¹ Analyst (1915), 40, 57. Egg albumin solution is prepared by slightly beating the whites of six newly laid eggs, adding two volumes of 1 per cent, sodium chloride solution, filtering and diluting the filtrate so that 15 c.c. contain 0·4 gm. of coagulable protein. Of this standardised solution 15 c.c. are placed in an Erlenmeyer's flask and 1 c.c. papain solution added (prepared by dissolving 1 gm. papain powder in salt solution and diluting to 100 c.c. and leaving for hour) and 9 c.c. of 1 per cent, sodium chloride solution added. The flask is transferred to a thermostat at 80° C. and, after 15 minutes' digestion, 1 c.c.N/2 acetic acid added and the flask transferred to a water bath at 100° C. where it is kept for 10 minutes. The undigested protein is collected on a tared filter paper, washed free from chlorides and then successively with 10 c.c. 95 per cent, alcohol and 10 c.c. ether and dried at 100° to 150° and weighed to constant weight. A control experiment shows how much protein is present in 15 c.c. of egg white solution.