TRANSACTIONS OF SECTION 1. 557 
LRIDAY, SEPTEMBER 1, 
The following Papers and Reports were read :— 
1, Lhe Administration of Chloroform. 
By Aveustus D. Waturr, M.D., LL.D., PRS. 
The author said; The subject on which I would like to invite your consideration 
and criticism to-day concerns the value of acquiring a physiological and arith- 
metical conception and understanding of the conditions of safe anesthesia. 
Picture the lungs with a surface of 100 square metres, a blood surface of 
75 square metres containing a total volume of air of 5 litres, and a tidal air at 
each inspiration of half a litre, or 500 c.c. 
Successful chloroform anwsthesia requires the regular respiration of air in 
which chloroform is maintained between the limits of 1 and 2 per 100, In my 
experiments in the laboratory on isolated frog’s nerve 5 per cent. vapour is found 
to be the outside limit of safety, and is fatal if persisted in ; and it so happens that 
Snow fifty years ago named 5 per cent. as the limit beyond which one dared not 
go in anesthesia of the human subject. Snow, in 1850-55, and Paul Bert, in 
1880-83, did their best to place the administration of chloroform upon a rational 
basis. But, partly by reason of the difficulty of getting out chloroform percentages 
and partly by reason of the facility with which chloroform can be administered 
without any reference to percentages at all, the teaching of Snow and Bert did not 
produce its full effect upon clinical practice, and fatal accidents continued to take 
place—fatal accidents that could not have taken place if the principles of Snow 
and Bert had been properly appreciated. 
I regard as a substantial contribution towards safe anesthesia, not the publi- 
cation of fragmentary ‘statistics,’ nor the advertisement of ‘ safe’ instruments, but 
the acquisition of a simple method by which we can rapidly ascertain the per- 
centage of chloroform offered to inspiration by any means. And of the study in 
which I have been engaged during the last ten years I should attach greatest 
importance to the realisation of the simple fact that a quarter litre of air and 
chloroform weighing one to two centigrammes more than a quarter litre of air 
ulone contains 1 or 2 per cent. of chloroform vapour, since by this means we 
can easily test the percentage in any method of administration. This method of 
densimetry was introduced by myself and Dr. Geets in 1902. The principle upon 
which the method is based is as follows:— 
1,000 c.c. of CHC], vapour _— weighs 5,325 mg. 
. - atmospheric air », 1,293 meg. 
Difference = 4,032 mg. 
te, 1,000 c.c. CHOI, replacing 1,000 ¢.c. air gives an increment of weight of 
4,032 mg. 1 ¢.c. CHCl, vapour replacing 1 ¢.c. air gives an increment of weight 
of 4 mg,, or, that is, 2°5 c.c. of CHC], vapour; 2°5 e’c. of air gives an increment of 
weight of 10 mg., so that with a 250 c.c. bulb each 25 c.c. of CHCl, vapour, 
that is, each 1 per cent., is represented by an increment of weight of 10 mg. 
Corrections for temperature and pressure and volume may be made, if thought 
desirable, from the formula log P = 1:8377 +log M—log N+log T—log B, where 
P is percentage, M increment of weight in milligrammes, V capacity of densimeter 
in cubic centimetres, T absolute temperature, B barometric pressure and 1 8377. 
At Johannesburg B is 600 mm. 
Two glass densimeter bulbs are weighed against each other and the weights 
adjusted to balance them: one of them is then filled with the vapourto be estimated 
and weighed again, and the difference in weight indicates the percentage. The 
bulb is inserted in the delivery or aspirating tube and protected by indiarubber 
bags, so that it can be stoppered and unstoppered without entrance of atmospheric 
air. The vapour supplied from a skinner’s mask has been tested in this way, 
drawn by aspiration from beneath the mask. 
In practice, as recommended by the Scotch school of anesthetists, ‘plenty of 
