1082 EXCRETION 



of these salts varies between 19 and 25 grm. per day, of which sodium 

 chlorid is the most abundant, because it is excreted in amounts of 10 

 to 16 grm. in a day. Evidently, the chlorids of the urine are derived 

 almost wholly from the chlorids of the food and hence, their amount 

 must vary very closely with the character of the material ingested. If 

 the latter is rendered relatively chlorin free, the chlorids may dis- 

 appear almost completely from the urine, although the blood retains 

 its normal composition in this regard. Quite similarly, the intake of 

 large quantities of table salt raises the chlorin content of the urine. 

 It is diminished in certain diseases, such as acute pneumonia. 



Sulphates. The sulphates of urine are principally those of potas- 

 sium and sodium, but since the salts of sulphuric acid, owing to their 

 bitter taste, etc., do not form an important constituent of our food, 

 the sulphates in the urine are derived almost exclusively from the 

 oxidation of the sulphur of the proteins. The nitrogen of these sub- 

 stances leave the body chiefly as urea, while their sulphur constituents 

 are converted into sulphuric acid which is passed into the urine in the 

 form of sulphates. Consequently, the output of sulphates may be 

 employed as an index of protein metabolism, in the same way as urea. 

 The average daily output of sulphates varies between 1.5 and 3.0 grm. 



In addition to the sulphates of the alkaline metals, urine also con- 

 tains a small proportion of them in the form of conjugated or ethereal 

 sulphates (10 per cent.), principally as phenyl sulphate and indoxyl 

 sulphate of potassium. The latter originates in largest part in the 

 putrefactive processes within the intestine, chiefly from indole, and as 

 it yields indigo when treated with certain reagents, it is usually called 

 indican. The presence of this substance is of some importance, be- 

 cause it allows us to estimate the intensity of intestinal putrefaction 

 and the power of our body to convert these poisonous derivatives into 

 the innocuous ethereal sulphates. A small proportion of the sulphur 

 contained in urine, is present as neutral sulphur representing its un- 

 oxidized form. 



Carbonates. These salts are present only in alkaline urine, and 

 are represented by the carbonates and bicarbonates of sodium, calcium, 

 magnesium, and ammonium. They arise from the carbonates of the 

 food, and must, therefore, be most evident in herbivora and vege- 

 tarians. A urine of this kind becomes cloudy on standing, owing to 

 the precipitation of its carbonates, chiefly calcium carbonate, and also 

 phosphates. 



Phosphates. These salts are derived partly from the phosphates 

 of the food and partly from the oxidation of the organic phosphorus- 

 containing bodies of the tissues, such as nuclein, lecithin, etc. Their 

 daily excretion varies between 1.0 and 5.0 grm., calculated as P^Os,, 

 and is almost wholly dependent upon the phosphate content of the 

 food. Thus, if much calcium or magnesium is present in the latter, 

 they are excreted in the feces as calcium and magnesium phosphate, 

 sometimes as much as 30 per cent, of the total choosing this medium 



