1904] Properties of Solutions of Chloroform in Water, etc. 391 



precipitate is thrown out on standing, as above described, which is 

 quite insoluble in water or saline, but easily soluble in dilute sodium 

 carbonate solution, and then gives the spectrum of alkaline haematin. 



The blood begins to give this precipitate when about 1*5 per cent, of 

 chloroform has been added at room temperature, but with a lower 

 concentration, and more rapidly when heated to body temperature in 

 the incubator. Two per cent, of chloroform gives a precipitate in the 

 cold, and on heating to 40° C. a red flocculent precipitate leaving a clear 

 colourless fluid above. 



The third method for determining the solubility of chloroform in the 

 fluids experimented with consists in shaking up thoroughly for several 

 hours with an excess of chloroform, and then pipetting off and 

 determining the amount of chloroform in the solution. 



The difficulty here is a rapid and accurate method of determining 

 the amount of chloroform contained in a measured volume of the given 

 saturated solution. 



The procedure finally employed for this purpose, which is also being 

 experimented with as a method for quantitative estimation of chloroform 

 in blood and serum at lower values reaching to the anaesthetising 

 value, was as follows, and led to very accurate results. 



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 connections 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 Concentra- 

 tion 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 o£ 



2 E 2 



