SCIENCE NOTES.

Otago Witness, Issue 2371, 10 August 1899, Page 54

SCIENCE NOTES.

— The heat of- the electric furnace-, -which _~ due simply to an electric arc enclosed in a crucible of incombustible material, is the greatest, that can be obtained artificially. M hen this was rui . up to about 6300deg Fahr. i>y Professor Moisson it was thought that the limit had nearly been reached ; but Professor Tucker, of Columbia University, has_beaten Ihe French professor by several hundred degrees An interesting resul f if. that whereas the artificial diamonds that could be made in Mpisson's furnace — perhaps its mo^L interesting; produota — were exceedingly email.

much larger stones have been produced in the improved Tucker furnace. Says Electricity : " Some time ago Professor Moisson, by means of a specially devised electric furnace, succeeded in making artificial diamonds, the largest, however, not measuring much over forty thousandths of an inch in diameter. The heat then generated, the most intense ever produced up to that time, was about 6300dcg Fahr., whereas, if leports are to be credited, Professor Tucker succeeded recently in obtaining a heat of between 6500 and 6700 degrees. The principal aim of the experiment was to determine the commercial value of the extreme heat obtainable from an electric arc, and with this object in view a special furnace was devised which is said to be an , improvement over that made use of by Pro- | fe£sor .Moisson. - Artificial diamonds were made by Professor Tuckei in much the same manner a'- those made by Professor Moisson before a New York audience some three years ago, namely, by placing cast-iron chips in a plumbago crucible' and covering them with carbon. The whole was then subjected to the full heat of the furnace, after which the crucible and its contents weVe withdrawn and plunged intc icy water, the sudden contraction of the molten iron furnishing the necessary pressure for crystallising the carbon. The experiment is said to have been very successful in that a diamond larger than any so far made was produced. Aside from tin's fact, Hie experiment was interesting as showing tho enormoua heat which may lie produced by the electric furnace, probably the most intense yet obtained, and which should ultimately be the means of reducing the cost of production of certain subslances, such, for example, as calcium carbide, now in demand for commercial purposes." — Sir Norman Lockyex has lately been experimenting with flexible film, with the idea of adapting it to spectroscopic photography. The large concave Rowland grating which Sir Norman Lockyer is now using for his solar spectroscopio photographs has 20,000 lines to the inch ruled on its surface, and is of 2]^ft radius, giving a spectrum of 30 inches long. The focal plane of this grating is of necessity considerably curved ; in fact, the plane of accurate definition at the edges of the field is about 0.5 inches in front of the similar plane at the centre. It is, therefore, impossible to get a sharp photograph of the whole spectrum on a glass plate ; in fact, not more than 18 inches '.o 20 inches of the spectrum can be brought into focus on the same plane. . . This difficulty is, of course, got over by the use of a flexible film, which can be bent to the curvature of the field. One of Sir Norman's photographs taken with a Rowland concave grating must be the longest solar spectrum photographed at a single operation. It is 30 inches long, and shows the arc spectrum of iron -with a comparison spectrum of the sun from wave length 3600 to 5200. Sir Norman Lockyer also hopes that by using films instead of glass plates at the next solar j eclipse he will be able to obtain a greatly I increased number of photographs, owing to the rapidity with which the film can be shifted in the short space of time available foi photoaraubio operations.

— The recent outcry for a form of lucifer match the manufacture of which shall be innocuous to the workers has led to the introduction of a, new coating composition, which is now, after a period of satisfactory trial, being used exclusively in France. The principal substance used is a combination of amorphous or red phosphorus with sulphur — the sesqui&ulphide of phosphorus, as it is called — which has all the good qualities without the baneful ones of the ordinary white phosphoru=. It emits no vapours, and can hardly be regarded as a poison, for a dose which would contain enough phosphorus to coat thousands of match-heads has no perceptible action upon an adult human being. The new product is mixed with chlorate of potash, powdered glass, etc., in order to give it the necessary inflammable and percussive qualities. A match matlo by the new French formula will strike on any surface, and one of its chief recommendations is that the process of manufacture is in no sensible degree altered from that of former days. — "There are lots of mysterious things about the phonograph that puzzle even those who are most familiar with its mechanism," remarked a gentleman who has had long experience in the talking machine business. "As a matter of fact, no scientist has ever been able to explain exactly why the thing talks. -They say a ' duplicate vibration ' is set up, but when you pin them down they are obliged to admit that they don't know why the operation of the transmitter should produce any such result. Then, again, the difficulty, in recording certain tones has always bean a puzzle. The most improved form of 'the machine has an extremely large cylinder, nearly four times the size of the ordinary one, and for some unknown reason it very materially increases the volume of sound. It would seem, then, to be a logical inference that the bigger the cylinder the louder the tone, and, proceeding on that theory, a very clever young electrician started the other day to make an instrument that was really gigantic. He put it together without much trouble, and made an experimeptal cylinder nearly a foot in diameter. I was present when it was tested. Every ,part of the machine worked perfectly, and a beautifully engraved record was secured, but when the transmitter was attached we were astonished to find that the sound was barely audible. As nearly as we could calculate, the tone was magnified up to a certain point by making the cylinder larger, but beyond that the process was reversed, and it wrts progressively diminished." — The electric locomotive was — like many other modern engines — first completed and employed in America. It is immensely powerful, having a, motor on each of its four axles. Its unfamiliar, funnel-less appearance will be seen from the diagram. Particularly is it useful for work in tunnels, where it is

desirable that no smoke shall accumulate. There the engine of a train going through shuts off steam, the electric locomotive is hitched on in front of it, and does the hauling work instead. The electricity is usually collected from a rail running overhead. — Mr James Quick, in an instructive article in the current issue of Knowledge, dealing with clouds and their classification, pays that in considering the conditions affecting cloud formation may circumstances determine when and where the water vapour is condensed. It may rise only a comparatively short height above the sea level before the change takes place, or circumstances may require its ascension to high altitudes. For instance, suppose a cold north-east wind, or a f=outh-east wind already laden with moisture, or a lowering of the barometric pressure to set in, all these will tend towards an early formation of cloud. Upon a dry, calm day, however, the vapour will generally have to travel up a long way before it will change its condition. In fact, sometimes under these circumstancs. it only changes into water drops to be directly transformed- again into ice particles, resulting in the delicate fleecy cirrus clouds. Again, water vapour possesses: a good heatabsorbing power. A cloudy sky, therefore, or an atmosphere already charged with vapour will, in one respect, cheek condensation by preventing free radiation of the heat out into bpace. But there is yet another important condition, Ihe^presence or absence of which materially aids or prevents any cloud being formed at all. This essential factor in the atmosphere is dust. Dust, or minute particles of matter of some description, in the air to act as nuclei is apparently as necessary as the water vapour itself, as unless the vapour finds something to act as a nucleus around which to form a water drop, it will evaporate before it has had time to grow. — The late Professor Tyndall, in one of his charming books, has laid it down that the blue colour of the Lake of Geneva is due to the reflection of blue rays from particles of dust floating in the water ; but M. Spring, at the recent congress of hydrology and climatology. Liege, maintained that the blue colour of tho lake is the natural colour of pure water. When water is yellowish, it is because of the dust in it ; and the Lakes of Constance and Neuchalel are po green because the yellow tinge of the duet is blended with the blue of the water.