i88 THOMPSON YATES AND JOHNSTON LABORATORIES REPORT 
Benzol 
Solubility in water at i 5 0 C. = 0*15 per cent. 
Solubility in serum at 1 5 0 C. = o - 6 per cent. 
At 0-5 per cent, commencing precipitation and opalesence, 0'6 per cent, completely 
dissolved, 0-7 per cent, not all dissolved. 
Xylol 
Solubility in water at r 5° C. = o - oi6 per cent. 
Solubility in serum at 1 5 0 C. = o - 2 per cent. 
At O'l per cent, complete solution, cloudy from proteid precipitation, o*.2 per 
cent. dissolved, C - 3 per cent, not dissolved, 0-4 per cent, not dissolved. It is clear from the 
above results that a similar action and association between the anaesthetic and the 
proteid of" the serum occurred in each case to that found in the case of chloroform. 
The amount of ethereal extractive in the different samples of serum used for the 
determinations varied between o'2-\.~o-t ) 6 per cent., thus demonstrating (see p. 191) 
that the increased solubilities found could not be due to solution of the anaesthetic 
in lipoid or ethereal extractives present in the serum. 
Summary of Experimental Results, Discussion, and Conclusions 
The experiments recorded above show : — 
I. That chloroform and other substances possessing the properties of 
anaesthetics combine in either a physical or chemical manner with proteids in solution, 
and in so doing alter the properties of the proteid so that (i) the solution becomes 
opalescent or turbid, or it may be viscid, according to the anaesthetic employed, the 
change stopping short of actual precipitation of the proteid ; or (ii) at higher 
concentrations there may be actual precipitation of the proteid which increases with 
rise of temperature, and may be either complete or incomplete. 
Thus, chloroform, in the case of serum, causes a marked opalescence at 
concentrations far short of saturation, and at higher concentration a slow precipitation 
at room temperature (15 0 C), and at body temperature, a rapid though incomplete 
precipitation. In the case of haemoglobin, one and a half to two per cent, of chloro- 
form causes a change of colour and commencing precipitation at room temperature, 
which becomes almost complete in the thermostat at 40 0 C, while five per cent, and 
over causes complete precipitation even at o° C. 
Other anaesthetics have been tested and found to produce similar opalescence or 
turbidity, and a tendency to precipitation in serum. 
1. That the maximum solubility of chloroform and a number of other 
anaesthetics in serum is much higher than in water or in saline of comparable strength 
to that of the fluids of the body. Thus, serum at a temperature of I3°C. was found 
to dissolve almost four per cent, of chloroform, while water dissolved less than one 
per cent. (0-95), and saline solution dissolved 0-83 per cent. 
