“Variorum mixtura novas sæpe vires generet, in simplicibus nequaquam reperiundas longe saluberrimas.”
Gaubius.
It is a truth universally admitted, that the arm of physic has derived much additional power and increased energy, from the resources which are furnished by the mixture and combination of medicinal bodies. I by no means intend to insinuate that the physician cannot frequently fulfil his most important indications by the administration of one simple remedy; I only contend that, in many cases, by its scientific combination with other medicines, it will not only act with greater certainty and less inconvenience, but that its sphere of influence may be thus more widely extended, and its powers so modified or changed, as to give rise to a remedy of new powers. Such a theory is amply justified by the state of combination in which certain medicinal principles are found in our more efficient vegetable remedies, while the medicinal practice founded upon it is thus, as it were, sanctioned by Nature’s own prescriptions; enter but her laboratory, and you will soon be satisfied, that many of her potent remedies do not owe their valuable powers to any one specific ingredient, but to the combined or modified energies of various, and sometimes opposite principles. This view of the subject opens an interesting and unexplored field[[239]] of medical and chemical research, and I shall endeavour to avail myself of the novelties its investigation may present, and of the hints it may suggest for the improvement of extemporaneous combination. By contemplating the laws by which Nature effects her wise purposes, we may learn to emulate her processes, and even in some cases to correct and assist her operations:[[240]] such at least has been the happy result of our labours in the other departments of natural knowledge. It is said for instance that by observing the means used by nature for preventing the diffusion of light in the eye-ball, Euler derived an important hint for the improvement of his telescope; and more lately, the structure of the crystalline humour of the eye has been successfully imitated in the invention of achromatic lenses. On the other hand, it is hardly necessary to observe to what extent these instruments of art are capable of improving and multiplying the powers of that natural organ, to the contemplation of whose structure and functions, we are, as I have just stated, so greatly indebted for their origin and perfection. So shall I endeavour to shew, in the progress of this work, that the combinations of nature, as exemplified in her more valuable remedies, are capable, if properly studied, of suggesting many important hints for improving the arrangements of art; while art in return may frequently supply the defects, or extend the advantages of natural compounds.
AN ANALYSIS
OF
THE OBJECTS TO BE OBTAINED BY MIXING AND COMBINING MEDICINAL SUBSTANCES.
The objects to be attained, and the resources which are furnished, by Medicinal Combination, together with the different modes of its operation, and the laws by which it is governed, may with much practical advantage be arranged in the following order.
I.
TO PROMOTE THE ACTION OF THE BASIS, OR PRINCIPAL MEDICINE.
A.—By combining together several different Forms, or Preparations, of the same substance.
The utility of such a combination is obvious, whenever we desire the full and general effects of all the principles of a medicinal body in solution; thus, where the Bark is required in the cure of an intermittent fever, and the stomach will not allow the exhibition of the powder, it will be eligible to conjoin in one formula, the tincture, decoction, and extract, as exemplified by Formulæ 42, 126, 127. The necessity of such a combination may be expressed by the following canon. Whenever the chemical nature of the medicinal substance will not admit of the full solution of all its active principles in any One Solvent, and its exhibition in substance is at the same time impracticable. For farther illustrations see Form. 2, 25, 33, 38, 70, 109.
Practitoners, probably without having reasoned upon the theory, have very generally adopted the practice, of combining the different solutions of the same substance; for in the prescriptions of practical physicians we commonly find, that the decoction or infusion of a vegetable remedy is quickened by a certain portion of a corresponding tincture.