February 8, 1906] 



NA TURE 



339 



brake horse-power, while for a corresponding plant 

 using- Diesel oil engines the formula is 300+ 10 T. 

 The annual costs for a year of 2700 working hours 

 for these are stated as 200 + 37T and uo + 2-<)T 

 respectively. 



Steam engines are treated in like manner ; thus in 

 the case of a high-speed tandem compound engine 

 the price is found to be represented by 



140 + 0-05 S — 



30,000 



240 +s 



where S is the final volume of the steam in cubic 

 inches swept out by the low-pressure piston per stroke. 

 Formulae are developed for boilers in terms of E, the 

 evaporative power in pounds of water per hour, and 

 the pressure, p, in pounds per square inch ; thus the 

 price of Lancashire boilers in pounds sterling is ex- 

 pressed by 1 10+ (o.oi6 + o-ooo3^>)E. 



The information brought together in this section 

 has evidently involved much labour, and it should 

 prove extremelv useful. The remaining half of the 

 book is devoted to questions involving a considerable 

 acquaintance with thermodynamics, in which the 

 author introduces several new terms, such as " trans- 

 power " (p. 155), to signify the time rate of trans- 

 mission of energy, " dynothermic coefficient " (p. 

 229), defined as the " ratio of resilience to heat trans- 

 mission creating it." 



Great stress is laid on the irreversible character of 

 practical heat-engine cycles, and the author's views 

 may be judged by his remarks on p. 178, where he 

 says :— 



" The conditions of life require rapid work, so that 

 the sooner we give up worshipping reversibility as a 

 fetish worthy to be aspired after and approximated 

 to, the better will we succeed in engineering." 



The dependence of maximum economy upon size, 

 indicator diagram, initial and back pressure, working 

 speed, antl furnace temperature are all dealt with in 

 detail, and combinations of the best values for effect- 

 ing economy arc considered by graphical methods. 



The complex nature of the problems attacked make 

 this part of the book decidedly hard reading, and the 

 difficulty is much increased by the author's notation. 

 The book is well illustrated by diagrams drawn by 

 Mr. H. M. Hodson. E. G. C. 



MATERIA ME DIC A. 

 A Text-book of Materia Medica for Students of 



Medicine. By C. R. Marshall, M.D. Pp. xi4-635. 



(London : J. and A. Churchill, 1905.) Price 105. 6d. 



net. 

 ' I 'HE compilation of a satisfactory text-book of 

 -L materia medica is a somewhat difficult task, 

 since the author should, at least in an ideal text-book, 

 be equally conversant with the chemistry of 'drugs, 

 the botany of those which are of vegetable origin 

 and the therapeutics of all. Dr. Marshall has been 

 singularly successful in preserving in this book an 

 even balance between these various divisions into 

 which the subject naturally falls. 

 NO. 1893, VOL. 73] 



The arrangement adopted, which differs some- 

 what from those commonly employed in text-books or 

 materia medica, is to be commended. The first por- 

 tion deals with the inorganic substances used in 

 medicine, then a chapter is devoted to the synthetic 

 products which have of recent years assumed so im- 

 portant a position as remedial agents, including anti- 

 pyrine, phenacetin, sulphonal, &c, and finally about 

 300 pages are occupied with the description of drugs 

 of vegetable or animal origin. The method of group- 

 ing these drugs is roughly that of the nature of the 

 " active principles " they contain, so that the subject 

 appears as a fairly coherent whole instead of as a 

 set of isolated groups of facts, which is the case when 

 the method of treatment adopted is that of the 

 botanical relationships of the plants from which the 

 drugs are obtained. The descriptions given of the 

 various drugs of vegetable origin are clear, and 

 though concise are sufficient for purposes of recog- 

 nition, especially when used in conjunction with the 

 carefully executed illustrations, which are one of the 

 best features of the book. 



In spite of the care which has evidently been taken, 

 both in the actual compilation and in the " proof " 

 reading, there are a few inaccuracies and doubtful 

 statements still existent in the text to which reference 

 may be made. It is not quite accurate to say thai 

 " no authentic case of antagonistically-acting alkaloids 

 occurring in the same plant is at present known " 

 (p. 6), since aconitine and aconine, which are stated 

 IP- 33°) both to occur in the root of Aconitum 

 Napellus, have been shown to possess opposed physio- 

 logical activities. Podophyllin is not, as suggested 

 (p. 8), a " neutral principle," which, when used in the 

 ordinary sense, means a single definite substance, but 

 is a mixture of resins. The reference to the " theo- 

 retically possible number of terpenes " (p. 11) is mis- 

 leading, since the number cannot be computed with 

 our present knowledge of these bodies. Gums are 

 not, as stated (p. 15), carbohydrates, and this state- 

 ment does not harmonise with that given later (p. 16), 

 that arabin, the chief constituent of gum arabic, is 

 a mixture of salts of organic acids. Potassium 

 hydroxide "can be handled with safety" (p. 111) is, 

 to say the least, not a wise saying to place before 

 students. Milk sugar (lactose) is wrongly described 

 (p. 233) as not fermentable. 



On general grounds exception may be taken to 

 such a loose and carelessly worded statement as " on 

 the differences in solubility of alkaloids is based the 

 principle of standardisation " (i.e. of drugs and 

 galenical preparations of these), and to such a sen- 

 tence as " hyoscine and scopolamine have a some- 

 what different constitution to atropine and hyos- 

 cyamine. " 



Such blemishes as are referred to in the preceding 

 paragraphs do not, of course, seriously detract from 

 the excellence of the book taken as a whole, and it 

 may be recommended to students as a safe guide to 

 modern materia medica, at least in so far as this 

 has received official recognition by the British 

 Medical Council. T. A. H. 



