viscid matter, which serves as a cement. Glues are of different kinds, according to the various uses they are designed for, as the common glue, glove glue, parchment glue, isinglass glue, &c. The common or strong glue is made of the skins of animals; as oxen, cows, calves, sheep, &c.; and the older the creature is, the better is the glue made of its hide. Indeed, whole skins are rarely used for this purpose, but only the shavings, parings or scraps of them; or the feet, sinews, &c. Those who make glue of parings, first steep them two or three days in water; then wash them well out, boil them to the consistence of a thick jelly, which they pass, while hot, through osier baskets, to separate the impurities from it, and then let it stand some time, to purify it further; when all the filth has settled to the bottom of the vessel, they melt and boil it a second time. They next pour it into flat frames or moulds, whence it is taken out pretty hard and solid, and cut into square pieces or cakes. They afterwards dry it in the wind, in a sort of coarse net; and at last string it, to finish its drying. The best glue is that which is oldest; and the surest way to try its goodness, is, to lay a piece to steep three or four days, and if it swell considerably without melting, and when taken out resume its former dryness, it is excellent. A glue that will hold against fire or water, may be made thus: mix a handful of quick lime with four ounces of linseed oil, boil them to a good thickness, then spread the paste on tin plates in the shade, and it will become exceedingly hard, but may be dissolved over a fire, as glue. Method of preparing and using glue. -Set a quart of water on the fire, then put in about half a pound of good glue, and boil them gently together till the glue be entirely dissolved, and of a due consist ence. GLUTEN; a vegetable compound, procured by repeatedly washing wheat flour in a large quantity of water, by which means the starch is dissolved, leaving the gluten behind in a very tenacious, ductile, somewhat elastic state, and possessed of a brownish gray color. It has scarcely any taste, and is insoluble in water, alcohol and ether, but is taken up by acids and alkalies. The acid solution is precipitated by an alkali, and, reciprocally, the alkaline solution by an acid. Dried by a gentle heat, it contracts its volume, and becomes hard and brittle. Its products with fire, or nitric acid, are nearly the same as those of gum and sugar. Gluten is present in most kinds of grain, such as wheat, barley, rye, oats, peas and beans; but the first contains it in far the largest proportion, which is the reason that wheaten bread is more nutritious than that made with other kinds of flour; for, of all vegetable substances, gluten appears to be the most nutritive. It is to the presence of gluten, that wheat flour owes its property of forming a tenacious paste with water, to which cause is due the formation of light spongy bread. The carbonic acid, which is disengaged during the fermentation of the dough, being detained by the viscid gluten, distends the whole mass, and thus produces the rising of the bread. Good wheat flour contains from 19 to 24 per cent. of gluten. The wheat of warm climates is richer in gluten than that of colder regions; to which cause may be attributed the difference between the wheat of the north and the south in the U. States. Gluten consists of two distinct principles; to one of which has been applied the name of gliadine, fron. ya, gluten, and to the other that of zymome, from (uun, a ferment. To obtain these principles, the gluten is boiled repeatedly in alcohol, which dissolves the gliadine and leaves the zymome in a pure state. On mixing the powder of guaiacum with the latter substance, a beautiful blue color instantly appears; and the same phenomenon ensues, though less rapidly, when it is kneaded with gluten, or the flour of good wheat moistened with water. With bad flour, the gluten of which has suffered decomposition, the blue tint is scarcely visible. The intensity of the color thus produced is entirely dependent on the relative quantity of zymome contain ed in the flour; and, since the quantity of zymome is proportional to the quantity of gluten, the proportion of the latter, and therefore the quality of the flour, is tested by the action of the guaiacum. When glue is to be used, it must be made thoroughly hot; after which, with a brush dipped in it, besmear the faces of the joints as quick as possible; then, clapping them together, slide or rub them lengthwise one upon another two or three times, to settle them close; and so let them stand till they are dry and firm. Parchment glue is made by boiling gently shreds of parchment in water, in the proportion of one pound of the former to six quarts of the latter, till it be reduced to one quart: the fluid is then strained from the dregs, and afterwards boiled to the consistence of glue. Isinglass glue is made in the same way: but this is improved by dissolving the singlass in alcohol, by means of a gentle heat. (See Cement.) cary. His persevering efforts obtained him the reputation of being one of the greatest botanists of his time. His principal works are his Flora Sibirica and his Travels.