Dr. Garrod concludes from analysis that the antiscorbutic articles of diet are distinguished by containing an abundance of the salts of Potash, but that the reverse is the case with the materials which form the staple food of those who are most liable to Scurvy.
He gives the following as the amounts of potash obtained from one ounce of each of the articles of diet named:—
| Wheaten bread | .259 grains. |
| Oatmeal | .054 " |
| Salted beef | .572 " |
| Boiled potatoes | .529 " |
| Lemon-juice | .846 " |
Thus it appears that lemon-juice and potatoes contain more Potash than wheaten bread, and much more than oatmeal. But they do not so much excel salt beef in this particular, and that is one of the chief articles of diet among sailors. And if this deficiency of Potash were the sole cause of Scurvy, then it should be unknown in Ireland, where quantities of Potatoes are eaten, and very common in Scotland, where Oatmeal forms so important an article of diet among the peasantry. I am certainly not aware that such is the case, but believe it is rather the reverse.
In spite of the very able arguments and the instances adduced on the other side, it seems to me that the probability is still in favour of the vegetable acid being the active or curative agent in these antiscorbutic vegetables. It seems to exert a purifying power over the blood in this disorder, of the exact nature of which we are not aware. It is probably not only Citric acid that is efficacious, for it appears that some other vegetable acids, and vegetables which do not contain Citric acid at all, may be used with advantage in Scorbutic diseases.
Ord. VI. Antiperiodics.
Certain mineral medicines of the Catalytic division are employed in the treatment of periodic disorders.
Arsenic is a medicine of considerable power, which, when given in too large a dose, or indeed when given at all in most cases, becomes a poison. It has already been shown to act in the blood, and to produce in it a number of effects of a particular kind. One part of this operation is that it is capable of antagonizing the poisons of intermittent disorders, as also of certain convulsive affections and skin-diseases. In health a poison, in disease it proves a remedy. But the dangerous nature of its action is such as to demand considerable care in the administration of the preparations of Arsenious acid.
Dr. A. T. Thomson states that the action of Arsenic is liable to exacerbations and remissions, and sometimes even intermissions. Thus we may suppose that there is a certain degree of analogy between its operation and that of the malarious poison, by virtue of which it may perhaps exert a corrective power over the working of the latter in the blood. (Vide page 166.) Such an analogy could only exist in the case of a Catalytic medicine. It is not observed of Quina, which is employed in intermittents on the Restorative plan. Arsenic is foreign to the blood, and is in every way a Catalytic medicine.