May 27, 1875] 



NATURE 



out, would much reduce the inconvenience. He recom- 

 mends those who can do so "to join a 'mutton chib,' 

 buying the lambs of a full-sized breed, and keeping them 

 to at least three-and-a-half years old before killing. The 

 price per pound will not be less than charged by the 

 butcher, but it will supply an article twice as good as his." 

 The remarks with reference to eggs are also very much 

 to the point. " High game has fortunately gone out of 

 fashion, and the most frequent form in which we now 

 meet with decomposing albuminoid matter is that of a 

 fusty egg. Some housekeepers seem to consider this 

 quite good enough for made dishes, and thus spoil 

 material worth ten times what they save by their nasty 

 economy. No egg should be allowed to enter the kitchen 

 that has the slightest smell of rotten straw." 



In accordance with the opinion of most of the medical 

 profession and of a large body of the public, we read that 

 " as a regular beverage for a healthy person there is no 

 wine in the English market equal to claret." No doubt 

 the statistics of a few years hence will prove that the present 

 reaction against port and sherry will make itself evident 

 in the considerable diminution of the number of those 

 who are liable to be attacked with the gout, and so 

 demonstrate the advantages of the lighter wine. 



In the section on the special dietetics of health many 

 important remarks are to be found. Hints are given to 

 those who pursue the commercial, the literary, and pro- 

 fessional life, special chapters being devoted to each. 

 The regimen of infancy and motherhood, of childhood 

 and youth, are not emitted. Dr. Chambers is not the 

 cnly author who inveighs against afternoon tea, and we 

 cannot agree with the argument on which his objections 

 are based. He tells us that " the dilution and washing 

 away of the gastric secretion weakens its power of digest- 

 ing the subsequent dinner, improperly blunts the appetite, 

 and not unfrequently generates flatulence and dyspepsia." 

 But the gastric juice is not secreted if solid food is not 

 taken, and any fluid introduced into the stomach can 

 hardly but be absorbed within a quarter of an hour or so. 

 The substitute suggested, " a biscuit, and an orange or 

 an ice," is, in our estimation, much more injurious. 



Over thirty pages are devoted to the question of the 

 value of alcohol, the results being too lengthy to sum- 

 marise on the present occasion. They are well worth 

 reviewing. " So me well-meaning persons think to disen- 

 courage intemperance in drink by affecting a cynical 

 carelessness as to the quality of that which is consumed. 

 . . . However little a man's purse allows him to drink, let 

 it be good." 



The question of the dietetics of disease will appeal to 

 all who have the charge or any interest in those who are 

 invahded. They bear the same practical impress as the 

 other portions of the work. Though some of the author's 

 suggestions may appear to be founded on a somewhat 

 dogmatic basis, they all have an clement of truth in them 

 which may lead the reader to think twice of the reasons 

 why he is accustomed to adopt any line of action which 

 may be directly opposed to them. 



OUR BOOK SHELF 



An Elementary Exposition of the Doctrine of Energy. 

 By D. D. Heath, M. A., formerly Fellow of Trinity 

 College, Cambridge. (Longmans, Green , and Co.) 



In this book we have a very good elementary exposition 



of the Doctrine of Energy ; perhaps, however, better 

 adapted for the use of schools than for the general public. 

 Indeed, we are told in the preface that the work was deve- 

 loped from a set of lectures given to the senior classes of 

 Surrey County School. In his discussion of fundamental 

 units the author makes some very good and original 

 remarks. He tells us, for instance, in connection with 

 the first law of motion, that "the rate and the direction 

 of motion with and in which (respectively) a bo dy is 

 moving at any moment is to be considered as part of its 

 actual conditiott at that moment, which it will retain until 

 some adequate cause changes either the velocity or the 

 direction, or both. We may reasonably inquire how it got 

 the motion it has, as we may how it came by its shape 

 or its temperature ; and again, under what circumstances 

 it will change any of these properties ; but not why, 

 having got them, it keeps them." 



After dismissing the subject of fundamental units, the 

 writer goes on to dynamical energy, a subject which is fully 

 and fairly discussed. The author next proceeds to ther- 

 mal and other energies, and ends by a brief account of 

 molecular theories. If we have any fault to find, it \i that 

 undue preference seems to be given to the British system 

 of units, while the decimal system is overlooked. 



We think, too, that in the introductory part of the work 

 the author is not very clear in his statement with regard 

 to energy, where he tells us we may define it to be " the 

 capacity or power of any body or system of bodies, when 

 in a given condition, to do a certain measurable quantity 

 of work ; that is, to change its own condition and that of 

 other bodies, exhausting its power by the using of it." 

 We think that the second part of this definition might 

 have been omitted with advantage. 



The author, as he tells us in his preface, has endea- 

 voured to give the young student some conception of the 

 possibility of explaining the conservation of energy by 

 the theory that all phenomenal changes are really in 

 themselves changes of motion and position among the 

 molecules or ultimate atoms of substances ; and he adds 

 the hope that he has succeeded in presenting this as ex- 

 hibiting a probable surmise, which may be false without 

 vitiating the doctrine previously developed. 



This strikes us as being very well put. The conserva- 

 tion of energy would hold if we imagine the universe to 

 be composed of ultimate atoms with forces acting in lines 

 between them; but should it be found that this last con- 

 ception is inapplicable to portions of the universe, as, for 

 instance, the medium which conveys light, nevertheless 

 it does not follow that the conservation of energy does 

 not still hold true. 



The Commercial Handbook of Chonical Analysis. By 

 A. Normandy. New edition, enlarged, by Henry M. 

 Noad, Ph.D., F.R.S. (London : Lockwood and Co., 

 1875.) 

 When the late Dr. Normandy first pubHshed his work 

 on Commercial Analysis the Adulteration Act did not 

 exist, and the book was chiefly used by chemical manu- 

 facturers and by the small class of practical analysts. 

 Dr. Noad's enlarged edition of the work appears very 

 opportunely, and it will be found to be essential to the 

 analysts appointed under the new Act. It contains, in 

 alphabetical order, a concise list of all ordinary substances 

 which can require to be analysed in connection with food 

 and drink, and in addition the methods of analysing 

 many substances which can only be required in special 

 manufactures, or are only used as drugs. Each article 

 commences with an account of the substance in its pure 

 state : this is followed by a Hst of the most common im- 

 purities or adulterations, and then by the best means of 

 detecting them. The adulterations of some common 

 commodities are somewhat startling; thus, bread may con- 

 tain rye and barley flour, oatmeal, pea and bean meal, 

 potato starch and rice flour, while of mineral constituents 

 there may bCjlime, alum, magnesia, ground soapstone, 



