On Dry Leaven. 431 



ply desired, it may be renewed by adding some of the 

 remaining dry yeast to hop-water, and promoting their 

 fermentative action by a due application of warmth. 

 When the carbonic acid gas shall be in free evolution, 

 the action is retarded by adding Indian corn meal to 

 stiffness, as before ; and afterwards stopped, by dry- 

 ing the lumps and morsels of it, in the solar rays. 

 Such is the history of this economical composition, 

 whose inventor is unknown. By a succession of hicky 

 expedients, the result has probably been attained here, 

 as in various other cases, by persons who possessed 

 the capacities of artists, and the faculties of observers, 

 without the accomplishments of philosophers. It is ne- 

 vertheless, the true business of philosophy to draw im 

 portant facts from obscurity, to state them fairly for 

 consideration, and to display the usefulness of their ap-= 

 plications. In the present instance, science may con- 

 template with satisfaction, the formation, the suspen- 

 sion, and the renewal of fermentative motion, in a class 

 of substances intimately connected with the comfort 

 of social and civilized man. 



