Sulphuric ether is generally considered to be a safer anaesthetic agent than chloroform, as but comparatively few deaths have resulted from its inhalation; but it is not absolutely free from all dangerous effects, and when death has ensued from its inhalation either serious kidney or heart affections have been present. The discovery of its anaesthetic properties was first made in 1844, by Dr. Horace Wells, a practicing dentist, of Hartford, Conn.; and Dr. Morton, of Boston, also a dentist, first demonstrated the application of its anaesthetic properties in dentistry and surgery, in 1846.

As the physiological actions of both ether and chloroform are similar, they may be considered as follows: When the vapor of ether or chloroform is inhaled, the first effect is faucial irritation, to a greater or less degree, according to the strength of the agent employed, a feeling of suffocation, with cough, a flow of mucus and the reflex act of swallowing. The desire for air may cause more or less struggling, especially in the case of children. The sensibility of the glottis, however, is soon relieved, the cough ceases, and the inhalation of the agent proceeds without further resistance.

The primary effect is a general exhilaration; and, in the case of ether especially, it is often one of excitement, which, in the majority of cases, may continue for a short time only, while in other cases, it may, from its duration and violence, give rise to considerable trouble. But, if the inhalation can be continued and this stage of excitement passed over, insensibility soon occurs. The pulse increases in frequency, the respirations become more rapid, and may assume a convulsive character. There is flushing of the face, cerebral intoxication, to a greater or less degree, according to the temperament, such as talking, laughing, singing, crying, etc. In those of a mercurial or hysterical disposition this stage of excitement is more pronounced and persistent, and during its continuance sensibility to pain is considerably diminished, although the sense of touch is still preserved, while those of taste and smell are lost, and complete insensibility soon follows.

When the patient is of a full habit, and in robust health, and the inhalation of the anaesthetic agent has been rapid, the stage of complete insensibility is preceded by a convulsive stage, during which there is rigidity of the voluntary muscles, stertorous breathing and lividity of the face. If the inhalation of the agent be still further continued, the tetanic rigidity of the muscles subsides, the lividity of the face disappears, the breathing becomes quiet, complete muscular relaxation ensues, power of movement is lost, as shown by the arm, when raised, dropping without resistance, and the conjunctiva of the eye, under mechanical irritation, being perfectly insensible to pain. During complete anaesthesia the surface of the face is cool and bathed in abundant perspiration; the countenance is calm, the eyes closed and the pupils somewhat contracted, the respiration easy and the pulse slower. The functions of respiration and circulation continue, all others being suspended. From such a condition the patient will soon emerge, provided the further inhalation of the agent be stopped; on the other hand, if the inhalation be continued, the functions of respiration and circulation will be suspended, and life will end with the cessation of the action of the heart and the respiratory organs. Sudden death from the inhalation of anaesthetic agents is due to paralysis of the cardiac ganglia. When death occurs during the stage of rigidity and stertorous breathing, it is due to tetanic fixation of the respiratory muscles and obstruction of the pulmonary circulation, accumulation of venous blood in the heart and the arrest of the heart's action.

Death may also ensue by paralysis of the respiratory muscles during the stage of complete muscular relaxation; also by paralysis of the heart during complete insensibility, the motor ganglia being paralyzed.

Death may also occur from depression of the functions and the shock of the accident, or of the surgical operation.

Mr. Woodhouse Braine divides anaesthetics into two classes: (1) Those which produce death through the lungs as well as through the heart; this class includes chloroform, bichloride of methylene, dichloride of ethidene, and many others of the chlorine series; (2) those which produce death through the lungs alone, the heart's action continuing for some time after respiration has quite ceased: this class includes ether and nitrous oxide; and he says, that in choosing an anaesthetic three factors are to be considered: (1) The nature of the operation; (2) the amount of insensibility necessary; (3) the length of time during which insensibility has to be kept up; and he sums up as follows: (1) It is well to avoid all anaesthetics which tend to depress the heart's action; (2) for short operations nitrous oxide is the best agent; (3) for long operations, except where it is desirable to avoid hemorrhage, or where the cautery is used, ether answers perfectly; (4) the best time for operating is the early morning; (5) nitrite of amyl is the best cardiac stimulant.

Dr. W. M. Barton sums up the practical advantages of ether as follows:

" 1. The excitement stage is rarely seen except in alcoholics, and is more violent if the anesthetic is hurried.

" 2. All the time the patient is kept under ether a sonorous sound is heard, contrary to what passes with chloroform, where respiration is silent, so much so that the ear may have to be placed close to the chest to hear respiration. This snoring is the tranquillity of the surgeon; his ear perceives it and he is not preoccupied with the condition of the patient. He does not have to stop to ask 'if all is well;' if the patient breathes well,' etc.

" 3. If the anaesthetic is given in too large doses and is accumulating, the snore is transformed into a deep rhoncus, grave, and less regular, the face becomes cyanotic, the eye is congested. It suffices to remove the mask and to pull out the tongue and all is well. But there never appears that pallid tint, that cadaveric look which we see preceding a chloroform syncope.

"4. The pulse, very active at first, soon slows, becomes regular, and is always strong and vibratory, contrary to chloroform narcosis, in which it is rapid and soft.

" 5. The heart-beats are strong. Here is the indisputable advantage of ether. The etherized never have that terrible, sudden syncope, coming like a thunder-bolt out of a clear sky, followed by death, notwithstanding all we can do.

"6. The accidents with ether are purely respiratory, slow and progressive, and consequently they leave us time to act.

"7. The operation terminated, the patient may recover perfectly in one-fourth to one-half of an hour his normal animation and color; there is none of that adynamia which we observe with chloroform. As Poncet has said, 'The chloroformed are in a state of apparent death, the etherized in a state of profound intoxication.'

"8. Vomiting is certainly less frequent during and after ether. Of course a good deal of mucus comes up, but the patient can often eat an ordinary meal on the same evening.

"Such is the comparison. Ether stimulates the circulation and heart, so it is especially precious in reduced patients. It is certainly less dangerous than chloroform, not only because the figures show this to be the case, but because the latter attacks the bulb and produces vaso-motor paralysis and deleterious effects far beyond our control to, limit. In ether the danger is more respiratory; it is slow and we can intervene, often successfully."