^2 CEMENTS, LIMES, AND PLASTERS. 



Cummings, of Akron, N. Y., in his volume entitled ' American Cements, 

 1898', on page 288." The remainder of the table is compiled from the 

 United States Geological Survey reports on the production of cement. 



In making a comparison it must of course be borne in mind that 

 the barrel of Portland cement contains 380 Ibs. net, while the natural- 

 cement barrel varies from 240 Ibs. to 300 Ibs. 



Prospects of the Industry. 



Reference to the tables of statistics on preceding pages will show 

 that the natural-cement production of the United States has been prac- 

 tically stationary since 1890. During this period, while the annual 

 American production of Portland cement has advanced from 335,000 

 barrels to 22,342,973 barrels, the annual production of natural cement 

 has varied between 7,030,271 and 9,868,179 barrels, the lowest pro- 

 dution for any year being that of 1903. In view of these facts and of 

 freely expressed prophecies that the natural-cement industry is gradu- 

 ally nearing its end, it seems desirable to sum up the prospects of the 

 industry from the viewpoint of a disinterested outsider. 



Engineers, both in text-books and in conversation, bring two 

 charges against the natural cements as a class. Since the fate of the 

 natural-cement industry will be decided finally by the verdict of the 

 engineer who uses the product, it will pay to critically examine these 

 charges. The -faults alleged are: (1) lack of strength as compared 

 with Portland cements, and (2) lack of uniformity in both composition 

 and strength. 



It may as well be admitted that both of these charges are true as 

 regards the majority of natural cements as now made, but the writer 

 cannot admit either that these faults are universal, or that they are 

 unavoidable. 



In regard to the first point an advocate of the natural cements 

 could point out that three brands of natural cements are now regu- 

 larly advertised and sold as Portland cements; that they have been 

 tested for use in both State and Federal public works, including canals, 

 locks, dams, and breakwaters; and that neither State nor army 

 engineers seem to have even suspected that they are not Portland 

 cements. This is surely a proof that all natural cements are not so 

 low in strength as to be readily distinguished from Portlands by ordinary 

 physical tests. So far as lack of uniformity is concerned, attention 

 might be called to several American brands of natural cements whose 

 variation in composition and strength is no more than is shown by the 



