On Syrup of Tolu.
BY E. CLAASSEN.
The beautiful yellow color and the fine appearance of the Syrup of Tolu prepared according to the formula of the old Pharmacopoeia are, without doubt, the reason that many apothecaries continue, without making any tests, to prefer this syrup to that made as the new Pharmacopoeia directs. An exact answer to the question, "Which of these two syrups has more strength, and is the best one?" seemed to be, therefore, both interesting and useful. For this purpose I took equal quantities of the syrup prepared from the Tincture of Tolu by means of magnesium carbonate and of the syrup made directly from the balsam. It is well known, as I may state here, that all the effect and power of the Syrup of Tolu is lying in the presence in it of the benzoic and cinnamic acids. These two acids are easily soluble in ether; ether will extract them readily from the syrup, leaving of them behind but a small balance. Each one of these two samples of syrup was therefore shaken with an equal volume of ether, and the ether, after separation from the syrup, evaporated in a glass dish in the open air. The ether taken from the syrup made directly from the balsam left a considerable quantity of a yellowish white residue having the characteristic smell and properties of the two acids, while the ether shaken with the syrup made from the tincture of Tolu left behind a small amount of resinous matter only. After addition, however, of some hydrochloric acid, enough to acidulate the syrup, and after shaking with ether, the last one left, when evaporated, a good deal of the acids. By this experiment it was evidently demonstrated, that in this syrup the acids in question were not present in a free state, but were liberated by the hydrochloric acid added. If any doubt could be sustained that they were combined with magnesium in the syrup, this doubt was at once destroyed by the chemical test made, viz., by the white crystalline precipitate resulting after the addition of sodium-ammonium phosphate. The magnesium carbonate used for preparing the syrup may be regarded as insoluble in water; its presence in the syrup is therefore due to the acids, which dissolve a corresponding part of it forming magnesium salts. The determination of the quantity of magnesium found present in any sample of syrup of Tolu, that was shaken after addition of water with magnesium carbonate, and afterwards filtered, will certainly furnish a good means for finding the approximate amount of the acids present. The above experiments prove, I think, evidently, that the formula, as given by the new Pharmacopoeia, for making syrup of Tolu is by far the best. Every apothecary will do well to follow the same, and not allow the substitution of an almost worthless syrup, the syrup of the old Pharmacopoeia. Cleveland, O., June, 1884.
The American Journal of Pharmacy, Vol. 56, 1884, was edited by John M. Maisch.