HAMILTON CEMENT ROCK. 



401 



the data, with which comparison is made, were compiled from trials 

 made at various times, and under varying conditions and manipula- 

 tion. 1 The Milwaukee cement was prepared by calcination in cru- 

 cibles with varying degrees of torrification, and, in the absence of 

 experimental knowledge of the peculiarities of the rock, it cannot be 

 supposed that the maximum of good results was secured. Mr. "Whit- 

 temore expresses the opinion that, with proper care, a better com- 

 mercial article than the one used might be manufactured. 



The commercial cements were obtained as fresh as possible from 

 the stock in the market, a selection being made from large quantities, 

 and only those used, that, upon trial, were found to be of good qual- 

 ity. To secure uniform fineness, only that portion of each product 

 was used that passed through a sieve of 2^704 meshes to the square 

 inch. 



The following table shows the tensile strength in pounds per square 

 inch of mortars of clear cement, seven days old, the last six in water; 

 also of mortars composed of equal weights of cement and sand at 90 

 days, the last 89 in water: 



In the above table, the result for the Milwaukee cement was ob- 



1 Those who may wish to compare the results obtained by Mr. Whittemore with those 

 of others will find the means of doing so in Gen. Q. A. Gilmore's standard work on 

 Limes. Hydraulic Cements and Mortars. 

 Wis. SUR. 26 



