36 



Potash 01.54 



Sulphuric acid 02.22 



Hygrometric water 00.60 



BALCONT FALLS ROCK (VIRGINIA). 



Lime l'^-^8 



Silica 34.22 



Alumina 07.80 



Magnesia 09.51 



Carbonic acid 30.40 



Water and loss 00-69 



The analyses of many cements in extensive use show quite 

 a difference in the proportion of the lime, clay and sand ; 

 yet the best cements have a range of from fifteen to about 

 thirty-five per cent, of silica and alumina. 



This range in the proportion of the ingredients . renders 

 the making of these cements an easy task. 



ZEIDEOLITE 



Is a comparatively new material which has lately been 

 largely used in France in place of hydraulic lime. It is 

 said to be much superior to that article for uniting stone 

 and resisting the action of water. It is made by mixing 

 sulphur and pulverized stoneware and glass in the follow- 

 ing proportions : 



Sulphur 19 pounds.- 



Stoneware and glass 42 " 



Mix and expose to a gentle heat, and stir all thoroughly 

 together, and then pour into suitable moulds and let it 

 cool. It is as hard as stone at 230 degrees Fahrenheit, but 

 at 248 degrees it melts, and may be recast or made into 

 any desirable form by heating. Slabs of it may be joined 

 with a paste of it heated sufficiently to melt the edges of 

 the slabs. 



West of the Pecos,adobe houses are the chief and almost 

 the only buildings used, and this is also the custom in 

 northern Mexico. Adobes are made of clay dried in 

 the sun. The general form in use at El Paso, is 24 inches 

 long, 12 inches wide and 4 inches thick. A little straw or 



