SCIENCE, MECHANICAL INVENTIONS, ETC.

New Zealand Herald, Volume XL, Issue 12213, 7 March 1903, Page 4 (Supplement)

SCIENCE, MECHANICAL INVENTIONS, ETC.

COAL WITHOUT SMOKE. To bum bituminous coal without smoke (says the Locomotive) has long been the hope of inventors and engineers, for it is generally admitted that an enormous waste occurs when any considerable amount of fmoke isues from the chimney. It is true that smoke is a sure indication of imperfect combustion, but the vapour ordinarily seen coming from the chimney is not all smoke. The dense, black smokt. sometimes seen consists almost entirely or unconsumed carbon, but the composition of the lighter smoke is very, different. Most coal contains a considerable quantity of moisture,- especially bituminous coal; and this moisture is, of course,-evaporated by the heat- of the lire, and riven off as steam, in company with other products of combustion, giving the light vapour usually seen issuing from the chimneys. Even the densest smoke contains but a small quantity of unconsumed caibon, us measured in pounds, thougji it is likely to contain a considerable quantity of invisible gases that would have been burned and utilised had the combustion been more perfect. The black smoke is usually given off when long flames of a yellowish or reddish hue lap along the whole length of the boiler and perhaps pass into the flues. When the damper is right, and the draught good, and the fires -are well laid, so that all parts of the grate are evenly covered, the lazy, smoky flame is changed to a short flame of intense .brightness. Too much air is as capable of producing smoke as too little; for, by its chilling action it makes perfect combustion impossible, and causes th'e same dense cloud to appear at the stack. ? 'DENTISTRY operations. It is proposed to use currents of electricity of high frequency and high poteniality in place of anaesthetics for operations on the teeth. Tests have been made by MM. L. R. Regnier and H. Didsbury employing a d'Arsonval or Tesla apparatus with Oudin's resonator. One pole is connected to an electrode moulded to fit the tooth, and lined with wet asbestos to counteract any heating effect on the tooth itself. Five minutes suffices to render insensible a tooth with a single fang.- Molar teeth and' those with several fangs require longer. If there is periostitis or inflammation of the root the process is less successful, and further study of these is called for. *... A SUBMARINE.* Lieutenant Spear, a naval constructor, in describing a voyage of 15 miles in Pecomic Bay, U.S., while 18ft under the surface, says that no noise could be heard, but that of the electtric motor driving the " submarine" at a ' speed of seven knots. The captain stood with his head in the conning tower and steered by compass. The air was purer than in many ordinary rooms, and purer than in smoking-rooms. A wall of green water rushing by could be seen,, but objects ten feet away were invisible. A - NEW USE FOR GRANITE.' A new use has been recently discovered for granite. It is an insulator for electrical purposes. The process, which has been investigated by a committee of the Franklin Institute, ' involves the reduction of .granite chips to powder, and the mixing of theproduct with calcined felspar and kaolin so as to make a plastic mixture. THE BRITISH ASSOCIATION IN SOUTH AFRICA. Th 3 meetin & of the British Association in 1905 may be held in South Africa. Before the last meeting of the British Association at Belfast, invitations were sent from the municipalities of Capetown, Kimberley, Buluwayo, and other centres in South Africa, and it is understood that these have been accepted. Scientific papers will be read at various centres in the South African colonies, and visits will-be paid to various places of interest. A sum of £7000 is said to have been collected in South Africa for the entertainment of the association. While in Rhodesia, the members will be the guests of the Chartered Company,, who will place the railways at their disposal. r ' - COLOUR PHOTOGRAPHY ON PAPER. The following particulars of this' newprocess are from a pamphlet just issued by Sanger, Shepherd, and Co. The important new departure consists in dispensing with the • celluloid film as a component part of the, finished print. It was found . that if a gelatine relief, stained with, a suitable dye-stuff is laid in contact with a. damp sheet of paper, coated with a thin film of soft gelatine, the whole of the colouring matter - will in a few minutes leave the hardened gelatine relief and be absorbed by the softer gelatine coating upon the paper. Attempts have been made to use bi-chrd-mated gelatine surfaces to securc colour prints, from negatives in this fashion, but all have failed because of the difficulty of getting the printing, surface to part withthe correct amount of colour required for each print. In the new method, however, all the gelatine constituting the relief is insoluble, and each) particle of gelatine takes up relatively the same amount of the colour-, ing matter, the total amount taken up (the whole of which is subsequently transferred - to the paper) depending entirely on the varying thickness of the relief corresponding to the gradations of the negative. Registration of the three colour impressions is obtained ' accurately and easily, the second print (yellow) being laid down approximately over the first (pink) and squeegeed into contact; yet, owing to the two wet gelatine surfaces being in contact, the celluloid printing plate can be slipped about with ease, and, as the colouring matter does not begin to leave the plate for about a minute, there is ample time to register with/ exactitude. Similarly for the final impression (blue). ,

NON-INFLAMMABLE WOOD. As a result of extensive experiments in Portsmouth Dockyard, the authorities have sported unfavourably on various saraples if non-inflammable wood which it was pi posed should be used in warships. . Only * few cruisers are fitted with this, not to be "used any more. Neithei does light steel furniture nor furiiiture made pa - tially of asbestos and aluminium finj favo • it having developed unsuitable qualities. : the NEW CTNAEDEKS : phenomenal BOATS. A'Barrow correspondent states that. _ news was confirmed that one of the new Cunarders is to be built at Barrow by Messrs. Vickers, Sons, and Maxim, the other going to Swan Hunter, and Co., Newcastle. lUe vessels will be -760 ft long and of 32,000 tons displacement, and in order to ensure that they will steam from port to port at tlie unprecedentedly high speed of 25 knots they are likely to be practically full boxes of machinery the boilers and engines occupying, with the coal bunkers, the whole of the underwater part, excepting for the immense cold air rooms necessary for the carrying of food supplies. They will carry a population far in excess of the" 2000 or 2500 accommodated in the largest existing liners. Each ship will have three screws, driveri by an entirely separate engine capable of developin on the Atlantic 20,000 i.h p., so that the three engines will together be equal to the enormous total ;of > 60,000 h- •' ruple expansion-.system will be adopted, so that altogether there are likely to be 18 cylinders in the main propelling .engines. These will be the first ships fitted with three screws • for the Atlantic service. - As to tne price, a maximum has been fixed—about a million and a-quarter sterling for. each ship, but payment .will be according to the a o ™' ll cost, with a percentage of profit added, lhe time asked for building each ship is. from do to 27 months, with a month } extra for : the series of.trials, so that the new boats should be on their stations in May. or; June of 1905.