Ordinary Paste.—There are two distinct ways of rnaking ordinary household paste :—(a) About a tablespoonful of wheat flour is mixed in a saucepan with say pint of cold water, the latter being added gradually and thoroughly incorporated by continual stirring ; the vessel is then put on the fire, and the contents are unceasingly stirred till they boil, great csre being necessary to prevent their caking or burning on to the pot ; (b) The water is first heated to boiling, and the flour is then added with constant stirring ; to prevent the formation of lumps, the flour may be passed through a sieve, so as to ensure its more equable distribution ; agitation is conthmed till the heat has rendered the mass of the desired consistence, and, after a few moments' further boiling, it is ready for use.
To preserve paste from the attacks of insects, and to arrest its decomposition, it is well to add a small quantity of somo antiseptic material, e. g. a few drops of carbolic acid, or oil of cloves, or a little powdered corrosive sublimate, camphor, or colocynth. Thns treated, and placed in covered vessels, it will keep fresh for years. The addition of salt or brown sugar hes a similar effect in a minor degree. Paste which has become hard or dry may be softened by beating up with a little hot water. With the object of considerably increasing the strength of paste, bookbinders, paper hangers, and shoemakers usually add powdered rosin to the flour, in the proportion of or even a, of the weight of the latter ; it is then known as " hard paste." Sometimes a teaspoonful of alum is introduced into each 11 pint of water, for the same purpose.
Starch Paste.—The best method of preparing starch paste is as follows. The starch is saturated with eold water in a mortar, to produce a thick paste free from clots ; into this, is then poured a small stream of boiling water, till " starch " commences to form, which is recognized by the mixturo becoming transparent ; the remainder of the water is then added, the total requisite quantity being twelve to fifteen times the weight of dry starch used. Heating the mass is useless. The addition of a Tittle alum to the water helps to preserve the paste.
Cementing Compouncle.—The cements hitherto considered may be called simple, in con tradistinction to the multifarious compounds which have now to be described. In the former, the adhesive virtue of one or more simple solid bodies is brought into play by the application of water, or heat, or both ; into tho latter, is introduced a great variety of substances, sorne possessing cementing qualities, others serving only as carriers of the preceding, or as driers. These compounds
may be very conveniently divided into two classes, to be called respectively " resinous," and " non-resinous." a. Resinous.—Under the term " resinous cementing compounds," will be included all those preparations which owe their cementing properties to the presence of a resin, gum-resin, or gum, such as cornmon rosin, indiarubher, guttapercha, gum arabic, &c. Compounds of this class are numerous, the best known being the following :— Bottle-corks, for.—The black bituminous cement used for bottle-corks consists of pitch, hardened by the addition of brickdust and rosin.
Chinese.—(a) For wood. glass, ivory, jewellery, and all fancy work :—finest pale-orange shellac, broken small, 4 oz.; strongest rectified spirit (58 O.P.), 3 oz.; digested together in a corked bottle in a warna place till dissolved, when the mass should have the consistence of treacle. This is one of the best cements for repairing glass, china, &c. It is so strong that pieces of wood cut obliquely across the grain and joined by it cannot be made to part at the juncture. Throughout the far East, it is used in joining bows, arrows, &c. ; the fluid is smeared over the faces to be joined, a piece of very thin gauze is it iterposed, and the whole is pressed tightly together and thus left till the follow ing day. Joints made with it will resist even the eontinual bending of a bow ; it is invaluable for mending fishing rods, and similar articles. (b) Chan glass is reduced to a very fine powder, and passed through a silken sieve ; the powder is ground with white of egg on a stone slab, powdered glass being added till the required consistence is attained. It forms a very final cement for glass and porcelain, vessels repaired with it breaking in a new place rather than at the joint. (c) Shellac, 3 oz. ; borax, 1 oz.; water, pint ; the whole is boiled in a covered vessel till dissolved, then evaporated to the proper eonsistence. It dries slowly, hut is cheap end useful. Druggists and oilmen often employ it instead of gum, for fixing paper labels to glass or tin, where exposed to damp.
Cutlers'.—For fixing blades of knives in their handles, the hank of tbe blade is heated and pressed iuto the hole in the handle, which has previously been filled with one of the following compositions ;—(a) Rosin, 4 parts ; beeswax, 1 part ; and brickdust, or plaster of Paris, 1 part; (b) Rosin, 16 parts; hot whiting, 16 parts ; end wax, 1 part ; (c) Pitch, 4 parts; rosin, 4 parts ; tallow, 2 parts; and brickdust, 2 parts.