620 SCIENCE PROGRESS 



balance and a smoked cylinder served to give a record of the 

 rise and fall of the bulb with rise and fall of chloroform per- 

 centage, and incidentally served the useful purpose of damping 

 the oscillations of the beam and pointer. In order to avoid 

 accidental fluctuations of the percentage delivered to the 

 animal, it was advisable to use a vessel of considerable volume 

 containing the mixture on its way to the animal. I used the 

 case of the balance for this purpose. Air was pumped into it 

 through or over the surface of chloroform by the ordinary 

 respiration pump or by a bellows, and went on by a second tube 

 to the tracheal cannula or mask. The large capacity of the 

 balance case — in this case 30 litres — proved to be suitable for 

 the induction of anaesthesia, and for its safe gradual modification. 

 The chloroform percentage rose from zero to 2 per cent, in 

 about two minutes ; the lag of voluntary diminution and increase 

 was about ten seconds ; the pointer could at will be kept per- 

 fectly steady at any desired percentage. Finally, I may remark 

 that for all ordinary purposes of the laboratory a comparatively 

 coarse balance is best adapted. In the apparatus now in daily 

 use the graduation is from 1 to 3 per cent., which gives records 

 of 6, 12, and 18 mm. amplitude. 



Judging by the comments of visitors to the University 

 of London, acquainted with the various haphazard methods 

 in use for producing and maintaining anaesthesia of the 

 human subject, and witnessing for the first time the ordinary 

 procedure followed in the physiological laboratory for the pro- 

 ducing and maintaining of anaesthesia of animals, the usual 

 thought aroused seems to be one of regret that the human sub- 

 ject cannot be anaesthetised with similar uniformity and safety. 



My own feeling is one of intense surprise, that the clear 

 practical experience of the laboratory should be of so little use 

 to the medical profession, and that year by year the death-roll 

 of chloroform anaesthesia should continue undiminished. 



Occasional attempts have indeed been made in France, 

 in Germany and in England, to bring graduated apparatus into 

 use, and have met with a certain amount of success in the 



ordinary temperatures (18 C.) and pressure (760 mm. Hg) a bulb of 

 1054 c.c. would be required for these increments. Or if, as was the case of 

 the particular balance now in my hands, the bulb had a capacity of 870 c.c, the 

 counterpoising weights for 1, 2, 3 per cent., should be taken as 33, 66, and 

 99 milligrammes. 



