SCIENTIFIC AND USEFUL.

New Zealand Graphic, Volume VIII, Issue 26, 27 June 1891, Page 102

SCIENTIFIC AND USEFUL.

NEW MODE OF HEALING. Dr. Foveau de Courmelles of Paris alleges that he has succeeded in conveying by the electric currant to diseased internal organs of the human body the constituents of medicaments suitable for their recovery. METAL POLISHING. Small articles made of malleable iron are now finished and polished bright by being placed in revolving drums with curriers’ shavings, from which they emerge with all of the rough edges smoothed and the surface highly polished. A SUBSTITUTE FOR GUTTA PERCHA is reported from Goa. If this is true, it will be good news for the electric telegraph companies. It is the solidified fluid which issues fro m the nivol-cantern, which grows wild in tbeConcan district, an d is generally planted for hedges. Senhor da Costa st a t e s that it is insoluble in water, it softens under heat anj hardens in the cold. It receives moreover, and retains, a given, molded shape, can be cast into very thin sheets, all j is capable of taking the minutest impressions on its sarf ace> Though white when it flows from the tree, in its dri ec [ state it is of a chocolate colour closely resembling gutta-percha. OF INTEREST TO CYCLISTS. What is called a ‘ spokeless ’ cycle-wheel has been devised by Mr G. W. Douglas, of Moor View, Newcastle-on-Tyne. He uses two discs of very thin steel, fastened by rivets to the rim of the wheel, and mounted on an axle having a right and a left-hand thread cut on the part passing through the centre of the discs, or, rather, through the hubs to which the discs are riveted. By turning the axle, the hubs can be forced apart, and tension put upon the discs, so much that it will be impossible for the wheel to become untrue, while the air resistance, compared to a wheel with many spokes, will be reduced to a minimum. How this device, remarks the English Mechanic, will work out in practice remains to be seen, but a patent has been applied for. POISONS. The most familiar poison is, probably, morphia, or some similar narcotic. Prussic acid is the most rapidly fatal of all poisons in its action. Chemical tests can now be applied to detect with great certainty poison in food or water, and in the body after death. If scientific examinations and judicial inquests be possible almost any poison can be detected after death, either by the lesions produced in the organs effected, or by the extraction from the corpse of the victim of the poison itself, and by a study of the properties. As for poisoning being a lost art possessed in a higher degree of perfection by the Borgias and others, that belief is a fancy. The people of any other age could have taught us nothing new in that regard. The poisons of the Borgias would not now be considered beyond detection, or, in fact, at all difficult. ENLARGEMENT OF PHOTOGRAPHS. Mr Guttenberg, of Oxford-street, Manchester, has, according to the Mechanical World, just patented an interesting process for producing enlargements of photographs on a mirror background. A particularly striking effect is produced in this way, and it is increased if, as in the example we have seen, the photograph is skilfully painted after it has been transferred to the mirror. In this process the picture is cut out and laid face downwards on the mirror in order that the outline may be marked. The space the picture will occupy on the mirror is then filled in with paint. When this is dry the picture, moistened with water, is transferred to the painted surface of the mirror. The transfer paper, now uppermost, is stripped oft’, leaving the film (which is the picture) adhering to the painted surface. When dry the picture is ready for the final touches, and may be manipulated either in oils or water colours. LIGHT WITHOUT FIRE. To obtain a light instantly, without the use of matches and without the danger of setting things on fire is, according to the Mining and Scientific Press, an easy matter. Take a long vial of the clear est glass, put into it a piece of phosphurus about the size of a pea. Upon this pour some pure olive oil heated to the boiling point, the bottle to be filled one-third full; then cork tightly. To use the light remove the cork, allow the air to enter and then recork. The whole empty space in the bottle will become luminous and the light obtained will be a good one. As soon as the light becomes dim its power can be increased by opening the bottle and allowing a fresh supply of air to enter. In very cold weather it is sometimes necessary to heat the vial between the hands to increase the fluidity of the oil, and one bottle will last all winter. This ingenious contrivance may be carried in the pocket, and is used by watchmen of Pans in all magazines where explosives or inflammable materials are stored. PHOTO-ELECTRIC THIEF DETECTOR. Mr William H. Harbeck, of Toledo, Ohio, says the Chicago Journal of Commerce, patented a device by which an instantaneous photograph of an incoming burgular can be made by the Hash light camera that has been previously set and properly focussed towards the door. The essential features are a camera, using dry plate, and a flash light device, in which is provided mechanism to strike a match that ignites the flash powder, by which means the burglar is strongly displayed, and simultaneously with the flash the pivotted spring shutter is moved to cause an instant exposure on the sensitive plate, and the work is done. As the burglar opens the door he steps on a prepared mat or any other device, whereby electrical connections are made, and if he should be alarmed at the blinding flash and beat a hasty retreat, it would be too late, as his image would remain in the camera, positive and indisputable evidence of his visit personally, and his picture would be in the most natural shape, devoid of the * company smile’ or artificial pose.