SCIENTIFIC MISCELLANY

Otago Witness, Issue 3756, 9 March 1926, Page 79

SCIENTIFIC MISCELLANY

(Fob thi Witness.) A CITY’S RAIN. Each square mile of the densest part of Liverpool in the last year received from the rainfall 650 tons of organic matter—nitrates, bitumen, calcium salts, sulphides, and chlorides. Copper sulphate formed by rain acid from the bronze of the Queen Victoria monument penetrated the Portland stone base to a doptli of 4in. A PEARL TEST. A novel test of pearls suggested to the Paris Academy of Sciences consists in boring a fine hole and illuminating the interior with a tiny mirror. The natural pearl liar concentric spherical layers, and appears uniformly lighted, but the layers in the cultivated pearl are nearly plane, and show as stria when the interior is illuminated. A NOVELTY IN ARTIFICIAL MARRLE. The buff honeycombed surface of tr.avertine marble so popular in interior decoration has been closely imitated in a less expensive artificial product. Cement and sand, with ochre or like pigment, are mixed, and hot paraffin is irregularly introduced during the mixing. When the cement lias hardened, removal of the paraffin by the heat of a blowtorch leaves a porous material with the appearance of the natural stone. A RESISTANCE SUBSTITUTE FOR PLATINUM. Nitric acid is less plentiful and more expensive than it would be if the jewellery demand had not so raised the cost of platinum, which is so useful as a catalyst. The metal has even greater importance on account of its resistance to corrosion, but Professor J. P. Withrow, of Ohio State University, finds that the liewly-produ cd tantalum may replace it for this service, though lacking catalytic action. The tests made indicated that platinum would lose as much in electrolytic corrosion in GO hours as tantalum in 100,000 hours, or platinumiridium alloy in 125,000 hours. Tantalum costs one-twentieth as much as platinum. DURABLE STORAGE BATTERIES. For a number of years M. Charles Ferv, French scientist, has been studying the storage battery with the aim of overcoming the tendency to spontaneous discharge when left charged, and to develop sulphating of the plates when left discharged. Oxygen dissolved in the acid is decided to be the cause of the trouble, and the remedy found is to prevent oxygen from dissolving in the acid around the plates by placing the negative plate at the bottom of the cell with porous material over it to absorb the acid. One experimental battery left charged remained over two years before complete discharging, while a battery left discharged showed no sulphating iii the time. STEAM INSTEAD OF SAND BLAST. Cleaning old stone buildings is usually effected by the use of acid or the sand blast, both of which are harmful, or by slow and laborious scrubbing with hand brushes and soap potirder. The recent restoring of a Baltimore building of Indiana limestone by means of steam is thought to offer a process that is not only quick and harmless, but is in most cases economical. Live steam at 801 b pressure was used through sin steam hose lines, with simple galvanised pipe nozzles, and the dirt accumulation of 20 years was speedily removed with only* inexperienced common labour. Somewhat less blight than new stone, the cleaned Avails have the pleasing appearance of age. EVOLUTION OF THE TOY AGE. A phase of our changing life that is not to be overlooked is the development of plaj'things and of the plaything period. With mass production and the general increase of earnings toys have become liefter and more entertaining, and Prentice Wincliell points out in the Ir :i Age that the price at which they may sell has risen to 50 times that of 20 years ago. And children, moreover, use playthings until they arc 15 years old instead of 10. The campfire girl or girl scout gives up her lolls of other days, and must have a scooter and a coaster waggon, with balls and skates to compete with her brothers. For the boy the cheap tin horse wound with a key has given way to the substantial steel electric train, capable of real action. Then there are miniature automobiles, phonographs, and many kinds of mechanical toys, with machines for turning varied work into play. Toys have becomo more entertaining. So great has been their multiplication that 8000 lines of toys have been announced in connection with the latest New York annual toy fair, and it is predicted that the American toy bill already reaching 200,000,000d0l yearly will continue to mount higher. MICROBES IN CULTIVATION. Collections of living microbes have been maintained for many years at the

l’asteur Institute oi Paris, at Prague, and at the Museum of Natural History in New York, and have been drawn upon by health officers, research students, and industrial scientists for comparison with varieties encountered by these workers. The most extensive collection now seems to be that of the Lister Institute of Preventive Medicine in London, which has been recently increased by the Medical Research Council to more than 2000 living strains of bacteria and protozoa affecting animals and plants. These are listed in a new catalogue, and living cultures of most of them can be supplied. In 1924 more than 4000 cultures were distributed. Of the genus Aspergillus, which includes common molds, the collection contains 30 living species, and these have been obtained from widely-scattered animal and vegetable sources. Of tubercle bacilli there are more than 20 strains, derived from man, cattle, birds, a kangaroo, alligators, tortoises, frogs, and fishes. Botulism has been known in the British Isles only by the outbreak in Scotland in 1922, but this supplied cultures of Bacillus botulinus. Among other specially interesting organisms are those of the sleeping sickness and the tsetse-fly disease of Central Africa. COFFEE IN YOUTH AND AGE. While the consumption of coffee in the United States has reached or exceeded an annual average of 131 b or more for each man, woman, and child, there appears to be little suggestion of harm except during the growing period of life and in the stage of decline. The use of the beverage is evidently becoming common among the very young, and inquiry among a large number of children of preschool age in Gary, Ind., has shown that two-thirds drink coffee* habitually, 40 per cent, having it more than once a day. It is quite generally conceded that at such an age injurious effects are likely to result. Two chief reasons pointed out why these children should not be given coffee are that it tends to crowd out or replace the milk so necessary in the youthful dietary, and that it is an unneeded stimulant, likely to give rise to nervous disorders that will become of serious consequence in later years. It is asked whether premature coffee drinking may not have contributed to the lack of nervous balance now seen in many adults. In age as well as in youth the body is more sensitive to such stimulants as caffeine than in robust middle life, and gradual curtailing of coffee and tea is advised for advancing years. Failing this, likely effects are increased production of uric acid and irritation of the kidneys, increased nervous and muscle irritability, and increased blood pressure.