160 REPORTS ON THE STATE OF SCIENCE. 



rise and fall of percentage is in my opinion well-adapted to the ordinary 

 requirements for the induction and maintenance of anaesthesia. The 

 gradual rise to 1 and 2 per cent, during the first two or three minutes 

 is precisely what is required at the outset of administration. The rise 

 to 2'5 per cent, is not excessive, and is corrected by the use of an open 

 mask or by an occasional removal of the mask. The subsequent slow 

 fall to 1'5 is what is usually required in the maintenance of anaesthesia 

 after the period of induction. 



The Conditions of Ordinary Administration are thus naturally 

 favourable and simple. With a normal current of air of 10 litres per 

 minute delivered by a rotary pump (vide infra) through a single chloro- 

 form-vessel, the percentage of chloroform delivered at the mask is 

 approximately what is most suitable throughout an administration of 

 chloroform. The sole manipulation required consists in the turning 

 ' on ' of one tap; the mask is, as a general rule, given to the patient to 

 hold, at least for the first minute or two, and as a rule this helps to 

 secure confidence. Later, of course, or with a young or refractory 

 patient, the mask must be held on by the administrator. 



The main object of a chloroform-balance is to secure the uniform 

 delivery of chloroform-and-air in sufficient volume and at suitable 

 strength. The considerable capacity of the balance-case affords a reser- 

 voir of mixture that prevents the occurrence of sudden variations of 

 percentage and acts in the sense of a flywheel. By means of the tap 

 the percentage of chloroform can be readily raised or lowered. By 

 turning on the second tap the percentage can at once be raised if the 

 steady current through one bottle only gives a mixture that requires 

 to be enriched, and this augmentation of percentage can be effected 

 quite as rapidly as may be desirable. But the apparatus is not adapted 

 to sudden lowering of percentage for the purpose of immediately reduc- 

 ing an amount of chloroform that may be judged to be greater than 

 necessary. Such reduction should, of course, be started at once by 

 the obvious means at hand, i.e., by removal of the mask. 



The blood and tissues of an anaesthetised patient are in a reservoir 

 filled to a certain degree or tension by the chloroform that has been 

 inspired and absorbed, and evidently the first thing to be done when 

 the symptoms indicate that there is more than enough chloroform in 

 the body is to stop the supply altogether. 



At a time when my chief preoccupation was to influence the discus- 

 sion of the chloroform question in the direction of numerical measure- 

 ment I stated that safe administration consists in the continuous 

 administration of chloroform vapour and air between the limits of 1 and 

 2 per 100. I made this statement well knowing that in many cases 

 2 per cent, may and must be exceeded, at least nominally, but in the 

 belief that it was preferable to name a low rather than a high maximal 

 value. Whatever limit was named it was certain to be exceeded, and I 

 felt it preferable that a higher limit should be recognised as permissible 

 in consequence of the experience of independent observers than that 

 it should be stated from the outset. At the present time I am willing 

 to admit that the normal upper limit of 2 per 100 may and must 

 frequently be exceeded, because in administration by a mask the real 



