CEMENT.
482
SPFOTFIC GRAVITY DETERMINATIONS ON REGROUND MATERIAL, 3 DATS AFTER SPECIFIC ^^YxjNG W!TH DIFFERENT PERCENTAGES OF WATER.
[Dried at 110° C. before making determinations.]
Brand.	Specific gravity. Material mixed with percentages of water of—					
	5 per cent.	10 per cent.	15 per cent.	20 per cent.	30 per cent.	40 per cent.
			2.69 2.82 2.56 2.73 2.77׳		2.59 2.73 2.47	
Dyckerhoff		2.94	2.88				2.49 2.77 2.67
Bonneville Improved	 Mankato		2.69 2.83	2.73 2.80		2.75 2.77		
Determinations were made on the coarser and finer parts of the loose cement, using material taken from the barrel which was graded bjr sifting, repeating the determinations on the same grades after heating to redness. The results given below show in the two Portland cements lowest values in specific gravity for the grains finer than ".0027 diam-eter in the original condition as taken from the barrel. ^ In the natural cement examined a difference is seen between the grains coarser than ".0058 diameter and the finer parts. After heating, these differences are less, while each grade displays a higher value. A more conspicuous feature is the relative loss in weight of the different samples. It is seen that the loss with the finer material is twice or more times that of the grains ".0027 diameter and coarser.
SPECIFIC GRAVITY DETERMINATIONS ON MATERIAL OF DIFFERENT SIZED GRAINS IN ORIGINAL CONDITION AND AFTER HEATING TO REDNESS.
	Specific gravity.		Loss in	
Size of grain.	Original condi- tion.	After heating to redness.	weight on heating to redness.	Remarks.
Inch. >.0058	3.09	3.10	Per cent. 0.9	
.0050		3.14	1.0	
.0034	3.12	3.15	0.9	
.0027	3.12	3.15	1.0	
<.0027	3.04	3.10	2.0	
>.0058	3.07	3.11	0.7	
.0050	3.12	3.14	0.7	
.0034	3.08	3.15	0.7	
.0027	3.09	3.14	0.8	
<.0027	2.99	3.12	2.2	
>.0058	3.08		1.1	
.0027	3.00		1.4	
<.0027	3.02		2.8	. - .
Brand.
Star .
Alsen.
Material of different sized grains of the grades shown in the last table was mixed with water and the specific gravity determined 30 minutes after mixing, and later after having been mixed 5 days. _ It was then heated to redness, the loss in weight ascertained, and specific gravity again determined. The material from two of the brands was again mixed with water and its specific gravity determined 5 days later. These results agree with the examination of the loose material of the preceding table in respect to the greater changes in the values