Strength Of Chain

To ascertain the strength of short-linked chains: (1) Multiply the square of the diameter (reckoned in six-teenths of an inch) by .035; the product will be the weight the chain will support in tons. (2) The square of the diameter in eighths of an inch weight of chain in Lbs. per fathom. The square of the diameter in eighths + 2= breaking weight In tons. Thus for a chain made of 3/8 iron, the weight = 32 = 9 lbs. per fathom, and its breaking weight would be 32/2 = 4-1/2 tons. The ut most load put upon it should not exceed 1-1/2 tons, the safe constant load being 18 to 20 cwt.

Coating Copper And Brass With Zinc

Dip the articles into a boiling concentrated solution of sal-ammoniac containing finely-divided zinc.

Copper-Welding

A good welding mixture is composed of phosphate of soda 358 parts, boracic acid 124 parts.

How To Bronze Gun- Barrels

Clean thoroughly, and apply (by means of a rag) nitric or sulphuric acid diluted with its volume of water.

Hardening Pickle

Spring-water made into a brine strong enough to float an egg, then boiled to precipitate the lime, and allowed to cool.

Brightening Iron Articles

When taken from the forge or rolls, the articles are placed in dilute sulphuric acid (1 to 20) for an hour; they are then washed clean in water, dried with sawdust, dipped for a second or so in nitrous acid, washed and dried as before, and finally rubbed clean.

Welding Iron Rings Without Scaling

Take iron filings 1000 parts, borax 500 parts, resinous oil of any kind 50 parts, sal-ammoniac 75 parts. Pulverize completely and mix; heat the rings to a cherry red, powder the parts with the mixture, and join them together.

Simple Fire-Plating For Iron

By rubbing the surface of iron or other metals with soda amalgam, and then pouring over it a concentrated solution of chloride of gold, the gold is taken up by the amalgamated surface, and it is only necessary to drive off the mercury with the heat of a large lamp to obtain a fine gilded surface that will bear polishing. By writing or drawing a design on the iron, the drawing will be re-produced in pure gold. Silver and platinum salts are said to act in a similar manner to the gold.

How To Gild Cast Iron

The cheapest way is to use bronze or mosaic gold. The castings are first to be heated hotter than the hand can bear, but not so hot as to burn the varnish, and coated with mosaic gold mixed with a small quantity of alcohol varnish. If the iron is polished, it must be heated previously and rubbed over with a rag dipped in vinegar.

Determining Presence Of Lead In Tin Vessels

The metal to be tested is first touched with nitric acid and then heated, when the acid evaporates. If lead be contained, stannic acid and nitrate of lead remain. Iodide of potassium is then applied, forming yellow iodide of lead; while the stannic acid is white. The yellow stain, therefore, indicates lead, the white, tin. .