162 CASEIN. 



the stratum remains tough and leathery, without softening, 

 and it is perfectly flexible, so that the prints do not curl in 

 the bath. The finished prints will resist mechanical influ- 

 ences (scratching, rubbing, scouring, etc.) in a remarkable 

 degree, and their sensitiveness to light is thoroughly good. 

 The prints show soft, delicate gradation, somewhat softer 

 and with finer definition than albumen prints, without ex- 

 hibiting the hardness of gelatine or celloidin emulsion papers. 

 Hence the casein papers combine in themselves the pictorial 

 softness and the flexibility of the albumen papers, with the 

 permanence and improved definition, together with the ex- 

 tensive range of toning methods enjoyed by the celloidin 

 and gelatine emulsion papers, without the tenderness and 

 susceptibility to temperature of the latter, both in the wet 

 and dry state. 



Even if papers prepared in this manner cannot be intro- 

 duced into practice, the foregoing observations at any rate 

 indicate the way in which the most readily available albu- 

 minoid, casein, can be utilised as a medium for photographic 

 purposes. 



CASEIN OINTMENT. 



To prepare a drying ointment, pure, dry, pulverised casein 

 is dissolved in a mixture of equal parts of dilute ammonia 

 and glycerine. After heating the solution until the ammonia 

 has been expelled, the solution may be mixed with fats to 

 form an emulsion, which, when applied as an ointment to 

 the skin, soon dries to an elastic, cooling layer. 



CLARIFYING GLUE WITH CASEIN. 



According to Hewitt (New York), glue can be clarified 

 by an addition of casein, which is afterwards thrown down 

 by neutralisation (and warmth, if necessary), leaving the glue 

 perfectly clear, free from fat, colourless and inodorous. 



