URINE. 219 



of earthy phosphates. The phosphates increase after taking nitro- 

 genized food, and in acute affections of the nervous substance e.g. 

 in encephalitis (p. 49). 



It sometimes occurs, in the last months of pregnancy, that no 

 lime at all is secreted in the urine; there being little or none in the 

 blood also, as will be shown (Chap. VII). 



Traces of iron and silicic acid are usually found in urine ; and 

 gases are also dissolved in it, especially carbonic acid and a little 

 nitrogen. 



Some substances alimentary or medicinal pass unaltered into 

 the urine. These are such as are easily soluble in water, and do 

 not form insoluble compounds with the constituents of the body; 

 and which are, moreover, not readily oxidizable or decomposable. 

 Thus the nitrates, carbonates, chlorates, borates, and silicates of the 

 alkalies, and the chlorides, bromides, and iodides of potassium and 

 sodium, pass unaltered into the urine; while sulphuret of potassium 

 is oxidized, and appears in the urine as sulphate of potassa. All 

 the salts of the metals pass into the urine unchanged, only when 

 taken in large quantities; since they form insoluble compounds 

 with animal matters, especially with albumen. Mannite, quinine, 

 &c., are fully oxidized into carbonic acid and water. Most of the 

 organic acids, as well as sulphocyanide and ferrocyanide of potas- 

 sium, reappear in the urine unchanged. Tannic acid is, however, 

 converted into gallic, benzoic and cinnamic into hippuric, uric acid 

 into urea, and oxalic acid into carbonic acid and water. The neu- 

 tral salts of the alkalies, with the vegetable acids, reappear in the 

 urine as carbonates; and hence the urine speedily becomes alkaline 

 after their reception. Urea passes unchanged into the urine. Co- 

 loring or odoriferous matters generally pass unchanged or slightly 

 modified. The following, however, do not reappear, viz: camphor, 

 resin, inflammable oil, musk, alcohol, ether, cochineal, litmus, chlo- 

 rophyl, and the coloring principle of alkanet. 



The rapidity with which different substances appear in the urine 

 varies much. Iodide of potassium often appears after four to ten 

 minutes. 



The following abnormal constituents may appear in the urine in 

 pathological conditions, viz: albumen, fibrine, caseine(?), fat, sugar, 

 abnormal pigments, biliary acids, bile-pigment, xanthine, cystine, 

 carbonate of ammonia, sulphuretted hydrogen, butyric acid, and 

 arnmoniacal salts. 



