* * * * * The actual strength of ether breathed by the patient will depend upon:-- 1. The force and frequency with which the pump is compressed. (_N.B._ It is of course useless to pump during expiration). 2. The depth of ether in the bottle. 3. The temperature of the water bath in which the ether bottle stands. The warm water should only be put in at the last moment before starting, otherwise very strong ether vapour will collect on the surface of the ether, and the first puff of the bulb will expel a highly irritant vapour towards the patient. With specimens of this machine which have the addition of the chloroform bottle, it is perfectly possible to conduct even the induction stage of anæsthesia; a mere trace of chloroform vapour will be sufficient. It is unnecessary to give detailed instructions for the use of the machine. A preliminary consideration of the above physical facts, together with a little cautious practice, will enable the student rapidly to acquire facility with the method. IV.--RECTAL ETHERISATION. For such operations as the removal of jaw or tongue there are obvious advantages in being able to introduce ether vapour to the blood per rectum, since the mouth and air passages are thereby left free for the attention of the surgeon. Many years ago this was attempted by vapourising ether and propelling the vapour through a tube high up into the rectum. This method was abandoned, as it led to a good deal of inflammatory trouble afterwards. Recently, Dr Gwathmey suggested a new method of utilising the rectal route which has largely overcome this objection. Gwathmey’s Oil Ether Method. This consists in passing into the rectum a mixture of olive oil and ether. The bowel is first carefully washed out, and an hour before operation, the patient receives a hypodermic of morphia, gr. ⅙; atropine, gr. ¹⁄₁₂₀. A suppository of chloretone gr. v is also passed into the rectum to act as a local sedative. Half-an-hour later, the patient is put into the left lateral position, a soft catheter attached to a funnel is passed some six inches up the rectum, and the mixture of oil and ether poured into the funnel. It is wise to take at least five minutes to introduce the whole dose. The following table shows the dosage required:--