through it without any diminution of their brilliancy, and which revolves round the sun in 1,208 days, has its period slightly diminished during each revolution. It is evident 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 show 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, gasses 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 gasses 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 the form of matter last named 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 5000 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 127,000,000 (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.

Chemical division is equally successful and surprising. I have been able to show the presence of iron in the third dilution of the sulphate; that is, to detect the 1,000,000 (millionth) of a grain of the sulphate of iron; this particle was not a simple atom, but consisted, of course, of still smaller quantities of sulphur, oxygen, and iron. Sir Robert Kane says that a quantity of silver, equal to the 1,000,000,000,000 (billionth) of a cubic line, can be readily detected.'

Even organic substances, which are very compound bodies, and therefore experimented upon with more difficulty than minerals, can be detected in exceedingly small quantities. Mr. Herapath has given in evidence the following statement:

1 Elements of Chemistry,' by Sir R. Kane, 2d edition,

p. 7.

"I am perfectly sure that I could detect the 50,000th part of a grain of strychnine, if it were unmixed with organic matter. If I put ten grains in a gallon or 70,000 grains of water, I could discover its presence in the tenth part of a grain of that water." 1 Now an atom, the most minute conceivable particle of strychnine, is composed of about 30 atoms of carbon, 16 atoms of hydrogen, 1 atom of nitrogen, and 3 atoms of oxygen. Each of these particles must be very much less than the particle of strychnine, which contains 50 of them.

It can scarcely be needful to remark that any particle of matter, however minute, which can produce a visible effect upon an inert chemical re-agent, must have power to act upon the sensitive nerves of living animals. It is therefore not surprising to hear Mr. Herapath, after making the statement which I have quoted, go on to say, "I made four experiments with a large dog to which I had given the eighth part of a grain of strychnine. I have discovered it by change of colour in the 32d part of the liver of a dog."2

That particles become divided into less portions than is shown even in these examples is evident from the daily observation of the sense of smell. The violet fills a royal apartment with its sweet odour, which is thus readily perceived, but which eludes every other mode of observation. inconceivably small must be the particles of all odours! And yet they are material.3

How

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.

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,

'The Times,' May 23, 1856.

2 Ibid.

3 I express this as my belief, notwithstanding the suggestion lately made that odours may be undulations.

or the yellow fever of the West Indies?

The microscope

cannot show 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

are well-known examples. In the venomous serpents there is

found an 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 (6) 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.1

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.2

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

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

1 'The Animal Kingdom,' by T. Rymer Jones, p. 588.