481
CEMENT.
Determinations of the carbon dioxide driven off and water, taken by difference, upon heating this material to redness from 110° C. gave the following results:
Brand.	Loss on heating to redness. Material set in air at temperatures of—								
	70° F.			36° F.			0° F.		
	Total.	H20.	co2.	Total.	H20.	co2.	Total.	H20.	CO״.
	Per ct.	Per ct.	Per ct.	Per ct.	Per ct.	Per ct.	Per ct.	Per ct.	Per ct.
Star		8.68	1.68	7.00	9.92	5.02	4.90	7.12	3.52	3.60
Alsen		9.96	3.23	6.73	11.48	7.68	3. SO	7.08	3.88	3.20
Josson		8.96	2.66	6.30	10.56	5.96	4.60	5.38	2.55	2.83
	10.03	3.94	6.09				7.92	4.82	
Austin		7.84	1.76	6.08	10.12	4.12	6.00	4.92	1.92	3.00
Bonneville Improved	16.10	4.12	11.98	15.96	5.96	10.00	13.60	6.70	6.90
Hoffman		11.04	3.04	8.00	11.40	3.40	8.00	9.12	5.35	3.77
Norton		10.00	2.16	7.84	12.36	4.36	8.00	9.08	5.18	3.90
Obelisk		8.08	2.48	5.60	8.96	3.36	5.60	5.92	3.32	2.60
Means, omitting									
the Steel ce-									
ment		10.08	2.64	7.44	11.35	4.98	6.36	7.78	4.05	3.73
The original amount of water, by weight, used in mixing the above material and the ages of the samples when heated were as follows:
Brand.	Material set in air at temperatures of—					
	70° F.		36° F.		0° F.	
	Water.	Age.	Water.	Age.	Water.	Age.
	Per cent.	Days.	Per cent.	Days.	Per cent.	Days.
Star		23.4	60	25.7	78	23.4	60
Alsen		28.2	43	28.2	43	28.2	63
Josson		26.0	42	26.0	42	27.3	56
	34.4	41				
Austin		37.1	57	37.1	57	36.7	63
Bonneville Improved		35.9	44	35.9	44	38.6	62
Hoffman		35.5	58	35.5	58	35.7	
Norton		37.9	46	38.2	79	38.0	81
Obelisk		36.2	53	36.2	53	38.6	62
Determinations made on several brands in which different percentages of water were used, ranging from 5 to 40 per cent by weight, are found in the next table. The results show that a small quantity of water is adequate to bring about a decided reduction in specific gravity, causing a reduction not greatly ,modified when larger quantities of water were used.
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