THE "WESTMINSTER" SERIES 
The Testing of Rubber Goods. Gutta-Percha. Balata. Biblio- 
graphy. Index. 
Tells all about a material which has grown immensely in com- 
mercial importance in recent years. It has been expressly written 
for the general reader and for the technologist in other branches of 
industry. 
Glass Manufacture. By Walter Rosenhain, Superin- 
tendent of the Department of Metallurgy in the National 
Physical Laboratory, late Scientific Adviser in the Glass 
Works of Messrs. Chance Bros, and Co. With Illustra- 
tions. 
Contents : Preface. Definitions. Physical and Chemical Qualities. 
Mechanical, Thermal, and Electrical Properties. Transparency 
and Colour. Raw materials of manufacture. Crucibles and 
Furnaces for Fusion. Process of Fusion. Processes used in 
Working of Glass. Bottle. Blown and Pressed. Rolled or 
Plate. Sheet and Crown. Coloured. Optical Glass : Nature 
and Properties, Manufacture. Miscellaneous Products. Ap- 
pendix. Bibliography of Glass Manufacture. Index. 
This volume is for users of glass, and makes no claim to be an ade- 
quate guide or help to those engaged in glass manufacture itself. For 
this reason the account of manufacturing processes has been kept 
as non-technical as possible. In describing each process the object 
in view has been to give an insight into the rationale of each step, so 
far as it is known or understood, from the point of view of principles 
and methods rather than as mere rule of thumb description of manu- 
facturing manipulations. The processes described are, with the 
exception of those described as obsolete, to the author's definite know 
ledge, in commercial use at the present time. 
Precious Stones. By W. Goodchild, M.B., B.Ch. With 
42 Illustrations. With a Chapter on Artificial 
Stones. By Robert Dykes. 
List of Contents : Introductory and Historical. Genesis of 
Precious Stones. Physical Properties. The Cutting and Polish- 
ing of Gems. Imitation Gems and the Artificial Production of 
Precious Stones. The Diamond. Fluor Spar and the Forms of 
Silica. Corundum, including Ruby and Sapphire. Spinel and 
Chrysoberyl. The Carbonates and the Felspars. The Pyroxene 
and Amphibole Groups. Beryl, Cordierite, Lapis Lazuli and the 
Garnets. Olivine, Topaz, Tourmaline and other Silicates. Phos- 
phates, Sulphates, and Carbon Compounds. 
An admirable guide to a fascinating subject. 
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