798 THE INJECTOR. 



atmosphere forces some water into the space a a. 

 Gradually more and more air is ejected from a a, until 

 the space becomes filled with water ; then water alone 

 is forced out by the steam, but the suction now be- 



FIG. 392 (real size). 



comes much more effective because the steam in con- 

 tact with the cold water is immediately condensed to 

 water ; it occupies in that state much less space, and 

 an almost complete vacuum is produced at the mouth of 

 b ; the water in consequence rushes with great force 

 into the narrow part of c, and by its inertia continues 

 its motion, so as to issue at the other end of c. 

 When this happens a short piece of glass-tubing, 

 bent upwards at right angles and drawn into a fine 

 point, may be attached by an india-rubber tube to c, 

 and the water made to issue upwards in a powerful 

 jet. 



The construction of the little injector presents no difficulty, but 

 the dimensions of the various parts must be exactly those shown in 

 the figure, if the action is to be depended upon. Each side of 

 the right angle into which the jet tube is to be bent should be about 

 3 cm long, and the tube as wide as c ; the pointed end should be 

 like that of b or very little narrower. An india-rubber suction 

 tube, 10 or 15 cm long, may be attached to d. The india-rubber 

 tube employed for connecting the apparatus with the vessel in 

 which the steam is generated should fit very tight ; it must not be 

 tied with thread, so that in case the pressure of the steam becomes 



