CANNON, MA .sax or CASTING. Formerly the mould for -ousting eaunoa was of loam, and uaus$y leads of dry sand. Loam for mei* moulds, os as earth consisting principally of clay. It is passed through sieves and then mixed, whilst wet, with horse dung, cow's hair, chopped straw, Sr tea cut short; the loam being mixed ,up with one of these substances, they are well beat up togetherm a wooden heard with an iron bar; by this addition, the loam become susceptible of being dried aryully without tracking. The most attenuated loon is used for the surface of the mould that is to come in contact .with the metal, to the end that the sus- Ike may come off smooth. The lakoHnoulders we -a, particular class of workmen different from the common eand-moulders. The business to Aids they are bred, consists in making of loam .cud .of -dry sand, she moulds for ateam,eogine cylisdell, far vonveying meter, boilers, guns and ether ermarly GG siPefikag7NIXIdall Spindie, with straw ropes, a model was made of loam, copied the progressive population of different lands, exactly from the pattern giro; this model w0 ed over with a coat of wood ashes mixed with pos.' ter. By means of this coot, no adhesion took place between the convex model and the loam which was afterwards over this coat of ashes, maces sive coats of loam were applied, each being dried by fire before the next was laid on; the whole was bound externally with longitudinal iron bare, and with hoops transversely. Over this carcass of iron, a coat of plaster of Paris was applied. This was dried, and then the spindle and its envelope of straw was taken out. The interior convex model being thus deprived of its core and support, fell to pieces and was picked out ; and then a hollow mould of the gun remained. In this way the mould far the body of the piece was formed; the madds for the breech and head were made separately; these three parts were joined together so as to form a complete mould. This method of moulding gulls required the construction of a new convex model far every gun that was moulded; It was used in the French Government founderies of Douai, Basile, Dear Paris, and Strasburg, in 1794.
The following method of constructing the loam mould, is an improvement on that just mentioned : A model of wood, or to prevent clump of floras by moisture, a model of brass or pewter is made and fanned on the turning lathe, with its sato rior surface exactly resembling that of the gun, with its bead and the square piece at the caeca bid ; if the model is of metal, it is made hollow for the sake of lightness. Thie model is laid with its
longitudinal axis horisontal, and one half immersed in a bed.of sand; upon that part of the model which projects above the sand, successive coats of loam are applied and pressed on the model. When the first layer is dried by fire, a second layer is applied and dried, and so on till the model is covered with a eoat of loam four or five inches thick. Over this an iron carcass is applied, and over the carcass another coat of loam. The mould with the model in it is now turned, so that the half already covered with loam shall be lowermoot. The plain surface of the loam which bad been in contact with the sand, is painted over with a coat of blacking, composed of finely powdered charcoal mixed with clayed water; this prevents the adhesion of the fiat surface with the loam that is to be laid on it. A layer of loam is applied upon the naked half of the model. This is dried, and several more layers are applied succeg" sively. A carcass is put over the loam correspond. ing to the carcass of the first half; so that these two carcasses can be bound together with belts •and wedge-formed keys, with screw-bolts and nuts, or . tied with iron-wire. When the loam is dry, the upper half of the mould is lifted off, the model is taken out, and the intenkw surfaces of both parts of the mould are painted over with *chic% vents the loam from being melted, 404 ling to the hot instal. The two :halves of the would then put together, and the ceremsee are firmly connecaidly.ebeir belles the Abele is thoroughly dried by fire. When dried, the mould is placed ver- tic sly 113 the pit of the owning bone, with Ahe breech lowermost, sand is beat round itior airport, and. the metal is poured in at the top of the head. This method was practised in the Arsenal of Paris in 1794.