By means of this apparatus, with pure ether, a reduction of temperature to - 6° Fahr. may be obtained at pleasure. The skin becomes whitened and quite insensible in a minute or less. When the skin is divided, and the ether spray has access to the cut surface, its own anaesthetic influence is added to that of the cold. If pure ether is employed, no unpleasant sensation is produced, even in deep wounds; and, if the eye be first chilled with the lids closed, the jet may be directed upon the conjunctiva without any disagreeable effect. The reaction from the anaesthesia thus produced is in no degree painful. During the continuance of the insensibility, venous and capillary hemorrhage is almost entirely suppressed, and even small arteries are controlled. If the ether contain alcohol, or methylated spirit, or chloroform, more or less irritation will be produced. A degree of anaesthesia sufficient for all small surgical operations can thus be obtained, as proved by multiplied experience; and even extensive and capital operations have been performed, through the aid of this measure, with little or no suffering to the patient. In such cases, the knife is followed by the spray so as to benumb the deeper parts before the incision is made in them. An ovarian tumour has been successfully extracted, and the cesarian section twice performed with favourable results, with little or no pain. But the advantage of the measure is not confined to surgical operations. Neuralgic pains are almost instantly relieved; and all the therapeutical applications already mentioned of anaesthesia from frigorific mixtures, may be made also of this. One great advantage which it possesses over the freezing from mixed ice and salt is that the tissues are less hardened, and the most delicate dissection may be made without difficulty.

.* Dr. Richardson gives the following tests of the sufficient purity of the ether. 1. A little of it poured into the palm of the hand, previously heated as much as possible by the breath, should boil briskly. 2. If one or two fluidrachms of it be taken from the hand by the tongue, it should instantly pass off, without any smarting or burning, or other sensation than a slight coolness. 3. If a little piece of clean white blotting paper, moistened with it, be placed on a warm hand, the paper becomes dry in a minute, and remains without odour or moisture. 4. The spray, made to play on the bulb of a thermometer, should cause the mercury quickly to fall to 6° below zero; and the bulb should be covered with snow from the condensed atmospheric moisture. 5. The spray directed upon the back of the hand, from the distance of from half an inch to an inch and a half, should, in a time varying from thirty seconds to two minutes, cause a slight hoar frost on the skin, followed by diffused whitening; and the skin should now be quite insensible. 6. Litmus paper should not be affected by the ether. (Med. T. and Gaz., Feb. 1866, p. 169.) - Note to the third edition.

When only a very superficial insensibility is required, Dr. Richardson has found that commercial ether will often answer; and he is in the habit of employing, under such circumstances, ether mixed with alcohol or chloroform, the latter preferably. He uses two of these mixtures, the one consisting of six parts of ether and two of chloroform, the other, of seven parts of the former to one part of the latter. To produce insensibility with pure ether requires only from fifteen to fifty seconds; but with these mixtures not less than four or five minutes. With the former there is no disagreeable sensation till the part becomes white, when a sharp, pricking, burning sensation is experienced; with the mixtures there is a feeling of numbness and aching, of much longer continuance, and patients generally prefer the former. The mixture is preferable for superficial operations, as the skin is softer. For the deeper operations complete anaesthesia from pure ether is necessary; and among these is included the extraction of teeth. The slighter influence is to be preferred in the old and weak, as they are more easily affected. if desirable, the slighter effects may be obtained by increasing the length of the jet of spray, from one inch to three inches. (Med. T. and Gaz., March, 1866, p. 217.)

The ether spray may be rendered styptic by dissolving in the ether some astringent or haemostatic substance, as tannic acid. Dr. Richardson has prepared a liquid of this kind, consisting of ether saturated with tannic acid, with the addition of xyloidin a little short of saturation. He has found this mixture to coagulate not only blood in its ordinary state, but also defibrinated blood, which had been kept so long as to have begun to undergo decomposition. He believes that, applied in the form of spray, this mixture would arrest any hemorrhage from accessible parts, acting partly by cold, partly by its chemical influence on fibrin and albumen, and lastly by the extreme minuteness with which it is distributed to the bleeding surface. (ibid., April, 1866, p. 489.)

The method of Dr. Richardson has been employed to a considerable extent in this country; and Prof. H. J. Bigelow, of Boston, has found that one of the products of the distillation of petroleum, for which he proposes the name of rhigolene (from'piyos, extreme cold), is capable of producing a considerably greater degree of cold than even the purest ether. it does not appear to be a definite compound, but probably consists of several volatile constituents, and is prepared by distilling petroleum at a low temperature. it is the lightest of known liquids, having the sp. gr. 0.625; and it boils at 70° Fahr. Dr. Bigelow states that a temperature of - 19° can be readily obtained from it, by means of the common atomizer; the double tube of Richardson's apparatus not being necessary. He considers it a more certain anaesthetic than ether, to which it is preferable also by its comparative want of odour. {Bod. Med. and Surg. Journ., April 19, 1866, p. 238.) Dr. Calvin Page, of Boston, has also experimented with rhigolene; and finds it, under the same circumstances under which ether produces a cold of negative 4°, to reduce the thermometer to 19° below zero. An objection to it, however, is its extreme volatility, which requires that it should be kept cold, and renders its carriage from place to place, and particularly from a cool to a warm apartment, somewhat inconvenient. {ibid., May 24, 1866, p. 329.) f. As a Prophylactic Agent.

Cold may with great advantage be employed as a preventive of those affections which it is apt to produce. it is probably the most frequent cause of inflammations; but, as the system may be gradually accustomed to almost any disturbing agent not directly affecting its organization, the morbid influence of cold may be in great measure obviated by putting this principle in practice. The face and hands have been so accustomed to cold, that the system is rarely affected through them by that morbid agent. Allow other parts of the body to come into a similar relation to cold, and the same result will take place for all. The naked Indian, when asked why he did not suffer from cold, very pertinently answered that he was all face. Without departing from the usages of civilized life, we may in considerable degree acquire the same immunity. This is accomplished by the daily use of the cold bath, or the cold shower-bath; and even the simple introduction of the feet into very cokl*water, or washing the back of the neck and upper part of the chest, every morning, will have very considerable prophylactic efficacy. But persons accustomed to take cold easily; liable, for example, to frequent attacks of angina, bronchitis, or rheumatism; should not, especially if of feeble constitution, too hastily adopt the measure during cold weather. The best plan is to begin with general or local bathing in the summer, using water of the ordinary temperature, and to continue regularly the same practice with the advancing season, so that by the middle of winter, the system will have gradually become accustomed to a cold, equal, or nearly so, to the average temperature of the air. One rule, which must always be observed, is never to use the water so cold, or to continue the use of it at any one time so long, that efficient reaction shall not take place immediately after the application has ceased; and the reaction should be assisted by friction with a towel, which serves at the same time for drying the surface, stimulating the skin, and exciting the heart through the muscular exercise.