SCIENCE NOTES.

Otago Witness, Issue 2309, 2 June 1898, Page 48

SCIENCE NOTES.

■ . * Probably tbe most important announcement in connection with the X rays is that made by Dr Sorel, of Havre, to the Paris Academy of Medicine. Dr Sorel, it appears, claims to have cured the band of a patient ' smitten with elephantiasis by turning X rays upon ifc. The monstrous-looking hand in one of the photographs was cured in three Bittings. and it has now, according to another photogiaph, resumed its normal appearance. On the proposal of the president the case was referred to the medical committee.

• . In the " Archives de Medecine Navale et Coloniale " of last June, La Navui reports upon an interesting find of some old castiron projectiles, made during hydraulio operations- on the shore of Brest. The projectiles evidently come from a shipwreck, to which La Kayur, without, gome farther

into his reasons, assigns tbe date of either I 1745 or 1791 ; he leaves the historical part of the research to others. In any case the | projectiles would have been over a hundred I year 6in the sea water. The outside crust I consisted of a silicious and calcareous deposit and iron oxide ; the oak piug was well I preserved ; the powder formed a cake of sulphur and carbon, in which — in most cases — no trace of nitrate conld be discovered. The iron under the rusty crust was, to all "appearance, in a good state of preservation ; but it had a specific gravity of 3 1 only, was soft, could be cat with a knife, and was so eager to combine with oxygen that a thermometer, placed in the mass, spontaneously rose to 185deg Fafar. Under the microscope one noticed metallic particles coated with a greenish mass, which soon became brown by oxidation. On account of this rapid oxidation, and because hydrochloric acid developed sulphuretted hydrogen, Le Navnr thought that iron sulphide had been formed with the help of the sulphur from the powder, or from .organically reduced sulphates. But the disintegration bad clearly proceeded from the outside, and the percentage of sulphur found was too insignificant to sustain this view. The analysis yielded in per cent. : iron, free 56, combined 12, carbon 13, silicpia 25, sulphur 0 325, chlorine 1*75 ; as ip another part of the paper 2 6 per cent, of bulphur was spoken of, there is possibly a misprint in the l sulphur figures. The high percentage of carbon and the low percentage of iron are the most striking features, and indeed very suggestive. Analyses made in the United States — first, if we-remeinber rightly, by Rigge in Omaha — of iron conduits, corroded by leakage currents from electric tramways, show the same peculiarity. The pipes did not appear to have suffered much, but they looked pitted, and nodules could be taken out, which contained little iron and much carbon, suggesting a gradual dissolution of the metallic particles by electrolytic action, which left the insoluble constituents behind, lie Navur makes no allusion to this circumstance, but he also assumes electrolytic action, combined probably with chemical reaction, and he refers to the electrolytic determination of carbon in cast iron. His suggestion is that the electromotive force of the iron carbon couple decompesed the sodium chloride of the sea water; the chlorine attacked and dissolved the iron ; the sodium generated hydrogen, which provided that reducing atmosphere which the continuation of the process required ; the hydrogen bubbles would, moreover, loosjan the iron, which would thus become soft, and might also reduce tbe sulphates of the sea water. Owing to the presence of hydrogen the iron would further preserve that deceiving bright appearance, which may mislead the inspecting engineer. — Engineering.

' . At sea, when a vessel in moving, the base is fixed and measured upon the deck. A telescope is placed at either end of that line, and the lenses of both ai-a focussed upon the object to be shot at. An observation i» then taken, a mathematical calculation is made, the book of table? is referred to, and in a moment the gunnr. may, know whether the enemy's cruiser is^five and onehalf or six and one-fourth miles away, or any other given distance. This, of course, requires a great deal of technical skill and mathematical ability, bat it is said to be absolutely accurate, and the apparatus is so sensitive and regulated to such a fine degree fchat, by turning a key, a monster gun weighing 100 tone cau be instantly adjusted so that, witb a given quantity of powder, it will carry a projectile of a .given weight exactly the distance which the range-finder has determined Of course the gunner must know the contents of hie cartridge, because that is a material factor in his problem. He must also make allowances for the wind, for the resistance of the atmosphere, for the curvature of the earth, and for the movement of the enemy's fleet it, it is in motion. The range-finder is, however, a great deal more accurate than the human eye, and persons with defective vision will often insist that a gun is badly aimed and find oat to the contrary after the shot is fired. Although we have guns on our battleships and in the fortresses on the coast that will carry a projectile 13 miles, it would be folly to attempt to use them at that distance, because, owing to the curvature of the earth, it would be impossible to see the target. A man in a small boat udo2 the surface of tbe water casmot

