These extracts have already been enumerated among the others. In preparing them, the juice obtained from the fresh leaves, flowering tops or fruits, of the plant, by pressure, is heated to 130° F. to coagulate the green colouring matter. This is then filtered off and laid aside. The filtrate is next heated to 200° F. so as to coagulate the albumin; this is filtered off and thrown away. The filtrate is then evaporated at a temperature not exceeding 140° to a thin syrup. The colouring matter is then added to it, and the whole evaporated to a proper consistence. In the case of extracts of colchicum and taraxacum there is no chlorophyll to separate, as the juices are obtained by expression from the colchicum corm and the taraxacum root, and not from flowering tops. Consequently the juice is at once heated to the boiling point to coagulate the albumin, and after this has been filtered out the filtrate is evaporated at a temperature of 160° F. In the case of green extracts, the preservation of the green colour is usually regarded as a sign that they are good. It certainly indicates that the first and the last parts of the process have been conducted with care, as too high a temperature destroys the green colour. It is therefore probable that the whole process may have been carefully done; but this is not certain, for the juice may have been exposed to a high temperature, and thus injured during its evaporation after the chlorophyll has been removed and before it has again been added.

The green extracts of the B.P. are (8):-

Extractum Aconiti.

Extractum Colchici Aceticum.

Extractum Lactucae.

" Belladonnae.

" Conii.

" Taraxaci.

" Colchici.

" Hyoscyami.

Glycerina, B.P.; Glycerita, U.S.P. Glycerines. - These are solutions of soothing, astringent, or antiseptic substances in glycerine. Glycerine being thick and adhesive, they form most useful local applications, either to the skin or mucous membranes.

Those in the B.P. containing carbolic, tannic, and gallic acids have one part of the drug by weight to four of glycerine by measure; starch, being very light and bulky, is used in only half this proportion, i.e. one ounce of starch to eight ounces of glycerine. In the U.S.P. the starch is in the proportion of 1 to 9, i.e. 10 per cent. The glyceritum vitelli contains 45 parts fresh yolk of egg to 55 of glycerine.

B.P. (9).

Glycerinum.

"

Acidi Carbolici (1 to 4)

"

" Gallici (1 to 4).

"

" Tannici (1 to 4).

"

Aluminis (1 to 5).

"

Amyli (1 to 8).

"

Boracis (1 to 6).

"

Plumbi Subacetatis.

"

Tragacanthae (3 to 14).

u.s.p. (3).

Glycerinum.

Glyceritum

Amyli (1 in 10).

"

Vitelli (4 1/2 in 10).

Infusa. Infusions. - These are prepared by simply pouring boiling water on the drug, allowing it to stand for some time, and then straining.

There are four exceptions to this rule of using boiling water, viz. calumba, quassia, chiretta, and cusparia. Infusions of calumba and quassia are prepared with cold water. The reason for using cold water in the case of calumba is that the root contains a quantity of starch, which is extracted if hot water be used, and renders the infusion liable to decompose, especially in hot weather.

I have been unable to find any definite reason assigned for using cold water in the preparation of infusion of quassia, excepting that cold water is sufficient to dissolve the active principle.

In the only instance in which I have seen an infusion made with hot water used, it caused vomiting, so that perhaps an infusion made with hot water has a more irritating action than that made with cold.

Infusions of chiretta and cusparia are made with water at 120° F. instead of boiling water, as they are more agreeable when prepared in this way.

The infusions of substances not specified in the U.S.P. are directed by it to be prepared by taking ten parts of the substance in coarse powder and 100 of boiling water. These are to be put into a vessel with a tight cover, and allowed to stand for two hours. The infusion is then strained, and enough water passed through the strainer to make the product weigh 100 parts.

All the infusions both of the B.P. and U.S.P. are strained, with the exception of the infusion of cusso or brayera.

b.p. (28).

Dose

(Of all not specified 1-2 fl. oz.)

Infusum

Anthemidis...............

1- 4 fl. oz.

"

Aurantii..................

"

" Compositum

"

Buchu.......................

1-4 fl. oz.

"

Calumbae.................

"

Caryophylli.............

"

Cascarillae..............

"

Catechu...................

"

Chitratae.................

"

Cinchonas Acidum...

"

Cuspariae.................

"

Cusso (Brayera anthelmintica)

4-8 fl. oz.

"

Digitalis..................

1- 4 fl. dr.

"

Ergotae.................

"

Gentianae Compositum..................

"

Jaborandi.................

"

Krameriae................

"

Lini..........................

"

Lupuli......................

"

Maticae...................

"

Quassiae.................

"

Rhei......................

"

Rosae Acidum........

"

Senegae...................

"

Sennae...................

"

Serpentariae..........

"

Uva Ursi..............

"

Valerianae............

u.s.p. (5).

Dose

Infusum

Brayerae (Cusso)............

10 oz.

"

Cinchonae.......................

2 oz.

"

Digitalis .........................

1/2oz.

"

Pruni Viginianae............

2-3 oz.

"

Sennae Compositum .........

4 fl. oz.

B.P. Injectiones Hypodermics. Hypodermic Injections.-These are strong solutions for subcutaneous injection (p. 475). As the solutions may become decomposed by keeping, they should be freshly prepared; and even the injection of morphine should not be kept long. Any solid particles should be removed by filtration (p. 476). The injections of apomorphine and of ergotin are simply made by dissolving these substances in camphor water and filtering if necessary. The injection of morphine is prepared by dissolving freshly-precipitated morphine in acetic acid and water. It is ten times as strong as the liquor and is rather stronger than the corresponding preparation in the B.P. of 1867, containing 1 grain in 10 minims, instead of 1 grain in 12 minims.

1 This infusion is about twice the strength of the B.P. The dose is usually stated at 1/2 oz. twice a day, but in many cases this dose would probably prove too large, and it is safer to begin with a smaller dose, and gradually push it as the patient will stand it.

B.P.

Dose.

Injectio

Apomorphinae Hypodermica

(2 in 100).................

2-8 min.

"

Ergotini "

(1 to 2)....................

3-10 min.

"

Morphinae "

(l in l0) .................

1-5 min.