SCIENCE NOTES & NEWS.

Waipa Post, Volume VII, Issue 329, 10 July 1914, Page 7

SCIENCE NOTES & NEWS.

WATERPROOF SHOE DRESSING.

Melt some tallow, and, while it is hot, put in some scraps of rubber from old rubber shoes or boots. Be careful to select rubber that is free from cloth. Put in as much of the rubber as the tallow will absorb. Stir freely while it is melting, and keep it away from any flames. Allow it to cool and set away for future use. Take enough for immediate use and warm it sufficiently so that it may be applied with a brush. TO KEEP GLASS WIND SCREENS CLEAN. On damp days the moisture gathering on the wind shield obscures the motorist’s vision, and thus increases the danger of an accident. It has been found a good plan to carry a bottle of kerosene and glycerin, mixed equally, and to rub a little of this over the glass when the rain begins to fall. This causes the moisture to spread over the glass in a very thin sheet, enabling the driver to continue in comfort and greater safety. HISTORY OF THE SAW. The earliest tool that has been traced in Egyptian history is the saw. It was found first in the form of a notched bronze knife in the third dynasty, or about five thousand years before the Christian era, and was followed in the fourth or fifth dynasties by largertoothed saws, which were used by carpenters; but there are no dated sped--mens until the seventh century before the Christian era, when the Assyrians used iron saws. The-first knives on record were made out of flint, and were, in fact, saws with minute teethThey probably were used for cutting up animals, as the teeth would break away even on soft wood. Rasps, which are but a form of saw, -were first made of sheets of bronze punched and coiled round, but t’ne Assyrians in the seventh century used the straight rasp made of iron similar to the modern type. COLOURS OF THE RAINBOW. Violet, indigo, blue, green, yellow, orange, red are the colours of the rainbow; most are sure of that. It is true, however, of only a very few rainbows. The colours of rainbows vary with their width, and their width varies with the size of the raindrops, big drops producing narrow bow's with bright clear-ly-defined colours, small drops producing w'ide bows with pale colours. Here are the colours as generally seen—(l) When the raindrops average one millimetre in diameter, violet, light blue, bluish-green, green, yellow, orange, light red, dark red; (2) when the drops average three-tenths of a millimetre, in diameter, violet, light blue, bluishgreen, green, yellow, orange; (3) when the drops average m c-tenth of a millimetre, very pale violet, violet, whitishblue, whitish-green. GAS IN THE CAVITIES OF TREES. Professor J,. A. Ferguson, of the Pennysylvania State College, reports a curious phenomenon connected with the cutting of hai#.vocd trees in the Ozark Mountains. Cavities near the base of the trees are often found to contain gr\s. \\ hen these cavities are cut into by the oak tic cutters of the region the gas escapes with a whistling sound, showing it to be under pressure and if lighted it will burn with a' faint yellow flame. The sides of the cavities containing- gas' are in all cases 'darkened, and look as though seared with a hot iron. The. popular belief of the district is that these trees are connected through'their roots with a subterranean supply of natural gas, and the land on which they grow is valued accordingly. An examination of the gas collected from a cottonwood tree was made by Professor Bushong, of the University of Kansas, and it was found to be substantially the-same as natural gas, with the addition of .some free hydrogen. Professor Ferguson believes, however, that this gas is the product of decomposition of the heartwood of the trees.

IS YOUR DIAMOND GENUINE?

The experienced eye docs not find it difficult to decide whether a stone is genuine or not, for the facets of real diamonds are seldom so regular as those of fine imitations. With the latter the greatest care is taken, in grinding, to polish and smooth the whole stone bo that there will be no irregularity in the reflection, or refraction of the light. A necessary tool for testing is the file, which cannot scratch a real diamond, although it quickly leaves its mark on an imitation. Better than the file is the sapphire, for the sapphire is the next hardest stone to the diamond. Any stone that a sapphire can scratch is assuredly not a diamond. If you put a small drop of water on the upper face of a brilliant, and touch it with the point of a pencil, the drop will keep its rounded form, but the stone will remain clean and dry. In the case of an imitation, the drop immediately spreads out. Plunge a diamond into water, and it be plainly visible, and will glitter through the liquid;, but pn imitation stone is almost invisible. If you look through a diamond, as through a bit of glass, at a black dot on a sheet of white paper, you will see one single point clearly. If you see several points, or a blur of black, it is an imitation. The white sapphire, the white topaz, and rock-crystal are often sold an diamonds, but imitations are more commonly of glsigg-