SULPHATES. 173 



Those of the first class are called the inorganic, and the 

 second the organic, or ethereal, sulphates. The latter dif- 

 fer from the inorganic in not forming an insoluble precipi- 

 tate upon the addition of a barium salt as the inorganic 

 do. The two classes can be separated by this means. After 

 the removal of the inorganic sulphuric acid by barium 

 chlorid the organic sulphates can be decomposed by means 

 of boiling hydrochloric acid: 



KC 6 H 5 S0 4 +.H 2 == C 6 H B OH + KHS0 4 . 



The acid will then give the white precipitate of barium 

 sulphate if barium chlorid be added. 



The total amount of combined sulphuric acid excreted 

 by an adult in twenty-four hours is 2 to 3 grammes. It 

 is derived partly from that already formed in the food, 

 which passes without change into the urine, but, for the 

 most part, from the oxidation of sulphur compounds, like 

 albumin, in the body. Variations in the total sulphuric 

 acid in general indicate the rate of oxidation of sulphur 

 compounds. It is increased by taking* such compounds, 

 e.g., by a meat diet. It is decreased by a vegetable diet. 



The organic sulphates normally make up about 

 one-tenth of the total sulphates. The organic bases of 

 these are such compounds as phenol (C 6 H 5 OH), cresol 

 (C 6 H 4 CH 3 OH), indoxyl (C 8 H 6 NOH), etc. These bases are 

 formed by the putrefaction of albuminous substances; con- 

 sequently, when such putrefaction is in progress in the 

 body the organic sulphates increase in the urine. They 

 may be formed in the intestine or absorbed from some 

 other source. ' In the former case they are increased when- 

 ever there is a serious stoppage of the food, as in ileus or 

 in peritonitis with atony of the intestine. In ordinary con- 

 stipation there is no marked increase. In diseases which 



