the following process, which I found to 

 be very successful as a preliminary operation. I boiled the pul- 

 verized ore in a solution of subcarbonate of potash, and when the 

 solution was filtrated and allowed to cool, a sufficient quantity of 

 acetic acid was added to saturate the solution. In all these examples 

 I never discovered any sign of arsenic acid ; for, on presenting a 

 piece of dry nitrate of silver (lunar caustic) to the surface of the 

 solution, I invariably procured a bright yellow, and not a red or 

 Zfr/cA-coloured precipitate. This method, as far as I can learn, has 

 not been practised by any other person, I may therefore take this 

 occasion to claim it as peculiarly my own. 1 have had no oppor- 

 tunity to analyze the red arseniate of silver, or any other arseniate, 

 but 1 have little doubt that, if such a compound be submitted to the 

 same process, the result will be equally satisfactory, and that a hrick- 

 7rt/ coloured precipitate would confirm my anticipation of one com- 

 ponent part of such a mineral substance being the acid of arsenic. 



In regard to the nitrate of barytes, that its solution is immiscible 

 with nitric acid, and that the method employed by many chemists, 

 before my paper was published, namely, to purify the nitric acid 

 by adding the solution of this salt, is absurd and ineffectual, I re- 

 peat, that all I have said on that subject will defy Mr. Phillips's best 

 efforts. Dr. Duncan, jun. has read my papers, and evidently draws 

 a very different inference from my communication, and liiis Mr. 

 Phillips may see in the " Edinburgh new Dispensatory;" it there- 

 fore remains with Mr. Phillips himself to explain what M. Bouillon 

 I^agrange and Dr. Swediaur mean by acide nitrique. Before I 

 close this letter, allow me to observe, that the word harytic is 

 omitted by Mr. Phillips in the quotation from me, in one part of 

 his last letter ; and I may here add, that, to serve his own cause, 

 he made a material and very gross omission of this kind, in 

 his observations respecting the compound extract of colocynth, in 

 what has been termed his acute work upon the pharmacopoeia, 

 where he confounds proof spirit with the tincture exj)re5sed from 

 the colocynth, which must be cliarged with vegetable mucilage 

 and other principles, and therefore it can no longer be considered 

 as a proof spirit. 



I am truly sorry, Sir, to have occupied yoin- Journal by such an 

 unprofitable subject, I trust, however, that the present communi- 

 cation will be not altogether uninteresting to your readers. The 

 only apology I can make is founded upon the very illiberal, and, I 

 may add, unfriendly language in the latter part of Mr. Phillips's 

 first letter, which is evidently written with a view to injure my 

 character. I remain. Sir, your very obedient servant, 



LongJcre, Jpril 12, 1815. JoS- HuMK. 



[The editor hopes that neither of the gentlemen concerned will 

 continue this dis[nite any longer, as it is evidently fast sinking into 

 personal invective.] 



