150 SEC. 5. MOLECULAR PHYSICS. 



This is a common form of apparatus. The liquids whose tensions are to 

 be measured are inserted in the barometer tubes, and either steam or 

 the vapour of some liquid having a lower boiling point, such as alcohol, is 

 sent through the larger tubes. 



686a. Apparatus for illustrating the Tension of Vapours 



at or below the freezing point. Prof. W. F. Barrett. 



687. Diagram of Torricellian Vacuum. 1644. 



A. Galletly, Edinburgh. 



687a. Independent Bed Plate for Pneumatic Machines. 



Geneva Association for Constructing Scientific Instru- 

 ments. 



This plate is made entirely of cast-iron, as well as its stand, so as not to 

 become damaged in experiments where mercury is employed. 



68 7b. Sir Humphery Davy's Laboratory Note Book. 



Royal Institution of Great Britain. 



Davy's record of his decomposition of potash by the voltaic battery, 

 October 19, 1807. 



687c. Faraday's Laboratory Note Book. 



Royal Institution of Great Britain. 



Faraday's record of his condensation and liquefaction of gases, March 19, 

 1823. 



