volving nothing hypothetical, but the names which have been given them."

Whether, therefore, light be viewed as material particles emitted continuously, and in all directions, by luminous bodies, or as the vibrations of an elastic material medium, it is, in either case, dependent upon matter for its existence or production; it is matter, but exceedingly rare, subtle, and so minutely divided as to be to us absolutely imponderable.

It is probable that heat, electricity, and magnetism are motions, varying in kind, of the same ether.

That space is occupied by minute particles of matter admits of being proved in another manner quite independent of these observations on light. It has been ascertained by astronomers that one of the comets, called Encke's, which is a body not denser than a small cloud of steam, for the stars are seen through it without any diminution of their brilliancy, and which revolves round the sun in 1208 days, has its period slightly diminished during each revolution. It is obvious that its motion is impeded by a resisting medium, by which its centrifugal force is diminished, and consequently the relative power of gravity is increased; this brings the comet nearer to the sun, its orbit becomes contracted, and the time occupied by a revolution shortened. Thus, by another series of observations, we arrive at the same conclusion that there exists a rare, subtle, and imponderable form of minutely divided matter. Infinitesimal quantities of this imponderable matter are capable of acting energetically, and they do so act habitually, producing such impressions as those of light, &c., upon the living animal body.

Reasoning, then, from analogy, we may conclude it to be probable that other forms of matter, even though reduced by the successive triturations, into similarly small dimensions, may also act, and act powerfully, upon the living body.

II. Are there any facts which shew the action of infinitesimal quantities of ponderable matter upon the healthy body?

The beautiful adaptation of the different departments of nature to each other is justly adduced as a demonstration that the whole has been created and arranged under the guidance of infinite wisdom and power. In nothing is this adaptation more conspicuous than in the appropriate fitness of the corporeal senses of man to the surrounding world.

So far as we are cognisant of the material creation, it is disposed under the five following forms:-solid bodies, liquids, gases or airs, imponderable ether, and minutely divided particles of ponderable bodies. For the appreciation of these various forms of matter we have five senses. The sense of touch, mainly conversant with solid bodies; that of taste, which is impressed by

liquids only; the delicate organ of hearing, which can perceive the vibratory movements of gases or airs; the still more delicate organ of the eye, capable of receiving impressions from the undulations of the imponderable ether; and, lastly, the sense of smell, adapted to the condition of the particles of bodies, when they have become so divided as to be infinitesimal, that is, indefinitely small and imponderable.

It is this form of matter which we have now specially to consider. The particles separated from larger masses, which become by degrees so small as to elude in succession the perception of all our senses, and perhaps at length are reduced to a state similar to the ether.

A cubic inch of Platinum, the heaviest body we are acquainted with, weighs upwards of 5,000 grains. A cubic inch of Hydrogen, the lightest body which affects our balances, weighs 2 grains. These balances, by ingenious contrivances, are made very sensitive. I have one which readily weighs 0.005, or five thousandths of a grain. Others have been constructed still more delicate; but the particles we are now examining are far too light for any balance to appreciate.

Mechanical division can be carried to an almost incredible degree. Gold, in gilding, may be divided into particles at least one thousand four hundred millionths of a square inch in size, and yet possess the colour and all other characters of the largest mass. Linen yarn has been spun so that a distinctly visible portion could not have weighed the 127 millionth of a grain; and yet this, so far from being an ultimate particle of matter, must have contained more than one vegetable fibre, that fibre itself being of complex organization, and built up of an indefinitely great number of more simple forms of matter.

The perfection of modern chemistry is such that a quantity of silver, equal to the billionth of a cubic line, can be readily detected.*

That particles become divided into less portions than is shewn in these examples is evident from the daily observation of the sense of smell. The violet fills even a royal apartment with its sweet odour, which is thus readily perceived, but which absolutely eludes every other mode of observation. How inconceivably small must be the particles of all odours! And yet how obviously material they are.

A grain of musk may be exposed for a long period, and be unceasingly emitting particles, easily appreciated by the sense of smell, yet has it not lost in weight what the most sensitive balance can detect.

These are instances of infinitesimal quantities of matter acting upon the healthy body.

* Elements of Chemistry, by Sir R. KANE, 2nd Ed. p. 7.

B

Contagious malaria constitute a large class of agents whose power of injuriously acting upon our healthy body is so greatly dreaded, and no one has yet doubted that they are material. Who voluntarily crosses the Pontine marshes at certain seasons of the year, or exposes himself to the plague of Constantinople, or the yellow fever of the West Indies? The microscope cannot shew these terrible particles, nor can chemical analysis detect them. Ozone perhaps decomposes them.

To come nearer home, a clergyman visits a patient in scarlet fever, but does not touch him, he afterwards calls upon a friend, and shakes the hand of one of the children as he passes her on the staircase. The next day this child sickens with the scarlet fever, and her brothers and sisters take it from her; no other connection can be traced. This is no uncommon occurrence, and no one doubts the communication of infection in such a manner, neither is it doubted that the infection itself is something material. What is the weight of the particle of matter thus conveyed? Is it heavier than the millionth of a grain of belladonna which, it is asserted by Homœopathists, is sufficient, when given at short intervals, to arrest the progress of such a case?

