SCIENCE NOTES.

Otago Witness, Issue 2397, 8 February 1900, Page 58

SCIENCE NOTES.

— The only ionising inorganic solvents hitherto found in addition to Avater are nitric acid and liquefied ammonia. In the current number of the Berichte Professor Walden, of Riga, gives a preliminary account of experiments with liquid sulphur dioxide, which shows that this liquid acts to^an unsuspected . degree as a solvent for inorganic and organic substances. Since it permits of double decompositions, and giA'es electrolysable solu- | tions, liquid sulphide dioxide must iioav be Teckoned as an ionising solvent. Many subetances dissolve in liquid sulphur dioxide Ayith characteristic colours. Thus the iodides of the alkalis and alkylammoniums dissolve [with a yelloAV. colour. As an example of double •decomposition, the action of potassium iodide on tri-methlyammonium chloride may be cited. These substances in sulphur dioxide solution give a precipitate of potassium chloride. Ferric chloride and ammonium sulphccyanide give the visual red colour of ferric sulphocyamde. The electical conductivity of salts in sulphur dioxide solution is not the same in order as that in aqueous solution, nor does the molecular eleA'ation of the boiling point in liquid sulphur dioxide correspond altogether Avith that found in aqueous solutions. Professor Walden promises a thorough investigation of the many points of interest raised by this new discovery. — A Dutchman, J. Knipers by name, has patented a method of utilising the residues of the manufacture of potato flour. After straining this raAV material and separating From it portions of peel and other impurities, it is treated Avith glycerine and dilute acid. The resulting compound is a gummy, vi&cous mass, which is carefully dried and reduced to powder. The next operation is to moisten „ this poAvder with a certain percentage of water and to press, it into blocks, with the help of moulds if desired, the finished product being a homogeneous, wood-like solid Avith a metallic ring, which can be cut, turned, bored Avith ease, pnd Avill take the finest screw thread. It is believed that the material will conveniently take the place of Avood, vulcanite, celluloid, and even metal for many purposes. It ie said, moreover, lo be an excellent insulator for electrical purposes. The cost at which it can be produced is not slated. — In connection with some detailed investigation on the nutritive values of various substances, v bulletin has just beer, issued by tli3 U.S. Office of Experimcnf stations* on sugar as food. The Englibh-speaking people are the largest consumers of sugar, about BOlb per head being u&ed annually.* Germany, France, and Holland consume about 301b per head, but Italy. Grepce, and Turkey only use about 71b per head. There is a fair amount of positive evidence that sugar is food, if not in too great quantities or too concentrated, and that it lessens or delays fatigue and increases the capacity for muscular labour. During Mxq last autumn in.ajiceu.vrer in Ger-

