On the Use of Liquid Caoutchouc as an Addition to Emp. Belladonnae and Other Plasters.
By J. WILLITTS WORTHINGTON.
The author has treated this subject at some length in his Inaugural Essay before the Philada. College of Pharmacy, from which we abstract the following:
Much difficulty has been experienced by pharmaceutists in preparing belladonna plaster so as to retain its adhesiveness when kept ready spread for some time. The proposed improvement consists in the addition of india rubber used in the form of a solution, made as follows:
|Take of||pure Caoutchouc, cut in small pieces,||an ounce.|
|Benzine (from Petroleum),||a pint.|
Macerate with occasional agitation in a suitable stopped, wide-mouthed bottle until a thick, saturated solution is obtained. To prove its efficacy in preserving the pliability of plasters, the author prepared a mixture of 8 ounces of Burgundy pitch, 4 drams of yellow wax, 2 drains of rosin and 2 drams of lard. Melted and strained. This, when spread and kept two months, became very brittle and cracked on handling.
The same ingredients, with the addition of 4 drams of liquid caoutchouc incorporated when they were in a fused state, possessed the following characters:
Very little tendency to crack, retains its pliability, is more adhesive, and has a beautiful, smooth, glossy appearance. After two months, part of it very cold weather, this plaster retained its pliability.
Experiments were then made with officinal belladonna plaster, which resulted in the following proportion being considered most suitable:
|Take of||Belladonna plaster (U. S. P.),||seven drams.|
|Liquid Gum Elastic,||one dram.|
The belladonna plaster to be melted by a water-bath, And the liquid rubber then added and stirred well until united thoroughly.
The odor of the benzine disappears when the solution is added in this way. It is quite important to avoid an excess of heat, and hence the water-bath is recommended.
Liquid rubber will be found to act admirably in all plasters which may be made to keep through the summer.