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CASTOR.

of starch, by the appearance of its particles viewed in a microscope. They arespherical,all about l-1000th of an inch in diameter, and associated in groups; those ofpotato starch are irregular ellipsoids, varying in size from l-300tli to l-3000th of aninch ; those of arrow-root have the same shape nearly, but vary in size from l-500th tol-800th of an inch ; those of wheat are separate spheres l-1000th of an inch.

CASSIS, the black currant (ribes nigra, Linn.), which was formeily celebrated forits medicinal properties, with very little reason.

The only technical use to which it is now applied is in preparing the agreeable liqueurcalled ratafia, by the following French recipe : — Stone, and crush three pounds of blackcurrants, adding to the magma one drachm of cloves, two of cinnamon, four quarts of spiritof wine, at IS 0 Baume (see Areometre of Baume), and 2J pounds of sugar. Put themixture into a bottle which is to be well corked; let it digest for a fortnight, shakingthe bottle once daily during the first eight days; then strain through a linen cloth, andfinally pass through filtering paper.

CASTING OF METALS. (See Founding.) Casts from elastic moulds. — Beingmuch engaged in taking casts from anatomical preparations, Mr. Douglas Fox, Surgeon,Derby, found great difficulty, principally with hard bodies, which, when undercut, orhaving considerable overlaps, did not admit of the removal of moulds of the ordinarykind, except with injury. These difficulties suggested to him the use of elastic moulds,which, giving way as they were withdrawn from complicated parts, would return totheir proper shape ; and he ultimately succeeded in making such moulds of glue, whichnot only relieved him from all his difficulties, but were attended with great advantages,in consequence of the small number of pieces into which it was necessary to dividethe mould.

The body to be moulded, previously oiled, must be secured one inch above the surfaceof a board, and then surrounded by a wall of clay, about an inch distant from its sides.The clay must also extend rather higher than the contained body : into this, warm meltedglue, as thick as possible so that it will run, is to be poured, so as to completely coverthe body to be moulded; the glue is to remain till cold, when it will have set into anelastic mass, just such as is required.

Having removed the clay, the glue is to be cut into as many pieces as may be ne-cessary for its removal, either by a sharp-pointed knife, or by having placed threads inthe requisite situations of the body to be moulded, which may be drawn away when theglue is set, so as to cut it out in any direction.

The portions of the glue mould having been removed from the original, are to be placedtogether and bound round by tape.

In some instances it is well to run small wooden pegs through the portions of glue, s0as to keep them exactly in their proper positions. If the mould be of considerable size, it 15better to let it be bound with moderate tightness upon a board to prevent it bendingwhilst in use ; having done as above described, the plaster of Paris, as in common casting;is to be poured into the mould, and left to set.

In many instances wax may also be cast in glue, if it is not poured in whilst too hot:as the wax cools so rapidly when applied to the cold glue, that the sharpness of the im -pression is not injured.

Glue has been described as succeeding well where an elastic mould is alone ap-plicable ; but many modifications are admissible. When the moulds are not used soonafter being made, treacle should be previously mixed with the glue (as employed .printers) to prevent it becoming hard. *

The description thus given is with reference to moulding llio«c bodies which cann^be so done by any other than an elastic mould; but glue moulds will be found great!) ^facilitate casting in many departments, as a mould may be frequently taken bymethod in two or three pieces, which would on any other principle require many. ,

CASTOR. (Eng. and Fr.; Biber, Germ.)' The castor is an amphibious <l nruped, inhabiting North America ; also found in small numbers in the islands oRhone. In the arts, the skin of this animal is employed either as a fur or as a 01 . : c hthe silky hair called beaver, with which the best hats are covered. Beaver skins,form a very considerable article of trade, are divided into 3 sorts : 1. The fresh eskins from castors, killed in winter before shedding their hair; these are most inquest among the furriers, as being the most beautiful. 2. The dry or lean beaversthe skins of the animals killed during the moulting season ; they are not much es e ,as the skin is rather bare. 3. The fat castors: these are the skins of the first sort ’, ' vit hhave been worn for some time upon the persons of the savages, and have got imbuetheir sweat. The last are principally used in the hat manufacture. In Franc ®’ r 0 imarine otter has been for many years substituted in the place of the cas

CASTOR or CASTOREUM. This name is given to a secretion of the cast