84 CHEMICAL COMPONENTS OF THE HUMAN BODY. 



then always obtain one of the more common forms/' 1 Uric acid is devoid of 

 odor and taste; it requires 1800 or 1900 parts of hot water, and 14,000 or 

 15,000 parts of water at the ordinary temperature of 68, to dissolve it; but it 

 dissolves readily in solutions of the alkaline carbonates, phosphates, lactates, 

 and acetates, abstracting some of the alkali from the salts; it is expelled from 

 these solutions, however, by an excess of the free acids. Uric acid is one of 

 the weakest class of acids; it does not redden litmus paper; it does not directly 

 expel carbonic acid from carbonate of potash, but simply withdraws a portion 

 of the alkali, leaving the remainder in the condition of a bicarbonate; and it 

 does the same with a solution of basic phosphate of soda, changing its pre- 

 viously alkaline into an acid reaction, by the production of a biphosphate. 

 According to the analysis of Bensch, the formula of Uric Acid (usually stated 

 at IOC, 4H, 4N, 60) is really 50, 1H, 2N, 20+ HO. The acid has not been 

 obtained, however, in its anhydrous state; and its existence must be admitted 

 to be hypothetical. 



55. Uric acid, when subjected to the operation of various reagents, may be 

 made to undergo a great number of changes, and to give rise to a large series 

 of organic compounds. Some of these metamorphoses it is important to notice 

 here; as they throw light upon the phenomena of the living organism. Thus 

 it is found that urea may be produced by the artificial oxidation of uric acid ; 

 and this in more than one mode. Thus, if four parts of uric acid be mixed 

 with eight parts of moderately strong hydrochloric acid, and one part of chlo- 

 rate of potass be gradually introduced, Urea is formed, together with a new 

 compound termed Alloxan, which in its turn may be resolved by a further sup- 

 ply of oxygen into urea and oxalic acid, or, by still higher oxygenation, into 

 urea and carbonic acid. So, again, when uric acid is boiled with peroxide of 

 lead, there are formed, as the resultants of the process, an Oxalate of the pro- 

 toxide of lead, Urea, and Allantoin; this last being a substance which naturally 

 presents itself in the fluid of the allantois of the foetal calf (being, in fact, the 

 secretion of its temporary kidneys), and which there seems to take the place of 

 urea, although its composition is represented by a very different formula (80, 

 5H, 4N, 50). The production of Urea from Uric acid is thus represented by 

 Prof. Liebig: 



C. H. N. 0. C. H. N. 0. 



1 equiv. hydrated Uric acid = 5 223"] ["242 2 = 1 equiv. Urea. 



2 equivs. Water . . =2 2 | 3 6 = 3 equivs. Carb. acid. 



3 equivs. Oxygen . = 3 |- = -I 



5 4 2 8j [5 4 2 8 



Now it has been ascertained by the experiments of Wohler and Frerichs, 2 that 

 if urate of potash be injected in quantities of 30 or 40 grains into the blood- 

 vessels of rabbits, no uric acid shows itself in the urine, but the quantity of 

 urea is enormously increased, and oxalate of lime makes its appearance ; so that 

 a metamorphosis of uric acid into urea must have taken place in the circulating 

 current, and this probably by means of the oxidating process of respiration. 3 

 Further, there is evidence afforded by the phenomena of calculous disorders, 

 that there is a natural alternation between the deposits of uric and of oxalic acids ; 



1 "Physiological Chemistry," vol i. p. 210. 



2 "Ann. der Chem. und Pharm.," band Ixv. pp. 338-342. 



3 According to Liebig ("Familiar Letters," p. 399), this process is to be likened to the 

 reduction of the salts of the vegetable acids, the citrates, tartrates, malates, or to that of 

 the lactates, to the condition of carbonates; for, he remarks, "it is well known that urea 

 corresponds in composition to carbonic acid ; being carbonic acid in which half the oxygen 

 is represented and replaced by its equivalent of amide (N, 2H)." This view of its con- 

 stitution, however ingenious, seems far from accordant with the basic character of urea. 



