40 
ACTION OF ETHER ON GALLS. 
ART. V. — OBSERVATIONS ON THE ACTION OF ETHER ON 
GALLS. By Robert Bridges, M. D. 
Read at the Pharmaceutical Meeting of the College, Feb. 28th, 1842. 
The process usually directed for the purpose of procuring 
tannin from galls is that of Pelouze, viz, by the action of 
ether. This method affords the most ready and easy mode 
of accomplishing the ultimate result, but with regard to the 
primary effects of the action there exists some discrepancy in 
the statements of chemists. According to the original obser- 
vations of Pelouze, if galls be acted upon by displacement 
with ether which has been previously washed with water, 
there will result a liquid, which by repose will separate into 
distinct layers, the upper of which consists principally of 
ether, water, gallic acid, and a little tannin, while the lower 
consists entirely of pure tannin dissolved in water. Immedi- 
ately on the publication of this statement, the experiments 
were repeated by Liebig, who, acknowledging the great supe- 
riority of this over all previous methods, differs however in 
his statements as to the results; remarking, that the etherial 
liquor deposits only a very small quantity of the syrupy solu- 
tion of tannin, but that this effect is produced by the addition 
of a small quantity of water. The liquid then forms two dis- 
tinct strata, the lower of which is a solution of very pure tan- 
nin. In explaining this he states that tannin, when anhy- 
drous, is soluble in ether, but becomes insoluble by combining 
with water. M. Beral states that acting on an aqueous solu- 
tion of galls by ether, we obtain three layers, the lower of 
which is the solution of tannin. " The separation of tannin," 
he remarks, "is solely due to the property possessed by this 
substance of combining with determinate quantities of water 
and ether," forming a syrupy liquid which he denominates 
u liquid tannin." 
These discrepancies result from the different circumstances 
