DIGESTER is the name of a strong kettle or pot of small dimensions, made very strong, and mounted with a safety valve in its top. Papin, the contriver of this apparatus, used it for subjecting bones, cartilages, &c., to the solvent ac tion of high-pressure steam, or highly heated wafer, whereby he proposed to facilitate their digestion in the stomach. This contrivance is the origin of the French cookery pans, called trutoclavee, because the lid is self-keyed, or becomes steam-tight by turning it round under clamps or ears at the sides, having been ground with emery to fit the edge of the pot exactly. In some auto claves the lid is merely laid on with a fillet of linen as a lute, and then secured in its place by means of a screw bearing down upon its centre from an arched bar above. The safety valve is loaded either by a weight placed vertically upon it, or by a lever of the second kind pressing near its fulcrum, and acted upon by a weight which may be made to bear upon any point of its graduated arm.
Chevronl has made a useful application of the digester to vegetable analysis. His instrument consists of a strong copper cylinder, into which enters a tight cylin der of silver, having its edge turned over at right angles to the axis of the cylinder, so as to form the rim of the digester. A segment of a copper sphere, also lined with silver, stops the aperture of the sil ver cylinder, being applied closely to its rim. It has a conical valve pressed with
a spiral spring, of any desired force, esti mated by a steelyard. This spring is in closed within a brass box perforated with four holes ; which may be screwed into a tapped orifice in the top of the digester.
A tube screwed into another hole serves to conduct away the condensable vapors at pleasure into a Woulfe's apparatus. DIMITY is a kind of cotton cloth ori ginally imported from India, and now manufactured in great quantities in vari ous parts of Britain, especially in Lanca shire. Dr. Johnson calls it dommity, and describes it as a kind of fustian. The distinction between fustian and dimity seems to be, that the former designates a common twilled cotton cloth of a stout fabric, which receives no ornament in the loom, but is most frequently dyed after being woven. Dimity is also a stout cot ton cloth, but not usually of so thick a tex ture ; and is ornamented in the loom, either with raised stripes or fancy figures ; is seldom dyed, but usually worn white, as for bed and bed-room furniture. The striped dimities are the most common ; they require less labor in weaving than the others ; and the mounting of the loom being more simple, and consequently less expensive, they can be sold at much lower rates.