862 CUPULIFER^. 



Dr. R. Stockman has conducted a series of careful experi- 

 ments with gallic and tannic acids, with the object of determin- 

 ing the influences which the vegetahle astringents exert upon 

 the blood-vessels and animal tissues after absorption. He finds 

 that tannic acid on its entry into the stomach forms alkaline 

 tannates and tannates of albumin. A part of it, and sometimes 

 the whole, is converted into gallic acid in the stomach and 

 intestines, and it is difiicult to find a trace of tannic acid in the 

 blood, although it can be detected in the urine. Dr, Stockman 

 comes to the conclusion that tannic acid enters the circulation in 

 combination with alkalies and albumin, and is excreted with 

 such rapidity that only a trace of its presence can be detected in 

 the blood, but that its presence in the genito-urinary tracts and 

 in greater quantity in the intestines can be readily shown- It 

 does not appear to be excreted by the mucous lining of the air 



It was found that the urine of dogs, rabbits, and 



human beings, after the administration of tannic acid, contained 

 gallic acid and only a small quantity of tannic acid, but when 

 tannate of soda was administered the urine contained a large 

 proportion of tannic acid and but little gallic acid. These 

 results may be explained in the following manner : — When free 

 tannic acid is brought in contact with the contents of the 

 stomach, it is chiefly converted into tannate of albumin, only a 

 small quantity of alkaline tannate being formed. The tannate 

 of albumin being very insoluble is retained for a long time in 

 the intestines, until it is in a condition to be converted into 

 gallic acid, in which form it is at length absorbed; on the other 

 hand, the alkaline tannate is at once absorbed and passes off in 

 the urine. Under these circumstances, the administration of 

 tannate of soda naturally gives rise to the presence of a large 

 proportion of tannic acid and a small proportion of gallic acid 

 in the urine. 



Dr. Stockman did not find pyrogallic acid in the urine, but 



this experience is in opposition to that of other experi- 

 menters. 



When gallic acid was administered, that acid only was found 

 in the urine. 



