Solid extracts are seldom prescribed in mixture in this country, but they are on the Continent, and the following hints by the late Dr. Hager will be useful to the English dispenser.

When alcoholic extracts have to be dissolved in a mixture, the vehicle in which they are rubbed down into solution should not be hot.

If purely resinous extracts have to be compounded in a mixture, they should first be rubbed in a mortar with twice or three times their weight of powdered gum arabic, then combined with the vehicle perfectly cold. If any syrup is ordered in the mixture, the resinous extract should be rubbed down with it. Example:

M. et solve.

The extract should be first rubbed with powdered gum arabic 1.5, and with the chloride of ammonium, then with the liquorice extract in concentrated solution, and, lastly, with the cold water.

Extracts made with water and alcohol are difficult to mix with a purely spirituous solution. Example :

Misce.

In this prescription, the spirit of ether being only an adjuvant, a slight modification must be made. The extract must be dissolved in 2 parts of distilled water, then the tincture of valerian and 18 (instead of 20) parts of spirit of ether added. In the case where the fluid with which the extract is to be mixed is itself a strong medicine (tinct. digitalis aeth., for example) nothing remains but to rub it with its own weight of water, and then rub the quasi-solution vigorously with the tincture.

Inspissated Juices are similarly treated; but, when dissolved in water, they should stand in a measure for two or three minutes to settle, and the fluid should then be poured off carefully from the sediment.

The narcotic non-resinous extracts can be kept in concentrated solutions. Ten parts of extract should be dissolved in a mixture of 12 parts of water, 4 parts of glycerin, and 4 parts of rectified spirit. When dispensing from these solutions, three times the quantity of extract ordered must be weighed. The label should indicate this exactly. Some extracts, such as aconite, henbane, and belladonna, kept in solution, require to be well shaken before the solutions are weighed. [In Germany liquids are weighed.]

Lactucarium ought to be rubbed down in a mortar with twice its weight of sugar and a few drops of spirit of wine.

Liquorice Extract

'Solazzi'can be kept in solution in its own weight of distilled water, or in a mixture of 3 parts of distilled water and 1 part of glycerin, in 8-oz. bottles quite full, but ext. glycyrrh. liq. is the only preparation to use in prescriptions. Some acids and many salts of alkaloids can only be mixed with solution of liquorice in a very diluted condition, as they precipitate the glycyrrhizin. This is due in some measure to 'salting-out'of glycyrrhizin, but liquorice extract is acid, and the ammoniated preparation gives clear mixtures in many cases.

The brownish precipitate in a is cleared up by the addition of a few drops of ammonia solution. There is liquorice in aromatic cascara, but the ammonia expedient cannot be adopted for b, which has a heavy precipitate of glycyrrhizin. The addition can be made to neutral mixtures with advantage.