The little gold mine. Conklin's handy manual of the mechanical arts and house plans .. by Conklin

Author:Conklin, [George W.] [from old catalog]
Language: eng
Format: epub, pdf
Tags: Industrial arts, Workshop recipes, Architectural drawing
Publisher: Chicago, Laird & Lee
Published: 1889-03-25T05:00:00+00:00

powder will fall through it and collect beneath the liquid alcohol below unconsumed. This, however, is a scientific trick, and the experiment hardly justifies the sweeping assertion that iron is more combustible than gunpowder. The ignition of the iron under the foregoing circumstances is due to the fact that the metal particles, being admirable conductors of heat, are able to absorb sufficient heat in their passage through the flame — brief as this is — and they are consequently raised to the ignition point. The particles of the gunpowder, however, are very poor conductors of heat, comparatively speaking, and, during the exceedingly brief time consumed in their passage through the flame, they do not become heated appreciably, or certainly not to their point of ignition. Under ordinary circumstances, gunpowder is vastly more inflammable than iron.

Another method of exhibiting the combustibility of iron, which would appear to justify the assertion that it is really more combustible than gunpowder, is the following: Place in a refractory tube of Bohemian glass a quantity of dry, freshly-precipitated ferric exide. Heat tliis oxide to bright redness, and pass a current of hydrogen through the tube. The hydrogen wnll deprive the oxide of its oxygen, and reduce the mass to the metallic state. If, when the reduction appears to be finished, the tube is removed from the flame, and its contents permitted to fall out into the air, it will take fire spontaneously and burn to oxide again. This experiment indicates that pure iron, in a state of the ex-tremest subdivision, is one of the most combustible substances knowTi — more so, even, than gunpowder and other explosive substances which require the application of considerable heat, or a spark, to ignite them.

HOW IRON BREAKS.

Hundreds of existing railway bridges which carry twenty trains a day with perfect safety would break dovni quickly with under twenty trains an hour, writes a British civil engineer. This fact was forced on my attention nearly twenty years ago, by the fracture of a number of iron girders of ordinary strength under a five-minute train service. Similarly, when in New York last year, I noticed, in the case of some hundreds of girders on the elevated railway, that the alternate thrust and pull on the central diagonals from trains passing every two or three minutes had developed a weakness which necessitated the bars being replaced by stronger ones, after a very short service. Somewhat the same thing

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