196 THOMPSON YATES AND JOHNSTON LABORATORIES REPORT 
forms on standing either at room or body temperature. If the percentage of chloro- 
form exceed one-and-a-half, a precipitate is formed more or less readily according to 
the concentration of the chloroform, and also to the temperature, the precipitate being 
formed more readily at about 37 0 C. than at the room temperature. 
The highest concentration of chloroform in these experiments with haemoglobin 
solutions was 7-5 per cent. In this case a copious brick-red precipitate was produced, 
mixed with a little undissolved chloroform. Before this precipitation occurs, the 
solution also changes colour and becomes opaque. The precipitate was removed by 
centrifugalizi ng, and was washed several times with distilled water. On first centri- 
fugalizing, the precipitate settled down very rapidly, and left the fluid above clear and 
practically colourless. This fluid was examined for proteid, but only a trace was 
found, showing that the above concentration of chloroform is sufficient to remove all 
the proteid from solution. 
The nature of this precipitate was next investigated. It was thought that the 
proteid was, perhaps, simply thrown out of solution by the chloroform in an 
unchanged form, and experiments were carried out with a view to finding whether 
the proteid could be got into solution again. 
After the precipitate had been thoroughly washed, to get rid, as far as possible, 
of any mechanically adherent chloroform, it was warmed to about 40 0 C. with distilled 
water under the reduced pressure of a water-pump. Even at the ordinary tempera- 
ture a considerable volume of gas was seen to bubble off, and on warming it came 
off very vigorously for a time. When there was no further appearance of any gas 
coming off", the mixture of liquid and precipitate was filtered. The filtrate showed the 
spectrum of oxy-haemoglobin. This led to the idea that a considerable quantity, or 
perhaps the whole, ot the precipitate might be made to redissolve, and the remainder 
of it was thoroughly shaken up with water and the liquid examined, but no further 
action had taken place. This experiment was repeated several times, the various 
operations being carried through as rapidly as possible, but no further success was 
obtained in the efforts to get the proteid into solution again after pumping off the 
chloroform. The precipitate obtained on adding excess of chloroform to haemoglobin 
solution, after being washed several times, was found to dissolve readily in sodium 
hydrate, and also in a dilute solution of sodium carbonate, in the latter case giving 
the spectrum of alkaline haematin. 
In these earlier experiments it was assumed that the gas which came off on 
warming the precipitate with water was chloroform, or at least partly so, but no other 
method was adopted to prove the presence of or estimate the quantity of chloroform 
in the precipitate, and the experiments were for a time abandoned. After a short time, 
however, a method was tried, after being tested on aqueous solutions of chloroform 
of known strength. The method consists in warming the substance under examina- 
tion on a steam bath with a saturated solution of potassium permanganate in fifteen per 
