1815.] ^^P^ ^0 Mr. Phillips's Animadversions. >4^ 



arsenic was perceived ;" yet this article is not included in the list 

 of comi)Oi)e!!t parts. Page 54S. The solution of variegated cop- 

 per-ore in nitric acid " was tried by the proper re-ag^cnts for silver, 

 lead, zinc, arsenic, &.c." Here I am anxious to knew what re- 

 agent or test Mr. Klaproth took for the arsenic, for, a more suit- 

 able and altogether palpable case for exercising the silver test does 

 not occur in either volume. Page oG7. " One grain of sublimed 

 arsenic" is mentioned; " the arsenic escaped in vapours;" — " the 

 cobalt (after calcination with charcoal) was not yet entirely de- 

 prived of all portion of arsenic." In this case, I must observe, 

 arsenic seems to have been deposited in place of being dissolved in 

 the nitric acid. Indeed the whole of this essay, the analysis of 

 the white cobalt-ore, offers many opportunities which admit of the 

 silver test ; }'et it was never employed, certainly from no other 

 cause than that the author was not aware of the value of the silver 

 as a test, and this appears so evident through the whole of the 

 two volumes as to admit of no contradiction. 



In the second volume, page 150, the nitric acid Is used to dis- 

 solve the olive copper-ore, and the acetate of lead is preferred to 

 collect and separate the whole of the arsenic acid; and this pre- 

 cedes the next step the autlior takes, which Mr. Phillips, to serve 

 his own purposes, has separated from the whole process of Mr. Kla- 

 proth, viz. merely to regenerate wh.at the author supposed to be 

 the native compound, the arseniate of silver, described in the first 

 volume, page 125: and this was evidently done to prove that the 

 arseniate of load contained no svlphule of lead, and that the 

 arsenic found in the ore is in the state of an acid. I need not say 

 that such conclusion must be very uncertain in all cases where aa ' 

 ore has been subjected to the action of vilric acid. At page 153, 

 the author stales that " not only the crude ore itself, but also the 

 precipitate obtained from its nitric solution by means of acetated 

 lead, when reduced by the blow-[)ipe upon charcoal, give out a 

 vapour, which, by its garlic smell, sufficiently shows to be arse- 

 nical :" query, the metal or oxide of arsenic ? The last example 

 which Mr. Klaproth gives us in his very excellent and most valuable 

 essays, in which the arsenic is found, is in the pharmacoHte. 

 Here it will be seen that, after all the author's experience, including' 

 that analysis quoted by Mr. Phillips, he fixes upon the acetate of 

 lead alone for detecting, separating, and ascertiiinirig the arsenic 

 acid; not a word, or the slightest allusion to a silver test; nor is 

 there a single syllable, or the most trifling hint from Mr. Klaproth, 

 in any part of his work, to induce an operator to prefer silver to 

 lead as a test for white ar.senie. 



It is with much difTidence and hesitation that I ofFer any 

 observation on the woiks of such a celebrated master as Kla- 

 proth. It appears, however, that on many occasions the true 

 state in wliiih the areenie previously existed in the ore was 

 not completely demonstrated by subsequent ex|)crinu'nts; for, 

 by etiiploying niliic acid in almost every instance, the nirtal 

 became acidilicd, and, cousc4ucniIy, its priaiiiivc aod more 



