the Urine in Man and Carnivorous Animals. 467 



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 re-absorbed by the absorbing vessels of the intestinal 

 canal, 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 canal is larger than that con- 

 tained 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 

 ferrocj-anide o\^ potassium is substituted for common salt; in 

 this case, the first urine excreted after the injection of the sa- 

 line solution, and frequently even after so short a time as fif- 

 teen minutes, contains so copious an amount of ferrocyanide 

 of potassium, as to yield, upon the addition of persalls 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 I'SOOth of its amount in salts, 

 be drunk 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 

 urine, in this experiment, emitted in the last evacuation, will 

 be clear and colourless, like pump-water, and ihe amount of 

 salts it contains is little more than is contained in pump- 

 water. There are individuals who are capable of thus imbi- 

 bing from six to eight quarts of water consecutively without 

 any inconvenience. 



But the case is quite different with water possessing an 

 amount of salts equal to that of the blood; if even as little as 

 1-1 00th part of common salt be added to pump-water, and 

 from three to four glasses drunk, no evacuation of urine will 

 take place, even two liours after drinking. It is almost im- 

 possible to drink more than three glasses of this saline water, 

 ibr it weighs heavily on the stomach, as if the absorbent ves- 

 sels had no power of taking it up. This obviously arises from 



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