Thoiusou's System of Chemistrj/. 165 



or however absurd, are sure to find a place in the Transactions 

 of that learned body*." This assertion forces upon us the 

 trouble of shewing that the two latter epithets are not alto- 

 gether inapplicable to his own paper on oxalic acid. 



Vauquelin mentioned in his dissertation on cinchona, that 

 the crystallized oxalic acid contains about half its weight of 

 water. " But this ingenious chemist does not seem to have 

 been aware of the real composition of oxalate of lime f." The 

 Doctor, from a vast heap of experiments, made out this to be, 

 62.5 acid, and 37.5 base; while the crystals of acid contained, 

 according to him, 77 real acid, and 23 water. Let us see what 

 he declares in his system, to be the truth. " Berzelius has 

 shewn," says he, " that they (the crystals of oxalic acid ) are 

 composed of 



Real acid 52 



Water 48 



Hence, they seem to be a compound of 1 atom acid + 4 atoms 

 waterj." And oxalate of lime is now stated by him to consist of 



Acid 55.44 



Base 44.56 

 a very different proportion, truly, from that which he has given 

 above, " of which," he justly observes, " M. Vauquelin was 

 not aware." Bergman's old proportion of 48 acid to 46 lime ; 

 or in 100 parts of 51 and a fraction, to 48 and a fraction, is 

 prodigiously more correct. Yet, of this excellent chemist, Dr. 

 Thomson says, " there must have been some mistake in his 

 experiment." His mistake was precision itself, compared to the 

 Doctor's error. As all his subsequent statements, in this paper 

 on oxalic acid, are founded upon this erroneous analysis of oxa- 

 late of lime, it is needless to examine the superstructure. Oxa- 

 late of barytes is now made, in his system, to consist of 

 Oxalic acid 31.62 Barytes 68.38 



Or, 100.00 216.00 



In his memoir, it is 100.00 142.86 



being of base a proportion too little by jnore than one-half o( the 

 whole quantity. 



Though he does not refer us to the paper itself, yet he 

 says, " I found the composition of oxalic acid may be stated as 

 follows : 



Oxygen 64 



Carbon 32 



Hydrogen 4 



100§" 

 But that acid of his consisted of 32.5 water -f- 67.5 real acid in 



* Anntils of Philosop/ii/, Ov.UiUitr, 1H20, )). 296. 



t PltUii^DjiliicalTiiiii^uctiHUs Cor 1808. 



\SysUm\\. 1()'J. <; Ibid., 11. lUfl. 



