32 THE NORTHERN MICROSCOPIST. 
cutting sections by bedding the subject in fused napthalin, which 
is not open to the objection of contraction during solidification ; 
but which was afterwards improved, we believe, by Professor William- 
son and Mr. Charles Bailey, by the addition of stearine. This 
mixture does not contract in the slightest degree in the well of the 
microtome; it is not generally known; but when tried fairly we 
think that all microscopists will be satisfied with it. 
For some time there was a difficulty in procuring the materials 
at a reasonable price; this objection need no longer be urged as 
they may be obtained from Mottershead and Co., Exchange Street, 
Manchester, of a suitable quality, for the microscopist’s use. 
The great advantage possessed by the Rutherford microtome 
over most others, is that it may be used equally well for the 
freezing process. The tissue is hardened in the ordinary way, 
either in alcohol, bichromate of potash, or dilute chromic acid, and 
after cleansing, placed in the gum-bedding which is made by 
dissolving five ounces of picked gum-arabic in ten ounces of water, 
and when it has dissolved adding two drams of camphorated spirit 
and half a dram of glycerine, finally straining the whole through 
calico. After having been frozen with the usual mixture of ice and 
salt this medium cuts very much like a fresh gruyére cheese, and 
upon placing the section in water, the bedding agent quickly 
dissolves away leaving the clean section behind. The freezing 
process is specially useful for substances which have been injected 
with gelatine solutions, since it is clear that no imbedding agent to 
which heat is applied could possibly be used for this purpose. 
OUR BOOKSSHELE: 
The Study of Rocks. ¥. Rutiey, F.G.S. London: Longman, 
Green and Co. Pp. 319. 88 figures in text. 
Tuts little work is one of those, started by the publishers some 
years since, under the name of Text-books of Science, and is of 
the same quality as the others in the series, namely cheap and 
good, and as such can be confidently recommended to the 
beginner. 
We may at first be inclined to consider the study of rocks a 
German one; not that we possess a dearth of workers in this 
country, but we have no’ elaborate text-books to guide us in our 
first attempts such as the students in the Fatherland have. 
To those possessed of microscopes and not as yet active workers, 
