84 CASEIN. 



Hence the method consists in first preparing a non-adhesive 

 solution and then converting it into an adhesive by partial 

 precipitation of the casein. 



On the other hand, Jeroinin proposes to effect the same 

 result in a more direct manner. The dissociation and solu- 

 tion of the casein by alkalies is avoided, lime water being used 

 to make the casein swell up. In certain circumstances the 

 whole of the lime can be added at once ; but this is attended 

 with the aforesaid drawback of unequal distribution of the 

 casein, a contingency that is overcome in the present case by 

 the preliminary swelling of the casein in a small quantity of 

 lime water. It must not be forgotten that in the subjoined 

 recipe the quantity of lime water mentioned does not contain 

 enough lime to form a saturated casein compound, though it 

 is sufficient to cause swelling and thus prepare for the forma- 

 tion of a homogeneous mass through the subsequent mixing 

 and combination with the added lime. 



The method is performed as follows : 



Twelve and a half pounds of ground casein powder are 

 mixed with a threefold quantity of clear lime water, stirred 

 up in the same and left to settle for about forty-eight hours. 

 When the casein has swollen up under this treatment, the 

 mass, weighing about 50 lb., is mixed with 2| Ib. of lime and 

 25 lb. of water, the whole being kept well stirred for about 

 twenty minutes, after which 17^ lb. of water-glass are stirred 

 in. When this mass has stood for a while it may be further 

 diluted if necessary. 



In this manner a very uniform and effective adhesive is 

 obtained, one far superior to that furnished by the process 

 described in the German patent 60,156. 



The whole of the casein is acted upon and no uninfluenced 

 particles are left in the mass, as hitherto, to be a source of 

 weakness and diminish the waterproof properties of the ad- 

 hesive under the action of heat and pressure later on, owing 



