Chemical manipulation - 1827 Author:Michael Faraday Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: 194 Distillation—common still. Sect. vit. SECTION Vll. Distillation.—Sublimation, 389. Distillation and sublimation have the same object and requir... more »e the same means ; both consist in the conversion of a body into vapour, its transferrence in that state, and consequent separation from other substances, and its ultimate condensation. The difference generally consists in the state assumed by the vapours when condensed ; if the product be solid, the process is called sublimation; if liquid, distillation. All that is required is, that the substance to be distilled or sublimed, should be raised to such a temperature that it will assume the gaseous form, and in this form conducted into a receptacle of such temperature, as to cause its resumption of the fluid or solid state. 390. Simple as is the process in theory, there are few that are liable to greater variety of arrangement. The range of temperatures at which different bodies rise in vapour is very extensive ; for sulphurous acid or chlorine assumes that state at temperatures below the freezing point of water, whilst mercury or zinc require one verging upon, or even surpassing, a red heat. Thus on the one hand very low temperatures are required to effect condensation, and on the other very high ones to cause the requisite vaporization. The vessels and the apparatus to be employed must not only be adapted to these points, but also effectually to meet the innumerable varieties in the quality and quantity of the substances operated upon. 391. The common still will serve best to exemplify the ordinary "points requiring attention in the process of distillation. It may be used both for water and alcohol, and if the laboratory be not otherwise supplied with distilled water, must continually be had recourse to for that nece...« less