and plates under black rubber, as we ever see where red rubber is used. Two of these cases have had red rubber substituted for the black. The first case has healed sound and well under the red rubber plate; the other is of too recent date to say what the result will be. Dr. Hall says, I admit the possibility of mercuric sulphide injuring the mouth. I did not use the term at all. I did say, the less amount of red sulphuret of mercury used in compounding the rubber, the less liable to injure the mouth. I presume any one can understand that there could be such an excess of vermillion, that the caoutchouc would not prevent its disintegration in the mouth, and then we might look for what we have not yet seen-mercury absorbed by the gums from rubber plates. Yet, Dr. Hall advises the use of the rubber containing the most vermillion. Respectfully,

W. E. DRISCOLL.

GERMS AND ACIDS.

SUBSTANCE OF PAPER READ BY PROF. J. S. CASSIDY, M.D.,D.D.S., BEFORE THE KENTUCKY STATE DENTAL SOCIETY.

So much thought has been expressed of late in favor of and against accepting the so-called 66 germ" theory of disease in general, and of dental caries in particular, that I would hesitate to say anything on the subject were it not for an honest desire to accept both sides of the question and try to reconcile, in my own mind at least, the difference in the relationship between the germ and the acid, whether sought for in the human mouth or in other conditions, favorable to spontaneous passage of highly organized compounds towards what we call simpler forms of matter.

The influence of minute organisms in causing putrefaction or decay, has been recognized as a fact almost since "the morning stars sang together," Of late

years the microscope has demonstrated the existence of many distinct and indistinct species of the germs bacteria, and, perhaps in its own sphere and circumstance, really does promote the disease Iwith which it is credited. There still remains, however, the open question for science to answer : "In what way is their influence accomplished?"

All modifications of force effect chemical changes, easily or otherwise, according to laws and conditions, known or unknown, of mutual affinity between the reacting substances; and "vital" force, whether animal or vegetable, is the most persistent in its selective action, overcoming adverse physical conditions of matter in order to assimilate that by which the principle of life may be sustained. With bacteria, organized structure or the debris of such is required for food, much as with animals of more pretension; they cannot construct proteine from the mineral kingdom, hence inorganic material neither putrefies nor ferments. Neither would organized matter, when excluded from germinal influences, suffer the spontaneous decomposition; terms, by the way, having the same general chemical significance, except the odor. It is well known that the average human mouth is peculiarly favorable to harbor all the requisites for active changes. Eight different kinds of bacteria have been detected there, any one of which, at the normal temperature, can induce molecular disturbances in the semi-liquid, highly organized residue of food mixture and mucus. It is a most convenient and luxurious dish for them, as, indeed, are all other similar mixtures and more or less devitalized tissues generally. But in what way is the degenerative metamorphosis induced? the removal of certain constituents from the mass in order to nourish and multiply the bacteria ? or is it that they bring with them the essence of catalytic influence, which by mere contact changes the alrea

Is it by

dy predisposed complex fluid or living tissue into their own proper food? thereby, in the case of fluids, extraneous or otherwise, reducing the residual or most easily affected organic compounds into simpler forms, and with living tissue provoking inflammation, and, perhaps, specific disease. The latter view seems to be in consonance with the general idea of germ influence, premising, however, that the substance or part affected thus must in all cases be in such perfect physical and chemical condition as to furnish the bacteria with their natural and sufficient nourishment.

Nor

Now, in all fairness, in the light of experience and common sense, is a tooth, alive or dead, ever in such condition? We answer most emphatically, no. do many of the germ theorists claim such to be the case; a few, at least, admitting that the bacteria crawl, while a large majority, according to my reading, admit that the enamel must first be softened by an acid in order to permit the little animals to feed on the sweet gelatinous portion of the interior, and by such feeding merely comes the disease known as dental caries, in all its varieties. Is not this, so far, a fair statement ?

