Salicylic Acid

Originally procured from the volatile oils of SpirAea ulmaria and Gaultheria procumbens, but now obtained artificially from carbolate of soda by the action of carbonic acid on the former, at an elevated temperature. (See Pocket Formulary.) Kolbe, Kiersch, and Godefroy, have made experiments with this acid, from which it would appear that it possesses disinfecting, and considerable antiseptic properties.

Sulphurous Acid

For the mode of obtaining an aqueous solution of this acid, see Acidum Sulphurosum, Pocket Formulary. The following are cheaper methods of obtaining it for bleaching purposes, etc. Berthier directs a mixture of 100 parts black oxide of manganese, and 12 or 14 of sulphur, to be heated in a glass retort, and the gas received into water kept very cold. Mr. Redwood directs 1/2 oz. of powdered charcoal to be acted on by 4 fluid oz. of oil of vitriol. Treacle is sometimes used instead of charcoal; as also is linseed oil.

Tannic Acid

Tannin. See Acidum Tannicum, Pocket Formulary.

Acidimetry

Acids generally are estimated by the quantity of alkalies or carbonated alkalies required to neutralize them. Weigh 100 grs. of the acid and dilute it with a few times its weight in water. Then add sufficient dry or crystallized carbonate of soda, or carbonate of potash, to exactly neutralize the acid. The alkalimeter tube may be used for the solution of the alkali. By a reference to the table of chemical equivalents, the quantity of real acid of any kind represented by the quantity of alkali required to neutralize it, may be estimated. Consult the larger manuals.

Acidulated Kali

See Beverages.

Albuminous Size

Beat up the white of an egg with twice its bulk of cold water, until well incorporated. Used as a varnish for leather binding and kid gloves; also to size drawing paper.

Alcohol

There is, perhaps, no better method of obtaining absolute alcohol than that of the Edinburgh Pharmacopoeia. See Alcohol, Pocket Formulary.

Brass

Mostly made of copper and zinc, the proportions varying acccording to the required colour and the purpose for which it is intended.

Bronze

1. For medals and small castings: Copper 95, tin 4.

2. Copper 89, tin 8, zinc 3.

3. Ancient. Copper 100, tin 7, lead 7.

4. Kelly's. Copper 91, zinc 6, tin 2, lead 1.

5. For gilding. Copper 14, zinc 6, tin 4.

6. Bell-metal. Copper 78, tin 22.

German Silver

1. Copper 40 1/2, nickel 31 1/2, zinc 25 1/2, iron 2 1/2.

2. Pure copper 55, nickel 23, zinc 17, iron 3, tin 2.

Factitious Gold

Platina 7, copper 16, zinc 1; fuse together. See AURUM Mfsivum.

Common Gold

Copper 16, silver 1, gold 2.

Or-molu

Copper 45 to 48, zinc 52 to 55.

White Brass

Porel. Melt zinc with 10 per cent. each of copper and iron. This alloy has the fracture and appearance of zinc, but is tougher than cast iron. It does not rust, nor adhere to metal moulds.

Solders

1. For Gold: Pure gold 12 parts, silver 2, copper 4.

2. Soft Solder. Tin 2 parts, lead 1. For brass: Brass 2 parts, zinc 1.