SCIENCE NOTES.

Otago Witness, Issue 2055, 13 July 1893, Page 48

SCIENCE NOTES.

— A discovery which promises to be of great importance in the arts has recently been made in connection with the electrodeposition of copper and other, metals. Heretofore these processes have been carried on by immersing the metal intended to receive the deposit in an aqueous solution of a salt of the metal to be deposited. The new process makes use of insoluble salts of the various metals, which are reduced, to fine powder and mechanically mixed with water. The mixture is applied to the surface of the metal by means of a brush, to the handle of which is attached the electric conducting wire, so that the process of deposition resembles that of applying a coat of paint. Not only pure metals, but all sorts pf alloys, are applied as coatings to other metals with the utmost facility by this process. The hull of an iron ship, for example, may be painted over with a tough, adherent, and -impervious coating of metallic copper of any desired thickness. Experiments have been made which indicate that this process may be successfully applied to the plating of aluminum with silver or gold, a desideratum which has long been sought for, but hitherto apparently in vain. — Professor Marshall Ward has lately reported to, the Koyal Society the results of some experiments which tend to prove that the action of sunlight is a far more powerful factor in the purification of the atmosphere than has hitherto been imagined. Among other observations, he has discovered that the Anthrax bacillus is killed by direct sunlight, although it will withstand the greatest extremes of temperature. Sunlight acts in the same way in the purification of water. —Mr Baden-Powell, of the Scots Guards, 1 has devised an ingenious method of ' signaling by night with the aid of a paper fireballoon of 6£t or Bft diameter. When it is desired to send a message, some beads made of a brijliant-, quick-burning composition are strung on a piece of quick-match, leaving intervals, and using large and small beads to make the corresponding fhshes. The balloon is inflated by burning spirit, or even straw or wood. The message strkg is then suspended below it, a time f useattached, and the balloon being sent up, the message is flashed forth. The apparatus is described as very portable ; one man can easily carry it, and with it not only can one preconcsrted message be flashed, but a few w.rJs can be sent up at one time, and those can be answered from a similar balloon from another part, upon which other balloons can be employed to continue the signalling. — Many of the large manufacturing and engineering firms in Germany have adopted the use of a new material for the purpose of preventing rust on machinery. It is said to contain no acid injurious to metal, and does not turn rancid, as is the case with many greases. It is use d specially for the bright surfaces of iron and steel manufactured articles, especially when they are stored. Unlike copal and other varnishes, it never hardens, and can be easily removed with a cloth dampened with turpentine,

— When naturalists or other men of science tell us that a fly or other insect in flight moves its wings about 2000 times a second, it pnzz'es many of us to understand how they have managed to ascertain the number of such minute vibrations so precisely, or indeed to within a hundred or two. As a matter of fact, the motions never have been counted, but are determinable by other means equally to be depended on. When a bee, a gnat, or a cockchafer flies through the air, says Work, they each produce a buzzing sound, with a distinctve musical tone. By turning a toothed wheel round whilst a small piece of thin sheet metal is held against the teeth, a musical sound of any pitch can be made, differing with the rate at which the teeth pass the strip of metal, producing in this way a soundTTaving the same pitch as that produced by the. buzzing. The only

thing further necessary to find the rate of vibration of {the insect's wings is to multiply together the number of turns of the wheel, per second. — A highly ingenious and most serviceable invention is the pneumatic music-turner, an apparatus which can be easily fixed to the ordinary piano; or indeed, any music stand, and is operated upon by the foot. Before commencing a piece, the leaves have to be inserted between pins mounted on neatly adjusted arms, which lie parallel to the wooden ledge at of the stand. When the pedal is pat down the air is compressed and flows through the connecting rubber tube, finally operating upon the arms, , one of which swings from right to left at every pressure of the foot. The leaves are thus turned over apparently automatically, without the lealt noise and with precision and rapidity.

— Apparently, the glories of the Western medicine man are fading from him one by one. First we hear doubts cast* on Harvey's claim of being the discoverer "of the . ' circulation of the blood, and while we are still hesitatirg as to whom belongs the credit; 'Gome's the startlirg fact ' that Jenner's important investigations into the or'gin of cowpox and the wonderful power io possesses when innoculated in the human system of preventing the ravages of smallpox have been anticipated by the' dusky Hindoos many centuries ere the worthy doctor, appeared on the scene. In No. 67 of Notes and .Queries occurs this extract from the ' Lancet from an address delivered by Dr. Pringle :— ',' The smallpox produced from the udder of the cow will be of the same mild nature as the original disease. The peck 'should be of a good colour, filled with a cjear liquid and surrounded by, a circle 1 of . . . There, will 'ha only a slight fever of One, two, or' 1 " three days, but no fear, need be entertained of smallpox so 16bg .as life endures." Dr Pringle quotes this from, an ancient Hindoo - medical work. It is worthy of note, though not generally known,- that innocnlation for smallpox was in vogue in America and Europe long' before x Jonner's day, but the virus used was not obtained from the cow, • but from the sores of a man or woman ' actually suffering from the disease. It has been observed for- many ages that smallpox never attacks the same person twice. It was therefore argued that if a mild attack ' of smallpox could bs induced in a healthy person he would be effectually sa f e-guarded against future attacks, 'however severe, an epidemic might be. According to Dr Mead (1720) this theory .bad been practically ■ recognised by Ihe Circassians for hundreds of years ; indeed, the doctor considers them the inventors of this, -preventive system, although in other respects they were very ignorant of medicine and surgery. It would seem their belief in the operation was fortified by commercial interest, one of the strongest instinctai.of human nature, perhaps. The Circassian women were remarkable for their great beauty which, enhanced their value as slaves, for in such trade they formed a considerable and very profitable article. It was for the purpose of preserving, this valuable quality of a Circassian slave from the 'disastrous effects of smallpox to which they were peculiarly liable that this - prophylactic »ystem of - innooulation was adopted, and Dr Mead claims that their sue- - cess in this direction was extraordinary, a. case of failure but' rarely occurring.

— For some time past certain tramways in the United States have used a locomotive known as' the JConnelly ■ motor, whioti.^B driven by ,the explosive vapour from mineral , oil. This same motor, is now on its trial at , Greenwich (London), and it is repprted to ' be both efficient and economical in its workIng. The" engine, which is fixed on.a.separate car from that carrying the passenger*, has two oylinders' and develops 12-horse power. The oil; id stored in a receptacle, placed above the engine, and there is, an ingenious system of water circulation to keep the cylinders cool and the oil warm. This water, after cooling, the- oylinders, attains a heat of HOdeg Fahr., and is then insed for. warming the oil, after .Which it flows through - a number of tubes, which are exposed to the , atmosphere beneath the. car, and is again pumped up to resume its. alternate duties of ■ cooling the cylinders and warming the oil. J?he explosive vapour is fired by an electric Current generated by a small dynamo? machine, and stored in an This source of electricity also serves to illuminate the car at night: