222 THE FLOATING-MATTER OF THE AIR. 



out of the multitude of examples that might be cited in 

 proof of this statement. 



Fig. 22. On the 2nd of October four- 



teen of our ordinary retort-flasks 

 (fig. 22) were charged with a 

 neutralized infusion of hay. They 

 were boiled for three minutes in 

 an oil-bath, and hermetically 

 sealed whilst boiling. Thirteen 

 out of the fourteen tubes re- 

 mained perfectly barren, retain- 

 ing for months their pristine 

 colour and transparency. 

 On the 18th of November six retort-flasks were filled 

 with turnip-, five with cucumber-, five with beetroot-, 

 and four with parsnep-infusion. The six turnip-flasks 

 remained permanently pellucid, yielding a clear water- 

 hammer ring. The five beetroot-flasks remained also 

 permanently barren, all yielding the water-hammer 

 sound. Of the parsnep-flasks, two became turbid, but 

 two remained clear. Of the cucumber-flasks, three 

 became cloudy, while three remained permanently clear. 

 Neither in the case of the parsnep nor in that of the 

 cucumber could the water-hammer sound be obtained 

 from the cloudy flasks, and when their sealed ends were 

 broken under water, the vacuum was found defective. 

 In the clear tubes, on the contrary, it was found practi- 

 cally perfect. 



Again, on the 20th of November, seventeen retort- 

 flasks were charged with infusions of turnip, cucumber, 

 and parsnep. They were boiled for three minutes in an 

 oil-bath, and carefully sealed while boiling. The six 

 turnip-fl:isks remained permanently clear, maintaining 

 for months their sharp water-hammer sound. Of the 

 five parsnep-flasks, one became turbid and four remained 



