carborundum

There is no doubt that such a button — properly prepared under great pressure — of carborundum, especially of powder of the best quality, will withstand the effect of the bombardment fully as well as

This can most readily be done by use of carborundum marking. The procedure involves successive marking of the same mat with layers of carborundum at least twice.

At the same times, samples were taken to determine that the carborundum treatment did increase the amount of wear of the mandibles compared with insects on the diet without carborundum powder.