Simonoff and Katschenowsky noted a loss in weight, but when the patients were allowed to follow their own inclinations the weight increased. In this respect the effects are analogous to those following the inhalation of oxygen.

In conclusion, the pneumatic treatment favors rather than retards general nutrition; after a variable period of fatigue it causes an increase in strength and weight, and especially an increase in the power of the respiratory muscles. In addition, it exercises a sedative influence upon the nervous system.

The duration of a bath of compressed air is generally two hours; of this a half-hour is employed for raising the pressure to the desired height, for another half to one hour it is kept constant, and during the remaining time it is gradually decreased. Ventilation should be active throughout the procedure.

The elevation of pressure is ordinarily two-fifths to three-sevenths atmospheres (30 to 33 c.cm. of mercury). In the case of feeble persons a fifth of an atmosphere (15 to 16 c.cm. of mercury) is not exceeded.

The duration of the treatmeat varies, and from twenty to more séances are necessary to obtain a permanent result.

It is customary to give one séance a day in the beginning; toward the end of the treatment one every two or three days suffice.

Advancing emaciation, as well as an exaggerated appetite, are indications for the cessation of the treatment.

Compressed air is useful in many affections. In diseases of the respiratory apparatus it is valuable by reason of its mechanical effects, while in constitutional diseases advantage is taken of its influence upon general nutrition.

To its mechanical effects we may attribute (1) the diminution of pulmonary congestion in acute and chronic inflammations of the bronchi; (2) the reduction in secretion from the respiratory mucous membrane; (5) the absorption of inflammatory exudates, especially those of pleurisy; (4) the augmented capacity of the lungs in emphysema, chronic catarrh, chronic pneumonia, and in certain forms of phthisis; (5) the increase in power of the respiratory muscles.

To the chemical effects may be ascribed (1) the increased absorption of oxygen, the utility of which is manifested in dyspnoeic states, and, more doubtfully, in anæmia; (2) the greater activity in the processes of oxidation, which is of value in obesity, diabetes, rheumatism, and the convalescent state; (3) the sedative action on the ner

vous system, for which the increased absorption of atmospheric nitrogen is perhaps responsible.

Many patients subjected to the treatment by compressed air have, in addition to emphysema and chronic bronchitis, a more or less pronounced cardiac affection. When the contractions of the heart are strong no accident need be feared, but when the myocardium is weak the treatment should not be employed. Diseases of the kidney, the spinal cord, the liver, and the intestines have been considered contraindications to the treatment on account of the congestion which it engenders in these organs. But this is a purely theoretical view. The existence of a moderate fever, such as obtains in the subacute diseases of the air-passages, does not contraindicate resort to the treatment. When, however, the fever is high or hectic in type the use of compressed air should be suspended or entirely abandoned.

The bath of compressed air mentioned already necessitates the employment of a ponderous apparatus, such as can only be used in special establishments. Moreover, by this method, as it acts upon the entire body, the respiratory system is not very markedly influenced. The so-called portable apparatuses that have been devised are less complicated, and exert their mechanical effects more directly upon the lungs. In their application the active collaboration of the patient becomes a factor, but as the manipulation of the apparatus is simple this causes him no inconvenience.

The portable apparatus should be so constructed that the air can be compressed or rarefied at will, for it thus furnishes a form of respiratory gymnastics. More varied effects can be produced by this apparatus, and it fulfils more indications than the compressed air-bath. The effects the apparatus enables us to produce are:

(1) Increase of intra-thoracic pressure by inspiration of and expiration into compressed air.

(2) Diminution of intra-thoracic pressure by inspiration of and expiration into rarefied air.

(3) An alternate increase and diminution of intra-thoracic pressure by combining these means.

The combination most frequently utilized is inspiration of compressed air and expiration into rarefied air.

The first apparatus for the application of pulmonary gymnastics was invented by Broesicke, of Berlin, in 1857, but Hauke, of Vienna, in 1870 contributed the first portable apparatus. The number of different forms upon the market is now very large.

One of the best known is that of Waldenburg (Fig. 5). It is constructed on the principle of the gasometer, and furnishes both compressed and rarefied air, but does not permit the alternate use of them.

