DETECTION AND ESTIMATION OF TANNINS. 51 
Lowentlial used a solution of gelatin instead of hide 
powder. This solution was prepared by taking 20 
grammes of good gelatin, allowing it to swell for several 
hours in cold water, then dissolving with the aid of heat 
and more water, saturating the solution with common 
salt, adding 100 cc. of hydrochloric acid and sufficient 
water to make one litre. The infusion after agitation 
for some time with the gelatin solution was found to 
filter slowly, and Procter suggested stirring in about 5 
grammes of finely-powdered kaolin for causing a rapid 
settling of the precipitate and so giving a solution which 
filtered rapidly and clear. 
Simaud recommended the bone tissue previously de¬ 
scribed. 
Many more details and numerous suggestions of 
minor importance might be added, but they would 
serve rather to complicate the process given. To 
those who wish to study the original papers on tannin 
estimation more in detail, the following are recom¬ 
mended : Gauhe, Cecil, Lowentlial, Neubauer, Procter, 
Notzli, and the Report of the Commission of German 
chemists. 
