1815.] to Mr. R, Phillips's Animadversims. 295 



Hume, to substantiate his own discovery, makes acids weak, and 

 to prove another's ignorance they become strong. 



Tlie fate of so large a proportion of Mr. Hume's claims to ori- 

 ginality has naturally made him anxious for the remainder. Con- 

 cerning the " silver test," he evinces painful forebodings, which 

 are ill concealed by the seeming pleasantry with which they are 

 accompanied. In one of his numerous communications respecting 

 " this excellent test," he says, " the nitrate of silver is also ex- 

 tremely sensible in its operation upon arseniate of potash ; and it 

 seems most decidedly to distinguish this salt from the above solution, 

 or arsenite of potash ; for the colour of this precipitate is much 

 darker and more inclined to red or brick colour." Med. and Phys. 

 Journal, vol. xxii. p. 450. 



In his letter to you. Sir, Mr. Hume says, " I shall now expect 

 to be told that 1 have also been forestalled respecting my test for 

 arsenic, that the arseniate of silver, the hick red coloured com- 

 pound, had been prepared by others, &c. ;" and that " M. Kla- 

 protli had frequently got hold of it, analyzed it, regenerated the 

 same compound by means of nitrate of silver j but was so cruel 

 and unlucky as to disregard the silver as a test, always preferring the 

 acetate of lead, even to the end of the second volume of his 

 valuable analytical researches." Mr. Hume is the best judge of 

 the foundation on which this expectation is raised ; and that it may 

 not be disappointed, I refer him to the following passage from 

 p. 151, vol. ii. of Klaproth's work ; " To be more convinced that this 

 precipitate was an arseniated lead, I drenched it with water, and 

 digested it with half its weight of sulphuric acid. The liquor sepa- 

 rated by hltration contained uncombined arsenic acid, I neutralized 

 it with soda, and treated one part of it with a solution of nitrated 

 silver. This produced a copious precipitate of arseniated silver, 

 which possessed the brick red colour peculiar to it." By Mr. 

 Hume's indiscreet challenge of uiquiry, and triumphant defiance 

 of the result of it, he is reduced to a dilemma ; from which, if he 

 extricate himself, he will show that his talent for supporting his 

 claims is commensurate to his facility in making them. If, as must 

 be inferred from the above quotation in his letter, he have read 

 Klaproth's essays, how could he prevail upon himself to publisli as 

 his own the discovery that nitrate of silver is a test of arsenic acid; 

 when that author expressly asserts that he employed nitrate of silver 

 " to be more convinced" that a precipitate he had obtained was 

 arseniated lead ? If on the other hand he liave not read them, 

 how could he venture to assert thai ivlaproth preferred the use of 

 acetate of lead to that of nitrate of silver? 



To many persons invective is a " chea|) defence," and it costs no 

 one less than Mr. Hume \ in the use of it he is voluble, and seems 

 justly conscious that he may employ it without injury to his reputation. 

 Consistently with this style, he insinuates that 1 am " an hireling," 

 actuated by " flattery, ambition, malevolence, or jealousy ;" that 

 1 am " peevish," and evince " much malice and little candour." 



