228 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213. 
renders it available for all uses for which a nonconductor is desirable, 
as steam-pipe coverings, safe linings, etc. In 1884, Mr. J.J. Coleman 
carried out a series of experiments on the heat-conducting power of 
various covering materials. His results" were as follows, the con- 
ducting power of slag wool being taken as unity: 
Comparative heat-conducting power of materials. 
Slag wool . ---- 1.00 
Hairfelt , 1.17 ' 
Cottonwool . 1.22 
Sheep's wool 1.36 
Infusorial earth . ^ 1. 36 
Charcoal 1 . 40 
Sawdust 1 . 63 
Gas-works breeze 2. 30 
Subseqently more elaborate experiments were made by Professor 
Ordway, 32 materials being tested under conditions closely approxi- 
mating to those encountered in actual practice. The following 
results 6 have been selected by the writer from Ordway's list and 
rearranged and recalculated to permit the heat-conducting power of 
slag wool to be taken as unit}*: 
Comparative heat-conducting power of materials. 
Loose wool 0.62 
Loose lampblack .75 
Hair felt .70 
Compressed lampblack . . .82 
Loose calcined magnesia .95 
Slag wo< >1 1 . 00 
Light carbonate of magnesia 1 . 05 
Compressed carbonate of magnesia 1. 18 
Ground chalk 1 . 58 
Asbestos paper „ 1 . 07 
Compressed calcined magnesia • 3. 28 
Fine asbestos 3. 78 
Sand 4.77 
It will be noted that though Orel way's results are not so favorable 
to slag wool as were Coleman's, both experimenters established the 
fact that this material is the best of the noninfiammable coverings 
tested. 
PAINT STOCK. 
In 1891 Mr. A. Sahlin described 6 a plant then in operation at Boon- 
ton, N. J., at which slag was utilized in the manufacture of paint 
stock. The slags used were puddle slags and reheating cinder, 
which, of course, can not be utilized in the manufacture of cements, 
a Engineering, September 5, 1384, p. 237. 
b Trans. Am. Soc. Meeh. Eng., Vol. V, p. 73. 
o Trans. Am, Inst. Min. Eng., 1891. 
