tite will be increased and the digestion improved. If these effects do not result from the sun bath, the treatment is not of much benefit, or it is not being properly applied.

In order to bring the use of the sun rays to the reach of hospitals and institutions and physicians' offices where the rays of the sun cannot be properly applied, the Heraeus Quartz Light, or Alpine Sun Lamp, has been developed. The rays from a properly constructed quartz lamp will kill bacteria by its ultra violet rays, and will apparently cause many, if not all, of the beneficial results caused by the direct application of the rays of the sun. All kinds of diseases of the skin, tumor growths, bone diseases, and systemic diseases are being treated by some clinicians, apparently satisfactorily, with these artificial sun rays as furnished by these quartz lamps. The technique should be most carefully studied before quartz lamp treatments are given. Also the effect on the patient's skin must be watched, as well as care taken not to cause shock.

More recently convex lenses have been used to concentrate the rays of the sun on sluggish ulcers and sinuses, with reported

success.

While many of the reports of the results of the sunlight treatment are very enthusiastic, statistics are not yet sufficient to declare the exact value of the treatment in many diseases. The benefit caused by heliotherapy in tuberculosis has been described. It is certainly demonstrated that various methods of applying violet rays to the body are of great benefit, especially in painful nerves and joints, and that these rays can prevent germ growth; also it seems demonstrated that the actinic sun rays stimulate healing. Consequently, it seems justifiable at the present time to declare that an institution for the treatment of tuberculosis is not complete without its solarium for the therapeutic use of the sun rays, and that a hospital is not complete without roof gardens, sun parlors and apparatus for the sunlight treatment of many conditions.

The value of sunlight in the prevention of disease and in killing pathogenic germs cannot be too much taught, and light, airy houses and tenements, sun parlors and sun porches, and homes in the suburbs should be the battle cry against tuberculo

sis and pneumonia, the combined cause of the great majority of deaths in civilized communities.

Electric lamp cabinets are much used to cause dilatation of the peripheral vessels and perspiration. Care should be taken in these treatments to keep the patient's head cool and prevent faintness.

Colored light may have more than an historic interest, as blue light is supposed to be sedative, while yellow and red lights are supposed to be stimulant to the patient.

ELECTRICITY

Although electricity was discovered over two thousand years ago, and seems to have been used on human beings by early Roman practitioners, still it was not used regularly for medical purposes until after the discoveries of electrical activities by Galvani in about 1790, by Volta in about 1800, and by Faraday in 1831. From these sources are derived the names for the constant current, Galvanic, for the interrupted current, Faradic, and for the unit of electromotive force, the Volt.

Electrical treatments have been long given both by regular and by irregular practitioners, and though skeptics in medicine believe that a large amount of the good done is by suggestion, still there is a large practical, useful field for the medical use of electricity. Its power to stimulate nerves and to cause muscle contraction, and therefore its ability to awaken sleeping, sluggish nerves, to transmit messages along rusty wires, and to increase the nutrition and strength of weak and paralyzed muscles is unquestionable. Electricity can modify the general metabolism, when it is applied for this object, as evidenced by an increased nitrogenous output. Also the ability of this agent to increase the peripheral and general circulation as well as to improve the muscle tone can be clinically demonstrated. That electrical appliances, as well as the actual application of electricity, have a favorable influence on the mind is true of any physical treatment, and is true of any new treatment, and even of treatment by a new physician or by a specialist. Favorable impressions on the mind should not be left to the Christian Scientist or mental healer.

General Considerations.—A piece of copper wire 120 of an inch in diameter and 250 feet long represents exactly one ohm of resistance. The broader and shorter the wire, the less resistance it will present.

The unit of resistance is the ohm, from Ohm; the unit of intensity is the ampère, from Ampère. An ampère represents the quantity of electricity produced by a unit of electromotive force, the volt, circulating in a conductor having the unit of resistance, the ohm, during the unit of time, the second. The current strength equals the electromotive force divided by the resistance. The watt is the unit of measurement of activity or power, and equals 0.735 foot-power per second. The number of watts used will equal the volts multiplied by the ampères. A one horse-power per second equals 746 watts. The kilowatt equals 1000 watts or 1.2 horse-power per second. The ampère is too large for medical measurements, hence it is subdivided a thousand times, each subdivision being a milliampère, and the strength of the current passing through the human body is measured by a milliampèremeter.

