The next process is the volatilization of the mercury by heat, which is usually called by the workmen drying off. This is formed by first heating the buttons in an iron pan, somewhat like a large fry ing-pan, till the amalgam with which they are covered becomes fluid, and seems disposed to run into drops, on which they are thrown into a large felt cap, called a gilding cap, made of coarse wool and goat's hair, and stirred about with a brush, to equalize the covering of the surface by the gold. After this they are again heated, again thrown into the gilding cap, and stirred, and these operations succes sively repeated till the whole of the mer cury is volatilized. When the mercury is volatilized from the buttons, or, as the workmen denominate it,wh en the buttons are dried off, they are finally burnished, and are then finished and fit for carding.
The white metal buttons, which are composed of brass, alloyed with different proportions of tin,after having been cast as before mentioned,are polished,by turning them in a lathe, and applying successively several pieces of bulfaloe skin glued on wood,charged with powdered grindstone and oil, rotten stone, and crocus martis. They are then white-boiled,that is, boiled with a quantity of grain tin in a solution of crude red tartar,or argol,and,lastly,finish ed with a buff with finely prepared crocus.
Glass buttons. These articles are also frequently wholly composed of glass of va rious colours, in imitation of the opal, lapis lazuli, and other stones. The glass is in this case kept in fusion, and the but ton nipped out of it whilst in its plastic state, by a pair of iron moulds like those used for casting pistol shot, adapted to the intended form of the button ; the workmen previously inserting the shank into the mould, so that it may become imbedded in the glass when cold.
Mother of pearl buttons. This substance is also frequently used in the manufacture of buttons : in which case, the mode of fixing in the shank is somewhat ingenious. It is done by drilling a hole at the back, which is under-cut ; that is, larger at the bottom than the top,like a mortise,and the shank being driven in by a steady stroke, its extremity expands on striking against the bottom of the hole, and it becomes firmly rivetted into the button. To these foil-stones are also frequently added, in which case, they are usually attached with isinglass-glue. Steel studs are also often rivctted into buttons of this and various other kinds.
The practice of wearing buttons con sisting merely of a mould covered with the same kind of cloth as the garment itself being at present extremely general, it may, perhaps, be proper to remark, that this is prohibited on pain of pecuniary penalties, from 408. to 51. per dozen, by several statutes, which have been made at different times, for the promotion of this manufacture,andunder which several con victionshavetakenplace withinafewyears. BUTTRESS, a kind of hutment built arch wise, or a mass of stone or brick, serving to support the sides of a building, wall, &c on the outside, where it is either very high, or has any considerable load to sustain on the other side, as a bank of earth, &c.