SCIENTIFIC MISCELLANY

Otago Witness, Issue 3743, 8 December 1925, Page 80

SCIENTIFIC MISCELLANY

(Foe thb WitnemJ

I) VY LIGHT F.YEGI.ASSES. I„ the daylight spectacles of Pr H '™»™ Weis/ of Vienna, a layer of delicate but stable’blue dye in the lenses filters out the excess of reel and yellow m artificial light, leaving what is practically sunlight. Colours are more easily determined than with the expensive daylight lamps hitherto necessary. BUTTER WITHOUT MILK. The artificial butter of a European ohemist is made from tallow and waste fats, which are melted by steam in wooden vessels, boiled several hours after the addition of a little acid soda, strained through flannel, arid churned. The flavour is improved by the addition of a little honey. NEW LIGHT-WEIGHT ALLOYS. “Seleron" and “aeron" are German alloys recommended especially for electrical apparatus. Each contains 85 per cent, ot aluminium, and is given great elasticity and hardness by lithium, other constituents being copper, nickel, zinc, manganese, and silicon. The melting point is 6Godeg C., and the specific gravity 2.8 to 3. DRIED MILK SUPERIOR TO EVAPORATED. Dried cow’s milk, found to contain more vitamine B than evaporated milk, has been shown by experiments to have dietetic value greater than evaporated milk, and # equai or even greater than fresh milk. Rats were fed with white bread mixed with the different forms of milk, those on the different diets being kept under conditions otherwise the same, and the animals on evaporated milk were in the poorest physical state at the end of the test. TEETH WITH POOR ENAMEL. Imperfect or “honeycombed” teeth is a defect noted by Dr Percy Millican in 267, or 4.64 per cent., of 5757 children between the ages of five and fourteen years. Brown nits or generally deficient quality mark the enamel, the incisors and six-year molars leing most affected. The apparent cause is diseases of childhood—such as measles, wl ooping cough, nasal obstruction, and malnutrition, —and the trouble must be developed before the age- of three .and a-half years, when calcification of the teeth is practically complete. 100 little lime in drinking water is the explanation in some localities DR r ROT’S DESTRUCTIVENESS. “Dry-rot in its ravages in Alabama has affected other building materials besides wood (according to the Engineering News Record). Asphalt shingles and building ; papers may be destroyed, tarred roofing | may be rotted at' the ends in contact with ! decayed door, and the opening of nail kegs | may show' the nails covered with dense mats of fungus threads. Boxes of ba*dware may be similarly routed, within and without, with a heavily matted. growth. The infection may attack valuable electrical instruments, stored documents, and stationery, may discolour and warp cementaabestos shingles, and may lessen the value of wire fencing by its effect on the galvanised coa;. Almost anything coming in contact with it is damaged. DEVE /OPING THE THERMO-ELEC-TRIC: COUPLE. The rapid improvement in working efficiency that has followed the production of most electrical apparatus justifies the expectation that the thermo-junction of Dr T. F. Wall may result in a practical genera or for directly converting the heat energy of coal into electrical energy. As worke* out at the University of Sheffield, the thermo-junction is reported to have developed about 0.05 volt when suitably heated, and 60 compactly connected couples were capable of giving a useful current of three volts. Increased numbers of thermo couples yield correspondingly higher voltages, providing batteries adapted for charging accumulators, decomposing water, and many other purposes. In a thermojunction, in which the two metals form a tube a foot high and a foot in diameter, the coal is burned at the bottom of the tube, current being drawn off by means of two terminals. Improvement is already in sight, it is stated, and a combination of two metals with a third substance promises to yield more than a third of a volt per unit cell or junction for a temperature of about 600 deg C. This seems to foreshadow the day when wasteful steam boilers and rotating machines for generating electricity may be put aside.

NUTS IN THE AMERICAN DIET. Nuts are gradually increasing in import- '» ance in the United Stages dictury. The domestic product on a commercial scale includes only three kinds—pecans, walnuts, and ulmonds; but chestnuts, cocoanuts, filberts, hickory nuts, peanuts, pinenuts,, and pistachio nuts are grown to a greater or less extent. Almonds and walnuts claim a large acreage in California, while great * quantities of pecans are grown in the States bordering the Gulf of Mexico, and peanuts are rapidly gaining in favour as a southern crop. Of imported nuts, almonds come mostly from Spain; Brazil nuts from the Brazilian States of Para, Amazonas, and Marnnnhao; chestnuts from Italy, Bpain. Portugal, and Japan; cocoanuts from the We9t Indies, Central and South America, the Philippines, and the South Bea Islands; filberts from Italy, Spain, and Turkey; pistachios from Sicily; and walnuts from France, China, Italy, and Japan. Nuts contain a large amount of nutriment in concentrated and " ‘easily assimilated form. Tho average meat of three walnuts, states Artcma* I Ward, or 15 single peanuts or two Brazil nuts or 10 almonds or five pecans fcprwant* approximately as much energy food as two ordinary slices of white bread

or a cup of cooked oatmeal or a rounded tablespoonfui of granulated sugar. The vitainine content, except the widely distributed B, is negligible. TO GET MORE FROM THE SOIL The soil, which is comparable to a living creature, has been improved instead of exhausted by many centuries of cultivation, points out Milton Whitney, of the United States Bureau of Soils, in his new Soil and Civilisation,” but it is capable of great further development to meet future necessities. The modern concept of the soil recognises a digestive system that is influenced by the circulatory and respiratory systems and tho skeleton of the soil itself. The digestive system is dependent upon the number and kind of bacteria, the oxidation process, the enzymes, the insects, and above all on the organic feed supplied to these digestive agents —namely, the kind and association of plants grown. It is dependent upon and influenced by the amount and character of the cultivation, which is the only way we have of exercising the soil as we exercise an animal. In mediaeval times, when little attention was given to cultivation and the exclusion of weeds, where animals were small, under-nourished, and relatively inefficient, where the openfield method of cultivation made it impossible to vary crops at will, the soil was in a very low state of productivity. Under a more settled method of land tenure, with the teachings of careful husbandry, men resided on a single soil type until they began to know its requirements. How to develop the varied soil types to the utmost is still an unsolved problem. Exact classification of the types is a first step towards solution, and must be followed by intelli-* gent use of the better types and providing new crops and new industries for the poorer. In the last three centuries by improved methods England, France, and Germany have increased the wheat crop per acre from 12 bushels to 28 to 32 bushels.