METAL CASTINGS FOR DIES.

In the last number of the DENTAL PRACTITIONER I gave my method of preparing the molding sand, and explaining the necessary manipulations in procuring a good mold for the purpose of pouring the melted metal. The mold prepared according to these directions needs no drying over a fire or smoking, and is now ready for the pouring. If the metal is not ready to pour it had better be covered, to keep it from drying. If it becomes dry on the surface of the mold, the pouring of the melted metal over it will push away some of the prominent parts on the face of it, and the resulting cast will be imperfect; in fact, entirely spoiled.

The necessary points to keep in mind. are, to have porous sand, pack just close enough to hold together, and not to let your mold get dry on the surface. I have not had any success with marble dust or mixing sand with oil. Water is the clean

est and best for me.

Having obtained a good impression in the molding sand, the next thing is to fill it with a metal that is best adapted for the purpose you want it.

In` making an entire upper suction plate I use two sets of dies; the first set of zinc with lead counter-dies, to partly stamp and shape the plate; the second, or finishing se, is made of Babbitt's metal, without air chamber, and type metal counter-die, provided the ridge of the gum is hard or yields but little. As Babbitt's metal contracts but very slightly, a plate stamped over it fits a hard and unyielding gum very firmly. If the gum is soft, I use zinc and lead for the finishing set of dies, which frequently answer my purpose without a resort to other means. The contraction of zinc in cooling is of great advantage when the plate is for a soft gum.

The Babbitt metal I have bought has been invariably poor, coarse and grainy,

oxidizing very rapidly, and, after two or three meltings, becoming useless. I was compelled to manufacture it myself, which is a nice operation and requires careful watching throughout the entire process. The usual formula of tin eight parts, copper one, and antimony two, is the one I mostly use. Melt the tin first in a castiron ladle, and heat up to a cherry red; the copper in the form of nails is then added; when melted, stir well with an iron rod, or the loose ladle handle, until thoroughly mixed; after cooling a little add the antimony; this requires frequent stirring, and must not get too hot.

This formula remains essentially permanent through a dozen or more meltiugs, provided it is not overheated, and is used as soon as it becomes fluid enough to pour smoothly.

A cast of Babbitt's metal or zinc should never be less than an inch and a half in thickness, and for large, broad mouths, should be two inches at least. Care must be taken not to keep all your casts in one place. The Babbitt, with its counter-die, should be kept in a box by itself, so as to avoid mistakes in taking one, when you want the other; also use a separate ladle for each of the metals.

Type metal is the proper counter-die for a Babbitt cast; any other would require too much heat, and sometimes unite with the cast, even when washed over with chalk.

W. R. HALL,

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Besides this, I examined, as far as time permitted, some Roman skulls of the early Christian period.

It will be observed that with the exception of the Roman skulls, and perhaps a few of the Northwestern Indians, the people of whom these bones were relics lived before the time of contact with the whites, and were therefore pre-historic. They were not contaminated by the vices of our modern civilization, but lived a life that was as near the typical natural one as the most conservative fogy could desire. Some of them had a climate that was as near perfect as this globe affords. Nearly all of them lived in regions that furnish the most prodigal display of natural nutritious foods. The diet of some must have been almost exclusively vegetable, while the North American races existed mainly by the chase, and their food was mostly animal. Some of the races lived in huts formed by the branches or bark of trees, some in natural or artificial caves, while others had their habitation in a snowless and rainless region, and hence needed no protection from the weather, and their days and nights were passed almost exclusively in the open air. They had no mills to grind and bolt their grain into flour, and they were destitute of the condiments and palate stimulants of the present day. They drank no spirituous liquors, and only a portion of them used tobacco, and then only to smoke it in great clay pipes which must have extracted all the nicotine by absorption. They were clothed either in the skins of wild beasts, or the vegetable fabrics which their limited manufacturing skill enabled them to make, while some of the tribes were probably as ignorant of raiment as Adam and Eve before that wonderful serpent interviewed them.

Here were various races of people who were quite free from the "vices of civilization," who lived in that happy primeval state of which poets love to sing, and

some of our retrospective modern dentists to preach. Surely, if happiness, innocence and freedom from disease are to be found

"The heart that is humble might hope for it here."

What did I find? Allow me to say that I went there a believer in the modern origin of dental lesions. I was firm in the faith that toothache and stomachache and most other aches are due to our sins; that the human race is gradually deteriorating, and that man, as he departs further and further from nature's simplicity and surrounds himself more and more with the concomitants of a high civilization, as his life from generation to generation becomes increasingly artificial, so do his bodily ills increase, and diseases multiply in number and virulence. I had long been accustomed to tell my patients that were it not that the dentist's skill kept pace with the alarming increase of dental diseases, and were the law of heredity to continue in full geometricallyprogressive force, the human race must in a very few generations become edentulous. These theories were the result of my own reasoning, evolved from my inner consciousness, the fruits of pure logic, the results to which indisputable mathematical equations must infallibly lead. Like many another man whose theories are the results of chamber toil, when I put myself face to face with the records of actual fact I found that my fine-spun hypotheses would not hold water, and I dropped them at once, and again resolved for the thousandth time to speculate less and to examine more.

With the exception of the syphilitic diseases, there is not known to-day an oral trouble which all these nations were not familiar with, in its most exaggerated form. I say with the exception of syphilis, for in all those skulls I found but one that bore unmistakable traces of that dread scourge, and it was not at all certain that this was not intrusive and be

longing to a later period. This anomaly was found in a cave in Mexico, but it so differed in type from those found with it, and the cave bore such evident marks of having been opened in historic times that I strongly suspected this of being modern.

