Preservative Fluids

Canada Balsam, spirit and water glycerin, solution of gelatin, saturated solutions of alum, chloride of zinc, and chloride of calcium, are all used to preserve microscopic objects. The following formulae will be found useful:

1. Goadby's Solution. Bay salt 4 oz., alum 2 oz., corrosive sublimate 4 grs., boiling water 4 pints: mix and filter. It may often be more diluted.

2. Thwaites' Fluid. Mix spirit of wine 1 oz., with creasote sufficient to saturate it; rub up with chalk to form a thin paste, and mix gradually with water 16 oz. To this may be added an equal quantity of water saturated with camphor.

3. Simple Creasote Solution. Dissolve creasote 1 dr. in pyroligneous acid 1 dr., and mix gradually with cold water 1 pint.

4. Passini's Solution. For Hood-globules, nerves, and white tissues generally. Chloride of mercury 1 part, chloride of sodium 2 parts, glycerin 13 parts, distilled water 113 parts.

Condensed Milk

Cow's milk evaporated down in vacuo, and containing about one third its weight of sugar, when it is intended to be kept for any time. If required for early use, it contains no sugar.

Glycerine Jelly for Microscopic Mounting

Soak any quantity of good clear gelatine in cold water for three or four hours. Pour off the superfluous water, and melt the gelatine at a gentle heat; when melted, filter through flannel, and to the filtrate add an equal quantity of Price's glycerine. The above forms a good firm jelly, requiring little trouble in securing the cover. - Ed. Pharm. Journ.

Preserved (Bethel's Patent) Milk

The milk or cream is first scalded, and when cold, strongly charged with carbonic acid gas, by means of a soda-water machine. [Attempts have also been made to preserve milk by evaporating it to dryness; but it is necessary to remove the cream in order to effect it.]

Chameleon Mineral

See Chameleon Mineral.

Clay for Modelling

Knead up clay to the proper consistence with glycerine. - Barreswil.

Moirre Metallique

A method for ornamenting the surface of tin plate by acids. The plates are washed with an alkaline solution, then in water, heated, and sponged or sprinkled with the acid solution. The appearance varies with the degree of heat and the nature and strength of the acids employed. The plates, after the application of the acids, are plunged into water slightly acidulated, dried, and covered with white or coloured varnishes. The following are some of the acid mixtures used: - Nitro-hydro-chloric acid, in different degrees of dilution; sulphuric acid, with 5 parts of water; 1 part of sulphuric acid, 2 of hydrochloric acid, and 8 of water; a strong solution of citric acid; 1 part nitric acid, 2 sulphuric, and 18 of water. Solution of potash is also used.

Mordants

See Dyes, further back.

Multum

A name given to a compound of liqorice and quassia, improperly sold by druggists to brewers.

Nitrate of Bartya

This may be made from the carbonate by dissolving it in dilute nitric acid, evaporating, and crystallizing; but more cheaply from the sulphate of baryta, by converting it into a soluble sulphide by heating it with charcoal, and decomposing the filtered solution with nitric acid. M. Weiss recommends mixing the pulverized sulphate of baryta (" cawk or heavy spar") with one eighth of charcoal and one fourth of flour, heating it in a covered crucible, pulverizing the product and forming it into balls, with one eighth of charcoal and a little water, and again heating them placed between layers of charcoal. Hot water extracts the sulphide, which crystallizes from the filtered solution. By decomposing this by nitric acid (avoiding the gas which escapes) the nitrate is obtained. The other salts of baryta are obtained in a similar manner.