STUDY OF THE PHYSICAL CHEMISTRY OF ANAESTHESIA 163 
pig's blood. The serum used was obtained from clotted blood, and was thoroughly 
centrifugal ized before use. The haemoglobin was in all cases obtained by centri- 
fugalizing the blood corpuscles three times with normal saline, and then laking with 
distilled water and making up to the same volume as that of the blood taken. 
In the case of serum, we found that the fluid acquired, with less than one per 
cent, of chloroform (and greater quantities up to saturation), a peculiar opalescent 
and fluorescent appearance, but remained quite transparent to transmitted light. On 
the addition of over two per cent, of chloroform, there is a tendency to precipitation 
even in the cold, and at the end of twenty-four to forty-eight hours there is a slight 
precipitate present, but the effect is much hastened on placing the mixture in an 
incubator at 40 0 C, so that it becomes impossible to determine the maximum 
solubility of chloroform in serum at body temperature. Both in obtaining 
precipitation in the cold and more rapidly at 40 0 C. in presence of the natural 
alkaline reaction of the fluid, our results are at variance with those of Formanek 
and Salkowski. The results were obtained several times in succession. 
The marked opalescence in the serum was obtained in preparation of solutions 
of known concentration in chloroform for purposes of measurement of their 
vapour pressures, and leci us to doubt at first whether we were not dealing with a 
fine emulsion of chloroform in the serum. Since this point was of vital importance 
to our experiments on vapour-pressure, we investigated it as completely as possible. 
In the first place, examination with the microscope of the opalescent fluid showed 
no visible globules of chloroform, even with the highest powers. 
To make certain of the matter, a current of air from an aspirator was bubbled 
first through chloroform contained in a Woulff's bottle, afterwards through a 
similar bottle containing water, and then, at the same temperature, was sent through a 
third Woulff's bottle containing serum. By this procedure the serum never came 
in contact with fluid chloroform, nor with air more highly charged with chloroform 
vapour than corresponded to the saturation of the air in contact with it or passed 
through it. 
There could, hence, be no condensation of chloroform, and no means by which 
an emulsion of chloroform, finer even than could be seen with a microscope, could 
be formed. 
Very soon, however, after the chloroform vapour began to pass through, a 
distinct difference in appearance was observable between the serum and a control 
placed alongside, and after a time the serum charged with chloroform in this manner 
was as opalescent as the specimens made in the usual way by shaking with weighed 
quantities of chloroform, and gave similar results with regard to vapour pressure. 
These results show that the marked opalescence is not due to an emulsion of 
chloroform, and, further, that it is not due to precipitation of proteid in the ordinary 
sense of the word, for no precipitate can be seen with the microscope in the opalescent 
fluid. 
