and be placed in front of a window; the left end to contain the lathe head and driving wheel for grinding and polishing plates. A two-inch swivel bottom bench vise, bolted firmly to the middle of the bench, with parallel jaws, turns to right or left side, as is wanted. The right end has the filing stake of hard wood standing upright, and is movable, fitting into. a square hole near the edge of the bench. The drawers are below it, the upper and narrowest one to hold the tin pans for gold and silver scraps; the under and largest to catch the rubber filings, bits of plaster, etc., instead of throwing them on the floor. The ends and back of the bench should be enclosed with a strip of wood four inches high, to keep things from being pushed off and also to hold the tool rack.

The tool rack should be strong and extend the whole length of the bench. The neatest and strongest I have seen was made of a strip of number 22 sheet brass, five-eighths of an inch wide, punched an inch apart with holes large enough for a one-inch round headed screw to pass through, near to the top edge, by passing the screws through the holes in the brass strip into and through a half-inch long ferrule, and then screwed to the walnut strip. The ferrules are made by cutting with a jig-saw, half-inch pieces off a brass tube just large enough in diameter for the screws to go through. No rack I ever used ever equalled this, in neatness, strength or durability, and it never wears

out.

A drip box to hold the water and sponge for use when grinding teeth, polishing, etc., is made of sheet brass or copper, six inches long by five wide and two inches deep, and the top edge of one side and end is curied over to form a resting place for the hand; a false bottom of brass wire gauze is loosely placed half way from the bottom to keep the sponge out of the mud which collects at the bottom

of the box. The mud, which frequently contains gold and silver grindings, can thus be saved. At the back of the drip box, on the inside, a long loop of sheet brass is soldered at each end, to hold the dust catch-a piece of sheet brass four inches wide and long enough to curl partly over, and near to the polishing brushes when in use; when not in use it can be lifted out and put one side.

The brush and wheel box is another fixture made of tin, six or seven inches square, with a piece of inch-thick board nailed to the back part, some two inches higher than the box, in which headless nails are driven part way, for the purpose of holding the polishing brushes, corundum wheels, buffs, etc. The nails or pieces of wire are driven into the wooden back at different angles, so as to accommodate some two dozen chucks.

Felt wheels can be made more durable if the sides are coated with melted shellac before mounting them on the mandril; a heated knife blade held against the shellac will melt it part way into the felt; the buff treated in this way will remain the same thickness until entirely worn out.

Brush wheels can also be made to last longer by thoroughly oiling the wooden hub before mounting them on the mandril. Several coats of oil are necessary, allowing several days for the oil to soak through.

Blow-pipes of the latest make are a decided improvement on the old air pump and separate gas flame. The new ones, with double tubes, one for air, the other for gas, suspended and revolving on a stand, are about as near perfect as any one need want. A stop is provided to regulate the flow of gas, producing a large or small flame, as is required. A Smith bellows supplies the force and air, and the heat is sufficient to melt several pennyweights of scrap gold, or for making solder. I have melted as much as fifteen pennyweights of gold on a flat carbon

crucible attached to a tilting ingot, with this blow-pipe. In a few minutes a square piece is turned out, ready for the rolling mill.

The carbon crucibles are composed of clay, asbestos, plumbago and pumice pressed into a tin mould two inches square, the sides a quarter of an inch high; while still soft a flat depression is made in the centre, which confines the melt to one spot. The tilting ingot is made by the Buffalo Manufacturing Company, and sold at dental depots.

A clay support, to hold work to be soldered, is readily made of a sheet iron ring five inches in diameter, a handle riveted to one side. Punch a few holes near the top edge for wires to cross in different directions. The wires are covered with a batter of plaster, clay and asbestos, equal parts, about a half inch thick and well dried before using.

I have found the ordinary coal-oil lamp, with the notched or fluted chimney, an excellent heating lamp to dry invested teeth or small pieces of work for soldering.

