the closer the tube to the object the more destructive the ray. Low tubes excited by small currents are not so destructive as low tubes excited by heavier currents which are resistant. Very high tubes have very little effect. The destruction of tissue is due to the X-ray and not to the cathode ray, as is claimed by some.

DISCUSSION.

Dr. Wm. H. Dieffenbach of New York city detailed briefly the experiments conducted by a German scientist with reference to the effect of the ray on the procreative power of rabbits. The sexual power of the rabbits exposed to the ray for some time was lost entirely. The spermatozoa found in the testes and seminal vesicles of these animals were inert.

Dr. Henry E. Waite of New York city criticised the indiscriminate use of the words high and low tube, or hard and soft tube. These terms are devoid of any meaning having reference only to the amount of gas in the tube. It is the penetration we want. A good tube is one having a wellbalanced vacuum and a perfect focus..

Dr. Weston A. Price of Cleveland, Ohio, followed with a paper on:

"TECHNIQUE FOR MAKING GOOD DENTAL SKIAGRAPHS.” The two essentials are high penetration and a large volume; the former to secure contrast between dense substances like bone, tooth substance and root fillings, and the latter to secure good definition with such short exposures as are necessary in dental skiagraphy. This requires a very powerful generator and a good interrupter. He uses a large coil and the Wehnelt interrupter. A tube is required that will make quite transparent and white the bones of the hand. For locating abscesses use a tube having lower penetration than is used for locating root fillings. He uses a specially constructed film made of a very smooth, flexible and transparent celluloid. This is covered with a waterproof and light-proof flexible container (unvulcanized black dental rubber calendered thin). Next to the film he places bromide; it protects the film and always helps to give a good positive. The film cannot be scratched, bent or broken.

DISCUSSION,

Opened by Dr. L. E. Custer, Dayton, Ohio, he agrees with the author in the matter of using a large coil, but takes exception to the Wehnelt interrupter, because all electrolytic action is accompanied by heat, and when the concentration of current is sufficient at the metallic point of the Wehnelt interrupter an insulating vapor surrounds the point which causes the action to cease for the time being. The principle is the same in the Caldwell interrupter, but the manner in which it. takes place is not the same. My modification consists of a porcelain cup having an inside capacity of two by six inches. Near the bottom is a hole at an angle of forty-five degrees. The cup is poised in such a manner that it can be tilted so as to have the hole either horizontal or perpendicular. The volume of current is in direct proportion to the size of the opening, and the frequency of interruption is proportionate to the period of time that each bubble of gas is displaced and the circuit is again established. When the canal is horizontal it takes more time for the displacement to occur than when it is perpendicular. The thickness of the wall and the depth of the solution also modify the frequency of the interruptions. A filed rheostat in series with the primary also is an efficient interrupter.

A medium tube is best because too high penetration destroys the contrast. It should have a fixed vacuum, such as the Mueller and Gundelach tubes. The target should be heavy and the exposure should be made as quickly as possible so as to get all the microscopic detail. With reference to the film, he places two films face to face and then wraps them up in two separate coverings of black waterproof paper. This protects the films and gives us two films, which may be developed differently. The film should be held parallel to the teeth and the tube perpendicular thereto.

Drs. M. H. Cryer, Pancoast, Goodspeed, Cook, Leonard and Kassabian showed lantern slides of abnormalities of the teeth. Dr. Kassabian puts the plate on the outside of the jaw and places a two-inch block of wood between the patient's teeth so

that the rays can be sent in between. The direction of the ray is regulated according to the teeth to be skiagraphed. The time of exposure is a little longer than with the other method, but it has the advantage of showing the relation of the other teeth.

Replying to a statement made by Dr. Cryer that it is unfortunate that we cannot locate the roots of impacted teeth with respect to their direction, Dr. Price, in closing the discussion, said that he always took two skiagraphs from different angles, and by placing them in the stereoscope it is a very simple matter to locate either the tooth or the direction of its roots.