-2. Philip Frederic, brother of the preceding, was born at Tübingen, in 1721. After his brother's death, he became professor of botany and chemistry at Tűbingen, where he died in 1768. He wrote several botanical and medical works.-3. Samuel Gottlieb, a nephew of the preceding, was born in 1744, at Tübingen, where he studied physic, and, in 1763, took the degree of doctor of medicine. He afterwards visited Holland and France, and, in 1767, received an invitation to a professorship in the academy at Petersburg. The year following, by the command of the empress, be commenced, together with Pallas, Güldenstadt and Lepechin, a scientific tour through Russia. In 1769, he travelled along the western side of the Don, and passed the winter in Astrachan; in 1770 and 1771, examined the Persian provinces on the south and south-west side of the Caspian sea; in 1772, returned again to Astrachan, and there surveyed the regions on the Wolga, and, in 1773, the dangerous countries east of the Caspian sea. On his return, however, in 1774, he was imprisoned by the Khan of the Chaitaks, and died in confinement, July 27, of the dysentery. His widow received from the Russian empress 2000 rubles. His most important works are his Historia Fucorum, and his Travels in Russia (Reisen durch Russland zu untersuchung der drei Naturreiche.)-4. William Frederic, a distinguished engraver, was born at Badenweiler in the Brisgau, in 1745, and died at Rome, in 1821. His parents sent bim to Basle. Here, guided only by his genius, he overcame numerous obstacles. In 1788, Gmelin went to Rome, and subsequently to Naples. At the close of 1790, he returned to Rome, and there actively engaged in painting from nature, for the most part in Indian ink. He did not diminish the effect by descending to minute detail, but knew how to seize upon the peculiar characteristics of every view, and his style evinces a deep study of nature. He also engraved a good deal. His engravings are among the finest productions of the art. In some of his later productions, indeed, a hardness and an exaggerated expression are perceptible. He cut his plates very deep, probably to enable him to take many impressions. Gmelin amassed a considerable fortune, as his engravings were in great demand. with which the names of many places founded by the Moravians begin; as Gnadenberg, in Silesia, with 460 inhabitants, one of the chief places of that fraternity; Gnadenfeld, a village also in Silesia; Gnadenfrey, also in Silesia, with 800 inhabitants, and a Moravian institution for education; Gnadenhütten, a Moravian village in Ohio; Gnadenthal, a colony of 1377 inhabitants, among the Hottentots; and many others. GNAT (culex). These well known and troublesome insects are distinguished by having the body and feet very long and downy, antennæ garnished with hairs; large eyes; a proboscis composed of a membranous cylindrical tube, terminated by two lips, forming a little button, and sucker formed of five scaly filaments, producing the effect of a needle: the wings are placed horizontally over each other. They are but too well known in this country, particularly in the autumnal months, and more especially in marshy situations. Ever greedy of blood, they pursue us every where, enter our houses, especially in the evening, announcing their arrival by a sharp buzzing noise. When they bite, the sucker is plunged through the skin, and, as it buries itself, the sheath or trunk is drawn up towards the breast The pain of the wound is occasioned by a venomous fluid which they inject into it; the best remedy for which is the preparations of ammonia. It is a curious fact, that it is only the females which thus torment us. One species of these insects is known under the name of mosquitoes, against whose attacks various means have been resorted to in different countries, as curtains of gauze, and various essential oils; the latter of which appear to be only partially successful. The Laplanders drive them off by means of smoke, and anointing their bodies with grease. These insects also feed on the juice of plants. The female deposits her eggs on the surface of the water, in a long mass. In their larva state, these animals are aquatic during the greater part of the summer. All stagnant waters are full of these small worms, hanging with their heads downwards, whilst their hinder parts reach the surface of the water. In this state the stigmata, or organs of respiration, are placed in the posterior part of the body they are also, in this condition of existence, provided with small fins. After having remained in the larva state for about twenty days, they are tranformed into chrysalids, in which all the limbs of the perfect GNADE (the German for grace); a word insect are distinguishable, through the |