The operations to which, according to Dr. Arnott and others who have tried the plan, it is peculiarly appropriate, are those for cutaneous or small subcutaneous tumours, the opening of abscesses, paronychia, carbuncle, the forming of setons and issues, scarification, paracentesis, the cutting down upon arteries, the tying or cutting of varicose veins, phymosis, strangulated hernia, the evulsion of nails, and the various ophthalmic, dental, plastic, and orthopaedic operations.

The advantages of the measure are its safety, the absence of hemorrhage, the want of subsequent inflammation or suppuration, the healing by the first intention, and the non-occurrence of inflammation in the neighbouring parts.*

Among the surgeons who have put in practice the process of Dr. Arnott, and have spoken of it favourably, are Velpeau of Paris, Coste of Marseilles, who has met with results in the highest degree favourable (Med. Times and Gaz., Nov. 1855, p. 518), Paget of London, and Dr. J. Mason Warren of the United States (Bost. Med. and Surg. Journ., lii. 35).

After the publication of the first edition of this work, which contained the above statements, additional evidence was offered, from various quarters, of the efficiency and safety of this mode of producing anaesthesia for the more superficial surgical operations. it appears, however, that healing by the first intention is sometimes retarded, and blistering and even sloughing have taken place; but these results are ascribed to a too long and unnecessary continuance of the freezing application.

Still more recently, another and more convenient, as well as more effectual, method of obtaining the anaesthetic influence of extreme cold has been brought to the notice of the profession by Dr. B. W. Richardson, of London, whose first communication on the subject is contained in the Medical Times and Gazette for February, 1866 {page 115). His object was to unite with the means of reducing the temperature the anaesthetic action of a narcotic; and this was accomplished by employing ether as the frigorific agent. The recent discovery of the method of reducing liquids to the form of spray, suggested the idea that the volatilization of ether might be greatly increased, and the consequent frigorific effect equally augmented, by its application to the surface in this form, while its well-known anaesthetic effect might be added to that of the cold. After many trials, Dr. Richardson succeeded, by means of an instrument invented for the purpose, in accomplishing all that he aimed at; and the new anaesthetic method has now been submitted to so many practical tests, and so successfully, as to leave no doubt of its superiority over all other known means of producing local anaesthesia for surgical purposes.* it consists simply in directing upon the part to be acted on a sufficiently copious and powerful jet of ether spray mixed with atmospheric air. For full effect it is necessary that the ether should be very pure. The common ether of the shops, containing more or less alcohol, though it may produce superficial anaesthesia, sufficient for the slightest surgical operations, as a small puncture, is inadequate to the deeper effect which is required for most practical purposes. It should have a sp. gr. not exceeding 0.723, and it should boil at a temperature beneath that of the human body. As prepared for Dr. Richardson, one parcel had the sp. gr. 0.720, and boiled at 92° F.*

* The preceding observations have been gathered from various communications, most of which are contained in the Lond. Med. Times and Gaz. (March, 1854, p. 285; Nov. 1854, p. 488; and Nov. 1855, p. 518), and the Ed. Month. Journ. of Med. Sci. (July, 1854, p. 32).

* The instrument of Dr. Richardson is on the principle of Siegle's spray-producer, but differs in this respect, that, while in the latter the current of liquid to be atomize,d is drawn by means of a vacuum into that of the air, in Richardson's the ether and air are driven on together by a pressure acting on both, and thus the force of the current and the quantity of liquid atomized are greatly increased. The apparatus consists of a wide-mouthed graduated bottle for holding the ether, of various lubes, and of an elastic bellows to supply the power. The mouth of the bottle is closed with a cork, through which passes a double tube, one enclosed within the other. The inner and smaller tube extends to the bottom of the bottle, and at top ends in a point somewhat below the upper extremity of the outer, which covers it entirely above the cork. The outer tube ends, below, at the lower end of the cork, where it communicates with the bottle, and extends upward some inches, being somewhat curved near the top, and ending in a small orifice. A little above the cork the outer tube is perforated so as to admit a small lateral tube, with which the bellows is connected. This consists of a tube with two gum elastic expansions, one at the end, provided with valves to admit the entrance and prevent the exit of air, the other in the middle to sustain the current of air sent forward by contracting the terminal one with the hand. By the working of this bellows a current of air is impelled into the outer tube, and, while it enters the bottle and acts on the surface of the ether contained in it, escapes through the upper orifice of the tube, where it meets and atomizes the slender column of ether, driven upward through the inner tube by the pressure on the surface of the liquid. The instrument admits of various modifications. Thus, the bellows may be so arranged as to be worked by the foot instead of the hand; and the double tube may be replaced by two separate tubes meeting at their upper orifices. The jets also may be multiplied, and this may be accomplished by having a large central tube, with a number of terminal jets; or the number of tubes may be multiplied. in these cases, the capacity of the bottle should not be less than six fluidounces. To the lower end of the ether tube, jet tubes may be fitted of different sizes so as to regulate the dimensions of the column of ether sent up. Besides, tubes may be attached to the instrument by which the spray may be conveyed into interior cavities, as the vagina and rectum; and the inner end of the tube may be provided with a bulbous extremity, so as to cause the spray to be diffused. (Med. T. and Gaz., Feb. 1866, p. 115.) - Note to the third edition.