Observations placeholder

Memorials, Scientific and Literary of Andrew Crosse, the Electrician – Cornelia and Andrew Crosse

On the Acarus Electricus

In the year 1837 Mr. Crosse was pursuing some experiments on electro-crystallisation, and in the course of these investigations insects made their appearance under conditions usually fatal to animal life. Mr. Crosse never did more than state the fact of these appearances, which were totally unexpected by him, and in respect to which he had never put forth any theory.  In especial reference to these experiments in which animal life appeared, he says:-

 "I have met with so much virulence and abuse, so much calumny and misrepresentation, in consequence of these experiments, that it seems, in this nineteenth century, as if it were a crime to have made them. For the sake of truth and the science which I follow, I must state that I am neither an atheist, nor a materialist, nor a self-imagined creator, but a humble and lowly reverencer of that Great Being of whose laws my accusers seem to have lost sight.
It is my opinion that science is only valuable when employed as a means to a greater end. I attach no particular value to any experiments that I have made, and I care not if what I have done be entirely overthrown, Truth is elicited.
Though warmly attached to experimental philosophy, I have never for one moment imagined that it is possible to perform a single experiment which is absolutely perfect in itself, or indeed that we can carry out any train of such which are not more or less liable to objection."

 In speaking of the misapprehension of prejudiced persons, he says:

"By such I have been termed a self-imagined Creator. Man can neither create nor annihilate. To create is to form a something out of a nothing; to annihilate is to reduce that something to a nothing. The chemist plays with the substances brought under his notice; he decomposes; he recomposes; he is a humble imitator of Nature; to create or annihilate is not in his power."

 I now give Mr. Crosse's own account of the first experiment in which the acari made their appearance:-

"In the course of my endeavours to form artificial minerals by a long-continued electric action on fluids holding in solution such substances as were necessary to my purpose, I had recourse to every variety of contrivance that I could think of; amongst others I constructed a wooden frame, which supported a Wedgewood funnel, within which rested a quart basin on a circular piece of mahogany.

When this basin was filled with a fluid, a strip of flannel wetted with the same was suspended over the side of the basin and inside the funnel, which, acting as a syphon, conveyed the fluid out of the basin through the funnel in successive drops: these drops fell into a smaller funnel of glass placed beneath the other, and which contained a piece of somewhat porous red oxide of iron from Vesuvius. This stone was kept constantly electrified by means of two platina wires on each side of it, connected with the poles of a voltaic battery of ten pairs of five-inch zinc and copper plates.

The droppings of the second funnel fell into a wide mouthed bottle; and they were poured back again into the basin, when that vessel was getting empty.  It must not be supposed that the stone from Vesuvius was in any way connected with the result of the experiment. It had been selected principally for its porosity.

The fluid with which the basin was filled was made as follows: A piece of black flint, which had been exposed to a red heat, was reduced to powder. Of this powder two ounces were taken, and mixed intimately with six ounces of carbonate of potassa, and then exposed to a strong heat for fifteen minutes. The fused compound was then poured into a black lead crucible in an air furnace; it was reduced to powder while still warm; boiling water was poured on it, and it was kept boiling for some minutes. The greater part of the soluble glass thus formed was taken up by the water. To a portion of the silicate of potassa thus formed I added some boiling water to dilute it, and then slowly added hydrochloric acid to supersaturation.

"The object of subjecting this fluid to a long continued electric action through the intervention of a porous stone was to form if possible crystals of silica; but this failed. On the fourteenth day from the commencement of this experiment I observed through a lens a few small whitish excrescences or nipples, projecting from about the middle of the electrified stone. On the eighteenth day these projections enlarged, and struck out seven or eight filaments, each of them longer than the hemisphere on which they grew. On the twenty-sixth day these appearances assumed the form of a perfect insect, standing erect on a few bristles which formed its tail. Till this period I had no notion that these appearances were other than an incipient mineral formation. On the twenty-eighth day these little creatures moved their legs. I must now say that I was not a little astonished. After a few days they detached themselves from the stone, and moved about at pleasure.

 "In the course of a few weeks about a hundred of them made their appearance on the stone. I examined them with a microscope, and observed that the smaller ones appeared to have only six legs, the larger ones eight. These insects are pronounced to be of the genus acarus; but there appears to be a difference of opinion as to whether they are a known species; some assert that they are not. I have never ventured an opinion on the cause of their birth, and for a very good reason - I was unable to form one.

The simplest solution of the problem which occurred to me was that they arose from ova deposited by insects floating in the atmosphere and hatched by electric action. Still I could not imagine that an ovum could shoot out filaments, or that these filaments could become bristles, and moreover I could not detect, on the closest examination, the remains of a shell.

