I have frequently made experiments of this kind by exposing plants to a weak degree of electricity, and at other times to a considerable quantity, without ever being able to observe that plants under its influence prospered more than those which were not electrified at all. It even appeared to me more than once, that those which had been electrified were a little less thrifty than those which were not electrified.
In another place he says, Not being content with these experiments, I have made others infinitely more conclusive, by strewing seeds of mustard and cresses, over the largest plates of delf that I could procure, covering them with brown paper, and sprinkling them continually with a sufficiency of water. Each of these plates was covered with more than a thousand seeds; I kept them electrified night and day, according to the method which Mr. Schewankhard directed, in a letter quoted by Mr. Elermann, but which I shall not repeat in this place, lest I should swell this memoir: the vegetation of these little shrubberies was always more or less precarious, in proportion to the greater or less quantity of light that they received; the electricity really contributing nothing to advance the growth: thus the controversy stands, we leave the reader to form his own opinion.
That some plants are more affected than others by electricity is an unquestionable fact. It is however not true as some have affirmed, that the contractions of the mimosa or sensitive plant, are attributable to this cause. The plant is equally affected when touched either by a conductor or an electric.
CHAP. XVIII.
Medical electricity.
Electricity has one advantage over other medical applications, in as much as it may be applied to the healthy, as well as the diseased part of the body, without proving prejudicial, and because it requires rather a nice application, than a perfect knowledge of the complaint. In a number of cases it has unquestionably proved salutary.
When electricity was first used in removing bodily complaints, it was done only by means of the Leyden phial pretty highly charged; but this mode of administering it, was strenuously opposed by Mr. Lovet, who was a celebrated electrical practitioner, and in an essay called Subtil medium proved, asserts that electricity should be used in small sparks, by which mode of treatment he affirms he scarcely ever failed curing or at least relieving his patients.
The apparatus for medical electricity in addition to the machine described in chapter IV, is an insulating stool. This stool is made in the common way, only that the feet must be of glass, the upper or wooden part, should be about three feet square, so that a chair or bench may conveniently stand upon it; care must be taken to leave no sharp edges about the stool. For a representation of one, see plate letter W.
The next instrument necessary for the electrical physician is a coated jar, furnished with Mr. Lane’s electrometer. This instrument is made in the following manner. From the wire extending beyond the mouth of the jar, at about four inches from the upper extremity, let a piece of glass or baked wood three inches long, project at right angles. At the outer extremity of this stem let another piece of baked wood three inches long, be fixed parallel to the rod of the jar; the upper end of the parallel stem must be furnished with a brass socket, through which a graduated wire may easily pass. This wire must be furnished with a knob upon the end which is next the jar, and a hook or ring at its other extremity, to which a chain connected with the outer coating of the jar must be attached. From this construction it is readily perceived that the force of the discharge or shock, will be proportioned to the distance of the ball of the electrometer, and the usual ball of the jar; i. e. when the shock is large it will pass from one knob to the other at a larger distance, and when small at a smaller distance, and thus the distance will be the measure of the shock.—The next thing to be provided is a ball, either of metal, or of wood covered with tin foil; this must have a metallic handle, which may be separated from the ball at pleasure, having at one of its extremities a sharp point to receive a stream of electric fire; small pointed pieces of wood made in a conical shape, may be fixed on this point, when the patient requires a degree of electricity between a spark and a stream.
The bottle director is the next instrument to be described. It is exactly the same with the common Leyden phial, with the addition only of a hook cemented to the bottom. To use this director (suppose for instance you wished to pass a shock through the arm) let a communication be made between its inner coating and the prime-conductor, by which means it will be charged; then let a chain be fastened, by one end, to the hook which is at the bottom; then by applying the other end of the chain (which may be furnished with a ball) to one side of the arm, and the knob of the jar to the other, a shock will be given.
These are the instruments for the electrical physician. We are now to describe the manner in which electricity may be applied to the best advantage.