10] 



Evaporation of Liquids 9 



Such an attachment is 



keep the water at a constant level, 

 shown in fig. 5 on a steam oven. 



Either porcelain, platinum, or nickel vessels may be used 

 for evaporation, but the most generally useful is a beaker of 

 the form shown in fig. 9. This may be generally procured of 



ifSteri 



xrgA.trar 



s& 



Fig. 9. 



Fig. 10. 



very thin glass, which allows the heat to pass freely from the 

 water in the bath to the liquid in the beaker, and moreover 

 its shape allows it to touch the water (see fig. 10), which 

 keeps it at a higher temperature than is the case with a vessel 

 simply immersed in the steam. 



Another method of evapora- 

 tion will be found in paragraph 

 339, fig, 49. 



SOLUTION OF SOLIDS 



10. Solution is usually accele- 

 rated by heat, therefore sub- 

 stances soluble in water should 

 be dissolved by heating with 

 water in a beaker over a Bunsen 

 flame. 



Should any gas be evolved 

 during the process of solution — 

 e.g., when chalk or Iceland spar is dissolved in hydrochloric 

 acid — precautions must be taken to prevent loss^by spirting. 

 Fig. 1 1 shows a very useful arrangement. 



Fig. i] 