Cube has combined two gasometers, one giving compressed, the other rarefied air, and Weil, with the same end in view, has joined two Waldenburg apparatuses. The apparatus of Schnitzler is only a modification of that of Waldenburg.

The double ventilator of Geigel and Mayr is constructed on the principle of a wheel, and supplies both forms of air. It is considered in Germany the most practical appa

ratus.

[The best compressed-air apparatus that we know of used in America is. that devised by S. Solis-Cohen (Fig. 6), which he describes as follows:

The air-chamber is 8 inches in diameter and 24 inches high. The water-chamber is pierced at the level of the base of the overflow tank (7 inches from the top) with a row of perforations, allowing the water to escape into the tank under pressure of air in the air-cylinder. A glass tube connected with the tank shows the level of the water therein, and by means of a scale painted on the outer surface of the tank acts likewise as a gauge showing the pressure. The aircylinder carries, 2 inches from its open base, two shelves, one on each side, on which are placed ballast-weights for the purpose of lowering the centre

FIG. 5.

Waldenburg's Gasometer.

of gravity and thus maintaining the steadiness of the apparatus. Both shelves and weight are perforated to avoid undue resistance

of water. As the area of the top of the air-chamber is just 50 square inches, atmospheric pressure upon it equals, in round numbers, 750 pounds. With the ballast upon its shelves the cylinder weighs 10 pounds, giving an excess pressure of atmosphere. Weights are furnished in two sizes in the shape of rectangular blocks of iron about 4 inches by 2 inches surface, and about inch thick and 1 inch thick, respectively. The smaller ones are bored out to weigh 1 pounds each; the larger ones to weigh 2 pounds each.

Being placed on top of the air-chamber in successive pairs (one on each side, to preserve balance), they bring the pressure up to any desired amount not exceeding plus atmosphere. Thus:

Cylinder and bottom weights + atmosphere.

2 pounds (2 small weights) additional = 123 pounds + atmosphere.

2 pounds (2 small weights) additional = 15 pounds +atmosphere.

3 pounds (1 small weight and 1 large weight) additional = 18} pounds atmosphere.

6 pounds (1 small weight and 2 large weights) additional = 25 pounds +

atmosphere.

The air-cylinder is furnished with two goose-necks (Fig. 7), one (8) for the attachment of the tube (6, 7) from the bellows, conveying compressed air; the other (9) for attachment of the tube (10, 11) connected with the stopcock (12, 13) and face-mask (14) or mouthpiece, through which the patient inhales. A perforation 2 inches in diameter is fitted with a screw-cap carrying a hook on which may be placed a sponge saturated with any volatile medicament (e. g., terebene) that may be desired. The cap likewise contains a smaller perforation, into which a manometer may be fitted. When the gauge is not in use this is closed with a rubber plug. Still another perforation in the top of the air-chamber is fitted with a valve that permits escape of air should too much be sent over from the bellows. This valve, which is superior to my own arrangement for the same purpose, is the ingenious device of Mr. F. Metzger, of Philadelphia, who now makes the apparatus in every respect according to my instructions, and who has devoted much time and care to the details of construction in order to secure both strength and lightness. The escape-valve is composed of two flat plates of brass, the upper perforated, the lower unperforated. They are held in apposition by a spring, and when in apposition no air escapes. The lower plate carries a chain 35

inches long, to which is attached a weight that rests upon the floor of the water-chamber. Should too much air enter the cylinder, lifting it too high, the plates are pulled apart, the air escapes through the perforated plate, and the cylinder falls to the proper level. This obviates any liability to splashing of water, which before this attachment was made would occur if attention were not paid to a line

FIG. 6.

S. Solis-Cohen's Compressed-air Apparatus.

painted on the cylinder to indicate cessation of pumping. By means of the automatic escape-valve we are enabled to introduce a continuously acting pump if desired.

As an additional precaution against splashing the air-chamber and overflow tank are each provided with a deflecting hood about an inch and a half wide and inclined at an angle of 45 degrees.

The second gasometer is for expiration into rarefied air. The connection with the bellows is reversed, so that the latter takes air from