485
CEMENT.
different proportions, and these still remain intact with hardness due to their interval of aging apparently normal.
Material from the outside and inside portions of a 2" cube, mixed with 25.8 per cent water, and set in the air eight months, gave the following results on the reground cement in the original condition from the cube and the same after heating to 110° C. and to redness:
		Specific gravity.			Loss in weight after heating—	
Brand.	Description.	Original condi- tion.	After heating to 110° C.	After heating to redness.	To 110° C.	From 110° C. to redness.
Storm King..	Material taken ־within ".10	2.68	2.70	3.17	Per cent. 3.65	Per cent. 14.57
	from the surface of the cube. Material taken below 25.״	2.68	2.74	3.19	4.87	8.22
	from the surface of the cube.					
A fresh fracture of the above cube when treated with hydrochloric acid effervesced in that part which lay near the original surface. This behavior was restricted to a zone not exceeding ".10 in depth. There was a further examination of the same material when 11 months old, and determinations on reground sifted material of different-sized grains, also on material from a thin slab, measuring A" thick by 2" wide by 6" long, which set in air nineteen weeks and was found to contain 8.60 per cent of carbon dioxide.
Brand.	Description.	♦ Specific gravity.			Loss in weight after heating—	
		Original condi- tion.	After heating to 110° C.	After heating from 110° C.to redness.	To 110° C.	From 110°C. to redness.
Storm King.. Star		Material taken from the inside portions of 2" cubes. Grains ".0058 to ".016 diameter. Grains 0027.״ to ".0058 diameter. Grains <0027.״ diameter — Material from slab x 2״ x6".	2.71 2.73 2.77 2.70 2.72	2.79	3.23	Per cent. 6.54	Per cent. 7.67
						
						
			2.80	3.19	2.24	11.46