By J. C. WHARTON.
The tendency of some officinal syrups to ferment is strikingly manifested by the three above named, and, although the present formulae for their preparation are improvements upon older ones, there are still serious difficulties in following implicitly the directions laid down in the U. S. Dispensatory. As a consequence, there are various inequalities in the resulting syrups, and, as I believe, fermentation is sometimes actually promoted by the tedious and lengthy proceedings required.
It will be sufficient to offer as an instance the compound syrup of squill. As it is not necessary to give the formula in detailed proportions, the reader is referred to the U. S. Dispensatory, where it will be seen that after a percolated tincture of three pints is obtained the directions read: "Boil this for a few minutes, evaporate it by means of a water-bath to a pint, add six fluidounces of boiling water, and filter. Dissolve the sugar in the filtered liquid, and, having heated the solution to the boiling point, strain it while hot. Then dissolve the tartrate of antimony and potassa in the solution while still hot, and add sufficient boiling water through the strainer to make it measure three pints. Lastly, mix the whole thoroughly together."
In following these directions as strictly as possible I have almost invariably found that a large amount of albuminous or "pectin-like" matter was deposited, and in fact this is the stated design of raising the liquid to the boiling point. Here arises the chief difficulty, in my opinion; at any rate I have found it to be a great one, for in attempting to remove this deposit by filtration, especially if a considerable quantity of liquid is prepared, the filter is soon clogged by the gummy matter, and the liquid filters very slowly. I have known filtration to cease towards the close of the operation. In such a case the best that can be done is to provide a new filter and empty the old one into it, expressing it to avoid loss as much as possible. This is tedious and wasteful of the virtues of the drug. On one occasion I prepared a quantity of the tincture, and such was the tardiness of filtration that several days were occupied in completing it. Towards the end I noticed a few patches of a mouldy growth that had formed on the surface of the albuminous matter in the filter, and by smelling it perceived that the liquid was spoiled before the syrup was made. The failure was suggestive, and I concluded that if a few days were enough to spoil the liquid a few hours time might injure it, and, in fact, the germs of fermentation might begin to work as soon as the liquid was cold, since the protective agency of alcohol was gone.
Reasoning as above, I resorted to a method of filtration often used when a difficult precipitate is to be removed, namely, rubbing the muddy liquid with magnesia. In this case it acted with the double advantage of mingling its particles with the albuminous matter, thus, facilitating filtration and neutralizing any free acid that might be present from incipient fermentation. The result was very satisfactory. Filtration was greatly hastened, and the syrup produced was not muddy looking or translucent, as is generally the case, but was beautifully transparent. It was kept a year without fermenting, though almost daily in use.
I have since tried the same method of filtration with syrup of ipecacuanha and syrup of seneka, with like results.
There is a point that may seem objectionable in using magnesia, or its carbonate as above, and it has been duly considered before offering these suggestions. It is this: Magnesia is alkaline in its reactions, and as the active principle of seneka is considered to be acid (polygalic), it would seem that they are incompatible, but as they are both feeble in their affinities and as filtration proceeds rapidly there is practically no objection to mixing them. There is, it is true, a very slight escape of carbonic acid when the carbonate of magnesia is rubbed with the concentrated liquid, but it may be due to a small amount of free acid of a different character, and even though a little polygalic acid should be removed by the magnesia the amount is so trivial as to be of no importance, and the objection is more than counterbalanced by the complete removal of the albuminous and pectinous deposit which generate fermentation, and would soon decompose more polygalic acid than the magnesia removes.
I therefore submit the following formulae, adhering as closely to the U. S. Dispensatory as practicable, and would remark that the use of carbonate of magnesia is sanctioned by that authority in the case of the active principle of ipecacuanha, which the reader will see by referring to the method of preparing impure emetia, U. S. D., under the article "Ipecacuanha:"
Syrupus Scillae Compositus.
