The Clover (or Hewitt wide-bore) instrument is interposed between the face-piece and the T. of the ethyl chloride inhaler, as shown in Fig. 47. A small dose of ethyl chloride only is requisite; for an adult, 3 c.c. is enough. This is vapourised over hot water in the usual way; a very light anæsthesia is induced in some sixty seconds, and the ether can then be turned on at a much quicker rate than if the induction be conducted by that drug alone. Scope. The gas-ether and ethyl chloride-ether sequences are most useful methods. They are quick, safe, and powerful. [Illustration: FIG. 47.--Clover’s Inhaler adapted for the Ethyl Chloride-Ether sequence.] Either may be used as “single dose” anæsthetic, the ether being pushed quickly up to “full” and the inhaler then withdrawn. If, however, no access to the mouth is required by the surgeon, ether anæsthesia may, by occasional breaths of fresh air be prolonged for as long as desired. CHAPTER XVI. THE ACCIDENTS OF ANÆSTHESIA. The minor difficulties of anæsthesia have already been dealt with, and if the instructions already given, particularly in Chapter III., are faithfully carried out, incidents of real danger will rarely occur. The soundest knowledge and the most conscientious care will, however, never entirely rid anæsthesia of an element of danger to life. The conditions now to be considered are:-- (_A_) Vomiting. (_B_) Failure of respiration. (_C_) Failure of circulation. (A) Vomiting. This always exposes an unconscious patient to the danger of inhaling solid or fluid material into the larynx, with resulting asphyxia. If the patient be tided through that immediate difficulty, he is liable to develop an inhalational pneumonia subsequently. A healthy patient properly prepared should not vomit during the induction stage, nor during the progress of the operation. If he does, it means that the induction has been too slow, or that the administration has been intermittent, and the patient has been permitted to come to too light a level of anæsthesia during the operation. During emergency operations where the patient’s stomach may be full of food, the case is different. Such patients commonly vomit early in the induction stage, and no skill can avert the incident.