1888-89.] Haycraft and Duggan on Coagulation by Heat. 371 
very dilute solutions of albumen ; these did not coagulate at all, 
until after the addition of the salts mentioned. He added very small 
quantities of the salts to the albuminous solution, viz., less than one 
per cent. Had he worked with coagulable solutions of albumen, 
and had he added larger quantites of salt, his result would have been 
different. While, as we shall afterwards show, these salts as a rule 
raise the point of coagulation, it is not at all. improbable that dilute 
uncoagulable solutions of egg albumen may be enabled to coagulate, 
when they otherwise would not ; in fact, our results point to this 
conclusion. If so, it is only one of the many facts which indicate 
how little is at present known as to properties of the albuminous 
molecules and the factors which determine their solubilities. 
In the preceding table we have placed some of our own results. 
In all cases the temperature, at which opalescence and coagulation 
occur, has been raised, though often, as in the case of common salt, 
to a very slight extent. 
The Precipitation of Egg Albumen by Single and by Double 
Saturation with Neutral Salts. 
By complete saturation of an albuminous fluid with a neutral 
salt the proteid may be precipitated at the temperature of the 
laboratory. Thus Hammarsten has shown that globulin may be 
precipitated from serum by the addition of magnesium sulphate. In 
this case the globulin is not converted into a coagulated proteid, but 
can again be dissolved after the magnesium sulphate has been diluted. . 
The Action of Magnesium Sulphate . — The egg albumen was 
diluted with one volume of water and freed as much as possible 
from membrane. A portion of this was saturated with magnesium 
sulphate and filtered. The saturated solution contained about 100 
per cent, of magnesium sulphate. In order to obtain solutions of 
albumen containing a lower percentage of the salt, the saturated 
solution was diluted with portions of the original albumen. 
The original diluted albumen became opalescent at 65° C., and 
coagulated, forming flocculi, at 6 6° -5 C. 
(a) The saturated solution became opalescent at 78° C., and 
coagulated at 80° C. 
( b ) Egg albumen, containing 50 per cent, of magnesium sulphate, 
became opalescent at 67° '25 C., and coagulated at 68° '5 C. 
