THE PIGMENTS OF THE URINE. 315 



with barium chloride. The excess of barium is removed with 

 carbonic acid and the filtrate evaporated to a syrup. This is ex- 

 tracted with absolute alcohol, when the remaining material is dis- 

 solved in a little water and boiled with hydrochloric acid. The 

 glycerin-phosphoric acid is thus decomposed, with the liberation of 

 glycerin and phosphoric acid. On evaporating to dryness, the 

 residue is extracted with water, and the presence of phosphoric 

 acid demonstrated in the aqueous solution by the usual tests. 



Ferments. 



Every urine contains ferments which were formerly regarded as 

 identical with the pepsin, ptyalin, and chymosin of the digestive 

 fluids. It can be shown, as a matter of fact, that substances are 

 present which are capable of digesting fibrin in acid solution, of in- 

 verting starch to maltose, and of coagulating milk. There is no 

 proof, however, that these bodies are derived from the digestive 

 glands, as Neumeister and others claim. 



In certain diseases of the pancreas lipase has been found. 



Gases. 



In normal urine a certain amount of oxygen, nitrogen, and not- 

 ably of carbon dioxide is found in solution, and can be withdrawn 

 by the air-pump. Under pathological conditions, a variable 

 amount of hydrogen sulphide may be encountered. This notably 

 occurs in cases of cystitis, in which the decomposition of albumin 

 and sulphur bodies may already take place within the bladder, owing 

 to the activity of various micro-organisms. But in a few isolated 

 cases the gas was apparently derived from the intestinal tract, and 

 absorbed either directly from the rectum or indirectly from the 

 blood. 



All urines when exposed to the air sooner or later contain hydro- 

 gen sulphide in the free state, which is referable, as stated above, 

 to the action of certain micro-organisms. Especially large amounts 

 are observed when cystin-containing urines are thus allowed to 

 undergo decomposition. To test for hydrogen sulphide, a strip of 

 filter-paper is moistened with a few drops of a solution of sodium 

 hydrate and one of lead acetate, and is then clamped in the 

 neck of the bottle containing the urine. If the gas in question is 

 present, the paper is colored a grayish brown or black, owing to 

 the formation of lead sulphide. When present in large amounts 

 it is detected also by its odor. 



Ptomains. 



So far as known, ptomains are not found in the urine under 

 normal conditions. In disease, however, various basic substances 

 have been encountered which supposedly belong to this class. But 