|Take of||Squill, in moderately coarse powder,|
|Seneka, in moderately fine powder, each||four troyounces.|
|Tartrate of Antimony and Potassa,||forty-eight grains.|
|Sugar (refined) in coarse powder,||forty-two troyounces.|
|Water, each||a sufficient quantity.|
|Carbonate of Magnesia,||sixty grains.|
Mix the squill and seneka, and, having moistened the mixture with half a pint of diluted alcohol, allow it to stand for an hour. Then transfer it to a conical percolator and pour diluted alcohol upon it until three pints of tincture have passed. Boil this for a few minutes, evaporate it by means of a water-bath to a pint, add six fluidounces of boiling water, rub the liquid with the carbonate of magnesia in a mortar till thoroughly mixed., filter, and add through the filter sufficient warm water to make the filtrate measure twenty-two fluidounces. Dissolve the sugar in the filtered liquid, and, having heated the solution to the boiling point, strain it while hot. Then dissolve the tartrate of antimony and potassa in the solution while still hot, and add sufficient boiling water, through the strainer, to make it measure three pints when cold. Lastly, mix the whole thoroughly together.
|Take of||Seneka, in moderately fine powder,||four troyounces.|
|Sugar (refined) in coarse powder,||fifteen troyounces.|
|Diluted Alcohol,||two pints.|
|Water,||a sufficient quantity.|
|Carbonate of Magnesia,||thirty grains.|
Moisten the seneka with two fluidounces of the diluted alcohol, then transfer it to a conical percolator and gradually pour upon it the remainder of the diluted alcohol. When the tincture has ceased to pass evaporate it by means of a water-bath, at a temperature not exceeding 160°, to half a pint. Rub it with the carbonate of magnesia in a mortar till thoroughly mixed, filter and add sufficient warm water through the filter to make the filtrate measure half a pint, and, having added the sugar, mix well together, and note accurately the measure of the mixture while cold; then dissolve the sugar with the aid of a gentle heat, strain the solution while hot, add sufficient warm water through the strainer to bring the syrup, when cold, to the previously noted measurement, and mix them thoroughly.
(Modified from former editions of the U. S. P.)
|Take of||Ipecacuanha, in fine powder,||two troyounces.|
|Water, each||a sufficient quantity.|
|Sugar (refined) in coarse powder,||twenty-nine troyounces.|
|Carbonate of Magnesia,||forty-five grains.|
Moisten the ipecacuanha with one fluidounce of the diluted alcohol, let it stand for twenty-four hours. Then transfer it to a conical percolator and gradually pour upon it diluted alcohol until one pint of tincture has passed. Evaporate this by means of a water-bath to six fluidounces, add ten fluidounces of warm water, and, having rubbed it thoroughly with the carbonate of magnesia in a mortar, filter, and add sufficient warm water through the filter to make the filtrate measure one pint; then add the sugar, and dissolve it with the aid of a gentle heat, and, having strained the hot syrup, add sufficient warm water, through the strainer, to make it measure two pints when cold.
It will be seen that the chief point of difference between the two first formulae above given and the U. S. P. requirements is the filtration of the evaporated tinctures through carbonate of magnesia instead of paper only; but I would call the attention of the authors and revisers of both the Pharmacopoeia and Dispensatory to the lack of explicit directions in many of the formulae for syrups, from which I, with many others, have suffered loss and trouble. The difficulty is mainly in the want of full and accurate directions in regard to the various measurements. For example, the closing directions in the formula for compound syrup of squill read thus Add sufficient boiling water, through the strainer to make it (the hot syrup) measure three pints" (while hot?) In view of the tartar emetic, the design of the formula must be to make the syrup measure three pints when cold, but a fair interpretation of the directions cannot mean that. Now it is plain that three pints of hot syrup will not, upon cooling, be three pints of cold syrup, admitting that no evaporation takes place in the act; but most commonly a considerable evaporation will take place during the process, and of necessity a crystallization of sugar takes place. The fault is even worse in the formula for syrup of seneka. The directions read: "Filter, and, having added the sugar, dissolve it with the aid of a gentle heat and strain the solution while hot." No account is taken of the loss of liquid in filtering, nor of evaporation in dissolving the sugar. If the directions are followed precisely, in such cases, crystallization will inevitably take place, even if the amount of sugar prescribed is not a little too great, as I am of opinion it is in the two first of the syrups herein discussed. I believe that in practice twenty-nine troyounces would be found to answer as well as thirty troyounces, or a proportional reduction of other quantities.
Nashville, Tenn., Jany. 24, 1871.
The American Journal of Pharmacy, Vol. XLIII, 1871, was edited by William Procter, Jr. (Issues 1-4) and John M. Maisch (Issues 5-12).