Ether, or ethyl oxide, (C2H5)2O, is obtained by distilling a mixture of sulphuric acid and alcohol. It is a very volatile, light, colorless, limpid liquid, with a burning, unpleasant taste and a characteristic penetrating odor. It boils at about 35.5° C. (96° F.), and should, therefore, boil when a test-tube of it containing some broken glass is held for a time closely grasped in the hand. It is highly inflammable, and its vapor mixed with air is explosive. It mixes freely with alcohol and chloroform, and is a solvent of resins, fats, oils, adhesive plaster, and collodion. It is soluble up to about 8 per cent. in water and 11 per cent. in blood-serum. Its chief impurities are acids, acetaldehyd, and peroxides. Even in originally pure specimens these impurities may develop in the presence of light and air. They are removed if the vapor is passed through water. Preparations and Doses. -

Ether (aether), by mouth, 15 minims (1 c.c). Spirit, 32.5 per cent., 1 dram (4 c.c). The long-used remedy, Hoffmann's anodyne {compound spirit of ether, consisting of ether, 32.5 per cent., and ethereal oil, 2.5 per cent.), 1 dram (4 c.c.), is no longer pharmacopoeial. It has a sharp, unpleasant taste, but is the favorite preparation for stomach administration.

Pharmacologic Action

Ether is a general protoplasmic poison.

Microorganisms

It is disinfectant. W. H. Park found that a mixture of 3 parts of ether and one part of olive oil would kill colon bacilli in one minute.

Skin, Mucous Membranes, And Peritoneum

If applied to the skin and allowed to evaporate, ether blanches and cools the part by its rapid evaporation; if it is applied in the form of a fine spray, it evaporates so rapidly that the part is numbed by the cold or may even be frozen. If applied to the skin and not allowed to evaporate, it irritates and is rubefacient. To mucous membranes it is very irritant, so for administration by stomach it requires dilution with water, and for administration by the lungs it requires dilution with air or oxygen. To the peritoneum it is not irritant.

Alimentary Tract

It has a burning, unpleasant taste, irritates the mouth, and induces a reflex flow of saliva and mucus.

In the stomach, if given undiluted, it burns and may induce vomiting. If moderately diluted, it is carminative, tending to promote the expulsion of gas and to relieve with great promptness the reflex and direct effects of a distended stomach upon the heart, the diaphragm, and the abdominal contents. It also overcomes colic. As it is so volatile, it is very prompt in its action, but it may produce eructations of ether-tasting gas, especially in fever or if given with hot water.

Absorption is very rapid, whether the administration is by stomach or rectum or lungs.

Circulation

From local irritation, whether from inhalation, swallowing, or hypodermic injection, there is a prompt but momentary reflex stimulation of the heart's rate and force with rise in arterial pressure. This is due probably to reflex stimulation of the accelerator center and reflex stimulation of the vasoconstrictor center. It is a slight effect at best, and is proportional to the degree of local irritation produced.

Muehlberg and Kramer have shown that the injection of a few minims of undiluted ether into the carotid artery of a rabbit, so that it passes at once to the medullary centers, is followed immediately by intense stimulation of the vagus and vasoconstrictor centers. Thus it causes vagus weakening of the heart, and at the same time excessive peripheral resistance. The result is stoppage of the heart in a condition of dilatation. In laboratory animals death in this manner frequently results if an overwhelming amount of ether is administered at the outset. In man no such deaths are reported, and this may be because ether is so irritant that it needs to be administered gradually.

For it is found that if the administration is gradual, whether by inhalation, by rectum, or by vein, the centers become narcotized so that they are resistant to the irritant effect. In careful anesthesia the effect upon the medullary centers is very little if any at first, but after a time they become depressed.

The heart muscle may be temporarily stimulated, as it tends to be by protoplasmic irritants, but after a time, in prolonged anesthesia, or if overwhelming amounts of ether are given, it shows weakening. Loeb found that when the perfusing fluid contained 0.4 per cent. of ether, an isolated dog's heart stopped in extreme diastolic relaxation.

With amounts such as are used in the average anesthesia there may be a rise in blood-pressure for the first fifteen minutes, and then a slight lowering to the normal or slightly below normal. The rate is somewhat increased, and there is marked flushing of the skin from dilatation of the cutaneous arterioles.

Blood

As administered to man, ether does not reach a concentration to interfere with the oxygen-carrying power of the blood. Viscosity and coagulation are scarcely affected, if at all. Mann says that the number and fragility of red blood-cells and the amount of hemoglobin are unchanged, but the number of leukocytes is regularly increased.

Respiration

The reflex stimulation from mouth, stomach, or respiratory passages extends to the respiratory center, and breathing is at first quickened and deepened. Henderson thinks that this, with the resistance in the first stages of anesthesia, is a possible cause of acapnia. After absorption, ordinary amounts have little effect; but large amounts, as in anesthesia, tend to depress the center. The usual cause of death is asphyxia from respiratory paralysis. In experiments with very dilute ether the respiration regularly fails before the heart, though the latter is very weak and interferes with restitution.

Nervous System

Like other strong carminatives, ether tends to overcome hysteric conditions and states of nervous instability. It probably acts reflexly from the stomach as a cerebral stimulant, promoting the control of the highest centers.