180 
THE GEOLOGIST. 
is to be added salt of jihosidioius ; and thus, after continued heating, the siliceous 
earths may be recognized in the sliape of Ijeads or points. The analysis by the 
moist way may be performed either with acids or water. Water can only dissolve 
a few natural salts, as, for example, rock-salt, alum, carbonate of soda, sulphate 
of soda, potass, salts of magnesia, protoxide of iron, oxides of copper and tin and 
lime ; the solution of each of these lias a peculiiU' taste, and when evaporated in a 
watch-glass, leaves behind the dissolved salt, which may now be readily analysed 
by the ordinary chemical ]nocess. 
" The acids act on several compounds of silica, especially such as contain water 
(the hydrous silicates), as, for instance, the zeolites ; they have also a solvent 
action on calcareous felspar, so that the silica se])arates like a jelly or slime ; 
other silicates must first be melted, or mixed with alkalies, if they are to be 
further examined. ()n the other hand, the acids dissolve most metallic oxides, 
with a determined colouring, wliich is indicateil to some extent in the accounts of 
the individual minerals." 
The relations of the chemical constituents to crystalline forms is admirably 
set forth in the same easy and definite manner ; and the chapter on this 
subject contains a valual)le table, displaying the Latin and English names, the 
symbol, electrical relations, the atomic weight, specific gravity, colour and appear- 
ance, modes of occurrence, &c., of minerals. The minerals noticed are also 
described in the same terse and exiilicit way, and for the student this must be 
regarded as one of the best, if not the very l)est, elementary treatise. All it 
teaches is necessary to be kno^vn, and to be relied upon, while lie has neither to 
wade through a mass of irrelevant matter, nor to learn under the dread of having 
to reject, on future reading, anything he has, from this book, acquired. 
On Copper-SmeUing. By Hyde Clarke, C.E. London : Mining Journal Office, 
Fleet Street. 8vo. 1858. 
This pamphlet, a rejirint of a report of a paper read before the Society of Arts, 
contains much valuable information on copper-smelting, and a considerable 
amount of statistical details of the copper-trade. 
A New Oeolof/ical Chart, shorving at one view the Order of Succession of the Slrafijied 
Hocks, with their Mineral Characters, Principal Points, Averaye Thickness, 
Localities, Uses in the Arts, <S;c. Arranged by John Morris, F.G.S., 
Professor of Geology in University College. London : James Reynolds, 
174, Strand. 
Li our last number we noticed one of the many admirable tables and sections 
for the publication of which Mr. Reynolds, of the Strand, is so well known, and 
it is with much pleasiu-e we notice this tabular chart, which we have received as a 
new publication since our last issue. 
What the title professes the work fulfils. We have, in the centre, coloured 
spaces, in which the succession of the beds and their thicknesses are duly 
registered and supported, on the one hand, by concise descrijitions of their uses 
in the arts, and their mineral characters ; on the other, by some half-dozen names 
of the characteristic points of each division, and the like number of localities in 
which each division is typically displayed. 
Little is necessary to be said of such works, and we feel ourselves only called 
upon to recommend them, or point out their defects, for the benefit of our nume- 
rous readers. Of this chart, we would say that it is worthy of a place alike in 
the libraiy of the student or the proficient in geological science, and that we are 
])leased to find that I'rofessor Morris has modified the nomenclature of the 
different divisions of the Crag, in a manner to rectify the otjectionable terms 
hitherto in use, to which we alluded in our notice of his former production. 
