URINE. 149 



property at a high temperature ; the phosphate of soda, in this 

 process, loses its alkaline reaction completely upon the addition 

 of uric and hippuric acids, and assumes an acid reaction. 

 The acid nature of the urine of man, and of the carnivorous 

 and graminivorous animals, is thus explained in a very simple 

 manner. 



"There are but two principal channels through which the 

 salts entering the organism with the aliments can effect their 

 exit from the body ; viz., they must either be carried off in the 

 faeces or in the urine. The most simple experiments show that 

 soluble salts are carried off by the faeces only when the amount 

 of salt contained in the fluids in the intestines is larger than 

 that contained in the blood; if the amount of salt in these 

 fluids is equal or inferior to that of the blood, the soluble salts 

 are reabsorbed by the absorbing vessels of the intestinal tube, 

 and enter the circulation, and are then removed from the body 

 by the urinary organs and channels. If the amount of salt 

 contained in the intestinal tube is larger than that contained 

 in the blood, the salts exercise a purgative action. 



" If, after previous evacuation of the rectum, a weak solution 

 of common salt (one part of salt to sixty parts of water) be 

 taken by means of a clyster, no second evacuation will take 

 place; the fluid is absorbed, and all the salt is found in the 

 urine. This experiment yields the most convincing results if 

 ferrocyanide of potassium is substituted for common salt; in 

 this case, the first urine excreted after the injection of the saline 

 solution, and frequently even after so short a time as fifteen 

 minutes, contains so large an amount of ferrocyanide of potas- 

 sium as to yield, upon the addition of persalts of iron, a copious 

 precipitate of Prussian blue. 



" The influence which salts in general exercise upon the se- 

 cretion of urine is, in the highest degree, worthy of attention. 

 It is a well-known fact that a very speedy emission of urine 

 takes place, in healthy individuals, after drinking fresh pump- 

 water. If ten glasses of water, of from six to eight ounces 

 each, containing no more than 1 -500th of its amount in salts, 

 be drank at short intervals, an emission of urine of the usual 

 colour will, after the lapse of about ten minutes, follow the 

 second glass, and from eight to nine evacuations of urine will 

 generally occur in the course of an hour and a half. The 



