SCIENCE NOTES.

Otago Witness, Issue 2572, 8 July 1903, Page 80

SCIENCE NOTES.

—In a paper road before the Aeademie Jes Sciences M. Callietet describes the union of gelatin© upon glass and other surfaces. When a glass object is covered with a thick layer of strong glue, the latter adheres strongly when wet, but upon drying it may be detaohed, and carries with it glass scales of different thicknesses which have been lifted from the surface. The glass which is blius treatc-d presents a surface whose designs reeemble those of frost on a window pame, and have a decorative effect. M. Cailletet made experiments with gelatine upon different substances, and found that tempered glass was easily attacked, an well as Iceland spar, polished marble, fluorspar, and .other bodies. A sample of quartz cut parallel to the axis of the crystal was covered with two layers of fish-glue ; after drying it was found that the surface was attacked, and showed a series of strife which wore parallel, rectilinear, and ran close together, while in the case of glass the striae were curved. When certain salts were dissolved im the gelatine — uatne-ly, those which we*e easily crystallised and had no action, there was produced on the glass a series of engraved designs which had a crystalline appearance. Thus, a solution of strong glue containing b per cent, of alum gave very fine designs, somewhat resembling moss in appearane? ; other salts, such as hyposulphite of soda, nitrate and chlorate of potash, will produce analogous forms. M. Cailletet told of th? strong mechanical action exerted by a layer of gelatine when drying. If a sheet of cardboard, leid, or even wire-gauze is covered with a gc'atine solution the surfaces are seen to curve into the form of a cylinder -as the gelatine oontracts. Upon thin glass the effect is striking ; when a layer of strf-mg glue is spread upon a cylindrical vcei el of thin glass the effect •>vhich it, exerts when drying i» sufficient to brcr'k ti'ie vp^-el with explosion. When a plate of thick glass covered with gelatine is examined by polari-ed light a powerful mechanical str^.n is observed in the gla-=.

— In both England and America marriage among the cultured elas-es ii at a discount, at loa .t during t) c early years of maturity, and tho duties of parentage are postponed or altogether shirked A race Miicide, in fact, is in 'dent progir^. Much is now eaid respecting the me?n.s of mbsi'-te-noe, but the Anglo-Saxon might well consider the- ovideness of his failing noweis to subsist. . . . We do not w ish our readers to imagine that we cms'der a country's good is dependent entro'y on mere numbers; but when, in ad 'ltion to our failing birth-rate, wo remember the recent con elusive evidences as to the oxecushe propagation of the inefficient and mentally and physically unfit, it is woree than folly to close our eyes to the serious fact that tho existence, of the Anglo-Saxon as a lead-r in the world's great purpose ia seriously threatened. — Medical Prrss.

— Electricity would appear to have something irt common with the forces of p!-mt life, say- the Lancet, and it is just possible that «ome clay the world's food supply will be furnished by its means. Already we know that whe-n intense electrical discharges occur in air nitr-c acid is produced, which, alien neutralise! with soda, potash, or lime, fiirn-hr- the indi^pensab'o nitrate for plant l'f'\ At the- presont moment the Falls of Niagara nre bom? utili-Ptl in this way. But ppp-m I'tly ol< etrieity is capable of producing frod substance* in a mucli more direct way lha-.i thi- Given carbon, hydrogen, ard owsjfMi in the Minp'o a.v=ociation cxi- 1 !!!; in c nboiMc acid ca=> and wn*er, the rurrMit undor cr'an cTduions will bring ibcut. niciidinir to irr^nt rf=Pirohe«» a reinvinerrrnciit nf the rl<Mivnt = , until at length •>arhobydrate-> me obmned. But we have ho reckon with lntro^n, the o= s ontial element of the protul cr fic-h fcrminc acr-

tion of all food. As its Greek derivation implies, proteid i* a vital constituent of all food, and it has been said "without proteid we die." Is it possible, then, that proteid will eventually be built up by electrical means in the same way as is carbohydrate? In such case plaint life will no longer be indispensable to man.

