BOOK REVIEWS 437 spent on, and more or less extravagant claims of, proprietary advertising. An account is given of the rather numerous voluntary committees that seek to restrict the greater excesses, without showing overt application of sanctions against the transgressors. It is much more difficult to prove that the advertising codes have been infringed in spirit rather than the letter: the former breaches seem less offensive to the author on the rather dubious analogy of parking offences he lists five species of contraventions: popular misconceptions, a grain of truth, false superiority over others, imputed need, pseudoclinical reports. The most serious result is that patent medicines may thereby be taken for ailments that are non-existent or require different treatment. Some teeth might be given to control of advertising, the author suggests, by a body the counter- part of Dunlop, with sanctions to prohibit further advertising for up to, say, a year from an offence. What is the alternative? Scrap the lot? Could GPs cope with a load that would probably be double the present number of patients? - Dr. Bradshaw thinks not. He dismisses too readily the prospect of professional advice from retail pharmacists (in contrast to suggestions for health education made by W. Duffy at a recent Pharma- ceutical Society branch meeting). His revolutionary proposal is that the patent medicine advertiser should be required to devote some space (or time) to approved health education relevant to his product. Otherwise the author foresees little major change: his main purpose is enlightenment. G. F. PHILLIPS. INFRA-RED INSTRUMENTATION AND TECHNIOUES. A. E. Martin. Pp. x q- 180 q- Ill. (1966). Elsevier Publishing Co., Amsterdam-London-New York. 65s. In a very brief preliminary historical survey the reader is reminded that short- range research single-beam spectrometers were well known in 1900 and he is then equally briefly introduced to the key stages in the development of the wide range of double-beam recording ir spectrophotometers that are available today. The first half of the book is divided into short sections in which are described the basic components: source, slit condensing system, monochromator, detector, amplifier and spectrum presentation. Five individual sources are critically assessed, with very brief notes on power stability. Reference is made to a variety of detector types and the corresponding optical systems. For monochromators, the design and operation of prism and grating are contrasted: the section on prism- and filter-controlled gratings is particularly instructive and includes descriptions of the means used to achieve linear scales for either wavelength or wavenumber and a clear comparison of the relative advantages of the two presentations. There is also a very helpful discussion of slit inequality difficulties. The optics of single, and a variety of double, beam operating conditions are examined and their relative merits .contrasted. Following this general exposition, some commercial spectrometers are described: only UK and the better known American instruments are included. It is very helpful to find some indication of the refinement that may be expected for finite price ranges. There is a useful accouni of the design features of spectrometers for very long (beyond 1511 ) wavelengths, with commercial examples of the complexities to which the design- ers are driven.

438 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS The remainder of the book is concerned with specialist instruments, accessories and techniques. Chapter $ includes the low resolution grating "Spectrosorter" the well known and versatile "IRGA" for the rapid determination of specific gases radiation thermometers and an automatic milk analyser. A particularly praiseworthy feature is a whole chapter devoted to the novel development of interferometric spectrometry: the conversion of the complex waveform to a suitable spectrum of a sample is usually achieved with the aid of paper tape fed to a high speed digital computer. Two commercial instruments, based on Michelson principles, are described but unfortunately there is no discussion of the practical difficulties that have slowed their development and the reader is referred elsewhere for reviews of fundamental work. In chapter 5 Dr. Martin recognises the manufacturers' obligation to anticipate the analyst's need for a wealth of accessories to cater for diversity of samples yet still furnish good quality spectra. He describes the principles and construction of many types of absorption cells - including micro and variable path - that are intended for a variety of operating conditions. Brief (half page) accounts are given of devices suitable for checking transmittance linearity provision for focusing with an external sample site or a reflecting microscope reflectance attachments reference beam attenuation electrical conversion of wavelength to wavenumber baseline, and trans- mittance to linear absorbance ordinate optical polarisation spectra long path multi-reflection cells for gases and low pressure yapours and desiccant systems. In a final chapter dealing with experimental methods and techniques, Dr. Martin briefly recommends special handling for organic, and especially aqueous, solutions and solids - using disc, mull, melt and film - and provides a slightly less sparse treatment of theroetical principles and commercial practice for Attenuated Total Reflectance spectra. Attention also is given to difference and derivative absorbance presentations. There is a non-critical list of the better known collections of reference spectra, a short appendix describing three crystal materials, a bibliography of 86 references cited in the text and a short but mostly adequate index. The book is couched in a condensed, almost telegraphic, style which conveys the impression of lecture notes but in a monograph of this type, such an approach is not unwelcome. Regarding instrument design there are frequent references to original papers and current manufacturers and there are many neat optical and mechanical diagrams illustrating features of principle or construction. In several important in- stances Dr. Martin provides a simple mathematical treatment: the physics of emission and detection of radiation,the optics of dispersion through prisms and gratings and the effect on transmittance of multiple reflections at interfaces, and the theoretical correlation between the Fourier transform of the interference pattern complex wave- form and a transmittance ratio spectrum for sample and reference beams. Altogether an interesting and authoritative monograph from an author much of whose professional life - in an earlier decade at the Government Laboratory and since 1946 with a leading instrument manufacturer - has been devoted to the develop- ment of ir spectrophotometry. G. F. PHILLIPS.