572 SCIENCE PROGRESS 



only for-a short" distance, and take a survey of the field that 

 has been traversed, as a guide to the work that remains to 

 be done. 



The first point that has been established is that anaesthesia 

 with known percentages of chloroform is more easily accom- 

 plished, more pleasant to the patient, and possesses fewer 

 elements of danger, than by the open method of unknown 

 percentages. When this latter method is carried out by experts 

 the difference is not great, but every one (even every medical 

 practitioner) who may be called up to give anaesthetics is not 

 necessarily thereby made an expert, and the results may (some 

 I have seen do) fall considerably short of the ideal. 



It is necessary for the success of the method with known 

 percentages that these shall be correct percentages. What 

 these are must be determined by direct observation. From 

 the cases already anaesthetised we can say that in the great 

 majority a percentage gradually rising to 2*5 per cent, and 

 probably 3 per cent, is required, if anaesthesia is to be obtained 

 in from seven to ten minutes. Later on, the patient requires 

 less chloroform — 2 per cent., 1*5 per cent., dropping to 1 per cent, 

 or even less if the operation extends much beyond an hour. 



All this seems so simple that the advantages of the method 

 are not at first realised. The chief of these is that the anaes- 

 thetist has now another guide in his procedure besides the 

 condition of the patient. Hitherto this latter factor has been 

 the only thing that was known. If the dose was correct the 

 patient was anaesthetised, if it was too little he came round, if 

 too much he died. As in most patients the same amount of 

 chloroform produces the same symptoms, the open method 

 works better in practice than might be supposed ; but, when 

 an exceptional case is met with, the anaesthetist can do little 

 more than guess at the amount of the drug that has produced 

 any given condition. An excellent instance of the uncertainty 

 attending this point can be found in the controversies that 

 periodically arise as to the cause of death in chloroform anaes- 

 thesia, one school holding that too much has been given, the 

 rival school believing that {mirabile dictu /) the patient has had 

 too little! 



When the percentage in the inspired air is known, at least 

 one cause of uncertainty is removed. Even allowing for every 

 possibility of individual variations, a patient that is being kept 