In the jaws of all the people whose skulls I examined, I found traces of all the diseases known to modern dentistry. There was caries of the most formidable character, black, white and brown. There were the marks of abscesses which devastated great regions of tissue. There was necrosis which had caused the loss of great sloughs of bone, though I must admit that necrosis was more rare than most other oral diseases. There were great masses of tartar enveloping all the teeth in the jaw. There were indications of all kinds of inflammation of soft tissues. There were exostoses and hypertrophies, absorptions and malformations, denudations and abrasions, exfoliations and irregularities. I thought to myself as I held in my hands the evidences of all this disease and suffering, what could these poor creatures do, tormented as they were without hope?—for there were no dentists in those days. Decayed teeth must remain until they could be removed with the fingers, for the primitive people knew not the blessedness, the comforting tenderness of modern forceps. I tried to picture to myself the victim of this terrible decay, that had in some instances destroyed every tooth in the head. I tried to imagine him brooding in silence and gloom over his misery; suffering in patience the exquisite torture with which, to his untutored mind, the Great Spirit had in infinite mercy and loving kindness, or in dark wrath and sullen judgment, visited His weak creations, or in unexpected paroxysms of anguish raising a whoop that shook the forest and caused his dependent family to quake with fear, and I said: "Poor fellow! your lot was a hard one. Why the mischief didn't you have it filled

with amalgam if you could not afford gold?" And then I recollected that he was deprived of that inestimable last gift of a good Providence, the modern dentist, and could only suffer and groan and howl and kick the furniture about, and try old-women quack-nostrums until he felt better.

There were fewer irregularities among the teeth of these people than are known at the present day. Their jaws, especially those of the mound-builders, were broad and well developed, giving indications of a muscular race. Nevertheless, bad cases of irregularity were not unknown. The teeth of the Southwestern Indians were the most worn by use, and it was not unusual to find whole dentitions worn completely down to the gums. The Sandwich Islanders had the handsomest dentitions that I ever saw. Their teeth were almost uniformly as white as ivory, and as regular and even as the teeth of a horse. they were, as a people, sadly afflicted with caries.

But

There were a number of points which I desired especially to note, and the results of these were usually disappointing to me.

The number of wormian bones did not greatly exceed those found in skulls of today, though some of them were unusually large. In one skull, from the moundbuilders, the parietal bones were divided by a suture extending clear across them, just above the summit of the squamous portion.

There were but three cases of persistent frontal sutures in adults, all from the Tennessee mound-builders, the others differing not at all in their apparent development from the skulls of moderns.

The number of the teeth has not changed. There were about the usual number of instances of apparently rudimentary wisdom teeth, and supernumerary teeth were not lacking. There were cases of entire lack of certain teeth, the nonappearance of wisdom teeth in adult and

also found a number of cases of noneruption of cuspid teeth. In some cases the wisdom teeth had been erupted while the canines were absent. I found such abnormalities as the appearance of a cuspid between the two bicuspids, and malposition of incisors. Usually, however, all the bicuspids and molars occluded perfectly. I found impacted teeth and teeth lying transversely or longitudinally in the jaw. I found some cases of narrow jaws, where there was not room for the eruption of wisdom teeth, which must have caused great annoyance and pain to the possessor.

At

Perhaps a typical semi-tropical race was that which inhabited ancient Peru. just what period this people lived, we have no knowledge, but it was some time before the advent of the whites upon this continent. They were a well built race of people, physically, and had made some advances in manufactures, being in this respect the superiors of the North American races. That they were a patient, rather industrious, laborious people, the works which they have left behind them show. They had well developed jaws, the lower one especially being broad and strong. Their teeth were large and fine, generally of a yellowish color, but they were badly troubled by dental diseases. Manifestly they took no care of them, for they were frequently encrusted with tar

tar.

The dentitions of the adults almost uniformly gave indications of wear, many of them being extensively abraded.

I had not opportunity or time to make careful statistics, but the following figures will give an approximate idea of the condition of the teeth of the early inhabitants of Ancon, Peru.

Of the skulls of adults of various ages, I made examinations, more or less careful, of two hundred, taking them as they came, and making no selection. I think they were a fair average of the whole. Of these, seventy-four had lost some of

their teeth during life. Forty-three only, so far as I could discover, possessed a perfect dentition and gave evidence of healthy mouths. One hundred and two presented indications of oral diseases. The remainder were in such a state that it was impossible to determine their condition at death. Thirty-one showed extensive absorption of the alveolar process, due probably to various inflammatory conditions. In thirteen cases I found the marks of deep alveolar abscesses, which had caused extensive wasting of the osseous tissue. How many others there were, not of sufficient severity to leave indelible traces upon the bone, it is impossible to say. In two mouths I found supernumerary teeth, and in two there were exostoses so great as to be visible. It will readily be understood that, as the remaining teeth were usually firm in their sockets, ordinary hypertrophies were undiscoverable without mutilation of the specimens. In fifteen cases there was no sign of the presence of wisdom teeth, nor of their loss. Seventy-two dentitions were extensively worn, some of them nearly even with what must have been the bor

der of the gums. In five instances the wisdom teeth were, in appearance, but rudimentary. In eighteen cases the wisdom teeth occupied an abnormal position through lack of room for their development, and this, notwithstanding the usually massive character of the maxillæ. There were four cases of decided irregularity, not counting unimportant deviations from the normal. There were scarce any dentitions that were entirely free from tartar, and some of the mouths contained large masses of calcareous incrustations. There was at least one case of an almost complete calcification of the pulp. How many others, only an examination of the pulp chamber could determine.

Of the ancient mound-builders of Tennessee I examined the skulls of seventyfive. Of these, twenty-seven could be set