SCIENCE NOTES.

Otago Witness, Issue 2240, 4 February 1897, Page 48

SCIENCE NOTES.

: . It la commonly estimated that green wood when out down contains about 45 per cent, of its weight in moisture, bat in some cases wood cat down in winter is said to hold more than 40 per cent, of water at the end of the following summer. Kept for several yean in a dry place wood retains from 15 to 20 per cent, of water, while tbat which has been thoroughly desiccated will, when exposed to air under ordinary circumstances, absorb 5 per cent, of water in the first three days, and will continue to absorb it until it reaches from 14 to 16 per cent, as s, normal standard— the amount fla.ctua.tinj:

above and below this standard, according to the state of tbe atmosphere. It- has been found that, by exposing green wood to a temperature of 212deg Fahr., the lobs of weight equalled 45 per cant. ; and, further, that on exposing small prisms of wood |in square and Sin long, cut out of billets that bad been stored for two years, to the action of superheated steam for two hours, their loss of weight was found to be from 15 to 45 per cent., according to the temperature of the steam. • . Sagbalien, on the eastern coast fit Siberia, presents a very curioos anomaly of climate, says Oosmog. " The island is bathed by two cold ocean currents, and in winter nothing protects it against the icy northwest winds coming from Biberia. At the sea level the snow falls continually, and stays on the ground till the end of May, and the seashore is very cold. Farther inland, however, etpecially as we go higher up, the climate ie modified— just tbe opposite to what is observed elsewhere. Ir has often been observed j in Siberia and in Central Europe that in j winter tbe cold is greater in the plains and I in the valleys, and that the highlands have a sensibly milder temperature ; ib is as if the denser cold air accumulated in tbe lowlands. This fact is very often observed in our climate ; there are several very good examples of it : all the trees and shrubs of a valley have been known to be killed by frost, white above a certain level, very clearly marked out, on tbe bill or tbe mountain, tbe vegetation has not suffered at all. The cold air often flows from the summits towards their bases. This is what takes place at Boghallen. The cold air accumulates in the low regions of the island and on the coast ; the higher regions bave a more elevated tern- ; peralure. So it happens tbat the lower parts have an- arctic vegetation, while the inter- i mediate altitudes bave the vegetation of a temperate zone, sometimes subtropical. . . . The bircb, the asb, the pine, and tbe fir abound in tbe low regions and form often impenetrable forests, but toward the centre of the island appear bamboos, hydrangeas, aralias, and other plants that one is greatly surprised to meet, and whose presence can be explained only by the altogether abnormal climatic conditions of the island." * . ■ In a Government report from Colombia appears the description of a tree, known as the ohaparro, which possesses the property of being fireproof. Ib grows on the vast plains of Colombia and the north of I South America. — extensive districts which are parohed with heat, except daring the*rainy season. It has long been the custom to clear the ground for the new vegei tatioa which springs up io luxuriantly on these plains after the rainy season by means of fire ; and such fires, miles in extent, kindled by the herdsmen, destroy every- ! thing in the shape of vegetation except the chaparro tree, which survives to afford a welcome shade in an almost treeless region. It la a nma.ll trae^ seldom, crowing to froze

