1888-89.] Haycraft and Duggan on Coagulation by Heat. 381 
the facts frankly stated by Dr Halliburton, seemed to throw some 
doubt upon the correctness of his deductions in the case of serum 
albumen, and this applied with equal force to the experiments con- 
ducted by MM. Corin and Berard on egg albumen. 
Our previous experiments have shown that, in alkaline solution, 
the more dilute a solution is, the higher is its coagulation point, and 
we have found that we could never completely precipitate any 
albumen at the temperature at which flocculi first appeared. The 
reason of this is very simple ; as soon as a solution begins to 
coagulate, the remnant, still soluble, is practically a more dilute 
solution of the same proteid, and must be heated two or three 
degrees more before it will begin to precipitate. In this case, also, 
the coagulating proteid will leave another soluble remnant, coagul- 
able at a still higher temperature, and so on. In fact, we may 
venture to make this general statement — In order to coagidate com- 
pletely any proteid it must be heated to that temperature at which 
its most dilute solutions are coagulable. We have not made so 
systematic an investigation upon the effect, on its coagulating point, 
of diluting acid solutions of albumen, but we have assured ourselves 
that the more dilute solutions coagulate at a higher temperature. 
One out of several experiments may be quoted the following : — 
Some egg albumen was diluted with two volumes of water and 
carefully neutralised. It was then brought to the same degree of 
acidity as is recommended for fractional coagulation, 1 cubic centi- 
metre of a 2 per cent, solution of acetic acid being added to 75 cubic 
centimetres of the albumen. This solution was found to coagulate 
at 53° C. 
When diluted with one volume of water, acidulated to the same 
degree, it coagulated at 54° C. 
With three volumes of water, it coagulated at 58° C. 
With seven volumes of water, it coagulated at 62° C. 
With fifteen volumes of water, it coagulated at 68° C. 
It is seen, therefore, that dilution has the effect of raising the 
coagulation point a great many degrees, the more dilute albumen 
requiring a much higher temperature for its separation. This may 
be shown in the most striking manner by heating some of the 
acidulated water to between 60° and 70° C. ; and dropping in some 
acidulated egg albumen it at first dissolves. Now divide the solu- 
