A volatile liquid prepared from Alcohol, and containing at least 92 per cent. pure ether. C4H10O.

Source. - Made by (1 and 2) distilling Rectified Spirit with Sulphuric Acid, purifying with Slaked Lime and Chloride of Calcium, and redistilling. (1) C2H6O + H1SO4 = C2H6SO4 (sulphovinic acid) + H1O. (2) C2H6SO4 + C2H6O = C4H10O + H1SO4.

Characters. - A colourless, very volatile liquid, with peculiar strong odour and hot taste. It is entirely dissipated in vapour when exposed to the air, boils below 105o Fahr., and is very inflammable. It contains 8 per cent. of spirit. Specific gravity, 0.736.

Impurities. - Alcohol; tested by specific gravity.

Lose. - 20 to 60 min.

Preparations.

1. Æther Purus. - Pure Ether. Ether free from alcohol and water.

Source. - Made by shaking ether with water, separating, purifying by quicklime and chloride of calcium, and distilling.

Characters. - Specific gravity, 0.720. Boils at 96° Fahr. Given by inhalation.

Impurities. - Alcohol and water; detected by specific gravity.

2. Spiritus Ætheris. - Ether. 1; Rectified Spirit, 2. Specific gravity, 0.809. Dose, 30 to 60 min.

From Spiritus Ætheris is prepared:

Tinctura Lobeliae .Ætherea. See Lobelia.

Etheris also used in making Collodion and Liquor Epispasticus; and in many pharmaceutical processes.

Action And Uses. 1. Immediate Local Action And Uses

Externally. - When allowed to evaporate, ether is a powerful refrigerant and anaesthetic, abstracting heat and depressing the nerves of the part. It is used in the form of Dr. Richardson's spray to relieve the internal local pain of neuralgia, and more frequently to prevent pain in minor surgical operations, the parts being completely frozen in the course of a few minutes by the spray of pure ether from a proper apparatus. If the vapour be confined, or the ether rubbed into the skin, a rubefacient or even vesicant effect is produced, as with chloroform. The Ethereal Extract of Mezereon and Liquor Epispasticus are powerful vesicants and counter-irritants.

Internally. - Ether has a powerfully burning, disagreeable taste, and causes local irritation and reflex salivation in the mouth, like chloroform. Reaching the stomach, it acts as a local stimulant to the blood-vessels, nerves, and muscular coat, and is therefore used as a carminative, relieving pain and sickness, and expelling flatulence, especially in nervous subjects. At the same time, it acts reflexly from the gastric mucosa upon the heart and respiratory organs, as a powerful systemic stimulant. It is a very useful ingredient of powerful anti-spasmodic draughts, as will be presently described. Given with cod-liver oil, it renders it more palatable to some patients, and more digestible, possibly by stimulating the pancreas.

2. Action Ox The Blood

Ether is absorbed into the blood with remarkable rapidity, and acts here like chloroform.

3. Specific Action And Uses

The specific action of ether and its employment as an anaesthetic so closely agree with those of chloroform that the reader is referred to the description of the latter drug, and the differences between the two substances only require to be mentioned here. These are:

1. Ether must be administered nearly pure, say 70 per cent. of the vapour with 30 per cent. of air; whilst but 3 to 4 per cent. of chloroform is given, with 97 or 96 per cent. of air.

2. With ether the stage of stimulation is more protracted; there is more struggling; and the stage of anaesthesia is shorter and the degree less profound. Ether is therefore said to bo safer than chloroform.

3. Ether depresses the heart and vessels less than chloroform, the heart continuing to beat after respiration has been arrested by an excessive dose. The respiratory centre is also less depressed. For these reasons, also, ether is called a safe anaesthetic.

4. Ether has a much less pleasant smell than chloroform.

In choosing between ether and chloroform, preference must be given to the safer anaesthetic, and the use of ether has accordingly been much revived during the last few years. Under certain circumstances chloroform is preferable, as in operations about the mouth, ether causing a profuse secretion of ropy mucus; in operations where a light or the cautery might come into contact with the ether vapour and cause an explosion; in operations which must be hastily undertaken and completed; and in parturition, where profound anaesthesia is unnecessary. Infants bear chloroform well, and their delicate respiratory passages are less irritated by it than by the pungent vapour of ether.

Given by the stomach in small doses, ether increases the activity of the circulation and nervous system - partly, as we have seen, by reflex action from the gastric wall; and is used as a powerful and rapidly diffusible stimulant and antispasmodic. It is given largely in cardiac failure, faints, angina pectoris, palpitation, and depression, being even more rapid in its effects than alcohol, but more evanescent, and of course less available in emergencies. Its antispasmodic powers make it useful in hysterical and epileptic threatenings; and in spasmodic cough and asthma it is one of the most valuable remedies during the seizure.

4. Remote Local Action And Uses

Ether is excreted like chloroform, and to a certain extent increases all the secretions, but is not employed with this end in view. It is believed by some to diminish the liability to gall stones, or actually to dissolve concretions already formed.