— Every ocean traveller is familiar with those curious tropical formations, coral reefs. To the geologist they have a special interest as the occasion of Darwin's miserable failurei. The man who preached the great but onoe unpopular gospel of evolution was also the author of a theory of coral reefs which, by a strangely reverse process, from being universally popular ia now almost finding oblivion. Hie one idea was that a reef, whether it took) the form of a ring of coral, half a mile across, known as an "atoll," or the Great Barrier Reef of North Australia, 1000 miles 'ong, was always caused by land subsidence. For example, in an island, the corals, requiring shallow water, would begin their growth round the coast, and thus a fringiing reef, as it was called, would be formed. Then subsidence would begin, the reef continuing to grow, so that a ring of shallow water would appear between 'the latter and the land. In ■the course of time, the original island would entirely disappear, Reaving nothing but a shallow lagoon within the coral belt. The ingenious simplicity of this theory doubtless captivated the older geologists, but the last 30 years have seen many an eminent observer take up arms against it. Prominent among these (says tho St. James's Gazette) is Piofessor Agassiz, who has lately published to the Royal Society an elaborate accost of 25 years' investigation in almost cvety region where coral reefs are to be found. The results are co widely various as to make it impossible to draw general conclusions. But it is worthy of note that Darwin's theory finds little enough support. Instead of subsidenoo there is often uphea\al, the lagoon being formed by the denudation of tho original rock, which w often found to be of volcrmic origin.

— Conditions of climate have more to do with health and even with life than mOht people realise. Persons of both sexes, after 50 years of age, prov:ding they are able to secure for them.seheb a, maximum of sunshine and open air life throughout the course of each year, may retain their energies and vitn'ity unimpaired until quite an old age. Of course, diet a.nd exfroise combined with common .sen-e are aL-o material factom in the maintenance of energy and Mgour after middle life, bait in practice tho mcro vigorous the man the more modeiate usually his appetite. Bodily health meane rr.cn' al \igour and- energy at their best.

It is a lack of intelligence rather than of ii'h which prevents tho majority of nndd!e-cla-s people in England from securing for tliPiiT-eUes the conditions of climate by a d.aiigo of lcsidcnco which after midtllo ago will 1 c^t promote their physical and mcnt-al well bi-mg .md \itahty — H'^pital.

— For pome years experiments ha\o from time to dine brn made by railuav < oin panics with pc'liol^iun a-, a fui 1. aii'l one of the great Kng'ii.-.'> I"" 1 -: ha>- found (<-iys tt-o Daily News) that thiie »•, no m<<<h. rural difficulty. A jot of steam is. u'od to Tjl<j\v the oil into ( ho- furnacp in t^e form of a finely-divided tpray or vapour, which <an bo regulated so a= to give- any mte-iibity of heat Thus there is not the nrc~bsitv for laborious stoking in preparation for a hc.ny grac!if-nt or the waste of fuel and annoymco of blowing off strom during a stop. Thfro h lo ■smoke, and much lct=% labour in cleaning, while tho ooF-t of handling coal and ashcb L-, -»a\ed Hitherto the difficulty has beon tho co^t, for. although petroleum has long com-pare-d favourably with coal, anything like general use an the railways would have put up rh«» pricn at once. The discovery of new oil fields and the higher price of coal have now given a fresh impetus to ton© uee of

petroleum. Mr A. L. Williston, in the Engineering Magazine, m^ntic-ns that in California oil is rapidly driving coal out of the field for power purposes. The same is true in Texas, amd of much of the territory lying in between. This general use of oil has affected not only the power and lighting and manufacturing plants in these regions, but also the railroads and marine transportations. One railroad in California is now burning oil cm more than 180 locomotive 5 .

— A new and interesting use has been diFcovered for carborundum, which has already found large employment as a substitute for emery. Capable of preparation only in a powerful electric furnace, where silica and' carbon are fused together in presence of sawdust and common salt, carborundum is highly refractory ; and it has beon obs-erved that a thin layer of the same substance applied to any other material of which furnaces arc usually constructed protects it from the heat, antl renders it almost- counlV refractory. Finely powdered enrbrn wlum is madp- up into a paste with water-glacis — i.e., sodium biheate, or 60me similar binding substance, and the p^ste is applied by means of a brush or otherwise to tho bricks which are intended to be used for building a furnace, or tho&e brioks are actually immersed in tho viscid liquid for a certain time. If the furnace' has already been built, the paste can be painted on to the exposed surfaces, giving one or more coat?, as may be desired. It i« stated that a layer 2mm. thick will protect the bricks from the attack of bhe highest terrpe-ratui'e. which is cvot produced by cMribiiFtim method* in ordinary work. Examination of tho bricks in such a furnace ha= shown Hint thfy had not differed in tho least. Tho ,«kin or carborundum does not chip off. and is hard enough to resist mechanical injury.