336 Prof. J. C. Draper on an Improvement in Filtration. 



The nozzle-tubes /, g being placed in position as shown in 

 the figure, steam is raised in the boiler (a) ; this passing through 

 the tube d e to g, issues with violence from the nozzle ; and in 

 passing through the nozzle of /produces an exhaustion in the 



interior of the tube / which may be applied as desired by a 

 flexible tube attached to k. The vacuum produced depends 

 partly upon the shape of the nozzles, and partly on their relative 

 position. The latter adjustment is obtained by slipping the tube 

 (g) through the stuffing-box (h) until the proper position is found. 

 In the arrangement employed by me, I have without difficulty 

 obtained with a pressure of one atmosphere of steam in the boiler 

 an exhaustion capable of raising mercury eight inches perpendi- 

 cularly in a tube attached to k, the exhaustion increasing steadily 

 as the pressure of the steam increased. 



At / m the filtering-apparatus is represented as attached to 

 the steam vacuum-tube (/) by the flexible india-rubber con- 

 nector (n). 



New York, March 12, 1870. 



