OBSERVATIONAL LESSON XII 



117 



Write down in your books which you think A, B and C are re- 

 spectively, and give your reasons. 



Make a table of the solid substances found in the water thus : 



Sketch the apparatus used. 



SUGGESTION FOR WORK OUT OF SCHOOL 



It is quite possible if you take trouble, and have the necessary 

 patience, to accumulate a great deal of solid matter by boiling a large 

 quantity of water. The water should be always taken from the same 

 source, and the amount weighed carefully before it is boiled. When 

 sufficient solid matter is obtained, care should be taken that it 

 does not stick to the side of the vessel in which the water is boiled 

 by putting in some more water as fast as it boils away. The residue 

 can then be weighed, analysed quantitatively, and an interesting 

 percentage arrived at. 



Occasionally an opportunity occurs for examining the copious 

 deposits which are laid down from water in pipes, especially those 

 connected with boilers and heating apparatus. 



