experience or observation." The fact that one purpose of the treatise is to interest beginners in the subject of political economy has also modified its character. "The author has not held himself, as strictly as he has sought in previous works to do, to the treatment of political economy as a science, to be distinguished from the art of political economy. He has allowed himself great freedom in assuming that certain results are desirable in themselves, and certain other results undesirable; and he has sought to show how these may be avoided and those attained. Much, which, in his other works, has been treated as belonging to the applications of political economy, is wrought into the substance of the present treatise." The work is divided into two chief parts, one treating of "Production and Exchange," the other of "Distribution and Consumption." Each section is numbered and has a title, and the volume is indexed.
Fuel and its Applications. By E. J. Mills and F. J. Rowan. Illustrated. Philadelphia: P. Blakiston, Son & Co. Pp. xx + 802. Price, $7.50.
It is one of the obstacles to gaining a competent knowledge of technology that its manuals become almost worthless when a few years old, but it is the glory of the sciences on which technology depends that they advance fast enough to make these books antiquated so quickly. This is especially true of the group of industries based upon the science of chemistry. In order to supply the lack of a comprehensive, authoritative new work dealing with these industries, a series of volumes has been projected, under the general title "Chemical Technology, or Chemistry in its Applications to Arts and Manufactures." It will be edited by Charles E. Groves, F. R. S., editor of the "Journal of the Chemical Society," and William Thorp, B. Sc. As much of the matter of Richardson and Watts's "Chemical Technology" as is available, especially the historical portions, will be incorporated in the new work. Of this series the present volume is the first. The most important sections of the general field, to be covered in later volumes, are "Lighting," "Acids and Alkalies," "Glass and Pottery," "Metallurgy," "Textile Fabrics," "Leather, Paper, etc.," "Coloring Matters and Dyes," "Oils and Varnishes," "Brewing and Distilling," "Sugar, Starch, Flour," etc. The present volume treats of "Fuel and its Applications" generally; its special employment in various branches of chemical manufacture being preserved for detailed consideration in the volumes devoted to the special subjects enumerated above. In the chapters devoted to the production of fuel, tables are given showing the composition of the different woods and coals, together with information concerning the formation of peat, lignite, and coal, the world's production of coal, explosions in mines from fire-damp and coal-dust, etc. The figures representing the output of coal in Britain and other countries show the enormous development which has taken place in the fuel industry all over the world. Methods of burning charcoal, both in heaps and kilns; and methods of coking, in heaps and in ovens, are described, with illustrative views and diagrams. On the continent of Europe, methods of cleaning, washing, and classifying coal have reached a great degree of elaboration, and the practice in Britain has progressed somewhat in the same direction. Considerable space is devoted to these methods, and the machines employed in them. The most marked advance in respect to the manufacture and application of fuels in the past generation has been in the control and utilization of gases. The waste gases from coking ovens are now collected for their ammonia, tar, and other by-products, the gases from blast-furnaces using coal and from gas-producers are also made to yield these products; and great advance has been achieved in the extraction of ammonia in shale distillation. More important than these is the use of coal-gas, and in America of "natural" gas also, as fuel. The methods and appliances for using gaseous and also liquid fuel receive a general representation in this volume, and copious references are given for specialists who may wish to study particular branches of the subject. The portion of the volume devoted to the application of fuel is introduced by chapters on the theory of heat and the nature of flame. The matters of chimney-draught, forced combustion, and smoke prevention are then taken up. The special application of fuel considered first
