NOTES ON SCIENCE, MECHANICAL INVENTIONS, ETC.

New Zealand Herald, Volume XXXIV, Issue 10575, 16 October 1897, Page 4 (Supplement)

NOTES ON SCIENCE, MECHANICAL INVENTIONS, ETC.

SALICYLIC ACID IH FOOD. It is well known to-day that salicylic acid is a powerful antiseptic. As each it retards the action of organised ferment* like the yeast plant and putrefactive bacteria. It hinders and prevents fermentation, the soaring of milk, and the putrefaction of milk. Its action upon unorganised ferments ia even more powerful It completely arrests the conversion of starch into grape sugar by disease and pancreatic extracts. This action is directly opposed to the pro*, cess of digestion, and, were there no other reason, the use of salicylic acid should be universally condemned. These facts in connection with salicylic acid have been recognised very thoroughly in legislation. The use of the acid has been condemned by most of the European countries having pure food laws. In France it is forbidden by law. In Austria, Italy, and Spain it cannot be used without the danger of incurring a heavy penalty, and all South American States having pure food laws have absolutely forbidden its sale. The laws of many of the States forbid its use. By a decision of Mr. Wells, the Dairy and Food Commissioner, the use of salicylic acid in food is prohibited in Pennsylvania. I wish to call attention here to another fact in connection with the use of salicylic acid which is of extreme importance, viz., the sale of preservalines, preservatives, etc., under various high-sounding names, intended for use in private families. A number of these, claimed to be perfectly harmless, are on the market, but actually contain salicylic acid as the main ingredient. The conscientious and careful housekeeper should put an absolute veto upon the use of any such compound. There is rarely any need for them, since, when pure fruits and vegetables are used and the proper directions for sterilising by heat, etc., are carried out, canned or preserved goods of all descriptions can be prepared that will remain in good condition for years without the aid of any preservative.— Sanitarian. ',',' NOVEL KLKOTKIO LIGHTING SYSTEM. Sboreditcb has just inaugurated an electric lighting system of a novel kind. The steam for the engines to drive the dynamos is being. generated by the burning, in specially-constructed furnaces, of the dust and refuse of the parish, which formerly cost the local authority » considerable sum to eel rid of. Current will be supplied to the public at a very low rate—6(l a unit for the first two hours and 4d afterwards, while during the day the price will only be 2d. It is expected that, at this low price, electric motors will largely take the place of gas engines for driving machinery. Lord Kelvin inaugurated the undertaking. The works, which are expected to cost £200,000, will include baths and washhouses, and provision is made on an adjoining site for a recreation ground and technical institute and museum. LOSS OF POWKK. Professor Benjamin, of Cleveland, has lately been making some experiments with a view to find out how much power is wasted in factories from the friction arising from the employment of belts and shafting. In all large faotories, the machines of which are driven from one source of power—a ■team engine— power must he transmitted from shop to shop by means of shafting and belts; and in 16 such factories Professor Benjamin's tests were,applied with somewhat startling results. At a' bridge material factory, where the various shops were spread over considerable space, no less than 80 per cent, of the engine's power disappeared amid the shafting. At a planing mill the loss was 73 per cent,, and at a sewing machine factory 70 per cent. The average loss for heavy machine shops was a trifle over 62 per cent., and for factories where lighter work was done about 55 per cent. It nay be noted that in places where electricity is employed for motive power, as it can be with great advantage where there is a source of energy available —such as a waterfall— loss by shafting or belting is incurred, from the circumstance that the necessary communication between one department of a factory and another is by wire cables. AN ELECTRICAL CAB. The electrical cab lias arrived in London, and in the opinion of many experts has come to stay. These are certainly among the most elegant of the horseless carriages, hitherto introduced. They are tastefully' upholstered, lighted with electricity, rubber tired, and furnished with 10 much glass that riders have a good view from the interior. The electrio current is supplied from accumulators placed immediately underneath the vehicle, and so arranged that they can be detached and replaced in a few minutes. The cost of running is estimated at 2s for 60 miles, and if the estimate should prove even approximately correct this means of traction will show a considerable commercial advantage over horse power. The steering and driving of the cab are quite simple, and require no skilled knowledge. The managing director states that out of 15 hansom cab drivora who were tried it was found that 12 were, in two days, quite capable of guiding the vehicle in any traffic. The brake power is such that the driver has the vehicle under more immediate control than is the case with any horse-drawn carriage. COLOUR EFFECTS IN HOUSE DECORATION. Theeffect of colourdependsonits situation, the light in which it is seen, and the colours associated with it. In a dimly lighted room, strong pure colours may be used, but the same colours would look bad in a strong light; a medium light is best for colour. Surface reflection also has a considerable effect upon colour results, a polished or varnished surface differing greatly from a reticulated surface. A number of contrasts must also be considered. There is contrast of tone, the gradations of a colour towards white and towards black; contrasts of hue, the gradations of one colour towards another colour—say from red to yellow, or red to blue, or blue to yellow; contrasts of texture, where various shades or colours are shown, according to the light that falls on it. For instance, an orange-coloured silk will look yellow in the high lights and brown in the folds; a blue will be violet in the shades, and a green will look blue in the lights; a crimson silk will be scarlet'in the lights, and almost a black in the shadows. Gold appears black or invisible in parts, according to the light in which it is seen. For this reason, gold is generally outlined with black or dark brown. By artificial light, green appears blue; crimson, purple; purple, violet; yellow, white; dark purple, black. All colours show a different effect when on different planes, and tones of colour obtain their value from their situation, as well as from their contrast with each other, It is advisable, therefore, to try all colours in the positions they are intended to occupy, and in the light in which they are to be seen. Colours which are incongruous when seen side by side or over-, lapping, give satisfactory results when separated by a line of white, black, or gold, according to circumstances. These three colours compensate for strong colouring ; being themselves neutral, their presence helps to give the necessary neutralisation.

, VARIETIES OF STONE USED FOB PAVING. . The stones and for street) pavements may be roughly classed in two divisions— granites and gritstone*. Granites and syenites, which are very simitar in their properties to granites, have the merit of being very bard and durable, and are almost universally adopted for pavements where the traffic ia very heavy. They have, however, the disadvantage of wearing to a smooth polish and becoming very slippery, as well as forming a very noisy pavement. The latter reason has led to them being replaced in some important thoroughfares by wood, which is comparatively noiseless,' bub; much more costly, especially in maintenance. It is questionable whether in the near future efforts will not be made to obviate the noise of traffic rather by improv< I ing the tyres of the vehicles, than by doing i away with the stone pavement. --•■.'•' A NEW METHOD FOR DISCOVERING FORGERY. This new method has been devised by Professor, M. Broylaats,. Professor is Chemistry in the University of Loavainji The portion of a document which 1 is so* pected of having been altered is ' first moistened, and then, after being dried, ii exposed to the action of vapour of iodide! The, portion; tons moistened, if it has bees altered, assumes a' violet tint, while the other portion appears a brownish yellow. This action ie evidently due to the removal of a portion of the starch contained in the size of the paper.' The same process wil even reveal toe.existence of pencil marks er'ajfd by robbing, " '- ■■•" , ; ;'- r„" ; r > x <> }', ■