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POPULAR SCIENCE REVIEW. 
bearing on the envelope a motto, also to be placed on the fly-leaf of the 
essay. The jury to judge on these essays is to consist of a mixed scientifico- 
technical committee of six members. — Dingier' s Poly tech. Jour., January, 
1872. 
Preparation of Pepsin. — This substance is now so much used in medicine 
that any improved mode of preparing it is of importance. Herr E. Scheffer 
thinks he has hit on some improvements in the following mode : — The mu- 
cous membrane of a previously well-cleaned hog’s stomach is dissected off, 
chopped finely, and macerated in water acidulated with hydrochloric acid 
for several days, during which time the mass is frequently well stirred ; the 
resulting fluid is strained, and, if not clear, set aside for twenty-four hours, 
in order to allow the mucus to settle. To the clarified liquid a thoroughly 
saturated solution of chloride of sodium is added, and the whole thoroughly 
mixed. The pepsin, separated from the rest of the solution by the addition 
of the saline solution, is found floating on the surface of the fluid, and is 
removed with a spoon, put upon cotton cloth to drain, and finally submitted 
to strong pressure, to free it as much as possible from the salt solution. 
Work done in 1871. — A. chemical retrospect for 1871 has been issued by 
Dr. Kolbe, in the “ Journal fur praktische Chemie ” [No. 20, 1871]. Of this 
the u Chemical News ” speaks very highly. It says that the author shows in 
this paper that he is not only thoroughly well acquainted with science, but 
also with the conditions existing in different countries ; his allusion to the 
United Kingdom, while courteous and complimentary towards its men of 
science, contains a very true and correct view of the disdainful contempt 
with which science in general, and chemistry especially, is treated in certain 
quarters. 
A New Edition of Gmelin's Handbook. — All chemists will heartily welcome 
a new edition of Gmelin’s indispensable Handbook, the inorganic portion of 
which has long been behind the science of the day, though still often con- 
sulted and never superseded. Already there are issued the first, second, 
third, and fourth Lieferungen of the second division of the first volume, 
and the first and second Lieferungen of the third volume. The entire work 
is under the charge of Professors Kraut, with Professors Naumann and 
Ritter and Dr. Jorgensen as collaborators, to ensure its rapid completion. 
The favourite old treatise appears with a larger and clearer page and better 
type, and apparently, with no abatement of its former thorough and con- 
scientious exhaustion of every topic treated. 
A Machine for estimating the Starch in Potatoes is described by Dr. A. 
Schwartzer, in u Dingler’s Journal ” for January. It is thus briefly noticed in 
the “ Chemical News.” The paper, it says, treats on a subject which is not 
much attended to in this country — to wit, the good quality of potatoes as 
ascertained by their specific gravity — it being a well-known fact that the 
more starch (the main constituent of the tuber) potatoes contain the higher 
their specific gravity. The author describes at length a contrivance (weigh- 
ing machine of simple construction) with the aid of which samples of potatoes 
(quantities of at least 5 kilos, together) can be conveniently tested for their 
specific gravity. 
The Devitrification of Glass. — The January number of u Dingier ” contains 
a paper on this subject by a practical glass manufacturer, Dr. H. E. Benrath, 
