134 SEC. 5. MOLECULAR PHYSICS. 



By alternately lifting and lowering the bulb attached to the flexible tube, 

 and drying the air by the admission of sulphuric acid through a glass valve 

 at the upper part of the perpendicular tube, a very excellent vacuum may be 

 obtained in a short time. 



592a. Improved form of Sprengel's Mercurial Air Pump. 



E. Cetti Co., Brooke Street, Holborn. 



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



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

 struction (in frame). 



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



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

 struction (in frame). 



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 Mitscheiiich's 

 system. (See the accompanying treatise.) 



Professor Dr. Mitscherlich, Mundcn, Hanover. 

 (See "Poggend Ann. of Chemistry and Physics," vol. 150, p. 420.) 



598. Two Magdeburg Hemispheres. 



Professor Dr. Lcpsius, Berlin. 



599. A book : " Ottonis de Guericke Experimenta 

 nova (ut vocantur Magdeburgica) de Vacuo spatio." Primum 

 a R. P. Gaspare Schotto e Societate Jesu et Herbipolitanae 

 Academiae Matheseos Professore : nunc vero ab ipso Auctore 

 perfectius edita, variisque aliis Experiments aucta. Quibus 

 accesserunt simul certa quaedam de Aeris Pondere circa Terrain, 

 de Virtutibus mundanis, et Systemate mundi planetario, sicut et 

 de Stellis fixis, ac Spatio illo immense quod tarn intra quam extra 

 eas funditur. 



Amstelodami apud Joannem Janssoniuin a Waesberge, Anno 

 1672. Cum Privilegio S. Caes. Majestatis. 



Professor Dr. Lcpsius, Berlin. 



600. Air Pump. Charles Gustavus Pinzyer, Breslau. 



This air-pump is provided with a double acting piston, and so arranged that 

 it can be used as evacuation and as compression pump. In the former case 



