through the courtesy of Prof. Martin and my friend, Prof. Geo. T. Kemp, an alumnus of that institution, and now of the Hoagland Laboratory, of this city, and with whom these experiments are being continued. I hoped to have completed them before presenting this paper, but delays in obtaining apparatus from abroad suitable for the work have rendered this impossible, and I have concluded to give to the profession these results, leaving a fuller discussion until the completion of our researches.

Before giving the results it would seem proper to present some of the views advanced by other writers. Dr. Watson says of nitrous-oxide gas: "It furnishes the simplest case of the circulation of unoxygenated blood through the arteries, and therefore through the capillaries of the brain. It is the privation of oxygen, and not the presence or increase of carbonic acid, which is suspensive of consciousness."

66

The International Cyclopædia of Surgery," vol. i., p. 423, says: "Nitrous oxide, in spite of its asphyxiating properties, is the safest of all anæsthetics for brief operations. This gas has been administered

more than a million times with but seven deaths."

Sir Humphrey Davy, after exhaustive investigations, as published in 1839, entitled "Researches on Nitrous Oxide," says, in his conclusions: "It appears that the immediate effects of nitrous oxide are analogous to those of diffusible stimuli; both increase the force of the circulation, produce pleasurable feeling, alter the conditions of the organs of sensation, and, in their most extensive action, destroy life." He then goes on to state that the nitrous oxide is probably decomposed in the system, the oxygen producing superoxygenation, the nitrogen remaining and raising the percentage of nitrogen above the normal. This, however, has been disproved by a number of later observances.

Dr. E. P. Howland, of Washington, D. C., in a paper read before the Biological Section of the American Association for the Advancement of Science, August, 1883, says: "I have administered pure nitrous oxide in over three hundred cases in the city of Washington; the longest time a patient was unconscious was thirty-five minutes." He further says: "If air, or oxygen, is mixed with nitrous oxide in sufficient quantity to prevent asphyxia, it will not produce anæsthesia."

M. Paul Bert, of Paris, and one German writer have acted on the theory that more oxygen should be supplied to the blood than in common respiration, and Bert has constructed a tight cage, large enough to admit patient and those required for the operation; here, under a pressure of two atmospheres, he administers nitrous oxide mixed with oxygen, and obtains satisfactory results.

The German writer supplies oxygen from a separate cylinder, connecting with his apparatus, and claims equally good results, without the cumbersome cage.

It will at once be seen how these various writers differ in their conclusions.

In experimenting upon animals, I have found that if pure nitrous oxide was administered, within two or three minutes the respirations become labored, and the register of the kymograph indicated impending dissolution, and, if the inhalations were continued, respiration ceased In two cases, when the animal was not connected with the kymograph, inhalation was continued to the point of cessation of respiration, but the action of the heart still continued. Artificial respiration was then induced, and in less than three minutes the animals (dogs) were playing about the room. In one case there seemed to be a slight inco-ordination of the movements of the limbs and a tendency to stagfor three or four minutes.

ger

11 34',

11 36',

11 40′,

II 42,

The details of one of these experiments may be of interest to some readers: At 11 29′ A. M. gave to a small dog equal parts nitrous oxide and oxygen. 11 31', animal lethargic. 11 32′ gave two-thirds nitrous oxide and one-third oxygen. 11 33, active; sensation present. all nitrous oxide given. 11 34 30", struggles; reflexes present. find that he gets some air; re-arrange apparatus to prevent this. give all nitrous oxide. II 41, reflexes blunted, but present. fully anesthetized, respirations labored. 11 42′ 15′′, one-half nitrous oxide and one-half oxygen given; respirations suddenly shallow. 11 44', reflexes present to touch and threat; two-thirds nitrous oxide and one-third oxygen given. 11 46', reflexes present to threat. 11 47', struggles. II 48', reflexes blunted. 11 50', all nitrous oxide given again; struggles. 11 51', reflexes barely present. 11 52', respirations ceased, but heart-beats continue; artificial respiration induced. 11 53", breathes naturally. 11 53' 30", stands on his feet, but drops over. 11 55', still a little unsteady. 11 57', trots about the room and 'answers to call by wagging tail; somewhat lethargic. 12 M., entirely

normal.

This additional experiment has been completed since the above was written, and is so instructive that I insert it: A small dog was attached to the kymograph in such a way as to register, by a delicate apparatus, the heart-beats, respirations, and number of seconds of time. The animal had been under chloroform for some time, and, during the adjusting of some apparatus, the valve of my inhaler was so turned that the animal breathed pure chloroform for about a half minute, when I noticed that respiration had ceased. Artificial respiration was immediately induced, and the animal resuscitated, though suffering some

what from shock. All nitrous oxide was now given for four minutes, when respiration again ceased; but the heart continued its beating for eight minutes, the beats gradually diminishing in force until the register recorded stoppage of the heart..

In the first experiment it will be noticed that but two minutes elapsed from the time all nitrous oxide was administered before respiration ceased. This was sooner than usual. It will also be noticed that the heart did not cease to act, and this accords with other experiments, and warns us that the danger comes first through disturbances of respiration.

This experiment indicates that the admixture of oxygen and nitrous oxide, in the proportion of two parts of the former to one of the latter, does not produce profound anæsthesia.

