144 CASEIN. 



this object, the sheets of paper are coated on both sides with 

 an ammoniacal solution of casein, laid one on top of the other, 

 and at once placed in heated moulds, the pulp being stamped, 

 by means of a press, into a tray or basin of the form most 

 suitable for the purpose in view. 



The moulds are made in two halves. In the case of a 

 flask or bottle, for instance, the basin is fitted at the top with 

 a lug for receiving the stopper, with the neck, and, under- 

 neath, the part on which the bottle is to stand. The stamp- 

 ing mould is gently warmed before the paper is inserted, so 

 that the casein solution sinks more deeply into the pores, 

 and at the same time the ammonia has a better chance of 

 evaporating. After a short time the paper mass will have 

 set hard, and the finished half bottle can be taken out, and 

 left in the air to dry completely. These halves are after- 

 wards thinned down at the edges where they are to be 

 joined, pressed together, cemented with casein glue, and 

 coated with a thin layer of casein solution inside and out. 



WASHABLE DRAWING AND WRITING PAPER. 



Any convenient sort of paper is treated with a first coat- 

 ing of casein, size or other suitable medium containing an 

 admixture of some finely pulverised mineral substance, such 

 as zinc white, chalk, lime, heavy spar, etc., and the requisite 

 colouring matter. It is then brushed over with, or dipped 

 in, water-glass containing a small quantity of magnesia, and 

 left in the air for a short time to dry, at a temperature of 

 about 77 F. This second coating may be replaced by one 

 of dilute formaldehyde. 



Paper treated in this way may be written or drawn upon 

 with pencil, chalk, coloured crayon, charcoal, transfer ink or 

 lithographic ink; and the marks thus produced may be 

 washed oft' again without any appreciable alteration of the 

 paper. 



