170 CASEIN. 



paring compounds of Acrolein with starch, dextrin, gums, or 

 proteids, e.g., casein, for therapeutic purposes. 



Casein acts as a weak acid and forms salts which are 

 neutral toward phenolphthalein, but alkaline towards litmus. 

 By Liebrecht and Rohmann's patented process not only are 

 these neutral lime and sodium compounds prepared, but also 

 solid casein compounds o$ alkalies and alkaline earths, with an 

 acid reaction. To do this the acidity of the casein is determined 

 with phenolphthalein, and the casein is then dissolved in the 

 calculated quantity of alkali and the solution concentrated in 

 vacuo. The resulting neutral compounds are well adapted for 

 painting, whilst the compounds acid to phenolphthalein are 

 of special importance for dietetic and similar purposes. 



The ammonium compound and the hydrochloric acid com- 

 pound of casein can be prepared (German patent 84,682) 

 direct in the solid form by passing gaseous ammonia or hydro- 

 chloric acid over finely powdered dry casein ; or by suspending 

 the latter in some liquid (e.g., alcohol, ether, ligroin or benzol) 

 in which it is practically insoluble, and treating it with one 

 of the aforesaid gases. The resulting compounds are in the 

 form of white powder, stable in air, and dissolve to a clear, 

 almost tasteless, solution in water. 



The feature of Dr. Dojen's process for preparing a com- 

 pound of casein and formaldehyde is that pulverised casein is 

 digested with formaldehyde, then dried, treated with dilute 

 caustic alkali and digested for a long time at ordinary tem- 

 perature with a concentrated solution of formaldehyde. The 

 product has the bactericidal properties of formaldehyde with- 

 out its irritating action. 



According to German patent 98,177, a dilute aqueous 

 solution of sodium or other glycerophosphate is mixed with 

 an excess of casein at a temperature of 30 to 40 C. ; and after- 

 standing for twelve hours, the filtrate is concentrated in vacuo 

 at 40 to 50 C. 



