274 
Notices of Books . 
[April, 
with scarcely any forms referable to species known from coeval 
formations of Europe, it presents in its whole a remarkable, and 
as yet unexplained, case of isolation.” He considers it probable 
that the first vegetable types, or at least the dicotyledonous 
ones, have appeared at the same or at different times, not only 
at different places, but with different original characters, consti- 
tuting here and there distinCt groups without homogeneity or 
relation of forms. Considering what is known of the succession 
of these groups, it seems as if some of the original types had 
persisted more or less indefinitely in the series, being modified 
perhaps by casual circumstances ; and as if other original forms 
or prototypes had appeared here and there, and multiplied the 
characters of the vegetable groups.” For a discussion on the 
origin of species, he considers the materials as yet too scanty. 
The flora of the cretaceous epoch alone, he remarks, comprises 
“ many hundreds of thousands of species, comprised under more 
than fourteen thousand genera.” If so — unless very different 
proportions prevailed between the various groups of the organic 
world from those which now obtain — the extinCt inseCt-species 
of that epoch must have amounted to millions ! But of these 
only units have left their traces in the “ great stone book,” which 
is in perhaps no other department so strikingly and so unfortu- 
nately imperfeCt, 
A Manual of Electro-Metallurgy, including the Applications of 
the Art to Manufacturing Processes. By James Napier, 
F.R.S.E., F.C.S., &c. Fifth Edition, revised and enlarged. 
London : C. Griffin and Co. 
This work, in its present form, commences with a history of the 
galvano-plastic art, including an account of the earliest experi- 
ments of Spencer, Jacobi, and Jordan, with a list of works 
written on the subject, and a notice of the patents taken out for 
improvements in the process. From this the author passes to a 
description of galvanic batteries, electrotype processes, the me- 
thod of bronzing, miscellaneous applications of the deposition of 
copper, the deposition of metals one upon another, electroplating 
and gilding, and the results of experiments on the deposition of 
other metals as coatings. The concluding portion of the work 
is devoted to theoretical considerations. The author, as he 
states in his preface to the fifth edition, upholds the unitary view 
of the eleCtric force, and in electrolysis holds that the electricity 
is “ conducted through the solution by the base or positive 
element in the electrolyte, which it does as if it were a solid 
chain of particles or wire.” The statements made in the first 
edition concerning the practical operations of the art have not, 
we are told, required alteration. 
