Various salts dissolved in water materially raise the boiling-point, and thus afford the means of obtaining a steady temperature at different degrees above 212°. The following are some of the most useful:
Rochelle salts at
Nitro-sulphuric Acid. Dissolve 1 part of nitre in 10 parts of oil of vitriol. Used for disving the silver from plated goods, etc. It dissolves silver at a temperature below 200°, and scarcely acts upon copper, lead, and iron, unless diluted. The silver precipitated from the solution, after moderately diluting it, by common salt, and the chloride reduced as directed, under Silver, to purify and reduce.
See Pocket Formulary. It need only be added here, that its acidity is removed and pre-vented, by rectifying it from neutral tartrate of potash.
Soak the sponges for several days in cold water, renewing the water and squeezing the sponges occasionally. Then wash them in warm water, and place them in cold water to which a little hydrochloric acid has been added. Next day take them out and wash them thoroughly in soft water; then immerse them in aqueous - acid (sp. gr. l.034) for a week. They are afterwards washed in plenty of water, squeezed, and allowed to dry in the air. For burnt, prepared, and waxed sponge, see Spongia, Pocket Formulary.
See Ivory, to Stain;
Stains, to remove. Stains of iodine are removed by rectified spirit. Ink stains by oxalic acid or superoxalate of potash. Iron moulds by the same; but, if obstinate, it has been recommended to moisten them with ink, then remove them in the usual way. See RUST, TO prevent and remove, further back.
See Scouring Drops.
Bed Spots on black cloth, from acids, are removed by spirits of hartshorn, or other solutions of ammonia.
Stains of Marking Ink or Nitrate of Silver, to remove. 1. Wet the stain with fresh solution of chloride of lime, and after 10 or 15 minutes, if the marks have become white, dip the part in solution of ammonia, or of hyposulphite of soda. In a few hours wash with clean water.
2. Stretch the strained linen over a basin of hot water, wet the mark with tincture of iodine.
3. They may also be removed by cyanide of potassium; but this should be done by the druggist, and not intrusted to any one else.
Starch is procured from various roots and seeds. Its varieties are numerous; but a few of the most important only can be noticed here.
The fecula of the tubers of the Maranta arundinacea. The fresh tubers are washed and beaten to a pulp, which is well stirred in a large tub of cold clean water, and the fibrous part wrung out by the hands, and thrown away. The water in which the fecula is suspended is passed through a hair sieve or coarse cloth, allowed to settle, and the water poured off. After being repeatedly washed, the wet starch is drained, and afterwards dried in the sun. [The other varieties of arrowroot (see Dietetic Articles) are prepared by analogous processes from the roots which yield them.]