Alum, calcined, loses in weight sixty per cent. Crude flint batch, melted and ladled out, loses in the average fifteen per cent. in weight. Hard coal will measure forty cubic feet to a gross ton. Glass in water. There are some peculiar phenomena connected with hot glass and water. If a ball of red-hot iron is placed in a vessel containing cold water, the latter is quickly agitated. But a ball of melted glass of equal weight dropped in cold water will produce no immediate agitation. The water will remain for some time quiescent; but when the glass is cooled to about half its highest temperature, it agitates the cold water violently. Technical terms, descriptive of glass, such as crystal, flint, tale, may be derived from these facts: the French used for their base crystal stones, burnt and ground fine; in England they had recourse only to flint stone, treated the same as the French used their blocks of crystal; tale was derived from the mode of selling, the best glass being sold only by weight, while light articles were sold tale. [Illustration] End of Project Gutenberg's Reminiscences of Glass-making, by Deming Jarves