cc more than four miles. From the bridge of the ordinary man-of-war, which may be 30ft from the water, a man with good eyesight or with a glass can see eight or nine miles. A man at the mast-head can see 10 or 12 miles, but very indistinctly, and that is the limit; of human vision on a level surface. — Chicago Record.

• . • Apropos of the earth's store of fuel and the probable length of time that it will last to supply man's needs, it is interesting to recall the statement recently made by Lord Kelvin, whila ia the United States, that the danger ahead is not that the coal will give out and leave the world to freeze, but that the osygsa, which, of conres, is destroyed along with tfas consumption of fuel, wilJ all be ased up, and leave that helpless being, man, to a fate no kinder than asphyxiation. Of course the creature must have his oxygen, and tbe only chance for his ultimate security, in Lord Kelvin's mind, is dependent on his capacity to create oxygen as well aa to cause it to be consumed. The maaaer of manufacturing oxygen thus being something for the world to think about, the wherewithal of man's primary means of subsistence, necessary even before his food, is a much more important matter than the fuel which shall keep him warm. Lord Kelvin emphasised, therefore, that the best system of producing oxygen — fchat of cultivating, in a broad way, vegetation— be adopted to avert; the groat disaster. What little danger there was to be feared from fuel scarcity would, he thought, probably be still farther diminished by future geological explorations which would yield, no doubt, much now unthoi'ghl-of information regarding the coal of the earth, notably of the contents of the soil in tha depths of the sea. There might be much fnel there which could be consumed. — Oassier's Magazine.

• . • A rather remarkable accident with chloroform is reported from the Catholic Hospital at Herce, Westphalia. Ifc appears that a man had to be operated upon at once for a gunshot wound, and the operation being difficult, the time esfcended to about four hours. Tbe iJluminant in the room was gas, and it is supposed that it decomposed the chloroform with evolution of chlorinated vapours, with the result of incapacitating the two surgeons and so seriously injuring the sisters in attendance that ouo died on the second daj, and the lives of tbe others were in great danger. The matter is of special interest, because operations have to be performed .occasionally without preparation, and it would seem, from this experience, that only the incandescent electric lamp can be safe.

• . ' Dry rot ia , timber is brought about by the growth of a fungus which spreads itself over the surface in the form of a white threadlike filament, the roots entering the wood, from which they derive their nourishment, and at the same time causing decomposition of the constituents of the wood, especially in the sapwoo'd, causing its fibres to lose their cohesion and crumble to a brown powder.

Warm, damp, and stagnant air, such as is frequently' found in poorly-ventilated or wholly nnventilated situations, as in cellars, floors covered with impervious materials, ends of beams built ia walls, and behind skirfcinge, window backs, &c, are favourable to the development of dry rot. NThe general signs of dry rot are : a musty oaour, swelling and warping, and a charred appearance. The wood, on being struck, will respond with a dull, heavy sound, and- in such cases as skirtings will split and crumble at a alight blow. In the case of exposed beams, if the rot has commenced from tbe outer surfaces, it will be, of course, at once apparent ; but if it has commenced from the interior or covered surfaces, the exposed surfaces will change to a dark colour. When dry rot is discovered, if it has not penetrated too far, the timber should be thoroughly cleaned from all traces of the fungus, and be washed with one or more coats of vitriolic acid and water. On the other hand, if it has got a fair hold, the only remedy is to cut away and remove all infected pieces and all traces of fungus, substituting non-sappy, sound, and well-seasoned timber. In either case thorough ventilation niuat be provided. Cold, much moisture, or circulating air are unfavourable to the development of dry rot. — From BuildiGfi; World for April. Tnl-rrn-?i dii I ' — I — n-i"—— — hi iiiii" ■ ~-ib hI ■» r 1 ■■ ■-*-■ ~«m