eokel] SALT AND GYPSUM OF SOUTHWESTEEN VIRGINIA. 
411 
An analysis, by Prof. M. B. Hardin, of the gypsum rock from the 
Barnes property is as follows : 
Analysis of gypsum rock from Barnes property , east of Bradford, Va. 
Calcium sulphate 78. 60 
Water 20.79 
Calcium carbonate 0. 21 
Calcium chloride Trace. 
Magnesium chloride Trace. 
Organic 0.12 
Silica, alumina, etc 0. 23 
At several points between the Barnes property and Saltville gypsum 
deposits have been opened, but none have been worked recently. 
At Saltville several large openings can be seen. One of these was 
worked during 1901 and the early part of 1902, part of the product 
being sold for use as land plaster, but most of it being sent to Glade 
Spring, at which point it was utilized in the manufacture of Keene's 
cement. This industry not proving as successful as had been antici- 
pated, the plant was dismantled during 1902. The product, though 
fairly satisfactory, was not equal to the imported material or to the 
Kansas product. 
The writer has recently a described this interesting gypsum product 
in some detail, and the following quotation may be of interest here : 
Keene's cement is sharply distinguished from the other members of the group 
of hydrate cements (or " plasters ".), not only by the properties of the product, 
but by its method of manufacture. In its preparation a very pure gypsum is cal- 
cined at a red heat, the resulting dehydrated lime sulphate is immersed in a bath 
of alum solution, and, after drying, is again burned at a high temperature. After 
this second burning the product is finely ground, and is then ready for the market. 
This sketch of the process is a general outline of the methods used, and in the 
essentials is followed in all plants, though slightly modified at different plants 
according to the experience gained by each manufacturer. 
The gypsum used should be as pure as possible, and especially it should be free 
from such impurities as might tend to discolor the product, which should be a pure 
white. Nova Scotia gypsum has been tried and, for some reason, found to be 
unsatisfactory. Even the Virginia gypsum, which on analysis shows but a trace of 
iron oxide, is not entirely satisfactory, for on heating to the temperature necessary 
for the manufacture of Keene's cement, minute red streaks appear in the lumps 
of gypsum. The following analyses show the composition of gypsum from Vir- 
ginia and Kansas, both of which have been used in a domestic Keene's cement: 
Composition of gypsum used in manufacture of Keene's cement. 
Kansas. 
Vh 
ginia. 
Lime sulphate . . 
77. 46 
20.46 
.10 
.19 
.34 
1.43 
} 
Water __.__ 
99. 58 
Iron and aluminum oxides _ _ . - 
.036 
Silica and insoluble . _ . 
Magnesium carbonate 
.116 
.221 
Lime carbonate 
"Plasters and. hard-finishing cements in the United States: Engineering News, Vol. XLIX, 
pp. 107-108, Jan. 29, 1903. 
