■ : M 



require mid also be applied to the cement as 



found in die market It- quality may be bo high that it will 



d |f v. and granular, and, on the 



•r hand, it may be bo low that no amount of pulverization 



u it In other words, fin i sure indication of 



ment, although all cements improved by 



Cement of the better now usually ground 



, n ] y fp.m ted by a neve of 2500 



ml it has been made bo fine that only 



of 32,000 mesh< square 



inch. The finer the cement, if otherwise good, the larger the 



ind it will take, and the greater its value. 



CHECKING OR CKACKIXQ 



The test for cheeking or cracking is an important one, and, 

 though Bimple, Bhould never be omitted. It is as follows: make 

 two cakes of neat cement, 2 or 3 inches in diameter, about i inch 

 thick, with thin 3. Note the time in minutes that these 



cakes, when mixed with water to the consistency of a >tirT plastic 

 mortar, take to set hard enough to stand the wire test recom- 

 ttded 1 . Gilmore, A inch diameter wire loaded with £ 



of a pound, and *V inch loaded with 1 pound. One of these cak 

 when hard enough, Bhould be put in water and examined from 

 day to da; e if it becomes contorted, or if crack- Bhow them- 



selves at the -. Buch contortions or cracks indicating that 



the cement is unfit for use at that time. In some he 



tendency to crack, if caused by the | ;e of too much unslaked 



lime, will disappear with remaining cake Bhould be 



kept in the air and its color observed, which, for a good cement, 

 old be uniform; the Portland cement- being of a bluish gray 

 throughout, yellowish blotches indicating poor quality; and the 

 natural cements being light or dark, according to the character 

 which they are made. The color of the cements 

 when left in the air indicates the quality much better than when 

 put in water. 



TFSTS TIFrOMMEXDED 



mmended that tests for hydraulic cement be confined 



thods 1" rndni] E -• liability to checking or crack- 



gth; and for tin- latter, for tests of seven 



and npward, that a mixture of mi.- part of cement to one 



I for natural cements, aid three parts of sand for 



