14 COMPANION TO TROPICAL READERS 



water is stirred rapidly and the water poured off, the 

 clay in suspension is carried away with the water, while 

 the sand settles at the bottom of the vessel (fig. 4). 



Fig. 4. Decantation 



x e> 



Evaporation. A liquid may be driven off in the form 

 of a vapour by exposing it to the influence of the sun's 

 heat. The change may be more rapidly brought about 

 by putting the vessel over a fire. 



Heating". The problem of obtaining a satisfactory 

 source of heat may prove troublesome. A spirit lamp 

 will be convenient, but will not give sufficient heat for 

 all experiments. The writer believes that a small and 

 inexpensive " fireplace ", neatly built with a few bricks, 

 in a corner of the schoolground, will prove useful. The 

 cover of a kerosene tin may be put across the top to 

 support whatever is to be heated. 



Cutting Glass Tubing. Draw one edge of a file 

 sharply across the tubing to be cut, at the required 

 length. Take hold of the tubing with both hands, 

 keeping the thumbs near to the mark made by the file; 

 snap sharply across. 



Bending Glass Tubing. Hold the glass tubing in the 