than 20ft in height, with a girth of about 1 3ft, and it owes its protection from fire to the nature of its hard thick bark. The bark lies on the trunk in loose layers, whioh do not readily oonduct beat to the more delicate parts of the strnoture. It is a general idea among the natives that this tree grows only where gold is abundant in the coll below. That it is common in au.rifer.ons districts is indisputable, but there is no ground for sup- ' posing that it doea not grow elsewhere. ' . ■ It is said that one of the lateßt products of the electric furnace is a compound of boron and carbon, whioh irf so hard that it will cab glass 88 easily as will a diamond. The new substance is due to M. Afoißsau, j who makes it by heating together boraolc acid and carbon ; ib is black, and, unlike the diamonds made artificially some years ago, which were microscopic in size, the new material can be proonred in large lumps. If this be true, the compound will be hailed by engineers as a valuable aid in the drilling of . hard rocks. ' . * Windows of cloth instead ol glass sounds like an impossibility, and yet it in a reality, and the employment of such a substitute is an acknowledged success. It is not ordinary ,olotb, but each as is translucent, through whioh light cornea-* just as through glass. To all intents and purposes this cloth window is similar to the jheefce of glass. It might be naturally assumed that; the translucent qualities of the fabric would be much inferior to that of glass, but a careful comparison has shown that the amount of light which ifc transmits equals that of ribbed glass one- quarter of an inch thick. * . * In bis address as president of the j chemistry and engineering section at the recent meeting in Glasgow of the British Institute of Public Health, Professor William Ramsay explained how the violet rays of sunlight act upon moist organic matter, producing hydrogen peroxide; how this peroxide beoomes water, and hands on the remaining- portion of oxygon to the organic matter, which it thus destroys or changes. Now, these changes are destructive to the life of minuto. organisms, such as the bacteria in sewage and the germs of many, perhaps all, zymotic diseases, such as typhus and anthrax. These are the conclusions to be gathered from the recent work of Professor Marshall Ward, Dr Arthur Rlohardaon, and Dr E. Frankland. We must have sanligbt; * . * Electric railways are still in their infancy, and it is impossible to foreßee what developments may accrue to them in the future. It is proved, however, that they are most certainly the beat means which can be adopted for underground traction, on account-, of the absence of all smoke or other noxious vapours. Sub there are some who prophesy for the electrio locomotive a wide' application above ground, and who' look forward to a speed of from 120 to 150 miles an hour as 'no impossibility. This lightning speed is to be attained, so it la said, oo a single line of rail designed by M. Lartigue. This line is supported some feot above the ground level ; and the oars, in pairs, are hung astride of it like a couple of sacks balancing one another on a donkey's baok. The oars are provided with wheels, and each carries beneath it two eleotric motorB ; there are also guide wheels .on the lower parts of the car which aot on guide rails, so as to keep the vehicle steady, It is claimed that this single rail line in mnoh safer than the present, system , and that it would be advantageous to erect snob, lines for paseenger service only at the Bides of oar existing railways. Up and down lines between London and Brighton,' the two connected at the ends and therefore in continuous circuit, could be built and equipped with rolling stock for about one million sterling. Such obstacles as tunnels, stations, &c, on the existing railway would be surmounted by the use of viaducts, or carrying the rail over hills on Bai table supports. A short length of line on the Lartigue principle has been open for some time in Ireland, and is said to give satisfactory results. ' * . * Charles S. Orowden, of Beeston, England, has devised a new process for joining tubes, or, as he terms it, " welding tubes by hydraulic power." With two tubes to join, one is made to "fit into the other. The inside of the outer one is spirally grooved along the length of the proposed join. Water power is brought to bear inside the Inner one. Tbe water endeavours to burst it, but it merely succeeds in pressing it. into the grooves of tho outer tube, which form n kind of mould to whioh the inner tube is' shaped. Tbe inner tube is not only shaped to the grooving of the outer by tbe water pressure, but it iB fixe/1 to it. On the removal of the pressure the two tubes are indissolubly united, and the object is attained. It is claimed tbab by this process a bicycle frame can be " welded " in five minutes qr less. ' . ' When a drop of human blood is placed between two plates of glass' and examined with a microscope it in seen to contain little whitish grains called •' white corpuscles." If tbe glass is warmed to a temperature equal to that of the human body these corpuscles, or phagocytes, as they are otherwise oalled, will be seen to put out and retract minute processes, which, as if acting the part of feet, enable the phagocytes to crawl over the surface o! the glass. Tho phagocytes in our blood feed upon the microbes of infections diseases when such microbes are introduced into the system. Phagocytes are the main defensive means possessed by tbe living body against} its microscopic foes. Whenever a wound is made in any part of tbe body, tbe phagocytes, like well-trained soldiers, rash to the breach and make war upon the putrefactive microbes endeavouring to enter phe system.