I. ANIMALCULA OF INFUSIONS. 21 



ing half an hour did not prevent the origin of 

 the lower animalcula. Boiling three quarters, 

 or a httle lefs, rendered the whole infufions 

 flerile. 



We know the heat of bpiling water is about 

 212°. The infufions had evidently acquired 

 this degree at leaft, from their ebuihtion, while 

 the furrounding water boiled. I fay at lead, for 

 philofophers know, that water boiled in a clofe 

 veffel acquires more heat than boiled in an open 

 one. 



The fir ft problem being folved, which was to 

 afcertain how much longer than two minutes in- 

 fufions muft boil to obflruft the produftion of 

 the lower animalcula. The fecond, which was the 

 invcrfe of the firft, remained fer folution, how 

 much within half a minute, boiling would admit 

 the origin of the higher clafs. A fecond watch 

 was ufed ; and the veiTels w^ere immerfed a cer- 

 tain number of feconds, beginning with twenty- 

 nine. In a word, boiling for a fmgle fecond pre- 

 vented the appearance of the higher clafs. Thus 

 I had tP take a lefs degree of heat, zs 2og^, 

 207°, 205°, 203°, until arriving at that which 

 did not obftrud their exiftence. To be abfolute- 

 ly fure the heat had time to penetrate the 

 infufions, the water was gradually warmed, 

 till attaining the requifite degree, which was in- 

 dicated by a fmall thermometer alfo immerfed, 



B 3 But 



