6 



DR. BASTIAK ON THE 



tal fluids would mostly be exposed to temperatures higher by 

 7°-10° r. than had been intended — as I have ascertained by actual 

 trials. 



II. Heat as a Promoter of Fermentation, 



The great dependence of the processes of fermentation upon 

 heat is one of the commonplaces of science. It is known, for 

 instance, that nearly all such processes, if not all, cease at about 

 41° F. (5° C), and, speaking generally, that they increase in energy 

 with successive increments of heat till a temperature of about 

 86° F. (30° C.) is reached. It has hitherto been considered that 

 temperatures between 77° and 95° F. (25° and 36° C.) were those 

 most favourable for fermentations. The upper limits of favourable 

 temperature, however, had not been carefully defined ; and this 

 was the case especially in regard to the occurrence of fermentation 

 in previously boiled fluids. 



In previous experiments of this class no one had, so far as I am 

 aware, designedly made use of a generating temperature above 

 100° F. (38° C.) ; the heat employed by some investigators has 

 indeed been only too frequently below 77° F. (25° C). Previous 

 to the month of August 1875, I had myself never purposely 

 employed a generating temperature above 100° F. ; but early in 

 that month I discovered that some boiled fluids which remained 

 barren at a temperature of 77°-86° F. would rapidly become turbid 

 and swarm with organisms if maintained at a temperature of 

 115° F. (46° C). This important fact was ascertained whilst ex- 

 periments were being made with hay-infusions and milk which 

 had previously been subjected to destructive temperatures consi- 

 derably higher than 212° F. 



Soon after I discovered that an incubating or generating tem- 

 perature as high as 122° F. (50° C.) may be had recourse to with ad- 

 vantage in dealing with some fluids. Organic infusions which would 

 otherwise have remained barren and free from all sigus of fermen- 

 tation, have under its influence rapidly become corrupt and turbid. 

 But although the high temperature proves to be so favourable for 

 initiating chemical changes of a fermentative type in some, it must 

 not be assumed that it would be equally provocative in respect to 

 all organic fluids. The conditions most favourable for the initiation 

 of such changes must be separately studied for each kind of fluid 

 with which experiments are being made, since important speciflc 

 difl'ereuces may be encountered. I have already, however, ascer- 



