94 LOUIS PASTEUR 



sion, and after bringing the contents to a boil, he 

 sealed the necks by fusing the glass with a blow 

 pipe while the steam was escaping. He then car- 

 ried these flasks to where he wished to study the 

 atmosphere, sterilized the necks, snipped them off 

 with sterilized pincers, thereby allowing the air to 

 rush into the flasks; then he re-sealed them. As 

 a rule, some flasks remained clear, and others not, 

 depending upon whether or not germs happened to 

 be present in the sample of inrushing air. Of the 

 ten flasks opened in the calm air of the cellar under 

 the observatory at Paris, only one showed any signs 

 of contamination. Of the eleven flasks opened in 

 the yard of the same institution, all gave evidences 

 of the development of life. 



During his vacation in i860 Pasteur decided to 

 experiment with the pure air of the Alps. On Sep- 

 tember 20th of that year we find him ascending the 

 Montanvert, near Chamounix, with a mule laden 

 with cases of flasks. In his first experiment, being 

 unable to close the necks of his flasks until he re- 

 turned to the inn where he was stopping, he found 

 that nearly all of his infusions became contami- 

 nated. His next experiment was carried out on the 

 Mer de Glace glacier. After sterilizing the neck 

 of each flask he raised the flask high above his 



