SCIENTIFIC MISCELLANY.

Otago Witness, Issue 3672, 29 July 1924, Page 66

SCIENTIFIC MISCELLANY.

(Fon the Witness.)

A PROBLEM OF THE AIR. Very minute transparent spherical particles in the dust of English cities, differ from the ordinary irregular particles and have some characteristics of glass. What they are* is a -mystery. They vary in abundance, and in March they constitute about 50 per cent op the total dust of Jxindon air. BERYL PORCELAIN. Porcelain in which 25 to 45 per cent of beryl, instead of feldspar, is mixed with silica and clay, has been found by the U S Bureau of Standards to have very high electricial resistance and 4tf> show very slight expansion and contraction under temperature changes. This porcelain, therefore, seems to be especially suitable for electrical purposes. But bervl is not an abundant material and the new product is not yet commercially available. DRIED MILK CURD. The curdled milk produced by the process of David D Peebles, of Eureka, Cal., is claimed to contain all food constituents of the milk, and to be adapted for cheese-making, or for use in cooking or otherwise, as dried milk. After removing 80 per cent of the water in a suitable evaporator, the milk is curdled with rennet or acid when fresh milk is used, the solid curd so produced, which is so compact that the w'hey is mechanically retained, is suitable for cheese manufacture, and ni some cases even skim milk curd may be used. A little more drying produces dried milk, which may be ground to power of any desired fineness, for feed for stock or human use. EUROPE’S BIGGEST PELTON TURBINES. The five hydroelectric generating sets in the Swiss railway station at Amstecr, have a combined output of 71,500 horsepower. With a head of 900 feat, water in two jets, each 81,- inches in diameter, drives the 70inch twin Pelton wheel of each set, and with twenty cast-steel buckets on each wheel, a speed of 333 revolutions per minute is obtained, yielding 14,300 horsepower per turbine. Exceptional solidity of attachment was required for the buckets designed to withstand 333 impulses of tons per minute and at the same time to resist a centrifugal force of 102 tons.

A DIGGER-WASP’S TOOL WORE. The use of tools by sphecid wasps seems to have been reported by several observers. In the latest instance, as described oy Science, two naturalists, collecting in iexas, heard a loud buzzing, and on turning, saw a wasp tamping down the filling of its burrow with a pebble. With the aoaomcn pointed directly upward and the tool held between its mandibles, the wasp moved its body entire up and down, pounding in pile-driver fashion. The pebble was about a fifth of an inch in diameter, and the tamping done was quite compact. FAT INTOXICATION. This condition is recorded by Dr F M Allen of New York, as an effect of an excess of fat in the diet.. When dogs are fed on fatty diets, without sufficient quantities of other foods, indigestion is first developed, and this is followed by the constitut.ion.ail poisoning known as intoxication. The chief symptoms include a skin eruption, loss of tile hair, varying degrees of muscular incoordination, and twitchings that may end in convulsions and death. There may be some added glucose in the blood, but the intoxication is independent of acidosis and diabetes, and seems to be due entirely to the absolute and relative over-abundance of fat. DRY LIQUIDS HARD TO BOIL. The presence of water vapor has curious effects that were quite unsuspected until witmn a comparatively recent period. Since near the close of the last century, H. jlre.i'eton Baker, English professor of chemistry, has been investigating the influence complete dryness may have on common chemical reactions, and has shown that water appears to act as a catalytic agent in many such reactions. Perfectly dry hydrogen chloride and ammonia, for instance, do hot com bine, as these gases do when undried. The more recent researches have given some even more surprising results, and have brought to notice a remarkable raising of the boiling points of many liquids by freeing from all traces of water, the rise in the case of bromine being 55 degrees O (from 63 degrees to illß degrees) : mercury, 62 degrees (358 degrees to 420-425 degrees); carbon disulphide, 30 degrees (50 degrees to 80 degrees); ethyl ether, 48 degrees (35 to 83 degrees) ; and et-hyl alcohol, 60 decrees (78 to 138 degrees). Prof. G. N. Lewis, finds the only plausible explanation to be, that water is a catalyst for processes between various molecular states, and that its removal interrupts or inhibits such processes. lie suspects that dry liquids will be found having abnormally low, as well as abnormally high, boiling points. GAUGING THE HEARING. The audiometer, developed bv certain telephone research workers, is designed to give quantitative measurement of the acuity and quality of hearing of either ear, much as the eyesight is tested by the oculist. The source of the soundl according to the Electrical World, is a vacuum tube circuit, which can he set to give a pore tone of a desired pitch within the audible range, And the perteon under examination listens in a telephone receiver while the intensity of the sound is varied in definite scientific units by the operator. The point at which the sound is no longer perceived is recorded as the examinee’s limit of hearing. It is exnected that tests with this instrument will soon lead to better aids for impaired hearing, and that further improvement may result from the continued studies in telephony. Besides giving hope of relief to those hard of hearing, the audiometer will find other useful applications. Tt may aid in delicate diagnosis of, ear troubles, in determining the fitness o'f applicants for insurance, automobile licence, or army or railway service, and especially in schools as a guide to early treatment, or to special lining for children with permanently Effective hearing. REINFORCING ACTIVE SOLAR RAYS. In experiments to which Dr. Leonard Hill latelv referred, the effort is being made to determine and record the ultraviolet radiation received from the sun from day to day. Ultra-violet light comes not only from direct sunlight, but from the blue skv, and is reflected from bright clouds. It is found that twenty times as great a proportion of ultra-violet rays come to us in bright, sunshine as on a cloud-" day. Heliotherapy has achieved important results, and Dr Hill urges its wider application, and the adoption bv cities of regular systematic measurements of the daily amount of ultra-violet rays m the atmosphere. The measurements would bring a realizing sense of their loss to large cities where the factory smoke shuts out the sun on all hut "a few davs of the year. Evidence lias been acquired showing the immense value of sunlight in the prevention and cure of rickets, and where the sunshine is lacking or insufficient, as is the case in many localities for at least a part of the year, the curative ultra-violet rays may be supplied by means of the mercury-vapor auartz lamp. Such lamps are now a part of the regular equipment of hospitals in London and elsewhere.