361 



food is, for some reason or other, generally better adapted to meet 

 the collective requirements of the human organism than an exclu- 

 sively bread or other vegetable one, the testimony of common ex- 

 perience may be accepted as sufficient evidence. Whatever may 

 prove to be the exact explanations of the benefits arising from a 

 mixed animal and vegetable diet, it is at any rate pretty clear, that, 

 independently of any difference in the physical, and perhaps even 

 chemical relations of the nitrogenous compounds, they are essentially 

 connected with the amount, the condition, and the distribution of 

 the fat in the animal portions of the food. 



Fat is the most concentrated respiratory, and of course fat-storing 

 material also, which our food-stuffs supply. It cannot be doubted 

 that, independently of the mere supply of constituents, the condi- 

 tions of concentration, of digestibility, and of assimilability of our 

 different foods must have their share in determining the relative 

 values, for the varying exigences of the system, of substances which, 

 in a more general or more purely chemical sense, may still justly 

 be looked upon as mutually replaceable. 



By the aid of chemistry it may be established that, in the admix- 

 ture of animal food with bread, the relation (in respiratory and fat- 

 forming capacity) of the non-flesh-forming to the flesh-forming 

 substances will be increased, and, further, that in such a mixed diet 

 the proportion of the non-flesh-forming constitutents, which will be 

 in the concentrated form, so to speak, of fat itself, will be consider- 

 ably greater than in bread alone. Common experience also testifies 

 to the fact of advantages so derived. It remains to Physiology to 

 lend her aid to the full explanation of that which Chemistry and 

 common usage have thus determined. 



COMMUNICATIONS RECEIVED SINCE THE END OF THE SESSION. 



I. Note " On the Formation of the Peroxides of the Radicals 

 of the Organic Acids." By B. C. BRODIE, F.R.S., Pro- 

 fessor of Chemistry in the University of Oxford. Received 

 July 22, 1858. 

 The researches of Gerhardt showed a close resemblance which 



exists between the monobasic organic acids and the metallic protoxides. 



We have the chloride of acetyl corresponding to the chloride of the 



