Show blacker than coal to most of us coal seems to be the limit of blackness but there is one su substance that is much blacker silica black it is formed of coal crushed to a fine powder and mixed with pulverized silica this compound is heated in a vacuum at a temper temperature of degrees fahrenheit ren heit and when the gas and other products have been driven off the residue is found to be much blacker than coal says a writer in london tit bits magazine silica black has many uses paints shoe polishes insecticides and fume absorbents usually contain a certain proportion of it its value lies largely in the fact that it mixes easily with oil the color is permanent and it resists acids and chemicals |