A wire director to pull the melted solder into difficult places, had better be pointed with platinum wire, as it is more durable and leaves nothing objectionable to mix with the solder. A piece of number fifteen, about two and a half inches long driven into a brass tube, and that tube into a wooden handle, is about the best.

Instead of the old slate, generally used to rub up borax, a small cold-cream glass jar, with a glass stopper to grind up the powdered borax is neater, takes less room, and, what is better than all, keeps the slate out of the borax.

W. R. HALL.

As a medium to advertisers I have found the PRACTITIONER equal to, if not the best of, any dental journal in the east.

J. S. CHARLES, D.D.S.,
Philadelphia, Pa.

CELLULOID.

BY FRANK R. FABER, D.D.S., MECHANIC TO THE PROFESSION, PHILADELPHIA.

In answer to the oft-repeated questions regarding this material, "How do you like it? "How does it compare to vulcanite?' "Is it durable?" "Does it hold its color?" "Can it be repaired ? paired?" I have prepared this paper, setting forth my views of it, after some years of experience, for the benefit of all whom it may concern: The dentist who has never used it, the one who has, the strict partisan for it, who asserts and believes that there is nothing like it, the man who stands up for vulcanite and condemns celluloid. I have noticed many articles on this subject in our professional magazines, some setting forth the virtues of this base with an enthusiasm that almost amounted to absurdity when read by anyone who is at home in the laboratory, and who knows a little more of this branch of dentistry than is required in the mere construction of a set of teeth. Others berating it with equal zeal because they have had a few failures, not knowing how to treat it or manipulate it properly, relying upon the instructions given in the pamphlet which accompanied the apparatus for working it when brought, forgetting that the only way to learn anything in dentistry is to toil without ceasing until the desired end is attained. I do not write this paper to extol the merits of celluloid, neither will I cover up its deficiencies, for it certainly possesses both, but to present to the profession my idea of the places where it should be used and its place in dentistry, for it certainly possesses virtues which entitle it to one.

How is celluloid regarded? Just the same as the different methods of mounting an artificial crown. One man swears by one way, another swears at the same way. How does it compare to vulcanite?

Yes, when it is indicated; when the hygenic condition of a mouth calls for it; when the occluding teeth are favorable; when the acids of the mouth are weak. Does it hold its color? Being more porous than vulcanite it requires more frequent cleansing, a weaker state of the acids of the mouth, and an absence of tobacco in any form. Under these conditions the color will remain good for an indefinite time. I have had plate under my observation for four years where these conditions were observed, and the color is still good, slightly darker, but not enough to be objectionable, and on one or two of them, only noticeable when compared to a fresh piece. Can celluloid be repaired? Ah, here is the great drawback. There is only one way to repair it, and that can be done but once or twice,' at the outside calculation. No way has ever been discovered to make a new piece of celluloid join to a plate that has been worn in a manner that would serve all purposes, and that could be relied upon to the extent of repairing in vulcanite. have repaired many celluloid plates, some well, others poorly, but the most of them indifferently, not through any fault of mine, however. The proper spirit was manifest, but the execution failed. The old material absorbs from the fluids of the mouth, and when re-heated to repair seems to become softer than the new or repair piece, and instead of the new material pressing into the dovetails prepared to receive it, and the excess flowing into the waste gates, it presses down and presses the old material out flat, and then distributes itself over the surface to repair. Sometimes this will remain repaired for a considerable time, but

in

I

a majority of cases it is short-lived. Some of the most promising attempts at repairing celluloid have only lasted a few weeks. It is fair to infer that the difficulty of joining a new and an old piece of the material is due to the secretions coming to the surface when the heat is applied, burning into carbon when it is continued, and forming a barrier between the two, as oil between the impression and model.

Where should celluloid be used?
When is it indicated?

