Science Siftings

New Zealand Tablet, Volume 14, Issue 24, 14 June 1906, Page 29

Science Siftings

By 'Volt 1

Photographs by Electricity. The oldest photographs in existence are further remarkable from having been taken by the electric light. They are six micro-daguerrotypc-s, which were made by Leon Fouco.ult in 1844, and which have just been presented to the Royal Microscopical Society by a French microscopist. This use of the electric light was its lirst application to scientific studies. Hair Whitening. The whitening of human hair with age has been proved to be due to the action of the white bloodccrpuscles, which devour the pigment. Dr. E. Trouessait, the French naturalist, has found that the fur of certain mammals —such as the stoat —is similarly bleached in winter, and that these animals do not change their coats, as has been believed. The cold in some unknown way causes the pigment to shift to other layers of the hair, where it is devoured. Under ihtense cold a small mammal has turned white in a single night, jmst as human hair has blanched suddenly under intense emotion. Heat-forming Mantles. The Welsbach mantle transforms the obscure heat of a blue flame gas-burner into luminous- radiations, which are rich in yellow and green rays but contain little red. The similar incandescent mantle of Delage, a French engineer, is composed of a mixture of rare earths of which the highly-radiant cerium is chief, and instead of the brilliant/ light it .emits heat, its spectrum being made up of red and invisible rays. Its heat is estimated to be 40 per cent. greater thin that of any other gasburning device. The burners may be arranged on a movable stand of five or more, or may be placed in a radio-incandescent grate, and when warming a room the mantles are almost non-luminous, while throwing out horizontally an intense heat. Trees Ha-e to Sleep. Trees and nlants ha\e their regular times for going to sleep as well as boys and girls. They need the same chance to rest from the work of growing and oil the machinery ot life. Some plants do all their fcl eping in the winter, when the ground is frozen and the limbs are bare oE leaves. In hot countries, where snow never falls and it is always growing weather, the trees rest during the rainy season or during periods of drought. They always choose the time when they cannct work the test for doing their sleeping, just as mankind chooses the night, when he cannot see to work. A Norwegian scientist has made some interesting experiments trying to chloroform plants, and he lias found that the fumes of 'his sleep-giver make the plants sleep harder and grow faster when they wake up. A Coming Substitute for Coal. ' Another addition (says the Liverpool ' Weekly Mercury ') has recently been made to the list of art - ncial fuels which ha\e been placed upon the market, and, by reason of its simplicity, it seems destined to take a front place. The basis for the fuel is bogpeat, a substance whLh largely abounds in many districts throughout the British Isles. The first ' process which the peat undergoes after being dug out from the bog is to be " shredded "in a disintegrating machine. The removal of the rcots and coarse fibres is then an easy matter, and the remainder is then placed under the pressure of an enormous press^ which is so powerful as to reduce it by,so per cent, of the bulk, and in doing so gets rid o*f two-thirds of the water it originally contained. Once more " shredded," it is mixed with lime to further dry it, and after that is thoroughly worked up in a mixing mill with crude petroleum refuse and 'bituminous pitch. It leaves the mill in a semi-plastic condition, and is easily made into "bricks "of any desired size. As both the peat and the petroleum reiuse are waste products, it will easily be seen that the cost of production is reduced to a minimum, and should enable fuel to be sold very cheaply.' ___-—-—___■■——■