"DEVELOPERS,"

After a careful

by Dr. Gordon G. Burdick of Chicago. study of the most used developers he arrives at the conclusion that no one single developer answers the purpose; that by making a combination developer, submerging the bad qualities and bringing out the good qualities of each developer he has been able to obtain a developer that has given him uniformly satisfactory results. This is the formula:

Sol. A.-Potassium metabisulphite, 8 grams; metol and ortol, each, 15 grams; potassium bromide, 1 gram; distilled water, 1,000 grams.

Sol. B. Sodium sulphite (dry), 40 per cent; sodium carbonate (dry), 60 per cent; in water, 1,000 grams.

Use 30 c. c. of each and dilute with water according to the effect desired. The less water is used the greater the contrast; the greater the dilution the softer the negative and the greater the detail.

The ortol imparts a brown color which gives the greatest possible contrast; will not fog, no matter how long the plate is left in the solution. The metol brings in a wealth of detail and does not show any disposition to fog. The sodium sulphite imparts a black stain to the silver molecules. The metabisulphite of potassium preserves the developer and prevents the action of the oxygen in the air on the solution. The sodium carbonate is not required and usually is harmful; its

function is to save time. If used in too great strength there is a loss of the sharpness of the lines; the gelatin becomes soft, changes its position on the plate and all relation is lost. This developer is not suited for instantaneous work. For this amidol is the most suitable. It is very rapid, more so than any other developer, and gives a very transparent negative, but good positives cannot be obtained without the use of an intensifier.

DISCUSSION.

Dr. Mihran A. Kassabian, Philadelphia, said that most of the trouble arising from the developer is due to the fact that operators do not use any one developer long enough to become thoroughly familiar with it. If you learn to know your developer thoroughly you can modify it to suit the particular case. We must consider also the time of exposure, the thing exposed, what is wanted, the plate used, etc., in order to have good negatives. By developing slowly we get contrast; intensifying with bichloride of mercury gives detail. He keeps all his solutions in separate bottles so that he can use of each as much as may be required. In that way the work can be done with exactness and the result is better. Too much alkali is liable to veil and fog the plate. Use weak developer first and then work up as indicated. The solutions should be kept cold. Metol is superior to the pyro, but it is very irritating and cannot be used by an operator suffering from an X-ray burn. If we want a soft yellow print, as in hip cases, then the hypo gives the best results.

Dr. Wm. H. Dieffenbach, New York city, prefers edinol, a salt of metol. It brings out very good detail in cases of fracture, tuberculosis of bone and aneurysms and other lesions of the blood vessels.

Dr. J. P. Hetherington and Prof. Goodspeed stated that they had tried all kinds of developers, and that as they got through with one they threw it into a jar until finally they had a heterogenous mixture. Whenever they wanted to get a particularly good plate they would use this mixture, and always with excellent results. It may have been due to a

combination, as was suggested by the author, a submerging and intensifying process.

RECURRENT CARCINOMA OF THE BREAST TREATED WITH THE X-RAY.

Dr. W. F. Campbell presented a patient before the Brooklyn Surgical Society, who had come to him twenty months ago with well marked carcinoma of the breast. The tumor was noticed about three months before and there were some enlarged glands along the border of the pectoralis major and in the axilla. He performed a Halstead operation and the wound healed without incident. A year afterwards there was a return of the carcinoma along the scar and an infiltration of the glands in the supra clavicular space, about the size of an orange. He removed the nodules in the scar and subjected her to X-ray. Treatment was given for about eight months, the tumor being reduced to about one-third. During the treatments the skin had become bronzed but no deep burn had developed although the treatments had been given three times a week for eight months. There was marked relief from pain.

The doctor did not claim that the case would progress to a cure, but felt that the relief offered, justified the treatment.— Brooklyn Journal.

THE ACTION OF RADIUM ON BACTERIA.

H. W. Dickson and J. T. Wigham of Trinity College, Dublin, carried on this investigation. They used 5 milligrams of radium bromide and exposed for 4 days at a distance of 4.5 millimeters to the beta rays agar cultures of bacilluspyocyaneus, b. typhosus, b. prodigiosus and b. anthracis. They found that these cultures were not killed, but their growth was arrested by the rays. A patch inoculated with these organisms remains sterile on exposure to the ray. (Abstract from Nature.)