APPLICATIONS OF THE SIPHON. 



255 



Fig. 174 B is a siphon for objectionable liquids, which may be 

 put together by means of three tubes, one being wide enough to ad- 

 mit a small cork through which the other two are passed ; the cork 

 should be fixed with sealing-wax. The lower end I of the wider 

 tube should, if possible, be made more narrow by drawing it out ; a 

 piece of india-rubber tubing may then be attached to it when such 

 liquids are to be transferred as sulphuric acid, etc., the contact 

 of which with the finger should be avoided ; & is then closed, as 

 long as required, by pressing the india-rubber tube between two 

 fingers. 



A simple piece of india-rubber tubing is often used as a convenient 

 form of siphon, since it may be bent into any desired shape ; the 

 walls of the tube should, however, not be 

 |too thin, otherwise it easily forms a sharp 

 angle at the bend, and its upper portion 

 is liable to be compressed by the atmo- 

 spheric pressure which at the higher 

 points of a siphon always exceeds the 

 pressure of the liquid. 



The applications of the siphon are ex- 

 tremely numerous. Fig. 175 shows a 

 fountain, which is easily constructed by 

 bending a glass tube, one end of which 

 is drawn out into a fine point, four times 

 at right angles, and dipping the other 

 end in water ; when the tube is filled it 

 acts like a siphon. 



For many physical experiments a con- 

 stant and steady supply of water is re- 

 quired. Fig. 176 shows a reservoir 

 easily constructed for this purpose by 

 JTieans of glass tubing [and a capacious 

 earthenware pot, which may be placed 

 iipon some tall piece of furniture or on a 

 broper bracket. The tube a a is a si- 

 i)hon; over the outer end an india- 

 'ubber tube, a few metres long, is drawn, 

 1 nd firmly tied with thread, while the 

 tiler end is closed by a stout pinch- 

 (ock, or, better still, by a brass stop cock, 

 ne end of which can be inserted into 

 'he india-rubber tube. The tube I Z> is an indicator, which shows 

 he height of the water in the reservoir. It is a siphon one branch 

 f which is bent upwards ; the surface of the water is therefore at 



FIG. 1 75 ( real size}. 





