INORGANIC CONSTITUENTS OF THE URINE. 



385 



(C 3 H 7 N"S0 2 ). The last two, however, contain sulphur, and they may have 

 peculiar physiological and pathological relations that are not at present un- 

 derstood. 



These various substances are mentioned, although some of them have not 

 been found in the normal urine, for the reason that there is evidently much 

 to be learned with regard to the various products of disassimilation as they 

 are represented by the composition of the urine. While some of them may 

 not be actual constituents of the urine, but substances produced by the pro- 

 cesses employed for their extraction, some, which have thus far been discov- 

 ered only under pathological conditions, may yet be found in health, and 

 they represent, perhaps, important physiological processes. 



Fatty Matters. Fat and fatty acids are said to exist in the normal urine 

 in certain quantity. Their proportion, however, is small, and the mere fact 

 of their presence, only, is of physiological interest. 



Inorganic Constituents of the Urine. It is by the kidneys that the 

 greatest quantity and variety of inorganic salts are discharged from the 

 organism ; and it is probable that even now physiological chemists are not 

 acquainted with the exact proportion and condition of all the constituents 

 of this class found in the urine. In all the processes of nutrition, it is 

 found that the inorganic constituents of the blood and tissues accompany 

 the organic matters in their various transformations, although they are them- 

 selves unchanged. Indeed, the condition of union of inorganic with organic 

 matters is so intimate, that they can not be completely separated without in- 

 cineration. In view of these facts, it is evident that a certain proportion, at 

 least, of the inorganic salts of the urine is derived from the tissues, of which, 

 in combination with organic matters, they have formed a constituent part. 

 As the kidneys frequently eliminate from the blood foreign matters taken 

 into the system, and are capable sometimes of throwing off an excess of the 

 normal constituents, which may be in- 

 troduced into the circulation, it can 

 readily be understood how a large pro- 

 portion of some of the inorganic con- 

 stituents of the urine may be derived 

 from the food. 



Chlorides. Almost all of the chlo- 

 rine in the urine is in the form of so- 

 dium chloride, the quantity of potassi- 

 um chloride being insignificant and not 

 of any special physiological importance. 

 By reference to the table of the compo- 

 sition of the urine, it is seen that the 

 proportion of sodium chloride is subject 

 to very great variations, the range being 

 between three and eight parts per thou- 

 sand. This at once suggests the idea that the quantity excreted is dependent 

 to a considerable extent upon the quantity taken in with the food ; and, in- 



FIG. 129. Crystals of sodium chloride (Funke)- 



