which she works. We know that certain causes produce certain effects, long before we discover in what way and by the help of what laws the result is brought about. So we have been groping along with our various theories on light, heat, sound, electricity and the constitution of matter for hundreds of years. We believe and know that each hypothesis is a little better than the previous one, and that each theory proves up better than any that has been heretofore imagined. For all these things are a matter of imagination, and strange to say, it is not in the world of fiction, nor in the realm of poetry alone, that the one who had the most brilliant imagination is considered the most advanced thinker. In science we imagine a cause for the phenomena that we notice, and then go to work to prove as many cases as possible in which this cause will fit all the conditions of the problem.

There are some things that we think we know all about, till suddenly the scientific world is awakened from its security by an announcement right along the old beaten track, of a startling discovery. Such was the finding of argon and helium in the atmosphere about three years ago. There were hundreds of tons of the argon, or "lazy gas" as some have called it, in the air, yet we had never discovered it, simply because it was taking no part in chemical reactions. It was doing nothing, so its presence was not

recognized.

We are accustomed to regard matter as existing in the three states of solid, liquid and gas; and we regard these three states as dependent on conditions of temperature and pressure. Every known gas has been liquefied. This includes within the last few weeks hydrogen and helium. And we are familiar with the fact that by the use of liquid air it is possible to obtain a temperature of nearly 250 degrees below zero centigrade. Many of the laws of matter in the solid and in the gaseous state have been dug out; but more recently it has been left to such men as Ostwald, Pfeffer, Raoult, Arrheinus Nernst, and a dozen others, to show that the laws that apply to gases apply to solutions as well. This has been proved by careful laboratory and mathematical researches. It was not, however, done at a single, shrewd guess, but in the ordinary scientific method, by which each experimenter and thinker adds his mite to the accumulating pile of evidence, till finally a great symmetrical theory makes its appearance.

By studying the pressure of some of the gases or vaporized solids, it has been shown that at high temperatures they are broken up into distinct parts, or dissociated. For instance, the common

substance, ammonium chlorid, breaks up into N H4 and Cl. Again, the German physicist, Pfeffer, has studied pressure in solutions, as, for instance, the pressure of the molecules of sugar in a water solution, and has learned that this osmotic pressure, as it is called, is enormous in quantity, and is proportional to the degree of concentration of the solution. Van't Hoff says: "The osmotic pressure of a substance in solution is the same pressure that it would exert were it in a gas form, at the same temperature and occupying the same volume." Further, Arrhenius has shown that "those substances and only those that give abnormal osmotic pressure, are capable of conducting the electric current, and if these substances are dissolved in any other solvent in which they act normally, they lose that power."

This immediately brings up the question, How does a solution conduct electricity? It cannot conduct as a wire would, for the solution is decomposed and the wire is not. Grotthus assumed that the electricity was carried bodily, we may say, by particles of the dissolved substance from one pole to the other, and when the particles arrive at the poles they discharge their electricity. Many years ago Faraday gave the name "ions" to the little particles of matter which carry the electricity from one pole to the other. Now we have come to believe that all substances in solution, which conduct. electricity do so by means of ions, and these ions are the broken-up molecules. I admit that it is difficult to conceive of these ions; they are not really independent particles, but particles that can move independently of any other ions, for each ion is under the influence of some other ion, which has the opposite sign; if one is plus the other is minus. The conclusion has been reached that aqueous solutions of substances which conduct electricity, or electrolytes, as they are called, consist in part or wholly of separate ions; these ions respond to the slightest impulse; hence, they must move independently of each other. Referring again to the difficulty of conceiving what the ions are, Ostwald says, in the case of potassium chloride, for instance, we do not recognize the gas chlorine, nor the metal potassium in the solution, and we cannot readily understand how the dissociation can have taken place. But the elements, as we know them, are molecular combinations in the case of chlorin of two atoms, and in the case of potassium of an unknown number of atoms. No one ever pretends that he has seen an atom of any element, for the atom cannot exist, by its very definition, uncombined. The chlorin and the potassium in solutions may be regarded as the elements in the atomic condition. Again the elements contained in

this solution are charged with enormous quantities of electricity, positive and negative, respectively, and we should not expect these particles to behave as molecules of the salt behave.

One point more: In the case of a metallic salt, or of a strong acid or base, when this is in solution, a part of the substance exists as the original molecule, and a part is dissociated into its ions, and as the solution is diluted, more and more ions are formed, till finally the solution is in a complete state of dissociation, that is, all the particles are ions. This point of dilution differs greatly for different substances. The properties of a dilute solution must depend then on the binary properties of its free ions, and not on the properties of the original salt dissolved.

This much has been said, by way of preface, so that the generally accepted theory of solutions, which we propose to apply to the action of dilute solutions upon the mucous surfaces of the body, may be thoroughly understood.

The proposition that we intend to discuss is this: Is it not probable that in concentrated solutions of remedial agents, we get essentially the action of inactive particles on the system, while in the dilute solutions we get the action of the active particles or the dissociated molecules? Electrolytic dissociation was first announced by Arrhenius in 1887. He divided the molecules in solution into two classes the inactive ones, which can split up into ions, as noted above, and the active ones or those that already exist in the solution as ions. The inactive particles do not take any part in conducting the current; it is only the ions that are doing this. And is it not also probable that the action of the ions on the system would be entirely different from that of the undissociated molecules?

