158 



ILLINOIS ACADEMY OF SCIENCE 



amount of water practicable (about 35 per cent) the weight 

 of dry gypsum is only slightly more than half that of con- 

 crete. 



no 



%/00 

 \ 



30 



JO JS *0 45 SO J5 mo 



Percentage of Wafer 



so 



35 40 45 50 



Percentage of Wafer 



GO 



r7j.t: 



In all the tests referred to in this paper, except as other- 

 wise noted, the amount of retarder used was 0.1 per cent, 

 and the amount of water used was such as would give the 

 same consistency to the mixtures for all specimens. This 



