160 
THE GEOLOGIST. 
into optical properties ; physical properties ; otlier characters, such as 
streak, taste, odour, etc ; characters dependent on cohesion ; chemical 
characters; all of v^hich. are briefly but intelligibly explained. The system 
of classification adopted is tbat used by Mr. Warington Smyth in his 
lectures at the School of Mines, and the division is primarily into Non- 
metallic and Metallic minerals. The former into the five classes of— 1. 
Carbon and Boron ; 2. Sulphur and Selenium ; 3. Haloids and Salts ; 
4. Earths; 5. Silicates and Aluminates. The latter into four classes — 
1. Brittle and difficult of Fusibility ; 2. Brittle, easily Fusible and Volatile ; 
3. Malleable, not reducible by heat alone ; 4. Noble Metals, reducible by 
heat alone. This is followed by a list of symbols and signs, and explana- 
tions of the technical terms used by jewellers and lapidaries. The book 
consists of 420 closely-printed pages, and is teeming with outline illustra- 
tions, small, hut carefully executed. As a sample of its plan a single extract 
will suffice, and at the same time will probably convey information to 
some of our readers : — 
"Chloeite, Werner. Hexagonal ; occurs in tabular six-sided prisms. Colour 
various shades of d\ill emerald-green in the direction of the axis, and yeUowis h o 
hyacinth-red at right angles to it ; also piire white or yellowish. Massive varieties 
oHve-green. Semi-transparent to sub-translucent. Lustre pearly ; yields to the 
nail, and when in powder is unctuous to the touch. Streak corresponding to the 
colour. H. 1 to 1-5. S. G-. 27 to 2-85. Compact chlorite is amor^jhous. Chlorite- 
slate posseses a slaty structiu'e, and frequently contains imbedded octahedral 
crystals of magnetic iron, hornblende, and garnets. Earthy chlorite is composed 
of small pearly, glimmering, scaly particles. It has a somewhat greasy feel, and 
bears a striking resemblance to Green Earth. 
Composition. 4 (Mg Fe), 'a1, Fe, 2 Si, 3 H = 4 Mg Si -h 3 H. 
Analysis, from the Pyrenees by Delesse, Silica 32 '1, Alumina 
18-5, Magnesia 36-7, Protoxide of Iron O'G, Water 12-1 = 100-0. 
Chlorite fi-equently contains as much as 8 or 9 per cent, of protoxide of iron ; 
those kinds which have more (up to 28 or 29 per cent.) are classed with Eipidohte. 
Before the blowpipe some lose their colour and fuse at the edges ; with borax 
aifords an iron-i*eaction. — Localities. The tin mines of Cornwall, where it is well 
known by the name of peach. Also in Cumbei'land and Westmoreland, and near 
Llanberis m Caemarvonshne. At Portsoy, in Banflfsliire, it is mixed ^vith Ser- 
pentine, and is frequently cut and polished. — Name. From ;^Xcop6y, green. This 
mineral may be distinguished from mica by its laminae being flexible but not 
elastic, while those of mica are very elastic. It has been proposed by Descloiseaux 
to divide chloi'ite into tlu*ee groups, Pennine, Clinochlore, and Ripidolite ; to which 
may be added Leuchtenbergite. — Specimens. British Museum ; Case 52. Museum 
of Practical Geology ; Horse-shoe Case, i\os. 1039—1043, 1047." 
In this little book also the various names used by different authors have 
been introduced, as well as certain terms which, although now obsolete, 
are very useful for reading the works of the older mineralogists, in which 
they constantly occur ; while the copious lists of synonyms are very valu- 
able to the student in perusing the works of foreign authors. We could 
say much more of its merits. It is very easy to " cut up " a bad book, 
but it is by no means so easy to say properly all we would of a good one. 
We can recommend Mr. Bristow's book to our student-readers; and, as its 
price and dimensions bring it within the reach of every one's means, we 
advise them to test the value of our praise by buying it and reading it. 
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