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Boiler Incrustations

To Detect Copper in Pickles or Green Tea.

Put a few leaves of the tea or some of the pickle, out small, into a phial with 2 or 3 drs. of liquid ammonia, diluted with one-half the quantity of water. Shake the phial; when, if the most minute portion of copper be present, the liquid will assume a fine blue color. Or immerse a polished knifeblade; the copper will deposit upon it. For Iron. nary temperatures. It may therefore be used as a filter for solutions containing strong acids, alkalies, etc. To Determine whether Wheat Flour, or Bread be Adulterated with Chalk.

Mix with the flour to be tried, a little sulphuric acid; if chalk or whiting be present, an effervescence (arising from the discharge of the carbonic acid of the chalk) will take place; but if the flour Another Method.

Infusion of galls gives a bluish black, and ferro- be pure, no effervescence is produced. cyanide of potassium a blue precipitate.

For Manganese.

Sulphydrate of ammonia (made by passing a current of sulphuretted hydrogen gas through solution of ammonia until no more is absorbed), gives a flesh-colored precipitate.

For Mercury.

Protochloride of tin gives a grayish precipitate.

A piece of gold introduced into a solution containing mercury and touched with a piece of iron, has the mercury deposited upon it.

For Lead.

Pour boiling water on some slices of bread, and then pour into the water some sulphuric acid; if there be any chalk in the bread, an effervescence will ensue as before; but if none be in it, no effervescence will take place. To Prepare Soda Water.

Soda water is prepared (from powders) precisely in the same manner as ginger beer, except that, instead of the two powders there mentioned, the two following are used: For one glass, 30 grs. of carbonate of soda; for the other, 25 grs. of tartaric Sulphydrate of ammonia gives a black precipi- (or citric) acid. tate; chromate of potassa and iodide of potassium, yellow.

To make Oxygen.

Heat in a retort, flask, or test tube, finely powdered chlorate of potassa, mixed with about onefourth its weight of black oxide of manganese. The gas must be collected by attaching a tube to the flask, the end of which dips under water; a jar full of water being inverted over the end of the delivering tube.

To make Hydrogen.

Act on zinc scraps with diluted sulphuric acid; say 1 part of acid to 10 of water. A common bottle with a perforated cork fitted with a glass tube or bit of pipe-stem, and another bottle to collect the gas, are all the apparatus required. In collecting the gas, the tube must reach quite to the top of the collecting vessel. Care must be taken that all the air has been driven out of each vessel before a light is applied, or an explosion will ensue.

To make Laughing Gas.

Heat gently in a flask or retort, nitrate of ammonia (made by adding carbonate of ammonia to nitric acid until no more gas comes off). It should be allowed to stand some time over water before being breathed.

To make Carbonic Acid.

Pour muriatic acid upon fragments of chalk or marble. The gas being heavy may be collected without the use of water, by simply allowing the delivery tube to pass to the bottom of the receiving vessel. To make Chlorine.

Heat gently a mixture of muriatic acid and black oxide of manganese. It may be collected like carbonic acid. Care must be taken not to inhale it.

To make Sulphurous Acid.

To 12 oz. of sulphuric acid, in a glass retort, add 2 oz. of sulphur and apply a gentle heat.

This is a cheap and easy process.

To make Sulphuretted Hydrogen.

Pour dilute sulphuric acid on sulphuret of iron.

This is made by applying a roll of sulphur to a bar of iron heated white hot, or by heating in a crucible a mixture of 2 parts, by weight, of ironfilings and 1 of flowers of sulphur. Gun-cotton as a Filter.

To Prepare Ginger-Beer Powders.

Take 2 drs. of fine loaf sugar, 8 grs. of ginger, and 26 grs. of carbonate of potassa, all in fine powder; mix them intimately in a Wedgwood's ware mortar. Take also 27 grs. of citric or tartaric acid (the first is the pleasantest, but the last is the cheapest). The acid is to be kept separate from the mixture. The beer is prepared from the powders thus: Take two tumbler-glasses, each half filled with water; stir up the compound powder in one of them, and the acid powder in another, then mix the two liquors; an effervescence takes place, the beer is prepared and may be drunk off.

The effervescence is occasioned by the discharge of the carbonic acid of the carbonate of potass.

If the beer is allowed to stand for a few minutes it becomes flat; this is owing to its having lost all its carbonic acid. The cost of these powders is 20 cents a dozen sets.

To Determine whether Water be Hard or Soft.

To ascertain whether or not water be fit for domestic purposes, to a glassful of the water add a few drops of the solution of soap in alcohol. If the water be pure, it will continue limpid; if hard, white flakes will be formed.

To Preserve Phosphorus.

Keep it in places where neither light nor heat has access. It is obtained from druggists in rolls; these are put into a phial filled with cold water, which has been boiled to expel air from it, and the phial is enclosed in an opaque case.

Expeditious Method of Tinning.

Plates or vessels of brass or copper are rapidly and firmly coated with tin by boiling them with a solution of stannate of potassa, mixed with trimmings of tin, or by boiling them with tin-filings and caustic, potash or cream of tartar.