many a number of men avlio were given 10 lumps of sugar daily were compared in vaPious Avays Avith men performing the same amount of work in marching and drilling, bud Avhose food contained little or no sugar. The results we c in every way to the advantage of the men using sugar. Most ot the bad effects attributed to sugar are due to its use in larger quantities than the 3oa or 4oz a day, Avhich seem to ; be digested by a healthy adult without difficulty. There is no proof that sugar is harmful to the teeth, although, doubtless, SAveet food, allowed to cling to the teeth after eating, rapidly ferments, producing acids which may attack the teeth. This, hoAvever, is true of starchy foods ; and against the aspersion may be placed the fact that the negroes of the West Indies, Avho consume enormous quantities of sugar, have the finest teeth in the Avoiid. — A thermostat has been designed in America to giA r e warning of spontaneous combustion in coal pockets. A compound solderrelease thermostat, encased and protected by iron pipe, is placed in the centre of every lOf c cube of coal, both horizontally and vertically. The thermostat has tAvo operating points^ one at 155deg, the other at 286deg, and as these tAvo points are reached bells are rung and warning given of an approaching fire. — Not the least wonderful thing in modern astronomy is that, by means of the spectroscope, an observer can not only tell whether a distant star is approaching the earth or receding from it, but can calculate the rate at Avhich it is moving. Professor Campbell, of the Lick Observatory, has recently reported that the Pole-star of the northern heavens is approaching the solar system at the rate of 11^ kilometres (about seven miles) per second. He also, from his observations, deduces the circumstance that the star is not a single body, but one of a pair. The companion j star is invisible to us, but the I tAvc bodies revolve around their com- | mon centre of gravity in a period 'of four days, the orbit in which they move being comparable in size to that of our moon. It is also assumed that there is a third body Avhich exerts an attractive force on the binary system, and that this attraction causes a periodical variation in the rate at Avhich the Pole-star is moving toAvards us. The observations Avere made with a Mill's spectroscope in conjunction with the big telescope. —By the death of Sir William Dawson, science loses one of its most picturesque figures, and Canada one of her most distinguished sons. Still active and vigorous in his eightieth year, he was the last survivor of the pre-Darwinian group of naturalists headed by the elder Agasriz. Born in Nova Scotia, educated at Edinburgh, making geological explorations under Lyell before he Ayas five-aud-twenty, lecturing upon Natural History in his native Halifax, called to the principalship of M'Gill University, at five-and-thirty he had added Avhole regions to the geological lealm of his continent before the great mountain-fold of the "Origin of Species" sloAvly lifted itself across the plain of scientific thought. And he always remained upon the further slope of this "Great Divide." Sir William Dawson's contributions to our knowledge of the Canadian rocks, especially Ayith reference to the chain of lifeforms running through each epoch, were many and important. His proudest achievement Avas the di&coA'ery of traces of what was believed to be a living organism in the Laurentian beds, and his Eozoon canadense has become one of the mobt celebrated, orgam&ms in palaeontology. Sad to say, however, the balance of later opinion inclines to regard it as a crystal. He was literally the father of M'Gill UniA r ei'eifcy, Avhich, Avith the aid of such large-hearted and far-sighted Canadians as Sir Donald Smith (the Lord Strathcona of to-day), he built up, in the more than 40 years of his headship, from a tiny, povertystiicken provincial school to a. well-endowed University of 1300 students, and a world-Avide l eputation. — Outlook. 1 • — An illustration is given in the Chemical Ncwtj of the new heat process brought forAvard by Goldschmidt, a Germnn investigator. A rivet, such as i& employed in bridge-making, is embedded in a mixture o£ oxide of iron, hand, and aluminium powilei, and the Avhole plunged in band in a wooden box ; on top of the aluminium mixture, Avhich must just emerge from the .sand in the box, is placed a &mall lump ok a mixture ot aluminium uowder

and an easily-reduced oxide, in which is fixed the end of a short piece of aluminium ribbon. The reaction is started by lighting the free end of the magnesium, more sand being immediately placed on the top of the mixture, so that as little heat as possible may be lost. If at the end of a tow moments the contents of the box are emptied out, the rivet will be found to be quite red hot, and ready to be forged. Working in an analogous manner, the inventor claims, &teel tubes may be welded together at the most trifling cost, and even two bars of soft steel can be fu«ed together. Indeed, the temperature obtained under these conditions may, it is asserted, be higher than that realised in the electric furnace. — The competition of electricity with gas as a means of illumination has (observed Professor Sylvanus Thompson, in the course of an address to the Institution of Electrical Engineers) been rendered very severe by the improvement introduced during recent years in incandescent gas lighting. The discovery of the properties of the rare earths in giving an augmented illumination — the result of a purely scientific research — was the foundation of the invention of the Welsbach mantle. It is singular that the very same properties were not turned to account in electric illumination before the invention by Nernst of the lamp which bears his name ; a lamp for the commercial introduction of which electrical engineers are still waiting expectantly. The methods that were in vogue at the date when the Electric Lighting Act of 1888 made electric distribution commercially possible are being superseded. Larger generating units, are being used in our stations. Larger areas of supply and fewer generating centres in an area are a necessity of the time. From the row of little bipolar dynamos, each with its own small high-speed engine — a sight so familiar in the older lighting stations — we are gradually pa&aing to the use of large multipolar machines coupled to larger and more economical steam engines. Ten years ago a distribution at six miles from the generating station was looked upon askance by many electrical engineers. To-day it is recognised that the secret of economical work is to generate on the large seale — ''in bulk," as tho phrase goes — and to distribute over laigc arca^ at an appropriately high voltage.