Again, we have no right to assume that electric action is necessary to vitality until such fact shall have been most distinctly proved. I next imagined, as others have done, that they might have originated from the water, and consequently made a close examination of numbers of vessels filled with the same fluid: in none of these could I perceive a trace of an insect, nor could I see any in any other part of the room."

In another experiment Mr. Crosse observes:

"I used a battery of twenty pairs, between the poles of which were interposed a series of seven glass cylinders, filled with the following concentrated solutions:-

1. Nitrate of copper.

2. Carbonate of potassa.

3. Sulphate of copper.

4. Green sulphate of iron.

5. Sulphate of zinc.

6. Water acidified with a minute portion of hydrochloric acid.

7. Water poured on powdered arsenic.

All these cylinders were connected with the positive pole, and were electrically united together by arcs of sheet copper, so that the same electrical current passed through the whole of them.

"After many months' action and consequent formation of certain crystalline matters, I observed similar excrescences with those before described at the edge of the fluid in every one of the cylinders except the two which contained the carbonate of potassa and the metallic arsenic; and in due time the whitish appearances were developed into insects.

In my first experiments I had made use of flannel, wood, and a volcanic stone. In the last, none of these substances were present. I never for a moment entertained the idea that the electric fluid had animated the remains of insects or fossil eggs, previously existing in the stone or silica.

I have formed no visionary theory that I would travel out of my way to support.

"In some cases these insects appear two inches under the electrified fluid, but after emerging from it they were destroyed if thrown back."

The insects also made their appearance in silicate of potassa four inches below the surface of the fluid, also in fluo-silicic acid two inches below the fluid. These experiments were repeated and others instituted with a similar view by the late Mr. Weeks of Sandwich. He passed currents of electricity through vessels filled with solutions of silicate of potash, under glass receivers inverted over mercury,-the greatest precautions having been taken to shut out extraneous matter; and in some cases the receivers were previously filled with oxygen gas. After an uninterrupted action of about a year and a half insects invariably made their appearance, exactly resembling those that occurred in Mr. Crosse's experiments some years previously.

In some of Mr. Weeks' experiments, the acarus made its appearance in solution of ferrocyanuret of potassium. That gentleman, in a communication to the Electrical Society, stated that he had repeated these arrangements without electricity placing the apparatus in every variety of position favourable to the development of insect life, but none appeared. Mr. Weeks considered these negative experiments as very important.

Another and later experiment made by Mr. Crosse deserves notice. He says:-

"I calcined black gun-flints in a crucible, and flung them while hot into water: I then dried and reduced them to powder. Of this powder I mixed one ounce, and intimately mixed it with three ounces of carbonate of potassa. I fused them together for five hours, increasing the heat, until it exceeded that necessary to melt east iron. I removed the crucible, and then allowed the contents to become solid, which formed into a pale green glass. While still hot, I broke them into pieces: these hot pieces I threw into a vessel of boiling distilled water.

I had previously prepared an apparatus to act electrically upon this fluid. It consisted of a common tubulated glass retort. The beak of the retort rested in a cup of pure mercury, from which proceeded a platinum wire, which passed up through the whole length of the retort, and when it reached the bulb was bent at right angles, so as nearly to touch the bottom of the bulb. The glass tube, which fitted air-tight into the neck of this retort, had a platinum wire passed straight through it, the upper part of which was hermetically sealed into the upper part of the tube, and the lower part of the wire was continued downwards. The two platinum wires were at a distance of about two inches from each other. When all was ready I poured the solution still hot into the bulb of the retort, thus affording a conducting medium between the two platinum wires, connected with the opposite poles of a small voltaic battery. An electric action commenced; oxygen and hydrogen gases were liberated; the volume of atmospheric air was soon expelled.

Every care had been taken to avoid atmospheric contact and admittance of extraneous matter, and the retort itself had been previously washed with hot alcohol. This apparatus was placed in a dark cellar. I discovered no sign of incipient animal formation until on the 140th day, when I plainly distinguished one acarus actively crawling about within the bulb of the retort. I found that I had made a great error in this experiment; and I believe it was in consequence of this error that I not only lost sight of the single insect, but never saw any others in this apparatus.

 I had omitted to insert within the bulb of the retort a resting place for these acari (they are always destroyed if they fall back into the fluid from which they have emerged). It is strange that, in a solution eminently caustic and under an atmosphere of oxihydrogen gas, one single acarus should have made its appearance."

These insects also appeared in an atmosphere strongly impregnated with chlorine; but in this latter case they assumed the form of perfect insects, and remained undecomposed and unaltered for more than two years; in fact till the apparatus was taken apart; but, singularly enough, they never moved nor evinced any signs of vitality.

THE END