Soap Liniment U. S. P.
By J. C. WHARTON.
Although this preparation is not to be ranked among the difficult ones of the pharmacopoeia, yet a simpler and more expeditious manipulation is quite possible. The officinal process is not the most direct, and as it requires the heat of a water-bath, it presents at least two other undesirable features. One is the evaporation of the alcohol, and the other is the danger of fire from its inflammable vapor in careless hands. There is no necessity for fire to be used at all, and, in fact, it is but a slow method of arriving at a result which a little mechanical effort will reach in much less time, besides yielding a more satisfactory product. What is meant by the mechanical effort is simply to pound the soap in a mortar, gradually adding the water first, then the alcohol, &c., as given in the formula below. By the first step in the process a very soft mass is formed, just as would be the case if in making soap pills a little too much water should be added. The succeeding steps consist in dissolving the soap, camphor and oil of rosemary in the alcohol—an easy process, as will be discovered on trial. In beating the soap and water together it is best not to mix them immediately, as it would then be difficult to get the pestle upon the lumps of wet soap; but if the mortar is dry, and the soap is introduced dry, either in a mass, lumps or shavings, it may be easily beaten, and if it is well pounded in this condition, it is rendered so plastic that the water may then be readily incorporated, and the whole preparation completed in a short while. I think it no trouble to commence and finish the amount prescribed in the pharmacopoeia within an hour, which, considering the time occupied in filtering, is not longer than many extemporaneous prescriptions require.
The following method is therefore offered in place of the present one of the U. S. P.
| Take of | Soap, in pieces, | four troyounces. |
| Camphor, | two troyounces. | |
| Oil of Rosemary, | half a fluidounce. | |
| Water, | four fluidounces. | |
| Alcohol, | two pints. |
Beat the soap in a dry mortar until the lumps have disappeared; then add by degrees the water and triturate; when well mixed add the alcohol gradually, afterwards the camphor and oil of rosemary, rubbing with the pestle till all are dissolved, and filter through paper.
Nashville, August, 21st, 1871.