Its

For temporary cases, to be inserted soon after extraction, it is par excellence. If the lip is too long to set the artificial teeth upon the gum, a nice band of celluloid can be pressed above them, carved and festooned to imitate nature, obviating the necessity of using the piano keys which are made to imitate teeth, and sold under the name of vulcanite blocks. lack of durability when compared to vulcanite recommends it for this purpose. That it is injurious to the tissues of the mouth to wear an ill fitting plate is an established fact. Temporary plates soon become ill-fitting, and if the patient will not heed the advice of the dentist, the objection to the material when compared to vulcanite will become manifest, and a permanent plate will be the result, benefiting the health of the patient, ditto the dentist's bank account. Nothing approaches nature nearer, or is more desirable, with one objection, than a celluloid attachment properly constructed on a metal plate, not even continuous gum work, the objection being, the occasional replacing of the attachment should it become discolored, or should any of the teeth be broken, and considering the ease with which it can be done, in place of an objection I am almost inclined to consider it an advantage. All the advantages of a metal plate are secured, with all the qualities of one of vegetable base. The most natural design of teeth upon the

market are those made from celluloid. Its lightness gives it preference over continuous gum work.

Celluloid is best adapted to the construction of full dentures when used alone, or if used in partial cases, only those which have the teeth to be replaced all together. Where a break occurs in the arch, for instance, one or two centrals, canines, or bicuspids remaining in, as the case may be, celluloid is not indicated. It is not a desirable material to construct small partial sets upon, where one or two teeth which stand alone are to be replaced. While celluloid in bulk is strong, when stretched out it becomes weak. For partial lower plates it is good for nothing. My previous experience with partial lowers and vegetable bases has convinced me that of all the materials we use for this purpose, they are the poorest.

[TO BE CONTINUED.]

CARIES OF THE TEETH.

BY THEODORE F. CHUPEIN, D.D.S.

[Read before the Odontographic Society of Pennsylvania, Dec. 5th, 1883.]

We find caries existing principally in the enamel and in the dentine of the teeth. Sometimes it is found in the cementum, but this most generally occurs at the necks of the teeth when the gums have receded from these parts, thereby exposing this tissue to morbid influences.

The subject of dental caries and its causes is still invested in considerable darkness, notwithstanding it has been considerably written upon and discussed. Some contending that the disease is no disease at all, but only a result, viz.: Chemical decomposition, and amenable solely to chemical laws. Others assume it to be the result of morbid action in the vital organism.

The presence of caries is first noticed in or through the enamel; this tissue as

suming a black, bluish, or dark spot or streak at the point affected when the tooth is attacked on its crown surface; but when the disease appears on the proximate surfaces the indications are generally of an

This latter con

opaque or whitish color. dition seems to give this tissue considerable porosity, as it readily breaks down under slight pressure with dental chisels, and Dr. W. H. Trueman has stated that if a tooth thus affected be subjected to the action of analine fluid the affected part will readily absorb the coloring mixture, while the unaffected part will remain uncolored.

Prof. Tomes says "the first chemical change consists in the removal of the phosphate of lime from the gelatine, leaving the dentine of a consistency capable of being readily cut with a sharp knife." When caries is present discomfort or pain. is experienced, this is, or is not, always the case-some persons rarely suffering from toothache, although the tooth may be entirely destroyed, while others suffer more or less discomfort from the very incipiency of decay.

Toothache, however, from simple decay, has very different characteristics from toothache caused by such extensive decay as results in the exposure and inflammation of the pulp. In the latter there is the invariable throbbing and the sense of pain upon taking hot or cold fluids in the mouth. In the former the pain seems to be confined to the attacks of the disease at the peripheral parts of the dentine, for we observe that this pain seems to pass away after a certain part of the tooth has been destroyed.

The predisposing causes of decay have been attributed to various circumstances, viz., irregularity of position, crowded condition, close contact, an acid condition of the mucus and salivary secretions, extremes of hot and cold food, uncleanliness, the lodgment of particles of food between the teeth and in the fissures of