Volume 1

Electrotherapy / by George W. Jacoby.

  • Jacoby, George W., 1856-1940.
Date:
1901
Catalogue details

Licence: In copyright

Credit: Electrotherapy / by George W. Jacoby. Source: Wellcome Collection.

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    truin. For coiu'enience we speak of the tlierniic, luminous, and actinic rays of the spectrum, and these merge so closely one into the other that it is difficult to define their limits. It has alwa)'s been easy to reproduce the heat and the light areas of the spectrum ; but of the ultra-violet or chemical area, although recognized, little was understood until recently, when, through the discovery of Rontgen, this portion of the spectrum has been reproduced in the X-ray. Thus we have light proper as an intermediary between heat and the so-called X-ray, and these three forces are all recog- nizable by their effects only. So, too, electricity is known from its effects alone, and these effects are interchangeable, so that under certain conditions we can derive from them heat, light, and chemi- cal action. It would not be going too far, therefore, to consider electricity as a form of molecular vibration, and add it to make a series with our other natural forces. In the order of the rapidity of vibration our new table would read: heat, light. X-rays (or chemism), and electricity. A few fundamental experiments will also teach us that: (i) The electric state is one of relativity only ; (2) electricity is due to the equalization that takes place between two bodies in different degrees of excitation ; (3) the excitation of such bodies differs only in degree and not in kind. While our conception of the nature of electricity may be con- sidered assumptive and theoretic, we are by no means lacking in positive knowledge concerning its actions and the laws that gov'ern them. On the contrary, our knowledge in these directions is so precise and extensiv'e that it may be questioned whether there is any probability of its being broadened. Let us, therefore, begin our investigation of the therapeutic possibilities and uses of electri- city with a study of these effects and laws ; confining ourselves for the most part to positive knowledge, but making use of theory whenever it will render the facts more easily comprehensible. The earliest ideas of electricity were derived from the effects observed when one substance was rubbed against another, and in order, therefore, to gain a knowledge of the effects upon which our assumption of electricity is based, let us take up the earliest evi- dences that we are plea.sed to call electric.