428 Reply to Mr. Phillips's Aniinadversions. [June, 



Article VI. 



Reply to Mr. Phillips's Animadversions. By BIr. Hurae. 



(To Dr. Thomson.) 



SIR, 



Whkn your correspondent, Mr. Phillips, shall have finished his 

 consultation wi:h Klaproth's Essays he will find me ready to 

 proceed in my reply. Mr. Phillips has practised the art of garbling 

 most dexterously in his last letter to you, it is therefore incumbent 

 on him, in order to satisfy your readers at least, that he turn once 

 more to the Analytical Essays, and read and explain many pas- 

 sages which are more immediately connected with the subject. 



If Mr. Phillips be unwilling to perform the task, or ashamed to 

 admit the truth, J shall mention a few of the items to which I re- 

 fer, as proofs that Mr. Klaproth never applied nitrate of silver as a 

 test for arsenic, and that he never, on any occa?ion, combined it 

 Vi-hh the oxide oi arsenic, where alone it is so eminently useful; 

 for I never heard of a single instance where the acid of arsenic had 

 been exhibited as a poison from sinister motives. But I shall not 

 take up your time and space further than to offer the following 

 references to Mr. Klaproth's work. 



Vol. i. p. 5(16. " Both the solutions of the arsenical oxide in 

 water showed exactly the same appearances which are exhibited by 

 any other aqneous solution of arsenic." Here is an example, where 

 Mr. Phillips must acknowledge there can be no quibbling about 

 the author's acquaintance with the superior efficacy of silver, for 

 none was used. Mr. Klaproth then proceeds. " By combination 

 •with lime-water, they (the two solutions) yielded arsenia'e of lime : 

 %v'ith sulphuret of ammonia, yellow siilphuret of ursenic (orpiment) : 

 and the green pigment ofScheele, with ammoniacal oxide of copper." 



If the English translation here be correct, I may remark, that 

 arseniate of lime and the green pigment of Scheele are incom- 

 patible products from a solution of white oxide of arsenic in water ; 

 an arseniate of lime must require the acid of arsenic, and Scheele'^ 

 precipitate certainly is composed with copper and the white oxide 

 or arsenious acid.* 



In every case where great exactness was required to detect and. 

 appreciate the quantity of arsenic, 1 do not perceive that Klaproth 

 ever applied silver as a test. Thus, p. 140, vol. i. no silver test was 

 used, although at p. 142, " a weak arsenical smell was perceived.'* 

 He speaks of " a slight trace of arsenic ;" and some of it combined 

 with the cojjper, and some with the iron." Page 158. " The mu- 

 riate of sirver emitted some arsenical vapours." Page 160. " It is 

 then evident that this ore consists of silver, iron, arsenic, and 

 antimony." In the same place he notices " arsenialed iron." 

 Page 526. " A grey-yellow sublimate " and " a faint odour of 



« The En^Vs!i translation is inaccurate. The nords used by Klaproth ar« 

 arecnjkalisclic kalktrdc — T, 



