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POPULAR SCIENCE REVIEW. 
a few years since, still forms a feature of tlie Technological Museum in the 
Crystal Palace. 
In the chapters treating of solution of substances we find for the first time 
that Mr, M‘Leod still retains a form of nomenclature attempted to be intro- 
duced some years since, but which never obtained general acceptance ; we 
refer to such expressions as “ magnesic and zincic sulphate.” “ Magnesic ” 
is not nice, but “ zincic ” is “ most intolerable and not to be endured.” 
Further on, when dealing with the separation of bodies by cold, we find 
references to the observations of Rae, and the recent experiments of Buchanan 
and Guthrie. It is interesting to trace, under Light, the subject of prismatic 
analysis, of which so little was said in the first edition, extended to a re- 
port, rich in recent results, in the present edition ; it is brought down to date 
by reference to the lines of the new metal gallium. The woodcuts taken 
from photographic spectra of the elements on pp. 2 77- 8 are sadly blurred in 
the printing. As the production of cold by vaporization has attracted con- 
siderable attention of late, we were led to expect, what we do not find, a 
description of Carre’s newer and very elegant apparatus for the freezing of 
water, based on Leslie’s method, which is however mentioned, and which it 
so beautifully illustrates. The rapidity with which a pint of water can be 
frozen by its means renders it a most valuable aid in a chemical or physical 
laboratory, as well as a means of producing a very strikiog lecture experi- 
ment. Again, we cannot help feeling that the reader will experience some 
difficulty in grasping the principle of Holtz’s electrical machine for want 
of an illustration. The machine is of increasing practical importance from 
the fact that it will remain charged for many hours. We regard these as 
shortcomings, as we have noticed in another part of the work more than 
one illustration of the same apparatus. Many examples could be quoted in 
testimony of the aim having been in all the chapters to incorporate all recent 
scientific results of established importance, and we may content ourselves by 
alluding, in support of this, to the fact that the declination and inclination of 
the magnetic needle for the present year (1877), as registered at Kew 
Observatory, are given, and to a note on the remarkable experiments of De 
La Rue and Miiller with their new form of battery. The meanimg of an 
expression used in this note, 11 a condenser of 44.8 microfarad capacity,” will 
puzzle the general reader, while reference to the index will throw little light 
on the problem. 
THE ART OF ELECTRO-METALLURGY.* 
T HE present volume is, we believe, the most recently published of the 
valuable series of text-books of science which are being issued by Messrs. 
Longmans “ for the use of artisans and of students in public and science 
schools.” The author has provided a vast amount of information on the 
subject, and has increased the usefulness of his text-book, so far as some of his 
readers are concerned, by supplying, page by page, abundant references to 
original memoirs, thus placing those who consult his book in a position to 
* “ The Art of Electro-Metallurgy, including all known Processes of 
Electro-Deposition.” By G. Gore. Sm. 8vo. London : Longmans. 1877. 
