BUILDING STONES. 459 



ECONOMIC USES OF GYPSUM. 



Gypsum is used for making plaster of Paris, which is used for making 

 casts, making models, and for giving a hard finish to inside walls. 



It is also used as a fertilizer for the improvement of soils. 



There was used in the United States in 1886, the latest date of which I 

 have the information, over one hundred and two thousand tons of land plas- 

 ter, and ninety-eight thousand tons of calcined gypsum, or plaster of Paris, 

 worth in the aggregate over one million dollars. The most of this came from 

 foreign countries, and from beds that are much inferior to the gypsum of 

 this district. 



There are only two railroads that now penetrate this gypsum district from 

 the south and east. That of the Texas and Pacific Railway reaches the beds 

 in the vicinity of Sweetwater, in Nolan County, where there are fine beds of 

 gypsum. The Fort Worth and Denver Railway reaches the gypsum in the 

 vicinity of Quanah. At either of these places there is enough of the material 

 to supply any demand that could be made upon it for ages to come. 



Just what effect gypsum has upon soils by being strewn upon them has 

 not been fully determined, but that it produces a decidedly salutary effect upon 

 vegetation is not to be questioned. Prof. Lupton says: "As a fertilizer it 

 furnishes lime and sulphur to the plants, and is thought to have the power 

 of absorbing ammonia from the air and supplying it to the plant." To this 

 important property Liebig ascribes much of its wonderful effect upon young 

 grasses and wheat. "It has no caustic properties like quick-lime and guano, 

 and therefore seeds are not injured by being placed in immediate contact 

 with it. The vigorous, healthy start which it gives to the young plant is 

 very desirable for both corn and cotton, since weak, sickly plants are almost 

 sure to suffer from insects or perish from other causes. This is one of the 

 cheapest of fertilizers, and should be used by farmers or planters who desire 

 an increase of production by a moderate outlay of money." 



The fertility of the river bottoms and valleys of Texas are in a measure 

 due to the fact that these rivers have their sources in these gypsum beds. 



BUILDING STONES. 



In determining the quality of a building stone there are several things to 

 be taken into consideration, three of which are of paramount importance. 

 These are durability, texture, and color. The more satisfactory these things 

 are in one stone the more desirable it is as a building material. 



A stone that is granular will decompose more easily than the crystalline 

 rocks, yet if the grains composing a stone, as the sandstones, are cemented 

 together by a material that is inclined to harden on exposure it may be very 



