62 



CEMENTS, LIMES, AND PLASTERS. 



for one week. "The sand used was obtained from the Laramie River 

 and was composed of sharp-angled granitic fragments. It was sifted 

 through a millimeter sieve." 



1800 



1200 



1000 



600 Ibs. 



g 



I I IS. 19 I. II 



FIG. 18o. Effect of sand on compressive strength of plaster. 



Adhesive tests of plasters. The adhesive tests in Table 17 were 

 made by Prof. Marston "by taking pieces of No. 2 paving-brick from 

 Pes Moines and grinding them on the emery-wheel so as to make 

 approximately 1-inch cubes. Each cube had one face carefully 