I have made repeated experiments upon myself and also upon other persons, as well as upon animals, and have demonstrated beyond question that partial anesthesia can be maintained with a proper proportion of nitrous oxide and atmospheric air combined, anæsthesia becoming more and more profound as the quantity of air is diminished.

Of course, I could not demonstrate and maintain a condition of complete and prolonged anesthesia upon myself; but, having carried it to a certain point, I became convinced that there could be a proper equilibrium established as to the quantity of atmospheric air required in combination with nitrous oxide, and thus anæsthesia be maintained with safety for the necessary length of time, in an ordinary room or ward in a hospital, without depression, either in the pulse or respirations, if properly administered. "But why," says Dr. Fowler in his paper, "this peculiar condition? If it was not the result of the accumulation of carbon di-oxide in the blood, what was it?"

Neither the views of other writers, as quoted above, nor those of any that I have been able to find answer this question as fully as could be desired; and, having given those of a number of the best authorities, I venture to give my own, without comment upon those of others, leaving the profession to decide which is correct, well knowing that time will reveal the truth, and trusting to the conclusion of the series of experiments alluded to for the proof of the truth or falsity of my positions.

The Giver of all good so combined the two chemical elements, nitrogen and oxygen, in the atmosphere, that it best supplies the needs of the creatures he has made. If we go into the higher altitudes, where the air is rarified, respirations are increased, so that the necessary amount of oxygen may be supplied. If we descend to a point where the air is more dense, respirations are diminished, as more oxygen is supplied with each respiration, and only a given amount is needed for

the ordinary processes of life. The more quiet we remain the less the waste of tissue, and hence the less the demand for the renewing forces.

Nitrous oxide enters the circulation, and acts as an anesthetic agent. It is not suitable for continuous inhalation for a prolonged period in its pure state, because under the conditions existing in the blood the tissues are not able to decompose it and appropriate the oxygen. By its anæsthetic action, however, it modifies the processes of waste or combustion of the tissues of the body, so that less oxygen is required than in the ordinary processes of life. To state a well-known fact, each living being requires a given amount of oxygen to sustain life, some more, some less, depending upon the size and activity of such being; each act and movement of the body necessitating a certain amount of tissuecombustion, in which this oxygen is used, and the resultant carbon di-oxide given off. Now, if we can suppose a condition in which tissue-combustion is partially arrested, the amount of oxygen required would be lessened by so much. This is probably what really occurs in nitrous-oxide anæsthesia. The gas enters the circulation, produces anesthesia, and the processes of waste are diminished; hence the processes of repair are not called for, neither is there depression nor exhaustion on the contrary, there is, in many cases, a feeling of exhilaration on recovering consciousness.

The condition of nitrous-oxide anæsthesia is probably independent of partial asphyxia, most writers to the contrary notwithstanding. The cyanotic appearance is not due to carbonic di-oxide poisoning, but to the diminished amount of oxygen in the blood. The system, however, does not suffer from this diminished supply of oxygen, for its chemical activity is lessened by the nitrous oxide.

This is my answer to the question asked by Dr. Fowler in his paper, as fully as I can make it at present.

If all nitrous oxide is inhaled, as soon as the oxygen remaining in the lungs and bronchial tubes is appropriated by the tissues, all the processes of life cease; as no oxygen is obtainable from the nitrous oxide, it must be supplied from some other source. The exhalingvalve carries off whatever carbon di-oxide may accumulate, the suspension of the respirations is not therefore due to the effect of this agent. It is the lack of something, and that something is the life-sustaining necessity, oxygen. Without it life must cease, just as an engine stops when the fire is withdrawn from the furnace as soon as the accumulated steam is expended.

Those who claim to administer nitrous oxide in its pure state for prolonged anesthesia doubtless have had an imperfect apparatus, so that some air was admitted, or the struggles of the patient so disarranged the inhaler, that a fatal issue was thus averted.

For the shorter operations, such as lancing of felons, extracting teeth, etc., it can be administered to the point of complete anæsthesia pure, the inhaler being removed as soon as this condition is reached.

If these conclusions be correct, it will be seen at once what a simple process we have before us. The bulky cage of Bert is not required, nor a separate cylinder of oxygen. All that is needed for the proper administration of this anesthetic is a carefully constructed inhaler, so as to supply a sufficient amount of air with the nitrous oxide, and no more; and on the proper manipulation of this inhaler will depend the success or failure of those who undertake its administration. The inhaler used by the writer is a combination of his own ideas, joined to those of others well known to the profession. It is adapted to the administration of nitrous oxide, ether, or chloroform. The mouthpiece and valve are those in use in the Codman and Shurtliff inhaler.

Into the metal tubular extension of this are two stop-cocks, one closing the nitrous-oxide chamber and the other fixed on an extension at right angles, upon which there is an attachment with a bayonet-joint for the ether- or chloroform-receiver. This receiver is large enough to contain an Allis inhaler, modified in size, but large enough to give the requisite amount of evaporating surface. The top of this can is movable, for Into the bottom of the receiver a

the insertion of the Allis inhaler. flat sponge is placed, to absorb any surplus ether or chloroform.