703 



KEW YORK STATE MUSEUM 



is mucli sulfur in the fuel used. The effect of this sulfate of 

 lime, if it does not exceed 2^ or 3^, is to greatly delay the setting 

 of the cement and also increase its final strength somewhat. If 

 present to the extent of 4;^ or 6fo^ however, both these qualities 

 disappear, since the formation of calcic sulfid is brought about, 

 which in turn reacts with the iron compounds in the cement and 

 tends to disintegrate it. The effect of sulfate of lime is shown 

 in the accompanying table, taken from Prof. Johnson's work, 

 Materials of construction (p. 187). 



The German association of Portland cement manufacturers has 

 declared against any addition except up to the 2^ CaSOtto regu- 

 late setting time. It is the general practice in the United States 

 now to put in 2fo CaS04 to produce slow set. 



The following experiments are quoted by Lewis, showing the 

 effect of sulfate of lime on the rate of setting.-^ 





OKK SORT OF CEMENT 



SETTING 

 TIMK 



NEAT-CEMENT BRI- 

 QUET 



BRIQ. ■ 



i 



I CEMENT, 3 



SAND 



NO. 



03 



t- 



323 

 315 

 375 

 423 



318 



Efi 

 >> 



c8 

 00 



405 

 45t) 

 508 

 543 



450 



05 



518 

 572 



568 

 688 



550 



M 

 01 



620 

 623 

 695 

 718 



592 



u 



aJ 



1-1 



700 

 650 

 780 

 805 



618 



«3 



i> 



115 

 143 

 159 

 180 



168 



to 

 >i 



c8 



-a 

 §5 



168 

 212 

 238 

 263 



218 



02 



T-l 



238 

 339 

 311 

 305 



3 8 



0!1 

 0* 



302 

 353 

 868 

 375 



360 



>, 



1-1 



1 

 2 



As manufactured o 



Same w. .5$? gypsum ..•.•... 



0° 20' 



3° 30' 



10° C 



14<» 0' 



10° 30' 



360 



390 



a 



A% " 



384 



4 



.2% " 



410 



5 



No gyp. but kept in store for some 

 months 



431 









Results reported by John Grant in 1880.' 



MIXTTJRB 



7 days 31 days 60 days 90 days 



1-1 briq. average of 5 107 159 188 267 



il-l briq. w. H2SO4 added to water; 



average of 5 129 227 260 255 



Results reported by Prof. Tetmajer in 1894.^ 



» Min. ind. 6: 101. 

 « ' ' 6; 89, 90. 

 SMitth, d. Aus zur Priifung v. baumaterialien. 1894. 7 hfte, p. 39, 



