A Select Collection of Valuable and Curious Arts and Interesting Experiments, / Which are Well Explained and Warranted Genuine and may be Performed Easily, Safely, and at Little Expense.

by Unknown

107. Composition of various alloys.—Brass is composed of two parts of copper to one of zinc; or copper and calamine, (an ore of zinc,) equal quantities. Pinchbeck consists of from five to ten parts copper, and one of zinc. Bell metal is composed of three parts copper and one of tin. Gun metal, nine parts copper and one of tin. Tombac, sixteen parts copper, one part zinc and one of tin. The composition of pewter is seven pounds of tin, one of lead, four ounces of copper and two of zinc. That of type-metal is nine parts lead, two parts antimony and one of bismuth. Solder, two parts of lead with one of tin. Queen's metal, nine parts of tin, one of bismuth, one of antimony and one of lead. Jewel gold is composed of twenty-five parts gold, four parts silver, and seven parts fine copper. In forming metallic compounds or alloys, it is proper to melt such of the ingredients as are the least fusible first, and afterwards add the others, stirring them briskly till they are thoroughly commixed.

108. To produce various kinds of gas.—To three or four ounces of pulverized chalk or marble, moistened in a flask, with an equal quantity of water, add one ounce of sulphuric acid;—carbonic acid gas will be evolved in abundance, and will rise through the neck of the flask, and may be conducted by pipes, to any proper receiver. Instead of the marble or chalk, substitute granulated zinc;—in this case hydrogen gas will be evolved; but this may require a larger proportion of water. Pour sulphuric acid upon a similar quantity of dry muriate of soda;—muriatic acid gas will be rapidly evolved. Proceed in the same manner with a similar quantity of black oxide of manganese,—apply the heat of a lamp, and oxygen gas will be produced. Put into the flask, two or three ounces of lean beef, cut into small pieces; pour over them one ounce of nitric acid diluted with three ounces of water; apply the heat of a lamp, and nitrogen gas will be liberated. Powder separately, equal quantities of muriate of ammonia and newly burnt lime; put them together into a flask and apply gentle heat; ammoniacal gas will be evolved. Pour an ounce of nitric acid, diluted with five times its weight of water, upon one ounce of shreds or turnings of copper; nitrous gas will be rapidly evolved. Grind three parts of muriate of soda with two parts of black oxide of manganese; introduce this mixture into the flask, and add two parts of sulphuric acid, diluted with an equal quantity of water; apply a gentle heat and chlorine gas will be evolved. Note.—When either of the last mentioned gases are produced, great caution is requisite that they do not escape into the room, in any considerable quantity, as their action on the lungs is exceedingly injurious.

109. Various chemical tests.—When water is suspected to hold any foreign substance in solution, various means may be used to detect and ascertain the quality of the substances combined; thus, acids may be detected by immersing in the water, a slip of litmus colored paper, which, if acid be present, will be changed to red. In the same manner, alkalies may be detected by a strip of turmeric yellow paper, which will be also changed to red by alkalies. These tests are sensible to the presence of an acid or alkali in the proportion of one to ten thousand. Iron may be detected by a drop of infusion of galls, which will give to the water (if iron be present) a brown tinge. A drop of sulphuric acid, precipitates barites in the form of a white powder. Clear transparent lime-water (water in which lime has been slaked and then suffered to settle) will indicate the presence of carbonic acid by a milky whiteness. On the same principle, a solution of super-carbonate of potass will detect lime. A few drops of nitrate of silver will instantly discover muriatic acid, by a white flaky precipitate. Muriatic acid, consequently, is a good test for silver. Acetate of lead, in solution, is a test for sulphureted hydrogen, which occasions a precipitate of a black colour. Nitrate of mercury is an excellent test for ammonia, one part of which, with 30,000 parts of water is indicated by a blackish yellow tinge on adding the test. Liquid ammonia is a very sensible test for copper, with which it strikes a fine blue colour. Nitro-muriate of gold will discover the presence of tin, by a beautiful purple precipitate. Nitro-muriate of tin is, on the same principle, an excellent test for gold.

110. To produce a picture instantly, in a variety of colours.—Paint any picture on paper in the usual way, only instead of colours, use the following substitutes: for green, use a solution of nitro-muriate of cobalt, for blue, a solution of sulphate of iron—for yellow, a solution of nitrate of bismuth—and for a brown, a solution of sulphate of copper. Any of these solutions may be more or less diluted, as the respective parts of the picture are to be light or dark, but none of them must be strong enough to colour the paper. This pictture is invisible: but when it is required to appear, the paper may be tacked up on the wall, and having a glass of the transparent solution of prussiate of potass (which by sight cannot be distinguished from clear water) dashed suddenly upon it, the picture will instantly appear in its full colours. A similar effect may be produced, by drawing the picture with infusion of galls, and sub-carbonate of potass; this is revived by a solution of sulphate of iron, and appears in a yellow and a brown colour.

111. A cheap imitation of silver bronze.—Put into a crucible, an ounce of pure tin, and set it on a fire to melt; when it begins to melt, add to it an equal quantity of bismuth, and stir the mixture with an iron rod till the whole is entirely melted and incorporated. Take the crucible then from the fire, and after the melted composition has become a little cooler, but while it is yet in a fluid state, pour into it gradually, an ounce of mercury, stirring it at the same time, that the mercury may be thoroughly conjoined with the other ingredients. When the whole is thus commixed, pour the mass out of the crucible on a stone, where, as it cools, it will take the form of an amalgam, or metallic paste; which will be easily bruised into a flaky powder, and may then be applied to sized figures in the manner of gold or silver bronze, or may be tempered with gum-water, and applied to the work with a brush or camel-hair pencil; and if properly secured with varnish or laquers will be even more durable than either silver leaf or silver bronze.