484 
SUMMARY OF CURRENT RESEARCHES. 
infusorial earth. The first ingredient, owing to its method of prepara- 
tion, is harmless to the most delicate skin, while the latter is most 
deleterious. 
Microscopical Examination of Samples of Meal.* — Dr. Lange 
recommends the following method for the determination of the amount 
of silica in meals. Instead of by burning, the organic matter is destroyed 
by digesting the meal in concentrated sulphuric acid containing some 
anhydrous copper sulphate. A teaspoonful of the meal is boiled in a 
flask with about 20 ccm. of strong sulphuric acid and a teaspoonful of 
anhydrous copper sulphate until the liquid becomes colourless. The 
liquid is then slowly added to 250 ccm. of water, and the sediment 
containing the silica allowed to settle. The latter is then examined 
under the Microscope. The method is particularly useful for the 
detection of barley meal in other meals. 
Estimation of Lecithin in Plants.*) - — Herr Bela v. Bitto has made 
a number of measurements as to the quantity of letliicin in various seeds. 
He notes as to methods, that if a vegetable substance be extracted with 
ether and then twice with alcohol, with each for an hour, only part of 
the lecithin passes into solution. For quantitative measurements the 
substance must be boiled at least 30 times with ethyl-, or 20 times 
with methyl-alcohol, and each boiling must last 8-10 minutes, but not 
above a quarter of an hour. Simplification can hardly admit of less 
than 20 boilings with methyl-alcohol. 
* Zeitschr. f. angewandte Mier., i. (1896) pp. 369-70. 
f Math. Nat. Ber. Ungarn, xil (1895) pp. 36-46. 
