Page:A Practical Treatise on Brewing (4th ed.).djvu/228

212 low than too high; for too low a temperature may be corrected in the after process, whilst, on the other hand, we now have it distinctly pointed out to us, that too high a temperature is destructive.

This discovery of the French chemists may also lead to other very important results in the formation of extracts; but as it has only been pointed out to me by a friend since writing the foregoing pages, we are neither of us altogether prepared to give the results of any practical observations we have as yet made upon the subject. I know, however, that my friend, already mentioned, Mr. Robert Stein, had, long ago, ideas as to the formation of extract, which this new discovery appears completely to conﬁrm.

There can be no doubt that a peculiar change takes place in barley during the process of its being manufactured into malt, which change is absolutely necessary for the conversion of the starch of the grain into saccharine matter in the mash tun; but what this change really is, or how it is effected, remains still a matter of doubt. It was at first supposed, as stated above, that it was a certain component part of the malt, which, by chemical means, might easily be separated from it, and might per se be made available for other purposes. This opinion, however, is now losing ground, and chemists begin to doubt whether diastase as a separate principle really exists; at all events, it is in