640 SEC. 13. 



hence the difficulties are avoided which frequently impeded the employment 

 of earlier designed pneumatic water pumps. The rarefaction of air produced 

 by it, which is entirely dependent on the amount of pressure caused by the 

 influx of the water, may be increased with a single pressure of about one 

 atmosphere to a degree of tension equal to that of steam. 

 Described in Liebig's Annalen der Chemie, Vol. 176. 



2558. Apparatus for producing a Vacuum for purposes of 

 Crystallization and Filtration. Hermann Fischer, Hanover. 



2559. Spring- Vacuometer, belonging to the above appa- 

 ratus. Hermann Fischer, Hanover. 



The apparatus, which is principally intended to replace Bunsen's filtering 

 pumps, is constructed on the principle of the injection pump, producing a 

 vacuum by means of a powerful jet of water. The little vacuometer contains 

 a Schinz' tube. If the tube, marked water, be joined to the water supply 

 pipe by means of an india-rubber tube, and the tube which in the drawing is 

 not shown at all be joined to the waste pipe, and connexion be made with 

 the vessel which is to be exhausted, a corresponding vacuum is readily pro- 

 duced. With a fall of water of 1 1 m. a vacuum will be formed which at 

 most will only fall short by one cm. from the absolute barometric height. If 

 the water used be allowed to flow freely into a vessel, the level of the water 

 must be deducted from the height of the water column above the appara- 

 tus. The vacuometer is made small in order to render the apparatus more 

 handy. The apparatus may also be used without the vacuometer. 



The advantages of the whole apparatus are as follows: (1.) It is very 

 handy ; (2.) It may be used on every work-bench which is provided with a 

 supply of water ; and lastly (3.) It is very cheap. 



2554. A. Miiller's Subsiding and Washing Apparatus, 



provided with a set of sieves and a second indicator, for agricultural 

 analysis. Franz Schmidt and Haensch, Berlin. 



This apparatus is accompanied by a pamphlet descriptive of its 

 application. 



2565. Wolf's improved set of Sieves with Brushes. 



Franz Hugershoff, Leipzig. 



1959. Two Hydrostatic Rotary Engines or Precipi- 

 tating Machines, with table to which eccentric motion is 

 conveyed. The machines were invented by the exhibitor for the 

 purpose of facilitating the solution, aggregation, or precipitation of 

 chemical compounds, which they do as effectually in half an hour 

 as if the solutions were allowed to stand for 24 hours (tested by 

 quantitative experiments). The table is open in the centre, so 

 that a beaker or flask may be heated by a Bunsen burner, and 

 it is furnished with double-sliding clamps so as to securely hold 

 the vessel in its place. 



A, engine intended for delicate quantitative experiments. 



B, engine for ordinary purposes. 



Joseph William Thomas, Cardiff. 



