the canal is filled with moisture the greatest care should be exercised not to use a paper cone or any other substance in such a manner as to force the contents of the canal through the apical foramen. In order to satisfy yourselves how easily this latter mistake may be made, I advise every dentist to take a disassociated tooth with an open canal, fill the canal with water colored with eosin, or other matter that will render its presence on the outside of the root easily detected, and then endeavor to use a broach of pledget of cotton in the canal. Only the most delicate instrumentation will prevent the contents of the canal being forced through the foramen.

After the canal has been reasonably well freed from pus, disorganized pulp tissue and putrefactive matter, by the use of hydrogen dioxid and careful instrumentation, I dry it out with paper cones, still using great care not to use them so as to form a piston before which moisture must be forced through the foramen. The canal should then be filled with alcohol and a hot wire introduced. I use a wire heated by electricity, but the Evans root canal drier, or even a simple wire heated in the flame of the alcohol lamp may be used. The alcohol combines with the water remaining in that portion of the tubule adjacent to the pulp and canal and the diluted alcohol is evaporated by the heat of the wire. This treatment should be continued until the dentin lining the root-canal is thoroughly desiccated.

The reasons for this are twofold. Desiccation is, in itself, a sterilizing agent. But a more potent reason is to be found in the fact that wet dentin presents greater difficulties when the use of a Gates-Glidden drill is contemplated than dry dentin. More failures in the use of the drill in canals is attributable to wet dentin than any other cause. More broken drills are due to wet dentin than to carelessness in handling.

The next step in the treatment is the use of sulphuric acid in the canal. In my opinion a 40 per cent solution of commercial sulphuric acid in water will give the best results in the majority of cases. I have used as strong as a 50 per cent solution to advantage. If the solution is stronger than 50 per cent it has a tendency to disintegrate the cotton on which it is most convenient to introduce it. With a drop or two of the sulphuric acid solution at the entrance to the canal, I use a new broach, pumping the solution into the canal in the manner that is familiar to you all. This pares away all rough places in the canal and disintegrates the inorganic constituents of the dentin

with which it comes in contact. After reaching the constriction at the end of the root, or, if the case seems to call for it, before that time, I introduce a few drops of a saturated solution of sodium bicarbonat. The chemical reaction between the sulphuric and the sodium bicarbonat results in the formation of carbonic acid gas. If enough of the acid and alkali are used, audible explosions of carbonic acid gas may be heard issuing from the canal. This is an event to be desired and looked for. In this connection it may be well to state that occasionally a broach may be broken off in the root-canal. When this occurs no effort should be made to remove it by instrumentation. Such an effort is almost certain to result in the fragment being pushed further into the canal, and possibly wedged firmly down near the apex. As soon as it is ascertained that a fragment of broach has been broken off, the canal should be filled with the acid solution and some of the sodium bicarbonat solution placed in the crown cavity or pulp chamber. As the alkali works its way rootwards, successive explosions of carbonic acid gas will occur, until eventually gas will be formed by the action of the alkali on the acid in the root canal beyond the broken broach, and the latter will come up into the crown cavity in a boiling, frothy mass of matter. This seldom fails.

When the apex of the root has been reached and the walls of the canal have been smoothed by the broach and acid, the den tin should be again dried with the alcohol and a hot wire, and drills should be used to enlarge the canal. At least two sizes of drills are necessary, as the object is to give the canal a cone shape with the apex at the end of the root. The use of the acid renders the following of even quite orooked canals an easy matter. The acid partially disintegrates the mineral matter of the dentin, which, when dry, is most easily cut away.

The enlargement of the canal also serves a twofold purpose. It renders the introduction of dressings, medicaments or rootcanal fillings as an easy matter. But, more important than that, it cuts away the zone of dentin along the canal, in which it is reasonable to suppose disintegration of the organic matter and consequent infection has occurred. That is a most important achievement. The removal of this infected dentin also leaves the open mouths of the tubules ready for any medication that may seem necessary.

I said before that if there is caries in the crown at all it is fair to suspect infection of the dentin adjacent to the canal.

Miller proved this by showing cases where the micro-organisms of decay had passed through the tubules of the crown of the tooth to the pulp chamber, and down the pulp canal fully halfway to the apex, disintegrating the fibrils along the walls even before serious loss of tissue had occurred in the crown. And I also stated that if there were good grounds for suspecting infection of the entire area of the root-canal, infection of the tissues beyond the apical foramen must be considered. On the principle that "prevention is better than cure," I treat every case of partial or total cessation of function in the pulp the same. In these cases I proceed as above described, except that I get a free opening through the apical foramen into the tissues beyond. I do this usually with a drill. When an opening has been obtained, I pump sulphuric acid through into the tissues beyond, following it with the sodium solution. If diseased bone is present, the acid has a most beneficial effect upon it. If no diseased bone is present, the acid, if followed up with the alkali, produces no ill effects.

