jVA ture 



[XOVEMBER 4, 190? 



welding of sheet-iron, and various methods are 

 described. But surely it should not be necessary to 

 print letters from the Public Works Department of 

 Perth. W. Australia, and from other bodies, writing 

 in appreciative terms of a certain process which, as 

 we are not advertising it, we need not mention. To 

 our mind, in book-writing the author should use his 

 own judgment, which may or may not be influenced 

 by letters of recommendation, but it says little for 

 his analytical skill if he finds it necessary to print 

 the letters. 



The part of the book dealing with the welding and 

 cutting of metals is extremely interesting, and illus- 

 trates the great advance which has recently been made 

 in this direction. In all autogenous processes a re- 

 ducing flame which prevents the formation of oxides 

 is a sine qua noii ; but when a flame is to be used for 

 cutting purposes the reverse is the case. Most metals, 

 when heated to a sufficiently high temperature, will 

 burn in oxygen. This property is made use of in 

 cutting steel, for example. An oxy-hydrogen flame is 

 c-iused to impinge upon the metal, and at the same 

 time an auxiliary blow-pipe directs oxygen gas upon 

 the heated surface ; immediate combustion ensues. 

 The stream of oxygen is sufficiently powerful to drive 

 away the oxide as it is formed, and the cutting pro- 

 gresses very rapidly. For example, an armour plate 

 63 inches thick was thus cut to a length of i metre 

 in ten minutes. At Bremen a similar process has been 

 employed for cutting up and scraping ships. 



The book is suggestive, useful, and will, we hope, 

 «njoy a large circulation in spite of the few errors 

 here pointed out, and when the second edition is being 

 prepared we trust the author will take notice of our 

 friendly criticism. P. ^J. p_ 



PROBLEMS IN MTRITION. 



yolkscn}iihruiigsfiagen, and Kraft und Stoff im 



Haiishaltc der Natur. By Prof. Max Rubner. Pp. 



iv+143 and 181 respectively. (Leipzig: Academ- 



ische ^"erlagsgesellschaft, 1908, 1909.) 

 'T'HE.SE two little books contain three useful and 

 -L readable essays on those nutritional problems to 

 which Prof. Max Rubner has directed most of his re- 

 search work. The first of the above-mentioned books 

 contains two of these, and they treat of the minimum 

 protein requirement of man and of diet of the poor 

 respectively. The first question has within recent 

 years been brought prominently before the scientific 

 world, as well as the public at large, by the work of 

 Chittenden and others, who argue from their experi- 

 ments that, because they themselves have been able 

 for limited periods to maintain their health and 

 equilibrium on an amount of protein which is far 

 below the usually accepted Voit minimum, therefore 

 all men should permanently reduce their intake of 

 protein to the same low level. Those who believe that 

 the minimum is also the optimum would do well to 

 read and consider carefully the Berlin professor's 

 judicial commentary on their views. 



What most strikes the reader is the extraordinary 

 complexity of the problem. One factor, however, is 

 absent, and that is the effect of work and rest, for 

 .NO. 2088, VOL. 82] 



this causes practically no effect on the metabolism 

 of protein matter; but the question is sufficiently 

 complex without this. There is between different 

 people an enormous variation in what one may term 

 their metabolic habits, so that any hard and fast rule 

 is impossible. The mere body weight is not an 

 important clement, although, naturally, the heavier 

 a man the more protein will he require. If this were 

 all, it would be easy to adapt the dosage to the body 

 weight; but the difference is deeper than this; to 

 mention one point only, it is shown that, as a rule, 

 the thin person requires more protein to maintain 

 nitrogenous equilibrium than the corpulent. It must 

 have been a matter of common observation that the 

 stoutest people are not the biggest eaters. Another 

 complicating factor is what one eats with the protein, 

 and also the kind of protein one ingests. It is shown 

 that on a potato diet, for example, the minimum 

 necessary to maintain nitrogenous equilibrium is less 

 than with any other of the diets adopted. We have 

 further to take into account the presence, in most 

 foods, of nitrogenous substances which are not protein, 

 but which, nevertheless, have to be reckoned with. 



The second essay, on the diet of the poor (agri- 

 cultural labourers and the like), emphasises very 

 clearly one reason why a low protein intake brings 

 the consumer dangerously near to the margin. It 

 is shown beyond question that such a diet renders 

 people much more prone to take infectious diseases, 

 and there is a general lowering of the powers of 

 resistance. Considering that the bulk of the popula- 

 tion consists of those who are not well to do, this be- 

 comes a matter of national importance, and it is the 

 duty of the State to interfere. Prof. Rubner appears 

 to think that legislative measures should be adopted. 

 W'e can see, however, that the difficulty of legislating 

 on such a matter is very great; but at least the people 

 should be educated on the question of feeding ration- 

 allv, especially where children are concerned. Any- 

 one with any experience of hospital patients knows 

 that ignorance, in addition to poverty, is at the bottom 

 of most of the conditions of malnutrition which meet 

 us at every turn. Ignorance, moreover, is not con- 

 fined to the poor in regard to this most important 

 question. 



The third essay, which occupies the second volume, 

 is a summary of Prof. Rubner's work on nutrition 

 generally ; it is written in a more popular manner 

 than most of his publications, and a distinct philo- 

 sophical vein runs through it. The chemical events 

 which occur in the living body fall mainly into two 

 categories — (i) those due to the activity of enzymes; 

 in these there is but little transformation of energy ; 

 and (2) those which may roughly be described as 

 combustion, and from which the energy of living and 

 doing is derived. It is the second class of chemical 

 changes to which Prof. Rubner has mainly directed 

 his attention, and it is to him, in particular, that we 

 owe the experimental proof that the law of conserva- 

 tion of energy applies to the living cell as well as to 

 the world of inorganic matter. The law of the con- 

 servation of energy is so universal that one might, 

 perhaps, have assumed it would hold for living as 

 well as for lifeless material. But the scientific mind 



