164 REPORTS ON THE STATE OP SCIENCE. 



an ether-balance, which gave as a preliminary result that full anaesthesia 

 could be produced and maintained by ether-and-air at approximately 

 10 per 100. 3 



The administration of ether — first employed in 1846 at the Massa- 

 chusetts General Hospital, Boston, U.S.A. — has ever since continued 

 in use at that hospital to the complete exclusion of chloroform. The 

 method of administration there gradually elaborated, is based on the 

 same principle as that of the method referred to as ' open ether,' i.e., 

 ether is administered from a closed mask kept drenched with ether 

 gradually brought closer to the face until it is quite closely applied so 

 as to give a maximum value of ether concentration in the inspired 

 mixture of ether and air. 



The method of ' open ether ' has rapidly grown in favour in this 

 country, and this has afforded a reason for ascertaining for ether, by a 

 procedure similar to that followed for chloroform, what are the per- 

 centages of delivery under the ordinary clinical conditions of adminis- 

 tration. 



Mr. Symes, who took a series of densimetric estimations of chloro- 

 form delivery seven years ago ' under definite conditions as closely similar 

 as possible to clinical conditions, has carried out a similar task for ether, 

 using for the purpose a flannel mask applied to an artificial face pre- 

 cisely as practised by Sir F. Hewitt. The observations have been taken 

 with the face and face-piece (1) at the ordinary laboratory temperature 

 of 22° ( = 71-6° P.). and ( 2 ) at a temperature of 37° ( = 98-7° F.). 



In view of the fact that as regards ether administration the danger 

 of giving too much hardly exists, the chief difficulty being to give 

 mough, the information principally sought for was the value of maxi- 

 mum percentage afforded to the interior of a face-piece freely supplied 

 with liquid ether, and the fall that may be expected to occur in a 

 prolonged administration by reason of evaporation from and cooling 

 of the face-piece. 



Observation 1. — Artificial respiration air-pump at twenty-four 

 strokes of 250 c.c, i.e., 6 litres per minute. Densimeter placed on a 

 broad tube ( = the trachea) connected with the mouth of an artificial 

 face, over which the mask was placed as for anaesthesia of a subject. 

 In a first trial the tracheal tube was provided with an inspiratory- 

 expiratory valve, so that the expiratory stroke was into the atmosphere 

 and only the inspiratory stroke through the mask, and therefore only 

 suction took place from under the face-piece. Ether was then dropped 

 freely on the flannel. The following scale-readings were taken at 

 two-minute intervals. Boom temperature = 22°; barometric pressure 

 = 771 mm. Hg: — 



21-4 18 176 17 



which, corrected by the formula: — 



log P = 2- 1392 + log m-log v + log T-log B, 



where the litre-weight difference between ether vapour an d air has been 

 taken as 2"020 grams, gives the values : — 



22-12 1859 18-20 1757 



3 Waller, ' On the Dosage of Chloroform,' British Medical Journal, April 23, 1898. 



4 Lancet, July 9, 1904. 



