802 EXPERIMENT STATION RECORD. [Vol.40 



Some studies of casein, L. A. Maynabd (Jour. rhys. Chcm., 23 {lit 19), Xo. 3, 

 pp. t' f .')-153). — Casein prepared from skim milk according to the method de- 

 scribed by Osborne and Guest (E. S. R., 2ri, p. 504) was digested with 1 

 pe cent sodium hydroxid solution for 24 hours at room temperature. During 

 the digestion the phosphorus of the casein molecule was split off and changed 

 to a soluble inorganic form, and the loosely combined sulphur was also split 

 off. On addition of acids to the caustic soda digest, a white precipitate was 

 obtained which exhibited colloidal properties similar to casein as regards its 

 behavior with acids and alkalis, its response to protein tests, and its precipita- 

 tion by salt solutions. A limewater solution of the substance showed none 

 of the characteristic properties of a similar solution of casein, but when 

 phosphoric acid was introduced into the former in such a way as not to destroy 

 the colloidal solution a milky solution was obtained which on heating behaved 

 like a limewater solution of casein. This is thought to furnish evidence that 

 the white color of milk is due to the i>eptization of tricalcium phosphate by 

 the colloids in the milk. 



Action of neutral salts on the inversion of sugar by acids, H. Coi.in and 

 M. Lebebt (Ihil. Assoc. Chim. Surr. rt Distill., 35 {]918), Xo. 7-9, pp. 14-17).— 

 The inversion of sugar with small amounts of acid in the p re se n ce of neutral 

 salts was found to depend upon the following conditions: 



(1) If the hydrolysis is brought about by a strong acid in the presence of 

 the corresponding salt of an alkali metal (i. e., HC1 in the presence of NaCl), 

 an amount of the salt equivalent to the add produces a slight increase in the 

 speed of hydrolysis. (2) With a weak add the pr esen ce of its sodium or 

 potassium salt lowers the speed of hydrolysis in proportion to the weakness 

 of the acid, the action of acetic acid being almost completely paralysed by an 

 equivalent amount of sodium acetate. (3) If the salt present in the solution 

 is not a salt of the acid causing the hydrolysis (1. e., sodium acetate with 

 HOI), the effect produced depends upon the relations established between add 

 and salt. 



The results seem to indicate that any cause which tends to lower the II ion 

 concentration of the solution diminishes the velocity of hydrolysis by acids 

 for which reason invertin is recommended in preference to acids for the 

 hydrolysis of weak solutions of sucrose. 



The manufacture of invert sugar and use of sugar substitutes in ice cream, 

 EL A. ItiKiiK (Cream, ami Milk 1'lant Co., 8 (19J9), Xo. 2, pp. 45-48 ) .— The 

 author states that a solution of invert sugar of such strength that it can be 

 used to replace sugar pound for pound in ice cream formulas can be made by 

 boiling gently for .'10 or 35 minutes a mixture of 1(H) lbs. of sugar. 4"> lbs. of 

 water, and 50 gm. of tartaric acid. This solution contains about 71.4 per cent 

 of sugar and 28.6 per cent of water. The formula has been tried out by 

 several ice cream manufacturers who claim an actual saving of from 20 to j."i 

 per cent of sugar. 



From laboratory tests of the viscosity of the mix, percentage swell on freez- 

 ing, and sweetness of the product, the use of invert sugar thus prepared did 

 not appear to alter the quality of the ice" cream. The Substitution of corn 

 sugar for from 20 to 50 per cent of the invert sugar was found to be practicable. 

 but glucose proved to be less satisfactory on account of the lessoned mcstnesi 

 and coarser grain of the product. 



Remade milk and cream, II. W. Rkdfiki.u (Washington: lnt<rjiat. Assoc. 

 Dairii and Milk Insp., 1919, p. 32. pi. t). — This is a lecture given by the author, 

 from the Bureau of Chemistry, U. S. Department of Agriculture, before a 

 special conference of the International Association of Dairy and Milk In- 



