The flow of gases through tubes and orifices is then taken up, with emphasis on viscous, turbulent and "free-molecule" flow and the use of porous diaphragms and exhaust through tubes and orifices.
These two chapters are sufficient introduction to the practical problems in vacuum technique, which are approached first through a chapter devoted to mechanical pumps.
The commercially available rotary oil and molecular pumps are described in detail with the aid of numerous charts and operating drawings.
Constant-pressure, constant-volume, and circulatory methods for the determination of the intrinsic speed of pumps are described.
The next two chapters investigate "higher" type pumps, those depending upon steam ejection and mercury vapor, and vapor pumps using organic liquids.
These pumps incorporate for best operation specially designed nozzles, sketches of the most important types being given.
For the measurement of low pressures there are required different types of gages and manometers which operate according to a variety of physical principles.
Numerous ones are described, among which may be mentioned the following basic types: Rayleigh; McLeod; mechanical; viscosity; radiometer; heat conductivity; and ionization gages.
Closing chapters of the book are devoted to the sorption of gases and vapors by solids, active charcoal, silicates and cellulose; gases and metals; gases and electrical clean-up of gases at low pressures; vapor pressures and rates of evaporation; and the dissociation pressures of oxides, hydrides, and nitrides.
Many papers are referred to throughout the book, with detailed reference to the original works, in some cases sketches and text material being abstracted therefrom.
This adds much to the value of the present book, especially since the author has been so successful in thoroughly scanning the field and has used only really worthwhile references.
The encyclopedic nature of the book, as noted in the subject matter described above, should appeal not only to the specialist in vacuum technique, but also to the general scientist who may be uninformed and wishes to obtain authoritative information on one of the industrially important modern sciences.
As such it will be a good reference book, constantly to be referred to, by physicists, chemists, mechanical, electrical and chemical engineers who are most interested in research applications. S. CHARP.