vol 



6 



54.72 



24.27 



7.64 



1.89 



• • • • % 



• ••••' 



I.IME AND CEMENT INDUSTEIE3 



12 3 4 5 



SiOa 60.06 59.25 60 62.48 68.45 



AlA 17.79 23.12 22.22 20 11.64 



Fe^Og. 7.08 8.53 8.99 7.33 14.8 



CaO. 9.92 4.18 6.3 .75 



MgO 1.89 2.8 1.6 1.16 



KgO 2.5 1.87 1.49 1.74 1.9 



>a20 .73 1.6 .72 .37 2.1 



OaS04 6 2.73 .89 .60 



1 Province of Saxony . 4 Brandenburg 



2 Yorponunern 5 ) ..^ , 



3 Oberharz 6 f ^"^^"^^^ 



In most of the European cements the lime runs from 60^ to 

 65^^ while in the American it seldom exceeds 63^. In the French 

 and Belgian cements the sulfuric acid is low, in order that they 

 may comply with the engineer's specifications. The Portland 

 cements made in the eastern United States generally show more 

 magnesia than the western ones. The maximum percentage of 

 this material in American is about 4^, while in the European it is 

 2.5^. Magnesia was formerly considered very objectionable, but 

 opinion is now receding on this point. Those American brands 

 containing 4^ of magnesia are not shown to be at all inferior. 



In the various numbers of the Thonindustrie zeitung for 1897 

 and 1898, that is vol. 21 and 22, will be found a number of ar- 

 ticles and discussions concerning the effect of magnesia in Port- 

 land cement. Elaborate experiments of B. Dyckerhoff abroad 

 have not shown any injurious effects to come from 4^ MgO. 

 Many American manufacturers adulterate cement by adding sul- 

 fate of lime. This generally acts as a diluent, and it should 

 always be stated when it is done. 



The raw materials used in the manufacture of Portland cement 

 may sometimes contain sulfate of lime in the form of the mineral 

 gypsum, or sulfur may be present in the form of pyrite, which 

 in burning tends to react with some of the carbonate of lime, 

 yielding calcium sulfate. A similar effect may be caused if there 



