376 JOURNAL OF THE SOCIETY OF COSMETIC CHEM1STS (about 100 pages). On the other hand, the portion devoted to the industrial application of particle tech- nology appears short and almost superficial still, this section touches on many important practical as- pects. A typical example is the (too) brief paragraph on the control of particle size of therapeutic inhala- tion aerosols. Thus, the author states that the particles should be as small as can reasonably be obtained from a pressure package. On the other hand in the chapter on physio- logical action, the author correctly describes how the ratio of particles inhaled to particles exhaled depends on their size and that particles of different size are deposited in dif- ferent portions of the respiratory system. It is fairly well established that--depending upon the physio- logical action desired--there does indeed exist an optimum particle size for therapeutic inhalation aero- sols which is of the order of 1-3 micra. Admittedly, recognition of problems and raising of questions in a book of this type is proper but this re- viewer feels that the author has on occasion failed to state clearly those few answers that are available.--M. M. R•o•R--Warner-Lambert Re- search Institute.