42 CASEIN. 



When the ingredients have been carefully sifted they are 

 put through a mixer of the Werner and Pfleiderer " Univer- 

 sal " mixer type (|Fig. 10). As, with these cold-water paints, 

 powders of different densities have to be mixed together, the 

 machine should be fitted with two-speed gear fast and slow. 

 The fast speed acts as a sort of disintegrator, breaking up lumps 

 and large granules and thereby ensuring a more thorough ad- 

 mixture of the ingredients. Consequently, with a machine of 

 this kind, the preliminary sifting may sometimes be omitted. 



FIG. 10. " Universal " Two-speed Mixer. 



The product obtained by this process of fine sifting and 

 intimate mixing will satisfy all requirements. 



" MARBLE LIME " COLOUR FOR OUTSIDE WORK. 



The following ingredients are passed through a colour 

 sifting and mixing machine : 



100 parts by weight of casein, soluble in alkali. 

 100 ,, of caustic lime from marble. 



800 ,, ,, of levigated chalk. 



1 part by of borax. 

 2 to 2 parts by of ultramarine (for white only). 



