RETORT (Lat. retorquere, to twist or turn back), a word used in two distinct meanings: (i) a sharp reply, answer to an argument, statement or charge; (2) a vessel used in chemistry and manufacture. The chemical retort is a flask-shaped or bulbous vessel made of glass, earthenware or metal, with a neck, bent downwards, which leads to a receiver; such vessels are particularly used for distillation (q.v.). The name is also given to the apparatus, varying in size and shape, used in the distinctive distillation of various substances, such as coal, in the manufacture of gas.
Glass retorts are usually of the annexed form, with a receiver attached; they may be employed for the preparation of such products as do not require any extraordinary degree of cold for the condensation of their vapour: such a liquid is nitric acid. In this cut a represents the body of the retort, b the neck, and c is the receiver, secured to the retort by means of lulu. To prepare this acid, nitrate of potash is carefully conveyed by the neck into the body of the retort, and then sulphuric acid is added to it by means of the retort funnel d, which prevents any of this acid from remaining in the neck of the retort, and being washed down by and contaminating the nitric acid, as it condenses and passes into the receiver. In this case, when heat is applied to the retort, nitric acid and water rise together in vapour from the body of the retort, and are condensed in the neck; hut when the product is more difficult of condensation, the neck of the retort is lengthened by placing an adapter e between it and the receiver, to both of which it is secured by lute; it being understood that the wider end slips over the aperture of the retort, and the narrower one is admitted into the mouth of the receiver. In some cases condensation is accelerated by causing a small continuous stream of water to full ou the nock, el' the retort. A stoppered retort / is sometimes used instead of a plain one; these retorts are more expensive.but much mure convenient than common ones; for both the dry and the liquid substances to be employed in the operation are pasted intotLe body of the retort through the aperture, which u afterwards secured by a stopper, without having recourse to the retort funnel. Frequently also a quilled or tubulated receiver is used instead of the plain one above described: thisu represented by $; the tube is inserted into a bottle h, and this, when ammonia or other very volatile or difficultly condensible products are distilled, dips into water, or the receivingbotlle itself is immersed in water kept cold by ice or by i freezing mixture, as when hydrocyanic acid is distilled : i u the stand which supports the retort, and k is the lamp tj which heat is applied to it.
Glass retorts and receivers arc made of various si**, capable of containing from a few ounces to several gallon* and both (lint and green glass are used in their manufacture. Usually, instead of applying heat by a lamp, relorb are heated in a sand-bath, and sometimes they are subjects-, to the direct action of the fire ; but before this they are \erj commonly protected by a coating of lute.
Iu general, when the application of the higher temperatures is required for distillation or decomposition, earlhec retorts are employed. In preparing hydrofluoric acid, hr»4 is used ; and in concentrating sulphuric acid, platina, relcr;. are now largely employed, and would be universally so,were it not for their very high price.
Note - this article incorporates content from The Penny Cyclopaedia of the Society for the Diffusion of Useful Knowledge (1840)