5 oo THE POPULAR SCIENCE MONTHLY. 



We may therefore conclude that, regarding these from the point of 

 view of nitrogenous or flesh-forming, and carbonaceous or heat-giving 

 constituents, these chief materials of flesh and of cheese are about 

 equal. 



The same is the case as regards the fat. The quantity in the car- 

 cass of oxen, calves, sheep, lambs, and pigs varies, according to Dr. 

 Edward Smith, from 16 per cent to 31*3 per cent in moderately-fatted 

 animals, while in whole-milk cheeses it varies from 21'68 per cent to 

 32-31 per cent, coming down in skim-milk cheeses as low as 63. Dr. 

 Smith includes Neufchatel cheese, containing 18*74 per cent among 

 the whole-milk cheeses. He does not seem to be aware that the cheese 

 made up between straws and sold under that name is a ricotta, or crude 

 curd of skim-milk cheese. Its just value is about threepence per pound. 

 In Italy, where it forms the basis of some delicious dishes (such as 

 budino di ricotta, of which anon), it is sold for about twopence per 

 pound or less. 



There is a discrepancy in the published analyses of casein which 

 demands explanation here, as it is of great practical importance. 

 They generally correspond to the above of Mulder within small frac- 

 tions, as shown below in those of Scherer and Dumas : 



Scherer. Dumas. 



Carbon 54*665 537 



Hydrogen 7-465 7'2 



Nitrogen 15-724 16*6 



Oxygen, sulphur 22'146 22*5 



In these the one hundred parts are made up without any phosphate of 

 lime, while, according to Lehmann ("Physiological Chemistry," vol. i, 

 p. 379, Cavendish edition), " casein that has not been treated with acids 

 contains about six per cent of phosphate of lime ; more, consequently, 

 than is contained in any of the protein compounds we have hitherto 

 considered." 



From this it appears that we may have casein with, and casein with- 

 out, this necessary constituent of food. In precipitating casein for lab- 

 oratory analysis, acids are commonly used, and thus the phosphate of 

 lime is dissolved out ; but I am unable at present to tell my readers the 

 precise extent to which this actually occurs in practical cheese-making 

 where rennet is used. What I have at present learned only indicates 

 generally that this constituent of cheese is very variable ; and I hereby 

 suggest to those chemists who are professionally concerned in the 

 analysis of food, that they may supply a valuable contribution to our 

 knowledge of this subject by simply determining the phosphate of lime 

 contained in the ash of different kinds of cheese. I would do this my- 

 self, but, having during some ten years past forsaken the laboratory 

 for the writing-table, I have neither the tools nor the leisure for such 

 work ; and, worse still, I have not that prime essential to practical re- 



