316 IvEPOKT OF THE DePAKTMEI^T OV ChK.MISTRV OF THE 



PREPARATION AND COMPOSITION OF BASIC CALCIUM CASEINATE. 



The compound commonly known as basic calcium caseinate con- 

 tains the largest amount of calcium in combination with casein. 

 This is the compound that has been most frequently prepared and 

 studied by investigators, beginning with Soldner (see references on 

 page 312). Varying results have been obtained by different workers, 

 the percentage of calcium ranging from 1.66 to 2.13 per ct. (equiva- 

 lent to 2.32 to 2.98 per ct. CaO). 



This compound can be prepared in two different Avays: (1) By 

 decomposing calcium carbonate with casein and (2) by treating 

 casein with a solution of calcium hydroxide (lime-water). 



Preparation of basic calcium caseinate by treating casein vjith calcium 

 carbonate. — When casein is treated with calcium carbonate, the 

 results of the reaction can be measured in two ways: (a) By weigh- 

 ing the carbon dioxide displaced, and (b) by determining the amount 

 of calcium in the resulting compound. Both methods were used 

 by us. 



Casein prepared in the manner previously described was placed 

 in the flask of a Knorr carbon dioxide apparatus and an excess of 

 calcium carbonate suspended in water was added. The carbon 

 dioxide formed in the reaction was run into weighed bulbs con- 

 taining potassium hydroxide and the increase of weight due to 

 carbon dioxide determined at the end of the reaction. The results 

 are given in the following table. 



Table I. — Amounts of Carbon Dioxide Expelled from Calcium Carbonate 



BY Casein. 



For the purpose of measuring the results of the reaction by deter- 

 mining the amount of calcium in the resulting compound, the casein 

 was put in a mortar and thoroughly triturated with an excess of 

 moist calcium carbonate, the excess being removed by filtration at 

 the end of the reaction. The filtrate was treated with 95 per ct. 



