CHAPTEE V. 



CASEINE. 



UNDER tlie title of caseine perhaps it would be better to 

 say crude caseine -I mean to designate the entire nitroge- 

 nous material of milk. 



After the dry milk-solids have been got, and after the fat 

 has been washed out of them by means of ether, as was ex- 

 plained at length in the last chapter, there remain behind the 

 caseine, the milk-sugar, and the ash. By extracting with 

 strong alcohol, and ultimately adding a little boiling water, 

 so as in effect to extract, with yery weak hot alcohol, the 

 milk-sugar and the soluble part of the ash, i. e, the chlorides, 

 will pass into solution. The caseine which remains behind 

 is washed off the filter-paper into a little platinum dish, and 

 dried up in the water-bath till it ceases to lose weight. It 

 is weighed along with the containing vessel, and then ig- 

 nited, and the weight of the vessel and adherent ash (phos- 

 phate of lime) subtracted from it. As has been already 

 remarked, the phosphate of lime exists really in a state of 

 chemical combination with the caseine in milk. The quan- 

 tity of milk recommended for the estimation of fat viz., 10 

 grammes is suitable for the determination of the caseine. 

 Of course, if the product of the operation be multiplied by 

 10, the quantity of caseine yielded by 100 c. c. of milk will 

 be arrived at. 



Another method of procedure, which is very generally 

 recommended, but which I do not like so well as that just 

 described, consists in taking a considerable quantity of milk 



