Elements of pharmacy, materia medica, and therapeutics. / By William Whitla.
- William Whitla
- Date:
- 1882
Licence: Public Domain Mark
Credit: Elements of pharmacy, materia medica, and therapeutics. / By William Whitla. Source: Wellcome Collection.
Provider: This material has been provided by The University of Leeds Library. The original may be consulted at The University of Leeds Library.
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![in-evcntiug the bottle being tilled or corked. A few drops of spirit cause this to rapidly disappear, and it is a good plan, if there be any spirituous liquid in the prescription, to keep a little of this to the last for this purpose. All mixtures with any deposit .should have a label directing the bottle to be shaken before pouring out, and in all ca.scs where the dis- penser is in doubt about a mixture depositing a .sediment he should err on the safe side, and put on a '■ shake the bottle label before sending it to the patient.* The next cla.ss of mixtures includes emulsions. They require more care and skill in their preparation and prescribing than most other extemporaneous comjiounds. An emulsion is a watery mixture resembling milk in appearance, containing an oil or resin in suspension, and not capable of easy or ready separation. The suspension of the oil or resin is effected tlu'ough the agency of several substances, as gum, soap, alkali, or yolk of egg. Several substances when rubbed up with water in a mortar make perfect emulsions, the gum-resins ammoniacum, myrrh, and assafoetida behave in this way. The milky mixtures thus prepared are called natural emulsions, and the exjilanation of the phenomenon is simple; each substance contains in addition to its resin as much gum as will suspend it when wfiter is added. If the pharmacist ^vishes then to make an emulsion with a resin, he imitates this natural preparation by adding gum acacia, or tragacanth, such is the official mixture of guaiacum, in which the resin is ordered to be trituiated with a little sugar and gum, adding gradually the cinnamon water. Oils are emulsified either by rubbing with gum or by adding an alkali (which makes a sort of soap with the oil), or by both gum and alkali, which is the most common method. Copaiba is made into an emulsion in a similar manner. Volatile oils require to be mixed with some fixed oil before being made into an emulsion, or they may be rubbed up with yolk of egg. The powered gum aiid water, or mucilage, should be measured into a mortar, and the oil gradually added, with continual light » It is tlie custom to direct all inixtiircs containing i)riis.sic acid to bo shaken before nsc. This has arisen from a niistalicn notion tliat the acid floats \iimii the top when the mixture is allowed to rest. .Such is not tlic case, but the very volatile iunredieuts in a half filled bottle of mixture may rise in v.npour and condense ui>on the inside of the empty ])art of the bottle, .md on a dose being poured out it wonid contain a relatively larger propor- tion of the volatile substance, heni-e even in these cases a '■ shake the bottle'' label .should be put on, one thing being certain, it can do no harm if unn(H:efisary.](https://iiif.wellcomecollection.org/image/b21507296_0031.jp2/full/800%2C/0/default.jpg)