On the other side, (let us agree that it is the chemical side) the fact has always been well known that an organism of some kind was a necessity to fermentation. But fermentation is neither more nor less than chemical change, and, though the substances be whatever they may, if the process be allowed to continue uninterruptedly to the end, it will be found to consist first of due preparation for the reception of germs, then rapid passing through several stages, each stage producing its own peculiar compounds, until finally the acid stage is reached, at which point the process, per se., is at an end. Let a given mixture be prepared as food for bacteria, and we can foretell nearly all the several compounds which

will ensue, down to the typical acid of the special process. But with such mixtures of animal and vegetable matters as must of necessity exist, much or little, in the omnivorous human mouth, as soon as decomposition begins, the results are modified, not alone by the vicissitudes peculiar to the past, but also by the oft recurring changes in the composition of the heterogeneous mixture itself, so that no prediction can be made from day to day as to the probable result; the process is beyond our control. There is, however, one important fact to remember, that an acid is the usual ending of every process of fermentation, and there is no truth in chemistry of which I am more fully convinced than that an acid in its nascent state is the beginning of dental caries, and, indeed, the only solvent throughout the entire course of the disease.

PERFUMED CARBOLIC ACID.-Perfumed carbolic acid is prepared from carbolic acid 1 part; oil of lemon, 3 parts; alcohol, (36 degrees) 100 parts; mix. The antiseptic properties are in no way affected by the oil of lemon.-Med. Press.

THE QUERIST.

ED. PRACTITIONER:-What kind of varnish is best to use for sand-paper disks, and the best way to cut them so I can do it myself.-G. W. P., WIS.

ED. PRACTITIONER:-After vulcanizing a black rubber case in the new mode heater, and laying aside for a few days, I found my case turned a light brown. What is the cause of it?-A. F. G.

ED. PRACTITIONER:-Will some one enlighten me as to the durability of a Bunson Battery, and the time a set of zincs would last? What would be the objection to a Fuller Battery being used with the electric mallet ?—J. P. R., N. Y.

with the assurance of dealers of truthful and well-tried standing. The older the manufacturer's experience in the production of an article of specialty, the better trained is his judgment for certainty in combination, and the good policy of honest dealing. New competitors can rarely produce an imitation that should tempt the user from comparative certainty, for a majority of the vaunted discoveries and appliances in medical art are but the reproduction of past speculations in guise, adapted to the empirical tastes of the Gulliver family.

Even the class rated as valuable inventions and discoveries, such as the art of printing, innoculation, flesh ingrafting and projectile explosives, etc., are of undoubted Chinese origin, and the former were as plainly indicated in his descriptions as the latter, under the style of polvoro fulminati de Chinie, by Marco Polo. There is also abundant proof that dentistry in a primitive form was practiced by the Chinese ages before the discovery of America; and the decayed teeth of the Herculaneans were successfully filled with Pussolian cement long before the Vesuvian vulcan smothered them with an excess of raw material. But nature's hints, as well as the practical suggestions recorded in manuals of scientific research, are alike disregarded and forgotten in the passage of a generation, until some empirical adventurer, trusting to the engrossment of the public with affairs of the present, adopts the lusus and reissues it in disguise as a discovery of his own. No matter how absurd and ridiculous the benefits offered in exchange for the purchase money, the members of the Gulliver family, of which the public is largely composed, immediately seize upon the gudgeon bait, and make no attempt to disgorge until their vitals feel the hook. an illustration: There is in the Hunterian Museum of the Royal College of Surgeons the section of a hen's head. in

As

the comb of which is imbedded a human cuspid tooth, vide catalogue and illustration on page 628 of "Once a Week,” vol. 3, etc. Upon the illustration of this freak of nature Dr. Hunt, of Cincinnati, and Younger, of San Francisco, have advertised the medium of a cock's comb for preserving the vitality of human teethin waiting transition from one mouth to another-for transplantation.

