MUCOID PROTEIN. 63 



from the clear ethereal solution, which is separated by filtration, 

 washed with strong alcohol and afterwards with ether, and dried 

 in the air at the ordinary temperature. Storch found that if the 

 cream was mixed with water at 35 C. and separated in a cream 

 separator, and this process repeated several times, the protein 

 could be prepared from the washed cream. This method was, 

 however, more difficult than that involving the use of cane sugar 

 solution. 



The density of the mucoid substance containing 6-42 per cent, 

 of mucoid protein and 1-03 per cent, ash was found to be 1-0228 

 at 15 C. 



This substance appears to be identical with a product described 

 some years ago as ^-casein by Struve ; he separated it from his 

 a-casein by dissolving in ammonia, when the /9-casein was left ; 

 it was found in traces only in milk. 



Opalisin. According to Wroblewski, this may be salted 

 out with sodium chloride after the casein is precipitated with 

 acetic acid. 



Its composition is C 45-01, H 7-31, N 15-07, P 0-85, S 4-7, 

 27-11. After boiling with acids it reduces Fehling's solution, 

 and is abundant in human milk, less so in mare's milk, and 

 scanty in cow's milk. 



Lecithin, C^HgoOgPN, exists in small quantities in milk; 

 on saponification it gives glyceryl phosphoric acid, fatty acids 

 and choline ; it contains 3-84 per cent, of phosphorus, and gives 

 8-8 per cent, of P 2 5 on oxidation. 



Brodrick Pittard, also Osborne and Wakeman, find that 

 besides lecithin there is another phosphatide of the constitution 

 of a di-amino-monophosphatide. The latter observers state 

 that the phosphatides come down both with the casein by acid 

 precipitation, and with the albumin on boiling. 



Vitamin es. It is more than probable the lecithin is not the 

 only phosphorus containing constituent in milk, but that others 

 exist whose composition is unknown. It is probable that these 

 constituents are very important in nutrition, and that they, or 

 constituents accompanying them, even though present in minute 

 amounts, have an enormous influence. Such diseases as scurvy, 

 rickets, polyneuritis, etc., have definitely been traced to an 

 insufficiency of products of unknown composition called " vit- 

 amines," and these diseases are cured or ameliorated by the 

 addition of almost infinitesimal amounts of vitamines to the 

 food. The organic phosphorous compounds which have broadly 

 been classed as lecithin are an index of the vitamines, which 

 are destroyed by boiling. Milk contains a water soluble and a 

 fat soluble vitamine, and in this connection it may be mentioned 

 that butter fat which contains a vitamine also contains about 



