Dip a rose-colored ribbon into nitric acid, diluted with eight or ten parts of water, and as soon as the color disappears, which it will do in a short time, take out the ribbon and put it into a very weak alkaline solution, when the alkali will quickly neutralize the acid, and the color will reappear.
The Chemical Chameleon.
Put a drachm of powdered nitrate of cobalt into a vial, containing an ounce of the solution of caustic potash, when the decomposition of the salt, and precipitation of a blue oxide of cobalt will take place. Cork the vial, and the liquid will assume a blue color, from which it will pass to a lilac, afterward to a peach tint, and finally to a light red.
Musical Flame.
Fit a good cork into a wine-bottle; burn a hole through the cork with a round iron skewer, and into it fix a piece of tobacco pipe about eight inches long. Put into the bottle about two or three ounces of zinc, in slips, such as the waste cuttings from a zinc-worker; now pour water on to the zinc until the bottle is more than half full; then add about three parts of a wine-glassful of sulphuric acid (oil of vitriol); this causes a rapid effervescence at first, but which subsides to a moderate and continuous boiling for a lengthened period; as soon as the boiling is regular, the cork with the pipe through it may be inserted into the bottle. If a light be placed to the end of the pipe, a flame will be produced, which will continue to burn so long as there is any visible action in the bottle. This flame is the ignited hydrogen gas (water gas), resulting from the decomposition of water by the acid and zinc, and as such is an exceedingly interesting experiment. Now, to be musical, procure a glass or metal pipe, about sixteen or eighteen inches long, and from half to three-quarters of an inch in diameter; place the tube over the flame, and allow the pipe to be about three to five inches up the tube, which will act as a kind of high chimney; it must be held perfectly steady and upright, at a particular distance up the tube, which varies according to the size of the flame. A beautiful sound is thus produced, similar to an organ-pipe. This sound, or “musical flame,” varies in note according to the diameter of the tube, being deeper or more bass as the tube is increased in size. By using various-sized tubes, different sounds are thus readily produced. The true explanation of this singular experiment remains yet to be solved.
Optical Amusements.
The science of optics affords an infinite variety of amusements, which cannot fail to instruct the mind, as well as delight the eye. By the aid of optical instruments we are enabled to lessen the distance to our visual organs between the globe we inhabit and “the wonders of the heavens above us;” to watch “the stars in their courses,” and survey at leisure the magnificence of “comets importing change of times and states;” to observe the exquisite finish and propriety of construction which are to be found in the most minute productions of the earth;—to trace the path of the planet, in its course around the magnificent orb of day, and to detect the pulsation of the blood, as it flows through the veins of an insect. These are but a few of the powers which this science offers to man; to enumerate them all would require a space equal to the body of our work; neither do we propose to notice the various instruments and experiments which are devoted to purposes merely scientific; it being our desire only to call the attention of our juvenile readers to such things as combine a vast deal of amusement with much instruction, to inform them as to the construction of the various popular instruments; to show the manner of using them, and to explain some of the most attractive experiments which the science affords. By doing thus much, we hope to offer a sufficient inducement to extend inquiry much further than the information which a work of this nature will enable us to afford.
The Camera Obscura.
This is a very pleasing and instructive optical apparatus, and may be purchased for a small sum. But it may be easily made by the young optician. Procure an oblong box, about two feet long, twelve inches wide, and eight high. In one end of this a tube must be fitted containing a lens, and be made to slide backward and forward, so as to suit the focus. Within the box should be a plain mirror, reclining backward from the tube at an angle of forty-five degrees. At the top of the box is a square of unpolished glass, upon which, from beneath, the picture will be thrown, and may be seen by raising the lid. To use the camera, place the tube with the lens on it opposite to the object, and having adjusted the focus, the image will be thrown upon the ground glass, as above stated, where it may be easily copied by a pencil or in colors.