Even the conductor of the Rochester Odontographic Journal, in giving a reprint of the illustration, expresses a doubt of its authenticity, with the flippant heading of "The Innocent Abroad," which, in refering to the devotee excursion of the New York pilgrims to Jerusalem, as depicted by the humorist, affords an apt expression of his position and the times. In the scene of caricature he dismounts on reaching holy ground, and, with exemplary veneration, raises and bears the ass upon his shoulders, until the sighed exclamation of "Mark Twain" from the rear reminds him that appreciative humor can co-exist with reverenced absurdity. "When doubt and ignorance doth the head incline, Gosling wit flows rampant in every line."

NOTTE O. EILIMS.

METAL CASTINGS FOR DIES.

A perfect metal die and how to make it in the least possible time, is a question frequently occurring to the dental practitioner. If it could be made in a few minutes, without soiling the hands with damp sand and black ladles, it would be a pleasant and agreeable business, but until that desirable time arrives we will have to go on in the same old way, with an occasional improvement now and then.

Among these improvements I will here give some that I have adopted and found to expedite my plate work in a very satis. factory way.

I use the ordinary moulding sand, with the addition of powdered pumice stone,

which I have found, from long experience, to be better than the addition of powdered charcoal. The fresh moulding sand having too much clay, requires the pumice to make it light and porous, allowing the steam to pass through when the melted metal is poured on it. The proportions are two-thirds fresh sand to one-third powdered pumice, dampened with clean water.

I keep this moulding sand in a zinclined box with a tin lid. A little water thrown over the sand after using will keep it damp and ready for instant use for weeks, a saving of valuable time when hurried with pressing work.

The moulding box or flask I use is circular, without top or bottom; each edge is turned over a wire to stiffen it; with a groove about the middle to keep the sand from falling out when turning, and is made of galvanized sheet iron four inches in diameter, two inches and three-quarters high, made thus so as to take as little sand as possible. This box will answer for all cases, when the plaster casts will fall out with a slight tapping with the finger. Where the gum is considerably undercut, the Hawes flask is the proper thing, although I find but little use for it.

In moulding, the plaster cast is placed in the centre of the flask, a handful of sand is sifted over the top of the cast, a little sprinkled at the side of it, then gently pressed close to the face of the cast with the fingers. The box is then filled, and gently pressed down and smoothed off with a leveler. It is in pressing the sand into the flask where caution is needed. The instant the melted metal is poured on the damp sand, steam is made; it is bound to go somewhere, and if the sand is packed very hard and close, the steam will go through the melted metal, called, in technical language, boiling. To prevent this the sand. should be packed lightly, which allows the steam to penetrate through the sand

and escape in this way, without injury to the cast. W. R. HALL..

[TO BE CONTINUED.]

A FEW QUERIES ON THE SUBJECT OF DENTAL EDUCATION.

MR. EDITOR :-Why is it so frequently remarked by competent judges that if a class of students are good plate workmen they invariably do poor work at the operating chair? Is not two years a very short time in which to study anatomy, physiology, chemistry, therapeutics, and at the same time acquire proficiency in the art of filling teeth and of making artificial dentures?

Why should a man who wishes only to practice at the chair be compelled to learn to make artificial sets? or, why should the mechanical dentist be forced to take such an extended course in the studies which belong solely to the medical profession? It is just as absurd as it would be to require a physician to be able to make an elegant false leg, or to declare that a manufacturer of artificial limbs should not be allowed to follow his vocation unless he had been graduated as a physician. The courses on mechanical and operative dentistry differ so widely that they ought to be entirely separated. If a young man wishes to learn both branches, he can do so. But I do not consider it either just to the student or politic for the profession, to require it. Why are there no entrance examinations in the dental colleges to keep the scum of the farms and the blockheads of the counting rooms from pouring, without restraint, into our profession? As matters stand now, the man who fails in business because he can't write a respectable letter or add accounts correctly, the milkman who tires of rising early in the morning, the huckster whose throat has become worn out from excessive shouting, all may