STUDY OF THE PHYSICAL CHEMISTRY OF ANAESTHESIA 
67 
The procedure finally employed for this purpose was as follows :- — ■ 
A measured volume (usually 10 c.c.) of the fluid saturated with chloroform is 
placed in a flask fitted airtight with a double bored cork, and a stream of hydrogen 
is aspirated through the solution, the oxygen present in the flask and connexions is 
absorbed by passing through alkaline pyrogallate, and the mixture of hydrogen and 
chloroform is then burnt by passing over heated palladium asbestos placed in a very 
short combustion tube. All the chlorine in the chloroform is thus burnt to 
hydrochloric acid, and the amount of this absorbed in standard alkali is then estimated, 
first by back titration against standard acid, and then further checked, either by 
volumetric titration with standard silver nitrate solution or by gravimetric 
determination as silver chloride. 
The serum used in these determinations was examined for chloroform emulsion 
by the microscope, but no undissolved chloroform in suspension was observed. The 
precipitate in serum at atmospheric temperature obtained by this method of shaking 
up with excess of chloroform was very dense, so that the serum became quite opaque. 
The results obtained by employing this method were as follows : — 
Distilled water, dissolved 0-95 per cent., and serum, dissolved 5-08 per cent. 
III. — On the Vapour Pressure of Chloroform Dissolved in Varying 
Concentration in Water, Saline, Serum, and 
Haemoglobin Solutions Respectively 
A determination of the vapour pressure of an anaesthetic in solution at varying 
concentrations in serum, in haemoglobin, or in blood, is of high practical importance, 
since it is upon the relationship of this vapour pressure to the concentration of the 
solution that the amount of anaesthetic taken up by the blood circulating through 
the lungs depends. 
It has hitherto been taken for granted that the Dalton-Henry law can be 
applied, and that the amount of anaesthetic taken up is strictly proportional to, and 
varies directly with, the percentage of the vapour of the anaesthetic in the inspired air. 
This has never, however, to our knowledge, been experimentally tested, and it 
seemed to us desirable to attempt such a determination. We have investigated from 
this point of view solutions of chloroform in serum, haemoglobin solution (of equal 
strength in haemoglobin to the blood from which the haemoglobin was prepared) and 
whipped blood, and have contrastedlthe pressures obtained with those of solutions in 
chloroform, in water, and normal saline at equal concentrations. 
The vapour pressures have been measured corresponding to concentrations 
ranging from considerably below the anaesthetizing values for chloroform vapour 
pressure in air (viz., 8-10 mm.), observed by Paul Bert, up to the saturation points 
in most cases. 
