Page:Willich, A. F. M. - The Domestic Encyclopædia (Vol. 2, 1802).djvu/411

379&#93; GLU IJKtened to a frame, or Btrings, ■ it is sutten d to remain till completely dry. — The best glue tor common purposes used in iliis country u generally imported from Ireland, and is exempt even from khecoovoy-duryj whereas the obtained from foreign markets pays to the customs 9s. 3d£. per cwt. A very superior, but expensive, glue may be prepared from the hides of die oldest cattle, especially those of bulls. Its quality is likewise much improved by long keeping ; and its strength may be easily de- termined, by immersing a piece in water for three or four day^; at the expiration of which,, if it swell con- siderably without dissolving, and resume its former dry state, on be- ing exposed to the air, it may be considered as excellent. Glue is also manufactured from the skins, fins, heads, tails, and cartilages of porpoises, cuttle-fish, and odier sea-monsters. For this purpose, the parts above men- tioned should be boiled in water, being carefully preserved from smoke, and whatever may disco- lour the liquor, or render it turbid. When all die substance of the fish has been boiled down, the jelly is strained through a sieve, and suf- fered to cool. It is then again boiled with die same precaution, till the drops, when dried in the open air, concrete on cooling. Af- ter having acquired a proper con- sistence, it is twisted in a manner similar to paste, and suspended on strings for drying in die shade. Glue, thus prepared, is more or less perfect, in proportion to die care with which it is clarified : it should be completely soluble in water. Another very powerful glue may be prepared by a spirituous solution •f isinglass, which Mr. Boyle di- GNA [379 refts to be first steeped for twenty* tour hours in common brandy; when the isinglass is opened and ••:', die whole should bs gentlv boiled together, and stirred till it forms a perfect solution, and till a drop of the cold liquor indi- a strong jelly. It is then to be strained while hot, through a clean linen cloth, into a vessel,, which ought to be closely stopped. A gentle heat will be sufficient to dissolve this glue into a colo>iiess> and nearly transparent fluid, which is said to be so adhesive, that pieces of wood glued with it, separate elsewhere sooner than in the place where diey are joined. — See Isin- glass. GXAT, or Culex, L. a genus of insects comprising several species, which are well known by the se- vere punctures they indict. Gnats deposit their eggs to the number of 200, by each female, on stagnant waters where they are hatched into small grubs, in die course of two or three clays. On the sides are four small fins, by the aid of which ti.e inseft swims 1 about, and swiftly dives to die bottom. The larvae retain their form a fortnight, or three weeks ; when they are converted into chry- salis, in which state they continue three or four days, floating on the surface of the water, till they as- sume the form of gnats. These insects have a cylindrical body, consisting of eight rings. The sting, which is perceptible to the naked eye, contains five or six spiculae, or darts, exquisitely mi- nute. With these, gnats make puncmres in the skin, and are sup- posed to inject a small portion of liquor which renders die blood cir- culating near the wound more fluid, and tli us causes troublesome itch- ing