4 58 REPORTS REVIEWS. THE ANALYSIS OF DYESTUFFS AXW THEIE IDENTIFICATION IN DYED AND COLOU~ED MATERIALS, LAKE-PIGMEKTS, FOODSTUFFS, ETC. By ARTHUK G. GREEN, M.Sc., F.R.S., F.I.C. London: Charles Griffin and Co., Ltd. Price 8s. 6d. net. The appearance of this book is to be especially welcomed now that a determined effort is being made to place the manufacture of dyes in this country upon a firm basis, and Professor Green is to be congratulated on his lucid presentation of the masterly series of investigations which he has carried out during the past twentyREVIEWS 459 years.The valuable analytical tables, however, by no means exhaust the scope of this book. A short introductory chapter explains in simple language the general chemical characteristics of dyes, and succeeding chapters are concerned with a clear account of the classification of dyes both from the chemical and the dyeing point of view.Then follow the author’s schemes for the analysis of dyes in substance, and their identification on animal and vegetable fibres as well as in foods. I n a special chapter the analysis of indigo, both in substance and on the fibre, is discussed, and in another the analysis of pigments and lakes is dealt with.The last chapter-on the determination of the constitution of azo dyes-is concerned with the isolation and characterisation of the cleavage products of azo dyes obtained by the processes of reduction and nitration, and is particularly interesting. I n spite of the rapid increase i n the number of dyes that have been put on the market, Professor Green’s book is not one that will soon be out of date, for his analytical schemes are elastic, and allow of new dyes being rapidly classified, so that the groups to which they may belong are soon ascertainable.The book is well printed, and is singularly free from errors; the only one that was noticed was the phrase, (( To affect this transference ” (p.63), where “ affect ” should obviously be ( ( effect.” The style is straightforward and clear, and the unfortunate tendency that one notices in some chemical books of using a Germanic phraseology is here absent. One might perhaps suggest (p. 99) that the sentence, “These are formaldehyde condensation products of primary nitroamines,” would be better rendered, (( These are products of the condensation of formaldehyde with primary nitroamines.” There is no doubt that the analyst, as well as the manufacturer and the user of dyestuffs, will find it necessary to have Professor Green’s monograph on his shelves.J. C. CAIN. AIR, WATER, AND FOOD. Fnoar A SANlTARY STANDPOINT. By A. G. WOODMAN and J. F. NORTON, Massachusetts Institute of Technologi. Fourth Edition.Revised and Rewritten. 1914. John Wiley and Sons. London : Chapman and Hall. Since the last edition of this book was published in 1909 one of the original authors-Mrs. Ellen Richards-has died, and the entire volume has been largely rewritten, more particdarly the sections on air, water, and milk. Originally written from a ‘( missionary ” standpoint, its employment for college and technical school teaching has necessitated considerable modification in the character of part of the general discussion, and it is probable that the book has gained in consequence.For all detailed discussions and analytical methods the reader is referred to such writers as Wiley, Allen, and Leach, the present work being intended ‘( for the student who needs to study, as part of general education, only typical substances, and such methods as can be carried out within the limits of laboratory exercises in a college curriculum.” The standpoint of the authom cannot be better expressed than in their own words, which run as follows : c c The day is not far distant when a city will be held as responsible for the purity of the air in its schoolhouses, the cleanliness of the water in its reservoirs, and the reliability of the food sold in its markets as it is now Price 8s.6d. net.460 REVIEWS for the conditions of its streets and bridges. Nor will the years be many before educational institutions will be held as responsible for the condition of the bodies as of the minds of the pupils committed to their care ; when a Chair of Sanitary Science will be considered as important as a Chair of Greek or Mathematics; when the competency of the food purveyor will have as much weight with intelligent patrons as the scholarly reputation of any member of the faculty.” A most praiseworthy attempt has been made in the work under review to bring about these admittedly desirable results, and in the short space available for the task a valuable sketch has been attempted of methods employed in the examination of air, water, beverages, and food products, while their adulteration and sophistication also receive useful attention.On the whole, a wise discrimination has been displayed in the choice of the analytical methods described ; and the student who has worked through ‘even some of them, will, if he derives no other advantage, at least be well on the way towards realising the complexity of the problems which face the modern food chemist when confronted with the genuine article or with the products of the ingenuity of the professional sophisticator and mis-brander.” A curious error has crept into the section on beer, in which it is stated that “ the extract of beer cannot be accurately determined by evaporation and drying at 100” C., because of the dehydration of the maltose ’’ ; while serious exception must be taken to the “ simple analytical scheme due to Sherman ” (‘‘ Methods of Organic Analysis,” second edition, p.341) for the analysis of malted cereals, described on p. 189.) On p. 6, a printer’s error’ has resulted in attributing to corn a carbohydrate maxzmum of 52 per cent. and a minimum of 72-7 per cent. Useful appendices of tabulated matter, a very full bibliography, and an index, complete this stimulating and very readable volume. HENRY F. EVERARD HULTON.