A lever stuck between the spokes of the fly-wheel of an engine for the purpose of starting it, is a very dangerous instrument, it is liable to get caught and do a great amount of damage. If a lever is to be used, be sure that the steam is first turned off.
A cubic inch of water evaporated under ordinary atmospheric pressure is converted into one cubic foot of steam (approximately).
Steam at atmospheric pressure flows into a vacuum at the rate of about 1550 feet per second, and into the atmosphere at the rate of 650 feet per second.
Condensing engines require from 20 to 30 gallons of water to condense the steam represented by every gallon of water evaporated—approximately; for most engines we say from 1 to 1½ gallons per minute per indicated horse-power. Jet condensers do not require quite as much water for condensing as surface condensers. Surface condensers require about 2 square feet of tube (cooling) surface per horse-power of steam engine.
The best designed boilers well set, with good draught and skillful firing, will evaporate from 7 to 10 lbs. of water per pound of first-class coal. The average result is from 25 to 60 per cent. below this.
When you have your boiler furnace to repair, and cannot get fire clay, take common earth mixed with water, in which you have dissolved a little salt; use same as fire clay, and your furnace will last fully as long.
To make iron take bright polish like steel, pulverize and dissolve the following articles in one quart of hot water: Blue vitriol 1 oz., borax 1 oz., prussiate of potash 1 oz., charcoal 1 oz., salt 7½ pt.; then add one gallon of linseed oil, mix well, bring your iron or steel to the proper heat, and cool in the solution.
To write inscriptions on metal, take 4 oz. of nitric acid and 1 oz. of muriatic acid, mix and shake well together, then cover your metal surface to be engraved, with bees-wax or soap, write your inscription plainly in the wax clear to the metal, then apply the mixed acids, carefully filling each letter. Let it remain from three to five minutes according to appearance desired, then throw on water, which stops the etching process, scrape off the bees-wax or soap, and the inscription is complete.
To remove rust from steel.—Brush the rusted steel with a paste composed of ½ oz. cyanide potassium, ½ oz. castile soap, 1 oz. whiting, and enough water to make a paste; then wash the steel in a solution of ½ oz. cyanide potassium and 2 oz. of water.
A solvent for rust.—It is often very difficult, and sometimes impossible, to remove rust from articles made of iron. Those which are most thickly coated are most easily cleaned by being immersed in, or saturated with, a solution of chloride of tin. The length of time they should remain in this bath is determined by the thickness of the rust, generally twelve to twenty-four hours is long enough. The solution ought not to contain a great excess of acid if the iron itself be not attacked. On taking them from the bath, the articles are rinsed first in water, then in ammonia, and quickly dried. The iron when thus treated has the appearance of dull silver; a simple polishing gives it its normal appearance.