SUNDRY APPLICATIONS OF CASEIN. 



151 



of carbonic acid ; the coating will not peal off from the cask 

 staves ; and when it has suffered any injury from mechanical 

 influences, it may be easily repaired with casein solution. 

 Being completely insoluble, there is no risk of the beer 

 acquiring any flavour due to the absorption of casein. 



The solution of casein and formaldehyde acts as an anti- 

 septic; and the same property is possessed by the resulting 

 coating, which helps to preserve both the contents and the 

 material of the cask. 



The casein coating is insoluble, not only in alcoholic liquids, 

 such as wine, beer, etc., but also in acids and alkalies. Hence 

 it can also be used for casks destined for the transport or 

 storage of liquids belonging to these last-named classes. 



THE PREPARATION OF ARTISTS' CANVAS. 



Large quantities of canvas are used by artists and scene 

 painters. The material is mostly rough linen, more rarely 

 jute, and requires before being used for painting to be 

 coated with some composition that will convert the rough 

 surface into a smooth one that is adapted to receive the 

 paint. This operation is termed " priming," and the ma- 

 terial is then known as primed canvas. 



The canvas is required to be perfectly smooth and to 

 remain so without alteration. Canvas that would warp 

 and get " out of true " would distort the painting, and thus 

 cause the latter to lose its artistic value entirely. Since 

 artists' canvas is almost invariably sold in condition ready 

 for being stretched on a frame and painted upon, it is 

 therefore advisable for the maker of this prepared canvas to 

 commence operations by stretching it in a similar manner, 

 so that the tension is the same in all directions. The 

 priming composition is then applied to the surface by 

 simply painting it on with a wide brush. 



Some makers use for this purpose a composition consist- 



