APPENDIX. 173 



The inventor, however, claims that by exposing such varnish 

 to a temperature below the freezing-point of water for some 

 little time, it will separate into a clear, water-white layer and a 

 cloudy stratum, the former being then removed by decantation. 



MANUFACTURE OF CASEIN. 



(United States patent : H. V. Dunham, Bainbridge, 

 New York.) A process of producing a casein compound suit- 

 able for coating, which consists in curdling milk with com- 

 mercial hydrofluoric acid diluted to such an extent that it has 

 no appreciable corrosive action upon glass, and then separ- 

 ating the precipitated casein from the whey. A process of 

 producing a casein compound suitable for coating, which 

 consists in heating milk and mixing commercial hydrofluoric 

 acid therewith, in the proportion of one pint to one quart of 

 acid to one thousand quarts of milk and then separating the 

 casein from the whey. A solution for sizing purposes consist- 

 ing of approximately 94 per cent, of casemate of hydrofluoric 

 acid, and 6 per cent, of borax, mixed with water. 



IMPROVEMENTS IN THE PREPARATION OF CASEIN. 



(French patent 396,014 : C. A. Baechler.) Milk, coagulated 

 by means of rennet or an acid, is agitated in order to prevent 

 the flakes of curd from agglomerating, and is at the same 

 time treated with about one part per 1,000 of a substance such 

 as alum, which has a similar effect on the curd, the temperature 

 being then raised to about 52 C. and stirring continued 

 till the mass is cold. The resulting granular casein, which 

 may be separated by a centrifugal machine, is neutral, but 

 may be rendered alkaline by the addition of sodium bicar- 

 bonate, 3-5 per cent, of which (calculated on the dry weight 

 of casein) will suffice to make the casein soluble in water. 

 Acid casein may be prepared by treating the washed, neutral 

 casein with a minimum quantity of acid ; or an acid may 

 be used to coagulate the milk. 



THE END. 