If a so-called "blind abscess" exists, this method of treatment is most beneficial. If a fistulous opening exists, I pump the acid clear through until it comes out on the gum. In case of a recurrence of the abscess after the root has been filled, or in case of a very crooked root with a blind abscess on the end, I inject the gum with nirvanin, make a crucial incision, dissect back the flaps and make an opening through the alveolar wall to the end of the root. I then amputate the end of the root and bur away the bone freely. This operation is much easier and simpler than extracting a tooth, and the percentage of absolute cures is very high. It is almost a certain result.

I use chlora-percha* and gutta-percha cones, with which to fill the canal. I am not strenuous in regard to the material with which the canal is filled. The treatment of the canal, therapeutic and operative, is of more importance than the filling material, although the latter should be the best of which we have any knowledge. Gentleness in introducing the filling material is of the greatest importance. Hasty introduction of the guttapercha cone may make air pressure through the foramen that will cause pain, pain that cannot be relieved until the cone is withdrawn.-Indiana Dental Journal.

"Gutta-percha dissolved in eucalyptol is much preferable on account of its continued antiseptic properties.-ED. JOURNAL.

Professor of Electro-Therapeutics, College of Physicians and Surgeons of San Francisco.

Vibration is a to and fro motion of the molecules, with slight, if any, change of relative position. Vibratory action will be easily understood by accepting the theory of an interstellar, intermolecular and interatomic ether, a luminiferous body* co-extensive with space.

Molecules of matter, as well as matter in bulk, float in an ethereal ocean, and between the ether and what we consider as matter, there exists an equilibrium the disturbance of which is the cause of all vibration. By the creation of a so-called vacuum matter is excluded from a certain space, but ether is admitted; light and heat will travel through the vacancy, because ether is their medium of expression.

The continual contraction of the sun's substance or that of other luminous bodies, the chemical readjustment of molecules by the burning of a candle or jet of gas, the kinetic force of atomic ether in an electric current, and all other forces that produce illumination or heat, set free molecular ether and disturb the universal equilibrium. But for the other forces, the nascent ether would form a vacuum at the point of elimination, but the surrounding atmosphere acted on by gravitation rushes in and the ether again becomes intermolecular by displacement. The vibrations set up by the displacement constitute heat and light according to their frequencies. These phenomena are the physics of ether. Electricity is ether's chemistry.

All the world and worlds are divided into positive and nega

*If "body" is not applicable, a new term will have to be invented. On the other hand, the term "matter" in this article does not apply to ether. VOL. XLIII.-81.

tive, so it is with ether. Positive and negative atoms combined are the ethereal molecule; when the atoms are separated we have an electric potential, due to the general law that likes repel and unlikes attract. By the following formula the different manifestations of vibratory force as expressed, through the medium of ether and matter, and the relative positions of the ethereal molecule and electric charge to matter, will be made clear:

The spheres represent molecules of matter; the plus and minus combined represent molecular ether intermolecularly placed as to matter; while the extra plus represents atomic ether or a charge by positive electrification. If the material molecules vibrate freely, they will transfer by convection the atomic ether from molecule to molecule, as in the case of electric conductors; on the other hand, if the molecules are firmly set in position and vibrate slightly or with difficulty, they will constitute electric non-conductors. Glass is transparent because its slight molecular movement does not interfere with the free vibration of its intermolecular ether; at the same time it is a non-conductor, because the ether atom being adherent to the material molecule must be carried over the intermolecular space by convective vibratory action, which is not sufficient in this case. It will thus be seen that the charge of atomic ether must partake of all motory changes that take place in the material molecule; moreover it is clear that transmutation of vibratory action between molecular matter, molecular ether and atomic ether, must be reciprocal. This last postulate is of first importance to the subject matter of this article.

The above formula will equally represent the copper wire of the submarine cable or of the telephone, or the axis cylinder of nerve tissue, and here comes up the interesting subject of vibratory conduction by nerve trunks and vibratory appreciation by nerve centers; for nerve tissue must be capable of vibrating in sympathy with external vibratory action as manifested in sound, heat and light, before cognizance is taken of these external phenomena. Hence, from the necessity of this power of differentiation we cannot see with our ears nor hear with our eyes, nor smell, taste or touch with our optic or auditory nerves, although the difference in sensation is fundamen