Physical Properties of Water 



267 



When about 2 c.c. have been collected in the latter, 

 remove the burner, and rinse out the flask with this 

 first portion of the distillate. Throw away the rinsings. 

 Replace the flask in position and heat the retort once 

 more. When about half the water in the retort has 

 boiled away discontinue the heating and preserve the 

 contents of the flask for further investigation. 



Taste the distilled water after it has become cold 

 and compare its taste with that of some of the tap- 

 water. It will be found to be very insipid in compari- 

 son with the latter. Evaporate six drops on a watch- 

 glass by the method of Experiment 119. If the 



Fig. 85. 



distillation has been carefully carried out, the residue 

 will be scarcely appreciable in amount. (Total absence 

 of residue must not be looked for. since water at the 

 boiling-point attacks glass to a slight extent, the 

 attacked portion dissolving in the water, and being 

 left behind when the water is evaporated to dryness.) 

 Examine the appearance of the water left in the retort 

 and that of the bottom and sides of the vessel which 

 have been in contact with the boiling water. The 



