HYDROGEN

(Yunanca köken — orijinale bakınız.) This important element is only known to us in the gaseous or permanently elastic form. It was formerly called tnJtammable air, and was sometimes considered as identical with phlogiston, or the matter of heat. It is usually procured by the action of sulphuric acid and zinc or iron upon water, or by pa ing the vapour of water over red-hot iron. Pure hydrogen is a colourle , tastele , and inodorous gas. 100 cubic inches at mean temperature and pre ure weigh 2'13 grams; so that Its specific gravity compared with air U 2 O [s. 591]