104 



FRAGMENTS OF SCIENCE 



were coincident. In the first experiments the two ends of 

 the tube were closed by plates of rock-salt, and subse- 

 quently by plates of glass. For the sake of distinction, 

 I call this tube the experimental tube. It was connected 

 with an air-pump, and also with a series of drying and 

 other tubes used for the purification of the air. 



A number of test-tubes, like F, Fig. 2 (I have used at 

 least fifty of them), were converted into Woulf's flasks. 

 Each of them was stopped by a cork, 

 through which passed two glass tubes: 

 one of these tubes (a) ended immedi- 

 ately below the cork, while the other 

 (b) descended to the bottom of the 

 flask, being drawn out at its lower 

 end to an orifice about 0-03 of an 

 inch in diameter. It was found nec- 

 essary to coat the cork carefully with 

 cement. In the later experiments 

 corks of vulcanized India-rubber were 

 invariably employed. 



The little flask, thus formed, being 

 partially filled with the liquid whose 

 vapor was to be examined, was intro- 

 duced into the path of the purified 

 current of air. The experimental tube 

 being exhausted, and the cock which 

 FIG. 2. cut off the supply of purified air be- 



ing cautiously turned on, the air entered the flask through 

 the tube 5, and escaped by the small orifice at the lower 

 end of b into the liquid. Through this it bubbled, loading 

 itself with vapor, after which the mixed air and vapor, 

 passing from the flask by the tube a, entered the experi- 