The first reason to suppose the above proposition to be true is that in chemical reactions between different substances in solution, or solates, as they are called, no action takes place between the substances as a whole, but only between the ions of the substances. It is proper to infer from this that if the ions only act chemically, these will be the particles that will act therapeutically, when brought in contact with an absorbing surface of the body. To illustrate this theory with reference to chemical action a common test for sulfuric acid or a sulfate is barium chlorid, and it makes no difference whether the acid be free or combined, a white precipitate results from the mixing of these two substances. If sodium sulfate is examined, it is assumed that the SO, ion unites with the Ba ion, and the molecule of BaSO, results. The same thing is true of the use of silver nitrate as a test for chlorin, or any chlorid. Where

there is a free chlorin ion the silver salt unites with it; but in the case of potassium perchlorate (KCIO,), where the ions are K and CIO,, there being no free chlorin ion, there is no precipitation by silver nitrate. Reasoning by analogy, what is true of the action of chemical compounds, will be true of the action of remedial agents on the system. Then the dissociated particles, which it has been shown are present in a greater quantity proportionally in dilute solutions, will be the ones that will be absorbed and will act.

Second-It has been shown that only dissociated substances act as germicides. In other words, the solutions of substances, be they never so powerful, according to these researches, if they are not in a condition to be ionized, produce no effect on the bacteria. Every one who has experimented with such an antiseptic as corrosive sublimate, knows that it will act in extremely dilute solutions; it is asserted on good authority that I part in 15,000 is effective as an antiseptic, and that a solution of 1 in 300,000 has a decided influence in restraining the growth of some spores. Some of your own number have even reported that a solution of II plus 24 o's was fatal to certain lower forms of life. A solution of silver nitrate 1 to 1,600,000 inhibits the growth of aspergillus niger, and sufficient silver was dissolved by the action of water on a silver dish, so that the organism could not live in it. Is this not an illustration of ionization? Are these minute, delicate organisms not susceptible to the ions of dissociated substances, as they could never be to the undissociated molecule?

Third-It is a common practice among homoeopathists, in case very early action of a remedy is desired, to dissolve some of the substance in water, and to direct that small portions be taken at intervals. This exactly fits into the method that would be suggested by the dissociation theory. In the dilute aqueous solution we should expect complete dissociation to take place, and we should have the ions free and undisturbed by a large quantity of undissociated molecules, to act on the system. These conditions are then more favorable for speedy action than any other that we can conceive. The practice may be old, but the reason for this practice, if we accept this theory, is apparent.

Fourth-It is also the practice to administer a remedy upon the tongue. This may be exhibited in the form of a triturate with milk sugar, or some inactive substance. What are the conditions here? There would be comparatively only a few molecules in the powder that is placed on the tongue, this dissolves in the saliva, and there is nearly complete ionization; in other words, it acts as a dilute solu

tion. These ions are quickly absorbed by the mucous surface, and act on the system. We may not understand how the particles get into the circulation so quickly, but it is a fact that cannot be controverted, that a remedy is very quickly taken up by this method of administration.

Your speaker had a good illustration of this fact a few years ago, when, in order to taste the sweetness of nitroglycerine (glonoine, if you prefer), he licked an open cartridge. The effect with which you are familiar, violent throbbing in the temple, paleness and faintness, was apparent almost instantly. All practitioners agree in the rapidity of absorption in this way. It is stated that 1-1000 of a grain of aconite, held in solution in water, dropped on the tongue will cause a numbness that will last for an hour.

Fifth-When we are dealing with mineral acids and strong bases it has been found that here the ionization is quite complete even in solutions that are not very dilute. As we progress in the direction of weaker acids and bases and organic acids, the ionization is not as complete in ordinary solutions; that is, dilution must be carried farther to obtain complete dissociation. Sulfuric acid is dissociated into H and SO.. This ionization of acids has been thoroughly studied by Richards and later by Kastle. It leads us into the interesting field of the relation of taste to the acidity of acids, a subject that has been investigated by your speaker from several different standpoints, several years ago. In regard to acid muriaticum the molecular conductivity increases to 1-1000 normal, then it becomes constant. The molecular activity of acetic acid increases with the dilution as far as the dilution can be carried by the conductivity method. Many organic acids and bases are only weakly dissociated at ordinary dilution; acetic acid not at 10,000. "The dilution at which complete dissociation takes place lies far beyond the possibility of applying the conductivity method directly." (Jones.)

Sixth-Neutral salts are most completely dissociated, and hence could be given in more concentrated solutions to produce the same effect. Again, the authorities state that "Solutions of very difficult soluble substances may be regarded as completely ionized." This is of the greatest importance, as it will clear up a point that has been often misunderstood. How, say some, can any effects be obtained from a remedy that is insoluble, like silica, or sulfur, or aurum? It is conceded that solubility is only comparative; some substances are more soluble than others; none are theoretically absolutely insoluble. All elements it is supposed are found in the water of the ocean; in fact, a company has recently been formed to