These, then, are also instances of infinitesimally small quantities of matter acting upon the living body in health.

There are numerous liquids which have the power of affecting the healthy body, and some of them of taking away life, and yet in each instance the quantity of the active ingredient is so exceedingly small that hitherto no means have been effectual in detecting it.

The Vaccine matter has been so often mentioned that I will not allude to it further.

Several animals are furnished with poisonous liquids, which, when injected into a wound, occasion the disease or death of the wounded animal. Serpents, bees, scorpions, and spiders, are well In the venomous serpents there is found an

known examples.

apparatus of poison-fangs, constituting perhaps the most terrible weapons of attack met with in the animal creation. The poison teeth (a) are two in number, placed in the upper jaw, when not in use they are laid flat upon the roof of the mouth; but when the animal is irritated, they are plucked up from their concealment, and stand out like two long lancets. Each fang is traversed by a canal, through which the poison flows. The gland (b) which secretes the poison, is composed of cells communicating with a duct (c) by which the venom is conveyed to the tooth. The poison gland is covered by a muscle (d) which is attached to a thin fibrous line (e). This is part of the muscle which closes the jaw, so that the same power which strikes the teeth into the viper's prey, compresses at the same moment the bag of poison, and forces it through the fangs into the wound.*

The quantity of poison contained in the gland scarcely exceeds a drop, but the smallest portion of this liquid taken up upon the point of a needle, and inserted by a slight puncture into the skin of an animal, is sufficient to produce all its poisonous effects. From some serpents it produces almost immediate death. FONTANA first subjected it to chemical analysis, and sacrificed many hundred vipers in his experiments. Others have succeeded him in these labours, but nothing peculiar has been discovered. The poison is a yellow liquid, and has not been distinguished chemically from simple gum water.†

Here are examples of infinitesimal quantities of ponderable matter acting with frightful energy upon the healthy body.

66

Medicinal substances furnish other proofs. I must content myself with a single example. Inappreciable quantities of Ipecacuanha give an affirmative answer to our present question, so decisive and convincing that I make no apology for extracting the following cases from that well-known and highly respectable allopathic periodical the London Medical and Physical Journal:-An apprentice of mine, naturally healthful, and of an active disposition, is invariably affected with a most distressing and protracted sneezing on the most careful dispensing of the smallest quantity of Ipecacuanha. A more continued application of it, such for instance as happens in the preparation of the compound powder, is followed with dyspnoea, (difficulty of breathing,) cough, and spitting of blood. Having occasion some time ago to compound the medicine for several days together, he became seriously affected by it, in the way just stated, and he has not enjoyed full health since. It has evidently produced a disposition to

* "THE ANIMAL KINGDOM," by T. Rymer Jones, p. 588.

THOMPSON'S "ANIMAL CHEMISTRY," p. 538.

asthma, and an aptitude for pulmonary ailment, which he had not used to possess.

"In the year 1787 or 8, in pounding the root to make the Ipecacuanha Wine, I was suddenly affected with violent and reiterated sneezings, with a very profuse defluxion from the eyes and nose; these symptoms continued without intermission for many hours, accompanied by great heat and anguish throughout the cavity of the thorax, and the most oppressive dyspnea. Exhausted by the violence of the attack, I was conveyed to bed, where, supported, for I was unable to lie down, I remained more or less afflicted till the next morning. I arose extremely weakened, and with all the usual appearances of a severe catarrh. From this date I have been perpetually tormented by violent catarrhs. The slightest motion of the simple or compound powder of Ipecacuanha superinduces precisely similar, but more gentle effects. When weighing or mixing these powders afterwards, I carefully guarded my mouth and nose by a cloth; but an incautious removal of it for inspiration, till perhaps half an hour had elapsed, after the medicine was finished, occasioned the same inconveniences. At length I was compelled to quit the shop when Ipecacuanha was in hand; indeed I have frequently entered my own, or the shop of a stranger, long after it had been used, and by the instant recurrence of these very distressing sensations, have been able too accurately to ascertain the recent exposure of this drug.

"I never designedly had recourse to Ipecacuanha for more than twenty years. Two accidents lately, within a few weeks of each other, afforded me the opportunity of determining its present effects when inwardly administered. A friend hearing me cough in the street, presented me with a few lozenges; I took two at once; they were scarcely dissolved, ere I felt a pungent roughness in every part of the mouth, exciting a great secretion of saliva ; this, it is worthy of noting, was the reverse in the preceding attacks, when the excretory ducts uniformly denied their offices, and occasioned a disagreeable dryness of the mucous membrane. As this acrid sensation extended to the lips, they became prodigiously swollen and inflamed. On the fauces I experienced the like effects, with a most teazing itching irritation; it descended the trachea, producing pain and dyspnoea; it likewise proceeded down the oesophagus, creating a slight heat in the stomach, and passed with moderate gripings throughout the intestinal canal.

"Soon after, a powder was brought to my house, with an order to prepare more of the same kind. I conveyed a few particles to my tongue to discover its composition; I quickly experienced

*Mr. Spencer, Medical and Physical Journal, June, 1809, Vol. 21, p. 485.