Soy. 2?, Ib33.] 



♦ KNOWLEDGE ♦ 



313 



c><I^y^ AN [LLliSIRATED ^ i^ 



>*^ MAG/^ZINE o7 SCIENCE ^ 



PLAINLVWORDED-EXACTLYDESCRIBED 



I 



LONDON: FRIDAY, NOV. 23, 1883. 

 Contents op No. 108. 



The Chemistry of Cookery. XXIII. 



By W. Mattiea Williams 313 



The Senses in Infants. 1 314 



Pleasant Hours with the Micro- 

 scope {illui.) By H. J. Slack ... 316 



Editorial Gossip 31S 



The Face of the Sky. By F.E.A.S. 318 

 Saturn in a Three-inch Telescope 

 {iUui.) ByF.R.A.S 319 



PAGS 



Sun Views of the Earth. By R. k. 

 Proctor 321 



Correspondence ; Strange Sea-erea- 

 turea — A Moonlight Ascent in a 

 Balloon— Strant;e Phenomenon — 

 Anthropometry — Green Sun and 

 Sound Waves from Krakatoa, &c. 323 



Our Whist Column 321 



Our Chess Column 326 



THE CHEMISTRY OF COOKERY. 



By W. Mattieu Williams. 



XXIII. 



IN my last I referred generally to the high nutritive 

 value of cheese. I will now state particulars. First, 

 as regards the water. Taking muscular fibre without bone, 

 i c, selected best part of the meat, beef contains on an 

 average 72| per cent, of water; mutton, 73}, ; veal, 7-i^ ; 

 pork, 69| ; fowl, 73^ ; while Cheshire cheese contains 

 only 30^, and other cheeses about the same. Thus, at 

 starting, we have in every pound of cheese rather more 

 than twice as much solid food as in a pound of the best 

 meat, or comparing with the average of the whole carcase, 

 including bone, tendons, itc, the cheese has an advantage 

 of three to one. 



The following results of Mulder's analysis of casein, 

 when compared with those by the same chemist of albumen, 

 gelatine, and fibrin, show that there is but little difference 

 in the ultimate chemical composition of these, so far as the 

 constituents there named are concerned. 



Carbon 5.3-83 ~1 



Hydrogen 7'15 



Nitrogen 15'65 J- Casein 



^^Se" [23 37 



Sulphur ) 



Albumen. Gelatine. Fibrin. 



Carbon 53-5 50-.10 .'■>27 



Hydrogen 70 Gtjl Oy 



Nitrogen 155 IS'.'M 15-1 



Oxygen 220 2102 23-5 



Sidphur IG ., 1'2 



Phosphorus O-l „ 03 



We may therefore conclude that, regarding these from 

 the point of view of nitrogenous or tlesh-forming, and car- 

 bonaceous 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 carcase of oxen, calves, sheep, lambs, and pigs varies, 

 according to Dr. Edward Smith, from IG per cent, to 31 3 

 per cent, in moderately-fatted animals, while in whole milk 

 cheeses it varies from 21 08 per cent, to 3 2 '31 per cent., 

 coming down in skim-milk cheeses as low as ()-3. Dr. Smith 

 includes Neufchatel cheese, containing 18-71 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 ricottu, or crude curd of skim-milk 

 cheese. Its just value is about threepence per pound. In 

 Italy, where it forms tlie basis of some delicious dishes 

 (such as hudino di ricotla, 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 fractions, as shown below in 

 those of Scherer and Dumas : — 



Schorer. Dumas. 



Carbon 54665 537 



Hydrogen 7-465 72 



Nitrogen 15-724 16-6 



Oxygen, sulphur 22-146 22-5 



In these the 100 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 6 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 without, this necessary constituent of food. In 

 precipitating casein for laboratory analysis, acids are 

 commonly used, and thus the phosphate of lime is dis- 

 solved 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 consti- 

 tuent 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 contribu- 

 tion to our knowledge of this subject by simply determining 

 the phosphate of lime contained in the ash of ditlerent kinds 

 of cheese. I would do this myself, 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 

 research (especially of endowed research), a staH' of obedient 

 assistants to do the drudgery. 



The comparison specially demanded is between cheeses 

 made with rennet and those Dutch and factory cheeses the 

 curd of which has been precipitated by hydrochloric acid. 

 Theoretical considerations point to the conclusion that in 

 the latter much or even all of the phosphate of lime may 

 be left in solution in the whey, and thus the food-value of 

 the cheese seriously lowered. We must, however, suspend 

 judgment in the meantime. 



In comparing the nutritive value of cheese -with that of 

 flesh, the retention of this phosphate of lime nearly corre- 

 sponds with the retention of the juices of the meat, among 

 which are the phosphates of the flesh. 



These phosphates of lime are the bone-making material 

 of food, and have something to do in building up thebrainand 

 nervous matter, though not to the extent that is supposed by 

 those who imagine that there is a special connection be- 

 tween phosphorus and the brain, or phosphorescence and 

 spirituality. Bono contains about eleven per cent, of 

 phosphorus, brain less than one per cent. 



The value of food in reference to its phosphate of lime is 

 not merely a matter of jiercentage, as this salt may exist in 

 a state of "solution, as in milk, or as a solid very ditiicult of 

 assimilation, as in bones. That retained in cheese is pro- 

 bably in an intermediate condition — not actually in solution, 

 but so finely divided as to be readily dissolved by the acid 

 of the gastric juice. 



