m. p. 1.—That they act in the blood, and that their effect is permanent.
m. p. 2.—That there are naturally in the blood substances which resemble or coincide with them.
m. p. 3.—That they are not of necessity excreted, but may remain in the blood.
m. p. 4.—That they are of use when a disease depends on the want of one or more materials in the blood.
It will be seen that the first minor proposition affirms them to be Hæmatic medicines, according to the definition given before. The second is required; for if there were not a necessity in the blood for substances like them, they could supply nothing. The third also is necessary, for if they were excreted in all cases, it is evident that their Restorative action could not be lasting. An exception must be made in the case of those that are used to supply something which is necessary in order that a secretion may be properly elaborated. Medicines of the Sixth Order are particularly used with this intent; as also some acids and alkalies. But these are not repugnant to the blood, like Catalytics. In the fourth place it is affirmed that being thus fitted for the blood, and allowed to remain in it, they tend to cure a disease which depends on the want of a substance similar in nature to themselves.
After giving a brief account of each of the orders of Restoratives, it will be my object to prove that these affirmations are severally applicable to each of them.
Ord. I. Aliments.
An article of food is the simplest form, and in fact the type, of all medicines of this division. Out of the materials of the food the whole blood is constantly elaborated, and all the tissues are constructed.
Aliments were divided by Dr. Prout into four kinds:—(1) Aqueous; (2) Albuminous; (3) Saccharine; (4) Oleaginous. These kinds differ much in chemical conformation. The second kind alone contain Nitrogen. The last two are both called carbonaceous; but those of the fourth kind contain more Carbon than those of the third. The following will serve to illustrate the differences in the chemical composition of these groups.
1. Water = H O
2. Proteine = C40H31N5O12
3. Starch = C10H10 O10
4. Stearic Acid = C68H68O7