cies in the course of a few miles' flow. They see no objection to discharge into tide-waters or large lakes, and meet the argument as to waste of material by stating that the organic matter in sewage serves as food for low forms of animal life, which in turn sustain food fishes. The various modes of treating sewage—by chemical precipitation, broad irrigation, and intermittent filtration—are then described. Since rye grass, one of the species of useful plants that succeed best on sewage farms, does not cure easily, but may be readily preserved by ensilage, the silo beomes a valuable adjunct to the sewage works. In the portion of the volume devoted to descriptions of works, the establishments at more than twenty places are described with considerable detail and with figures, maps, and diagrams. There are also brief accounts of the use of sewage for irrigation at a number of places in the West. Various laws and codes of rules regulating the disposal of sewage in the United States and England are given in appendixes.
A Handbook of Gold Milling. By Henry Louis. London and New York: Macmillan & Co. Pp. 504. Price, $3.25.
But few arts remain that have not been brought under the sway of science, with the result of securing improved products, a reduction of waste, lessened drudgery for man and beast, or an increased return for the same amount of effort. The separation of gold from the rock and gravel in which it occurs was carried on by wasteful empiric methods so long as rich deposits were available, but now that lower-grade ores must be largely depended upon, a disposition to work in the light of exact knowledge is becoming manifest. The present volume is designed to aid in the technical instruction of gold millers. It gives no space to the separating operations connected with hydraulic mining, the stamp mill being its only theme. After some preliminary chapters on the occurrence of gold, the properties of gold and mercury, and the formation of amalgams, the processes and appliances for the several steps of the modern milling process are taken up in order. Rock breakers, mortar boxes, stamps, frames, guides, and their various accessories are described and are illustrated in views and detailed drawings. The processes of amalgamation, concentration, cleaning-up, and the cleaning, retorting, and melting of the amalgam are then discussed and the appliances required for them are set forth. Some information is given with regard to the cost of milling, labor, power, sampling, and assaying of ore, etc., and several useful tables together with an essay on the cam curve are contained in an appendix.
The Industries of Russia. Prepared by the Department of Trade and Manufactures, Ministry of Finance, for the World's Columbian Exposition. Editor of the English translation, John Martin Crawford, U. S. Consul General to Russia. G. P. Putnam's Sons, New York, American Agents. Five volumes. Price, $6.
The Russian Empire took an active part in the exhibition of 1893 at Chicago. Wishing to afford the American people a fuller idea of the industrial capabilities of Russia than the material exhibit of that country could convey, the Imperial Minister of Finance caused to be prepared this series of volumes which comprise sketches, by especially qualified writers, of the several chief industries of the empire. The first volume is devoted to manufactures and trade, and opens with a general view of this field by the distinguished chemist, Prof. D. I. Mendeléeff, who also contributes papers on the chemical industry and naphtha to this volume. Papers on the various textiles are furnished by N. P. Langovoy, professor in the St. Petersburg Technological Institute, and others on paper, leather, metals, glass, food products, tobacco, spirits, shipbuilding, etc., are contributed by other writers. Of a more general scope are the essays on the interior trade and fairs of Russia, the foreign trade, wages and working hours in factories, tariff systems, etc. The third volume, which is the largest of the five, containing over five hundred pages, is devoted to agriculture and forestry, the various features of these industries being treated by a large number of special writers. Mining and metallurgy are treated in a volume of a hundred pages by Mr. A. Keppen, mining engineer. The fifth volume is devoted to Siberia and the Great Siberian Railway, giving a description of the country and its resources, the history of its occupation by
