RETORT, a chemical vessel iwwhich distillation or decomposition is effected by the application of beat ; for different purposes retorts are made of glass, earthenware, and metal.
Glass retorts are usually of the annexed form, with a receiver This formula would give thicknesses considerably less than those usually adopted in practice ; for the general rule adopted by engineers is to make the thickness of retaining walls equal, on the average, to 1.3rd of the height, or It must, however, be borne in mind, that there is no allowance made in the formula for the numerous disturbing causes which are frequently met with, such as the subei sham of the ground ; nor dues it take into account the cohesion of the earth, nor that of the masonry; it is, in fact, only founded upon the theoretical oonditionm of the c ptilibrium of the materials. It is even desirable in addition to the extra thickness thus given in practice to the walla, beyond that which is required by the strict application of theoretical laws, to give a batter to the external faces equal to 1.24th of the height. A greater batter than this would be objectionable, on account of its catching and retaiuing the falling min ; and it is desirable that the internal face of the wall should be fennel in such a manner as 110t to hold up any water which might filter through the attached ; they may be employed for the preparation of such products as do not require any extraordinary degree of cold for the condensa tion of their vapour : such a liquid is nitric acid. In this cut a represents the body of the retort, 6 the neck, and cis the receiver.
To prepare this acid, nitrate of potash is carefully conveyed by the neck into the body of the retort, and then sulphuric acid te 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 care, 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 ; but 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 a 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 many cases condensation is accelerated by the use of a
Liebig'e condenser interposed between the retort and receiver. [CoNeresea.] A stoppered retort/ (fig. 4) is sometimes used instead of a plain one; these retorts are more expensive, but much more convenient than common cues; for both the dry and the liquid substances to be employed in the operation are passed into the body of the retort through the aperture, which is afterwards secured by a stopper, without having recourse to the retort funnel. Frequently also a quilted or tabulated receiver is used instead of the pLain one above described: this ie represented by g; the tube is inserted into a bottle h, and this, when ammonia or other very volatile or difficultly conden sible products are distilled, dips into water, or the receiving-bottle itself le immersed in water kept cold by ice or by a freezing mixture, as when hydrocyanic acid is distilled : i is the stand which supports the retort, and k ie the lamp by which heat is applied to it.
Clam retorts and receivers are made of various sizes, capable of containing from a few ounces to several gallons. and both flint and green glass are used in their mannfacture. Usually, instead of applying heat by a lamp, retorts are heated in a sand-Lath, and some time they are subjected to the direct action of the fire ; but before this they are very commonly protected by a coating of lute. [Lure.] in general, when the application of the higher temperatures is required for distillation or decomposition, earthen retorts are employed. In preparing hydrofluoric acid, lead is used ; and in concentrating sulphuric acid. platinum retorts are now largely employed, and would be universally so, were it not for their very high price.
In the destructive distillation of coal [Has Ltetrrrxo] iron retorts are need, and also, on the email scale, for obtaining oxygen from the peroxide of manganese, and various other chemical operations.