EFFECT OF TIME ON IRON.

Otago Witness, Issue 1240, 4 September 1875, Page 3

EFFECT OF TIME ON IRON.

Razors which have lost their keenness and their temper, recover, like mankind, when given time and opportunity to recuperate. A spring regains its tonsion when allowed to rust.- Farmers leave their scythes exposed to the weather sometimes from one season to another, and find their quality improved by it. Boiler makers frequently search old boilers carefully, when re-opened for repairs after a long period of service, to find any tools that may have been loft in them when last repaired, and if any are found, they are almost iuvariably of unusually good quality. The writer when a boy in the shop, frequently, if denied the use of their tools by the workmen, looked about the scrap heap, and tinder the windows, for tools purposely or carelessly dropped by tho men 5 and whenever one was found badly rusted by loin; exposure it proved to be of the best of steel. One of the most striking illustrations of this improvement of the quality of wrought iron with time has recently come to the knowledge of the writer. The first wrought iron T rails ever made were designed by Robert L. Stevens, about the year 1830, and were soon afterwards laid clown on the Camden and Ambo'y Railroad. These were Welsh rails, and when put down were considered, and actually were, brittle and poor iron. Many years later, these were replaced by new rails, but until quite recently some still reemained on the sidings. When a lot of unusually good iron was required, some of these rails were taken up, and re-rolled into bar iron. The long period of exposure had so greatly changed the character of the metal that the effect was unmistakable.

Curious Fact. —Friction impedes the progress of the railway train, and yet it is only through friction that it makes any progress. This apparent paradox is explained when we remember that, by reason of the frictioual bite of the drivers upon the track, they draw the train. The bearings of the wheels upon the rails aro a mere line where they come in contact, iron and iron, yet this slight and almost imperceptible hold is sufficient to move hundreds of tons of dead weight with the speed of the wind.

Calculating Horse - power. The rules, ordinarily found in works on the steam-engine, for calculating the horsepower of an engine, give results that rarely accord with those obtained in practice. Indeed, it is impossible to lay down rules that will apply to aJI cases, the construction and performance of different engines being so varied. Welding — A good welding composition 18 made of borax fused with one sixteenth of its weight of sal ammoniac, cooled, pulverised, and combined with an equal weight of quicklime. The compound is sprinkled on the red-hot iron, and the latter replaced in the fire. Sciiap Leather.— The scrap leather patent and enamel, from the carriagetrimming shop, which many burn or throw into the garbage box, command a good price in all large cities, and are eagerly sought for by the makers tf Q hjl,

Sorap steel, such as broken files, broken springs, old steel tires, and the cutting of steel tires, bring a much higher price in the market than scrap iron does. Ikon brakes are much cheaper, are strouger, and look much better when furnished with a neat scroll finish of wood than wooded ones plated with iron. Leaky Tubs.— Tho Scientific Amoric-in says :— -Tubs and pails saturated with glycerine will not shrink and dry up, the hoops will not fall oft", ;md there will be no necessity for keeping these articles soaked. Dry Rot.— lt is said that dry rot in' cellar timbers can be prevented by coating the wood with whitewash to which has been added enou.trb copperas to give the mixture a pale ye 1 >w hue. _To out «LAs.s to any shape without a diamond, hold it quite level under water, and, with a pair of strong scissora, clip it away by small liitd from the edges. Carriage Wheels. — Experience has shown that the larger the wheels, the less amount of draught is required. This is admitted by all without exception. A putty of starch and chloride of zinc hardens quickly, and lasts, a3 a stopper of holes in metals, for months. Restoring Polish. — The lustre of morocco leather is restored by varnishinowith white of egg. °