660 TRANSACTIONS OF SECTION I. 
a clear picture of the process of anzsthesia and of its principal danger—cardiac 
syncope. I do not wish to blur it with details. I shall therefore not enter into 
the question of primary cardiac syncope, nor call off your attention to other 
symptoms such as the state of the pupil and the character of the pulse and the 
colour of the face. Nor shall I at present lay any stress upon the fact that 
chloroform can be of variable quality, and that like alcohol it may act differently 
upon different people. 
First and foremost, if we are to secure the safe administration of a powerful 
poison like chloroform, we require to know how much of the drug is required for 
the production of the desired physiological effects, how much is dangerous, how 
much is necessarily fatal. Considering the fact that chloroform has now been in 
common use for sixty years,' and that the uniform experience of physiologists is 
to the effect that it is a dangerous drug as ordinarily used, it is astonishing that 
its administration should not rest upon any definite scientific basis. Occasional 
attempts have been made in the past—by Snow? first of all, by the French 
school of physiologists, Paul Bert,’ Grehant,* Dubois,’ and others, more recently 
by committees of medical societies and of the British Medical Association ‘—to 
determine what may be designated as the physiological arithmetic of chloroform ; 
but partly by reason of the difficulty in the way of measuring percentages of 
chloroform in the air and in the blood, partly by reason of the facility with 
which chloroform can be administered without any reference to percentages, the 
results obtained produced very little impression upon clinical practice, and 
deaths that could not have occurred if the principles laid down by Snow and by 
Bert had been properly appreciated and acted upon, were and still are regarded 
by the medical profession and by the public as the normal incidents of medical 
practice, and attributed to any but their true cause—an overdose of chloroform. 
I shall not venture to guess at the number of avoidable deaths that have 
taken place from this cause, but I place before you a diagram constructed from 
the annual returns of Somerset House and giving the number of deaths officially 
classified under the heading ‘ Anesthetics’ during the last fifty years. I do not 
wish to use the diagram in an alarmist sense, so I hasten to call your attention to 
the fact that the numbers are not percentages, but absolute figures which may in 
your opinion be sufticiently accounted for by the fact that the absolute number 
of cases has augmented in which anesthetics have been employed, and that 
official returns of fatal cases may have become more complete. 
Indeed, I do not myself base my judgment of the matter so much upon 
statistics, which are notoriously apt to be imperfect and misleading, as upon the 
common experience of most members of the medical profession and of many 
persons outside that profession; I have rarely met a well-informed person who 
was not personally acquainted with at least one accidental death by chloroform. 
Nevertheless I have presented to you the above statistical diagram because I 
consider that with due reservation this outcome of unprejudiced observation 
gives a by no means exaggerated picture of an actual fact, and because I believe 
it is an avoidable fact and will be diminished in future years by the wider know- 
ledge of the physiology of anzesthesia. 
T hope I shall not tax your attention too severely if I ask you to follow me 
through a short arithmetical argument in order to convince you that accidental 
deaths by chloroform must of necessity be expected to occur in the ordinary way 
of administration if the administrator is not fully alive to the physical and 
physiological properties of chloroform, and to outline in your minds a definite 
picture of some very simple and important measurements. 
By ordinary methods of administration the percentage of chloroform vapour 
in the mixture of chloroform and air inhaled may be anything between 1 and 
10 per cent.; let us say that it is 4 per cent.—z.e., that an inhalation of, say, 
1 The first major operation under chloroform was performed by Sir James 
Simpson on January 19, 1847. : 
2 Snow On Chloroform and other Anesthetics, 1858. 3 Paul Bert. 
* Grehant. 5 R. Dubois. 6 B.M.A. 
