156 Frank Carney 



Sand-li?ne brick. In 1901 at Michigan City, Ind., an artificial 

 sandstone or sand-lime brick was made. This new industry has 

 shown a healthy growth. Some plants have been established in 

 Ohio. Others doubtless will come into operation because of the 

 abundant lime manufactured here. 



This artificial sandstone is simply a combination of sand and 

 lime. A comparatively pure sand is required ; if the sand contains 

 much clay, the product weathers more rapidly, especially in 

 our climate. Usually coarse and fine sand are combined, three 

 parts of the former to two of the latter; with one part of lime, 

 twenty parts of sand are used. The lime is slaked, then the water 

 and sand added, and thoroughly mixed. Later it is shaped into 

 bricks, and hardened, generally by steam pressure. 



With the widespread glacial deposits of Ohio and the high per- 

 centage of sands which they contain, it is natural that this indus- 

 try should grow. 



CEMENTS 



Under this heading are included several mixtures each of which, 

 with water, will make a mortar that hardens as a binder, that is, 

 has cementing powers. The cement hardens or sets because the 

 finely ground rock takes up the water and crystallizes or sets. 

 The cement industry may be associated with the production of 

 lime, though not necessarily. In this state three kinds of cement 

 are manufactured. 



In the production of cements, Ohio does not rank high. The 

 position of any state in this product is conditioned by many 

 factors. The cements are used as building materials, consequently 

 the demand is greater near the larger cities, as activity in building 

 is a matter of population. The mere fact that a state may con- 

 tain abundant raw material for the manufacture of cements does 

 not insure that plants will be erected. Competition is usually 

 rife in supplies for building trades. Oftentimes the prosperity of 

 a cement plant depends entirely on freight rates, which have to be 

 figured in competition. 



Natural cement. This is also called Roman cement, and Rosen- 

 dale cement. It is made from a limestone which contains 30 to 50 

 per cent of clayey and sandy impurities. When this silico-alumin- 

 ous limestone is burned, it will not slake unless finely ground. 

 The ordinary carbonate, when burned, will slake in the lumpy 



