CEMENT.
486
The specific gravities of cements which were treated in considerable quantities of water, hot and cold, appear in the next table. The cement was stirred at frequent intervals to prevent caking in the water. The temperature of the cold-water bath was the temperature of the room. The hot-water bath was about 95° C. After treatment and drying in the air the cement was broken up and reground, then dried at 110° C. and specific gravities determined.
Brand.	Class.	Condition	Specific gravity, after treatment in water for periods of—				
		of water.	Half hour.	16 hours.	25 hours.	2 days.	5 days.
		Hot		2.94	2.61	2.58	2.50	2.45
		Cold		2.97	2.81	2.72	2.56	2.48
Dyckerhoff			do		Hot		3.03	2.96	2.79	2.76	2.66
		Cold		3.08	2.95	2.87	2.84	2.69
		Hot		2.64	2.61	2.57	2.57	2.53
		Cold.		2.66	2.62	2.59	2.55	2.53
Bonneville Improved .	Natural ...	Hot		2.72	2.71	2.70	2.68	2.65
		do		Cold		2.83	2.80	2.73	2.69	2.66
		Hot		2.94	2.86	2.80	2.72	2.61
		Cold		3.02	2.98	2.97	2.96	2.97
		Hot		2.80	2.71	2.61	2.50	2.39
		do		Cold		2.84	2.85	2.84	2.84	2.84
The results heretofore given refer to the loose material, either in the condition as taken from the original packages or hydrated material reground to a fine powder.
The results which follow show specific gravities of the material in the cake after mixing with water and molding into cubes or briquettes. These determinations were made by means of a chemical balance, weighing the material in air and in water. In order to make the necessary correction for water absorbed when immersed, the specific gravity was computed by dividing the dry weight of the material in air by the difference of its wet weight in air and weight when in water. The material was immersed in water four days before taking its wet weight in air and weight in water.
The following table shows the specific gravity of halves of tensile briquettes, from samples which set in air and from those which set in water:
MATERIAL IN THE CAKE.
Brand.	Class.	Specific gravity, briquettes which set in—	
		Air.	Water.
		2.23	2.29
		2.11	2.07
	Slag		1.74	1.79
		1.65	1.66
		1.79	1.77
		1.65	1.66
Atlas (material from 12" cubes)		Portland			1.92 to 2.17