48 THE BUTYRIC ACID GROUP. 



that sympton being only the occurrence of oxalate of lime is 

 entirely opposed to the spirit of rational medicine. 



From Wohler and Liebig^s discovery that uric acid is decom- 

 posed by peroxide of lead into urea, allantoin, and oxalic acid, it 

 has been pretty generally assumed that the oxalic acid of the urine 

 is due to an oxidation of the uric acid ; the oxalic acid, in this case, 

 not being converted into carbonic acid, as usually occurs in the 

 healthy organism. That the formation of oxalic acid may be in part 

 thus explained, is unquestionable, but there are many other substances 

 in the animal organism besides uric acid, which by oxidation yield 

 oxalic acid. No definite numerical ratio between the uric acid, urea, 

 and oxalate of lime in the urine, has been yet established. 



C. Schmidt * has propounded a very ingenious view regarding 

 the origin of oxalate of lime in the urine. He believes that we must 

 seek for the source of its secretion in the mucous membrane of the 

 urinary passages, and that the oxalate of lime is first produced by 

 the decomposing action of the acid urine on a soluble compound, 

 oxalate of albumen-lime, secreted by the mucous membranes ; for 

 oxalate of lime as an insoluble body could not penetrate with the 

 urine through a series of renal cells : oxalate of lime is also formed 

 from the mucus of the gall-bladder by this mode of decomposition. 

 When oxalate of lime occurs in the urine, we always find an aug- 

 mentation of the mucus. These reasons do not, however, appear 

 to be so decisive as to induce us to exchange the view we have 

 already given for that of Schmidt ; and indeed in another place we 

 find Schmidt f himself maintaining that the urea is in part com- 

 bined with oxalic acid. 



FORMIC ACID. C 2 HO 3 .HO. 



Chemical Relations. 



Properties. This acid possesses the general characters of the 

 acids of this group ; with water it forms two distinct hydrates, one 

 of which becomes solid at 1, boils at 4- 99, and has a specific 

 gravity of 1*2353, while the other, which contains 48'35-g or 2 atoms 

 of water, does not solidify at a temperature of 15, boils at + 106 

 and has a specific gravity of 1*1104. By concentrated sul- 

 phuric acid it is decomposed into water and carbonic oxide 

 (C 2 HO 3 :=:HO + 2CO) ; the salts of oxide of silver and of oxide 

 of mercury are reduced when warmed in it. 



* Ann. d. Ch. u. Pharm. Bd. GO, S. 55, ff. 

 f Entwurf u. s. w. S. 47. 



