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Hermetical Sealing for Bottles

Gelatine mixed with glycerine yields a compound, liquid when hot, but becoming solid by cooling, at the same time retaining much elasticity. Bottles may be hermetically sealed by dipping their necks into the liquid mixture, and repeating the operation until the cap attains any thickness required. 2239. Cement to Seal Bottles Containing Volatile Liquids. Chemists and others know well the difficulty of keeping volatile liquids. Bottles of ether, for example, are shipped for India, and when they arrive are found to be more than half empty. The plying with a brush some of the solution of remedy with exporters is a luting of melted the silicate of potassa on the parts to be joined, then they are left to dry, and the joint is hardly visible; and the joined part is far stronger than the remainder of the bone. Very delicate and porous anatomical pieces, as skeletons of birds, insects, etc., can be dipped repeatedly in more diluted solutions, and thus be rendered very hard and tenacious. sulphur, which is difficult to apply and hard to remove. A new cement, casily prepared and applied, and which is said to prevent the escape of the most volatile liquids, is composed of very finely ground litharge and concentrated glycerine, and is merely painted around the cork or stopper. It quickly dries and becomes extremely hard, but can be easily scraped off with a knife when it is necessary to open the bottle. 2236. Transparent Cement for Lenses, &c. It is frequently found necessary to cement together two surfaces of transparent

2240. Cement for Sealing Corks in glass, without destroying or injuring their Bottles. Take an equal quantity of resin transparency; this is especially the case in and bees' wax, melt them together, then put compound lenses. The best cement for effect- in an almost equal bulk of finely-powdered red chalk, add a small quantity of neatsfoot oil, let the whole boil 1 minute, then take it from the fire and stir it well; if too thick, add a little more oil. ing the union is Canada balsam, which, if too thick, should be thinned with a little turpentine, benzole, or ether. It is of importance that no air bubbles be present. In order to cement together the two parts of an achro- 2241. Cement for Sealing the Corks matic lens (this consists of a double convex in Bottles. Melt together 4 pound sealinglens fitting exactly into the concavity of wax, the same quantity of resin, and 2 ounces a plano-concave lens), having thoroughly bees' wax. When it froths stir it with a talcleaned the surfaces to be brought in contact, low candle. As soon as it melts dip the lay the glass, previously made warm, on a tamouths of the corked bottles in it. ble suitably covered to prevent the under sur- 2242. Painters' Putty. Putty is made face from being scratched. By means of a peg of wood or otherwise, convey a drop of the balsam to the centre of the lens, and then gently lower down upon it the lens to be cemented to it, also previously made slightly of common whitening, pounded very fine, and mixed with linseed oil till it becomes about the thickness of dough.