URINE. 303 



may be increased during fever; following the crisis, however, the 

 output of this element may be decreased. It may also be increased 

 in conditions associated with acid intoxication. 



Calcium and Magnesium. 



The greater part of the calcium and magnesium excreted in 

 the urine is in the form of phosphates. The daily output, which 

 depends principally upon the nature of the diet, aggregates on 

 the average about i gram and is made up of the phosphates of cal- 

 cium and magnesium in the proportion 1:2. The percentage of 

 calcium salts present in the urine at any one time forms no depend- 

 able index as to the absorption of this class of salts, since they are 

 again excreted into the intestine after absorption. It is therefore 

 impossible to draw any satisfactory conclusions regarding the ex- 

 cretion of the alkaline earths unless we obtain accurate analytical 

 data from both the feces and the urine. 



Very little is known positively regarding the actual course of the 

 excretion of the alkaline earths under pathological conditions except 

 that an excess of calcium is found in acid intoxication and some 

 diseases of the bones. 



Carbonates. 



Carbonates generally occur in small amount in the urine of man 

 and carnivora under normal conditions, whereas much larger quan- 

 tities are ordinarily present in the urine of herbivora. The alkaline 

 reaction of the urine of herbivora is dependable in great measure 

 upon the presence of carbonates. In general a urine containing 

 carbonates in appreciable amount is turbid when passed or becomes 

 so shortly after. These bodies ordinarily occur as alkali or alkaline 

 earth compounds and the turbid character of urine containing them 

 is usually due principally to the latter class of substances. The 

 carbonates of the alkaline earths are often found in amorphous 

 urinary sediments. 



Iron. 



Iron is present in small amount in normal urine. It probably 

 occurs partly in inorganic and partly in organic combination. The 

 iron contained in urinary pigments or chromogens is in organic com- 

 bination. According to different investigators the iron content of 

 normal urine will probably not average more than o.ooi gram 

 per day. 



