48o 



URIC ACID. 



Uric acid is dibasic, tasteless, odorless, and colorless, soluble with 

 great difficulty in water (in 15,000 parts of warm, or 18,000 parts of cold 

 water, though in 2,000 parts of a 2 per cent, solution of urea), insoluble 

 in alcohol or ether. It crystallizes in various forms (Fig. 148), the 

 basic type of which is the rhombic plate (i). Enlargement of the op- 

 posed larger angles causes the formation of the whetstone-shape fre- 

 quently observed (2). If the longer sides of the latter are flattened, 

 six-sided plates result. Large, golden-yellow crystalline resets (6, 8) 

 often separate spontaneously from diabetic urine. Precipitated by 

 addition of hydrochloric acid (25 cu. cm.) to urine (one liter) or of 

 acetic acid, the crystals usually assume the form of a barrel (9) or a 

 bundle of spears that are tinged brownish violet by adherent urea. 



Uric acid is readily soluble in alkaline carbonates, borates, phosphates, lactates, 

 and acetates. Removing a portion of the base from these salts, there result, 

 on the one hand, acid urates; and on the other hand, acid salts from the neutral 



FJG. 148. Different Forms of Uric Acid: i, rhombic plates; 2, whetstone-shape; 3, quadratic shape; 4, 5. elon- 

 gated forms with two pointed extremities; 6, 8, arrangement of several crystals in the form of a roset; 7, 

 crystals drawn out into the shape of a lance; 9, so-called barrel-shape obtained from human urine by means 

 of hydrochloric acid, in part darkly discolored. 



salts. Among alkalies, lithium (citrate) is especially noteworthy as a solvent of 

 uric acid. 



According to v. Noorden and Strauss, a favorable composition of the urine 

 will be obtained if calcium carbonate or calcium-salts of the vegetable acids (from 

 2 to 10 grams) are administered. Phosphoric acid leaves the body with the cal- 

 cium through the intestines. In consequence, the monosodium phosphate in the 

 urine is diminished, as it gives up the phosphoric acid and thus disodium phos- 

 phate results. The latter, however, is capable of dissolving uric acid, inasmuch 

 as sodium urate and monosodium phosphate are formed. Uric acid is soluble in 

 concentrated sulphuric acid, from which it is reprecipitated by water. Plumbic 

 oxid converts it into urea, allantoin, oxalic acid and carbon dioxid; ozone pro- 

 duces the same substances, together with alloxan. Reduced by hydrogen in a 

 nascent state, xanthin and sarcin are produced. Horbaczewski has prepared 

 uric acid synthetically by fusing one part of glycin and seven parts of urea. 



In the urine, the uric acid is dissolved principally in the form of acid 

 sodium and potassium urate. These salts are present also in urinary 



