Price $2.50. Nitrogen is a sort of Doctor Jekyll and Mr. Hyde among the familiar gases. Inert in its free state as it is in the atmosphere, it shows a wide range of chemical activities in combination. Its compounds are extremely numerous and of very varied characters, in some cases, for instance, strychnine, the compound may be permanent, but in the common high explosives we have extreme susceptibility to violent action. The element is an important one in biologic chemistry, essential to the formation of tissues in animals and plants. It has therefore functioned largely in agriculture and it has been found that one of the most useful forms is as nitrate. The world has relied for many years upon the remarkable and extensive deposits of sodium nitrate in the rainless area of Chile. Inventive genius has been applied to the problem of fixing the nitrogen of the air in some active compound and several different methods have developed; of these the present day operation is principally the formation of ammonia, and it appears from the book in hand about 722,000 tons are fixed annually as ammonia. It is well worth noting by Americans that of this amount 5oo,ooo tons are fixed in Germany.
In the present book there is presented a comprehensive summary of the several methods now in use for nitrogen fixation. Descriptions are clear and detailed; all those interested in this very important problem will find set forth in very satisfactory form the present state of this industrial operation. Excellent illustrations of important plants add to the value of the essay. The theory and practice of each process is given. The user of the book will, therefore, be able to keep up to date in all phases of nitrogen fixation. The book is well printed, on good paper. Its low price will enable chemists generally to add it to their libraries.
HENRY LEFFMANN.