THE BEGINNINGS OF LIFE. 351 



boiling water, three-fourths of it was filled with the 

 fluid which was to be made the subject of experiment. 

 With the aid of a small hand blow-pipe and the spirit- 

 lamp flame, the neck of the flask 1 , about three inches 

 from its bulb, was then drawn out till it was less than 

 a line in diameter. The neck having been cut across 

 in this situation, the fluid within the flask was boiled 

 continuously for a period of from ten to twenty 

 minutes. At first, ebullition was allowed to take place 

 rapidly (till some of the fluid itself frothed over) so as 

 to procure the more thorough expulsion of the air; then 

 the boiling was maintained for a time at medium 

 violence over the flame of a spirit-lamp, whilst the 

 greatly attenuated neck of the flask was heated in the 

 flame of another spirit-lamp placed at a suitable 

 elevation. The steam for a time poured out violently 

 into the flame of the lamp; and whilst my assistant 

 slightly moved the other lamp, so as to diminish still 

 further the violence of the ebullition, I directed the 

 blow-pipe flame upon the narrow neck of the flask, and 

 sealed it hermetically. When the orifice was closed, 

 the heat was immediately withdrawn from the body of 

 the flask. 



After a little practice I soon became able to procure 

 in this way a tolerably perfect vacuum. Even though 

 the vessels were so small, momentary ebullition could 

 generally be renewed again and again for the space of 



1 They were generally small, capable of containing from three-quarters 

 of an ounce to one ounce and a half of fluid. 



