192 



GENERAL SCIENCE 



Million Barre/s 



as limestone, and of the manner of use of this lime in building 

 operations, may be found in Chemistry texts and other 

 reference books. It has much of interest in itself, and its 

 discussion may well lead to further readings on many related 

 topics. One such topic is the nature of concrete and of 

 cement, both of which are used in enormous quantities 



annually for construction pur- 

 poses. The growth of the 

 cement industry in this 

 country from 42,000 barrels 

 in 1880 to 80,000,000 barrels 

 in 1912 was especially rapid 

 from 1900 on, marking a 

 period of intense industrial 

 activity. It made possible 

 the completion of great en- 

 gineering enterprises and 

 other construction works 

 previously out of question. One of the chief ends in those 

 study of General Science is arousing an interest in those 

 activities of men that are applications of science, and to 

 learn where to go to get information concerning them which 

 is both definite and sufficiently elementary. 



In the abundant limestone layers of the earth's crust the 

 geologist reads an intensely interesting chapter of the world's 

 history. In the rock he finds the "fossils" of shells. He 

 recalls that shells of clams, oysters, and other marine life 

 belonging to the division of animals known as the Mollusks, 

 are all very largely carbonate of lime. So is the material 

 of the great reefs and islands built by the little coral animals 

 out of mineral matter in solution in sea-water. The chalk 

 deposits of the southern English coast and elsewhere are of 

 the same chemical nature, and under the magnifying glass 

 these exhibit the remains of minute shells. The extensive 



1680 IO90 1900 1910 



FIG. 6 1. Growth of the cement 

 industry in the United States". 



