Notices respecting New Books, £97 



for science and for genius ; I am, therefore, astonished they 

 never had even heard of any one of my three letters ; while 

 Dr. Henry, a gentleman of no small fame as a philosopher, 

 and of whom and of whose works they cannot be ignorant, 

 writes thus, in his " Elements of Experimental Chemistry," 

 vol. ii. p. 391 — " A new process for detecting arsenic has 

 been proposed bv Mr. Hume, of London, in the Philoso- 

 phical Magazine for May, I809, vol. xxxiii. The test 

 which he has suggested, is the fused nitrate of silver or 

 lunar caustic." 



In my letter to the Editors of the Medical and Phyical 

 Journal, I have said — " in a future edition of this meri- 

 torious work (Dr. Henry's Elements), its eminent author 

 will, no doubt, prefer the 5i/yer-lest to all others, and place 

 it at the top of his list, where it will probably always re- 

 main." I have spoken nearly to the san)e effect in my 

 last letter to you ; — that this test, under whatever modifica- 

 tion or by whatever alkali we operate, '' must now super- 

 sede every other test for arsenic, and become the standard 

 to all future operators." I then gave you what I called 

 *' another prescription " for mv test, — another modification 

 of the same silverAcs,\.. This prescription, however, was laid 

 before you with no other intention than to rescue my test, 

 when ammonia is chosen for the medium, from the very 

 inelegant and crude method projected by Drs. Roget and 

 Market; — that of cmployuie lao glass rods, one of which 

 only is required to be clean ; and likewise to correct a pal- 

 pable error, — that of using the nitrate of silver and the 

 ammonia separately and without limitafion. 



I remain, sir, your obedient servant, 



Long Acre, London, Jos. HuME. 



Oct. 14, 1812. 



LI. Notices respecting New Books. 

 SirHuMPHRY Davy's** Elements of Chemical Philosophy." 



(Continued from p. 151.] 



In the section on "chemical attraction and the laws of 

 combination and decomposition," the Professor has ad- 

 nuitcd the only dcduclions which are of a nature entirely 

 theoretical. As these deductions are likelv to perform in 

 future as important a part in chemistry as Bergman's tables 

 of ai tractions have done, it is necessary (although they 

 frc not eniirtly new) to lay before the reader a more detailed 



account 



