SCIENTIFIC.

Otago Witness, Issue 1874, 21 October 1887, Page 36

SCIENTIFIC.

— The wax or tallqw of candles is turned jnto gas before being burned in the flame. Thjs may be proven by the following experiment, says sn exchange : After the candle has. been burning a few minutes, blow it out and l)old a Jjghted match in the smoke poming from the wick, and about one inch abo,ve it. The smoke (?) burns, the flame running down and re-lighting the candle. \yhat appeared to be smoke cqming from the wipk was gas' into whiph the wax or tallow p,f tlie pandle Jjad been' fuqied by the heat pf the flange. Sbqt or uncb'nsumed carbon w|ll tje deposited, because the gas formed J>as been pooled pelow th,e temperature at Which cartjop bums. The clouds of smok« eecaping from many furnaces have led engineers to estimate the loss of fuel. In no case does the loss amount to more than a fraction of a per cent, of the fuel consumed. Many devices which prevent smoke increase the consumption of fuel. There is, however, a loss from imperfect combustion which may or may not be accompanied by large volumes of smoke. The coal may be partially burned, forming an invisible gas called carbonic oxide, which, if completely burned to carbonic dioxide, would give out in the furnace a large amount of heat otherwise lost. Just as the combustion of the candle flame is hindered by cooling, so the carbonic oxide, unless the temperature is at the burning point, will not be consumed. The improved forms of furnaces, grate-bars, and settings have been devised with the view of supplying a sufficient quantity of air at such high temperatures that the fuel may be entirely consumed. — Dr M. H. Leskerstein, of Chicago, Reports £he remarkable effects of nitroglyperine in resuscitating life. His patient a woman, wjip sank rapidly and was {Apparently 4ead. Any aptjpn of the heart was imperceptible, the temperature of the body had fallen to 92deg Fahr., and every indication of death- was present. A solution of nitro-glycerine was administered hypodermically, when there" was a gasp, followed by three others within a minute. During the second minute six respirations were noted, with a faint fluttering of the heart, but no wrist-pulse was discernible. During' the third minute 18 respirations were evident and a feeble pulse. . During the fourth minute the pulse rose to 180 and above, the faoe was flushed, the eyes rolled, the muscles

slowly relaxed, and the patient became comfortable. —One of the finest and most powerful tools that mechanical science has yet j, achieved has just been finished at Mulhouse x for the French navy. It is a two-carriage universal lathe, which is a complete machine j shop in itself, being capable of performing I the most varied operations — such as mortis5 ing, shaping, boring and moulding— with the . most perfect accuracy. It is wonderfully I adapted to the delicate and complicated 5 working of pieces for armour-plating turrets, of helix supports, of rudders, 1 crank shafts, I pistons, &c, for modern war vessels. Its . weight is more than 340 tons, and it is driven by an engine of 25 horse-power. Comparison i of this tool with one of 7G tons, which was a , mechanical marvel some 25 years ago, gives a striking illustration of the almost in- ( credible progress of our generation , — A substance has been prepared by two , German chemists which will be of great , assistance in instantaneous photography. It consists of powdered magnesium, chlorate , of potash, and sulphide of antimony ; when ignited it explodes with a light of such brilliance as to resemble a Hash of lightning. With a sensitive plate and the flash from a penny's worth of this powder a photograph can bo taken in the .darkest spot. Instan. taneoas photography is not only being marvellously doveloped, but very widespread. In Vienna different photographers have taken portraits of rifle and cannon balls in their flight from the weapons, while the Royal Meteorological Society of England has invited photographer amateurs to go in for photograping lightning flashes, — We all know that tillage is promotive of vegetable growth ; but how does it do it 1 That is a question the answer to which is not so well known. Somebody has given a very clear and explicit answer as follows ; Sunshine is the source of oxygen, and the earth the source of hydrogen, and these combined in definite proportions is the source of the waters of the earth. These mentioned elements are the source of vegetation upon the earth from which is derived nitrogen, and nitrogen and oxygen combined in definite proportions form the atmosphere —the vital principle of all life, in whatever form found. But rains falling upon the compound matters forming the crust of the earth, compact and cement them together by percolation through them, and thus render them comparatively impervious to the vitalising atmosphere. In this condition boi.h the matters or the earth containing the elements of plant growth and the fibrous ends of the roots of plants are in a measure sealed up from each other, as a wet blanket smothers a fire by cutting of the supply of air. Now tillage opens up the eaith and allows the air to, penetrate to the roots and the dormant earths in which they repose, when the oxygen of the air leaves its connection with the nitrogen, and finding something to consume, forms carbonic acid, which in turn is decomposed by the vital action of the plant, its carbon appropriated to form plant fibre, and the oxygen again liberated to act and react in a similar manner as long as the ground is kept loose enough to facilitate motion.