The human skin is a poor conductor of electricity, unless the electrode is so moistened as to fill the air spaces in the epidermal layer with water. The resistance of a dry layer of skin may be several thousand ohms, but this resistance is reduced by moistening the skin to two hundred ohms or less. Often when the pain is greatest on the application of the galvanic, constant, current, but little electricity is passing, the pain being caused by the minute sparks penetrating the skin to the tissues beneath. After the current has passed for a short time through a moistened electrode the resistance seems to be overcome and the current passes more readily. This is quite probably because the tissues beneath the skin become hyperemic and therefore better conductors. The larger the electrode used, the less the pain, and with large electrodes, after the first contraction caused by the closure of the constant current, there is practically no sensation until the current is broken, consequently large electrodes should be used when it is desired to use a strong current. Generally the stationary electrode should be large, while the electrode that is used for treatment and

moved over different parts of the body should be small. If the deeper structures of the body are to be treated, both electrodes should be large, as tending to cause less pain. But the electrolytic and metabolic activity is just as active whether pain is felt or not.

The surface of the body is hypersensitive to electrical applications at the junctures of the mucous membrane with the skin and where the skin is close to bones. The parts where the skin is thin are also very sensitive to electrical applications, such as the inner surfaces of the arms and legs, and the fingers. Individuals vary greatly as to their susceptibility to electrical currents, depending on the thickness of the skin, and the nervous irritability. Some diseases increase and others diminish the susceptibility to electricity. On the mucous surfaces the electrodes do not require to be moistened.

In using the constant current, shock to the patient should always be avoided; consequently the current controller should be at zero when the electrodes are applied to the body, and then the switch slowly moved to the strength desired, to be again returned to zero before the electrodes are removed. Such management prevents pain and shock, and is the method used when it is desired to cause a general effect rather than stimulation of nerves and muscles.

Galvanism. The galvanic, or constant, current is perhaps the one of most importance in treating the general system by electricity. The current enters the body at the positive pole or anode, and makes its exit at the negative pole or cathode. The most pain is caused by the cathode as it is excitant, while the anode is mildly sedative, and at this pole the skin may become blanched. If the current of electricity is not broken, i.e., if the active electrode (the electrode which is moved about over the body) is not removed from the surface of the body, contraction of the muscles does not occur and pain is not caused, provided the electrode is properly moistened and applied with the proper amount of pressure, so that the skin becomes a good conductor and the tissues beneath alone are affected. Considerable strength of current may be tolerated if the electrodes remain stationary. As previously cautioned,

before the electrodes are applied and before they are removed, the current controller should be placed at zero. This treatment of gradually increasing and gradually reducing the current is sometimes quite sedative to painful nerves, provided there is no inflammation.

If the electrodes are stationary, polarization will occur (termed electrotonus), namely, at the anode for a short distance in the direction of the cathode the nerves will be depressed (termed anelectrotonus); while at the cathode for a short distance toward the anode the nerve is made more irritable and excitable (termed katelectrotonus). With the positive electrode stationary at an indifferent position, with the active electrode, the negative (the cathode), small and placed at the motor point of a muscle, when the current is closed the contraction should be greater than when the poles are reversed, i.e., when the electrodes are reversed, the negative being made indifferent and the positive active. When the current is broken with the cathode at the motor point the opening contraction of the muscle, i.e., when the current is turned off, should be less than when the current is broken with the positive pole or electrode at the motor point. When the negative pole (electrode) is at the motor point of a muscle, and the positive pole is on the back, the current is said to be descending. When the positive pole is at the motor point, and the negative pole is on the back, the current is said to be ascending.

When the cathode closing contraction (a descending current) is greater than the anode closing contraction (an ascending current) and the anode opening contraction (an ascending current) is greater than the cathode opening contraction (a descending current), the reaction of a muscle is normal. When these reactions become equal in intensity degeneration of the muscle has begun. When these reactions are reversed it is termed the "reaction of degeneration," and the muscle has degenerated.

To excite a muscle the current is interrupted by removing and re-applying the electrode, by a spring "make and break" contact on the electrode handle, or by a current interrupter on the electrical apparatus. These interruptions may be made from a few