THE NITROGENOUS EXCRETION. URINE. 359 



quently called phenol- and cresol-sulphuric acids, but the 

 former names are preferable. The alkali salts of indoxyl- 

 sulphuric acid are known as indican, the appearance of which 

 in the urine in quantities above minute traces is an indication 

 of the existence of excessive putrefactive reactions in the intes- 

 tines. The observation is therefore of value in diagnosis. 

 Accurate methods are known for the recognition of the sub- 

 stance in the urine. 



In addition to the oxidized or sulphate sulphur in the 

 urine there are always traces of so-called "neutral" sulphur 

 compounds present. According to various authorities the sul- 

 phur in these compounds, which are all complex organic 

 bodies, may make up 12 to 25 per cent of the total sulphur. 

 The sulphur bodies here in question are not easily recognized 

 in most cases and the existence of several of them described in 

 the journals is yet to be demonstrated. The fact of the excess 

 of sulphur over that contained in the mineral and ethereal 

 sulphates may be easily shown by determining the total sul- 

 phate sulphur directly, and then after complete oxidation of 

 the urine residue obtained by evaporation. Among the bodies 

 containing the unoxidized sulphur these have been recognized 

 with greatest certainty: cystin, taurin, oxyproteic acid and 

 alloxyprotcic acid, of which something will be said below. It 

 is not possible to give the exact significance of these bodies in 

 the urine, but they doubtless represent imperfect or incomplete 

 oxidation stages of the original proteins. 



THE PHOSPHORUS EXCRETION. 



As mentioned above some of our foods are very rich in 

 phosphates or phosphate-furnishing material. This is espe- 

 cially true of the cereals. The phosphates formed by oxida- 

 tion of these substances are mainly eliminated with the urine, 

 and in traces with the feces. A very considerable portion of 

 the urinary phosphoric acid comes from this source. An- 

 other portion comes from the breaking down of the nucleinic 

 acid of the cell substance and from the so-called phospho- 



