324 General Notes. [March 
A hut of the stone age discovered at Schussenried (Wurtemburg). By Dr. V. Gros. 
Matériaux, XVIL, 321-323. 
The horse in prehistoric and historic times. By C. A. Pietrement. Matériaus, 
XVII, 323-336. 
MICROSCOPY AND HISTOLOGY.! 
Pure CARMINIC ACID FOR COLORING MICROSCOPICAL PREPARA 
TIONS.2~Since Gerlach first called attention to carmin as a color- 
ing matter for histological purposes, many methods of pre | 
the carmin solutions have been published, but, so far as lam 
aware, none which result in anything but mixtures of variots 7 
carmin salts with undetermined and undesirable impurities, n 
as fatty matter, tyrosin, sugar, and salts of alkaline metals, Ui 
course the coloration produced by these mixtures has been some 
times good, sometimes bad, and the solutions have easily spoiled ; 
or decomposed, while their preparation often required consid 
able time and trouble. Several years ago I studied or 4 
chiefly from a chemical standpoint, and since then I have a 
wondered why naturalists usually used carmin solutions ey 
water, with some caustic or destructive material added, wa a 
principal solvent. Carmin of commerce, it is true, 1S al l 
soluble, even in water, until ammonia, borax, or some ot are i 
to solution is added ; but carminic acid, the basis of ha 
matter of carmin, has long been stated in the leading ¢ ce 
dictionaries and hand-books to be readily soluble in posts ays T. 
alcohol. Watts (Dict. Chem., 1872, 1st suppl., Pa and se 
carminic acid: “ This acid forms a purple mass, ne rahi | 
ble in all proportions in water and in alcohol. e a aht 
ydrochloric acid dissolve it without alteration. tos 4 
of 136° C. without decomposition.’ o E 
Earlier still Watts (Dict. Chem., 1863, V. 1, P. p ee 
fine red pigment known in commerce as carmin ra pee 
treating a solution of cochineal with cream of : 
tologice ie : 4 
: ‘ -half of the on 
some of the published recipes, more than one ge „e hitet pares | 
There are two ways commonly in use Er pre acid arti 7 
acid, which term Ihere use as distinguished ee hwveigget oe 
(the cochineal decoction for which Grenacher, ee | 
1 Edited by Dr. C. O. Wurman, Mus. Comparative wae society A E 
-3 By Geo. Dimmock. Read at the New York meeting ° ey 
ists of the Eastern United States, 28th Dec., 1883. 
