164 SEC. 5. MOLECULAR PHYSICS. 



593. Mercury Air Pump. Dr. H. Geissler, Bonn. 



594. Photograph of an Air Pump, the exhibitor's con- 

 struction (in frame). 



C. Staudinger and Co., F. W. von Gehren, Giessen. 



This air-pump has a double-acting barrel of 10 cm. diameter and 32 cm. 

 in height. The motion of the piston is effected by the rotation of a fly-wheel 

 in one direction. 



595. Hydro-dynamical Air Pump. 



Baron Dr. von Feilitzsch, Professor at the University of 

 Greifswald. 



An ordinary air-pump receiver communicates with a tube through which 

 mercury is passed with great rapidity in such a manner as to flow in 

 through a small aperture and to flow out again through a wide opening. 

 A vacuum will thus be produced under the receiver. 



596. Mercury Air Pump, with valve, on Mitscherlich's 

 system. Prof. Dr. Mitscherlich, Miinden, Hanover. 



(See " Poggend Ann. der Chem. und Phys.," vol. 150, p. 420.) 



600. Air Pump. Charles Gustavus Pinzger, Breslau. 



This air-pump is provided w r ith a double acting piston, and so arranged that 

 it can be used as an exhausting and as a compressing pump. In the former 

 case the barrel is placed in a diagonal position, and the pump provided with 

 glass plate and stop-cock, but if the plate with the cock be screwed off, and 

 the hose-screw attached to the wooden stand screwed on, and the barrel 

 detached from its support and placed perpendicularly, the pump can in that 

 case be used as a compression pump. Plate with cock are meanwhile 

 screwed again on the wooden stand. The cock below the barrel, by reason of 

 its parallel position, effects with this the connexion between barrel and plate, 

 and in its upward position, the communication between barrel and the external 

 air ; and, lastly, in its downward position, the communication between the 

 plate and the external air. 



601. Mercury Air Pump, on Professor von Jolly's system, 



Prof, von Jolly, Munich. 



This air-pump has been described by G. Jolly in Carl's Repertorium, 1865. 

 As regards the alterations which have since taken place, and which have been 

 introduced in the apparatus exhibited, a special description has been added 

 to the object. 



602. Apparatus for Demonstrating Marietta's and 

 Dalton's Law. 



Prof. Baron Dr. von Feilitzsch, University of Greifswald. 



This apparatus enables the laws in question to be demonstrated when the 

 pressure is above or below that of the atmosphere. A glass tube open at the 

 upper end, and a glass gauge tube, which can be closed at the upper end by 

 ft stop-cock, communicate by means of a long gutta-percha tube, and can be 

 displaced on a vertical scale. These are partly filled with mercury, the 

 latter tube containing the gas to be tested, or the combination of gases and 



