ii4 Common Science 



with the worm attached into the flask, and support the worm 

 with anothe'r clamp. Put a dry cup or beaker under the 

 lower end of the worm. Set a lighted burner under the 

 flask. When the mixture in the flask begins to boil, turn 

 the flame down so that the liquid will just barely boil; if 

 it boils violently, part of the liquid splashes up into the 

 lower end of the worm. 



As the vapor rises from the mixture and goes into the 

 worm, it cools and condenses. When several drops have 

 gone down into the cup, try lighting them. What is it 

 that has boiled and then condensed : the water, the alcohol, 

 or the blueing? Or is it a mixture of them? 



Alcohol is really made in this way, only it is already 

 mixed in the water in which the grains fermented and 

 from which people then distil it. Gasoline and kerosene 

 are distilled from petroleum ; there is a whole series 

 of substances that come from the crude oil, one after 

 the other, according to their boiling points, and what 

 is left is the foundation for a number of products, in- 

 cluding paraffine and vaseline. 



Experiment 40. Put some dry, fused calcium chlorid on a 

 saucer and set it on the plate of the air pump. This is to 

 absorb the moisture when you do the experiment. (This 

 calcium chlorid is not the same as the chlorid of lime which 

 you buy for bleaching or disinfecting.) Fill a flask or 

 beaker half full of water and bring it to a boil over a Bunsen 

 burner. Quickly set the flask on the plate of the air pump. 

 The water will stop boiling, of course. Cover the flask and 

 the saucer of calcium chlorid with the bell jar immediately, 

 and pump the air out of the jar. Watch the water. 



The water begins to boil again because water will 

 boil at a lower temperature when there is less air pressure 

 on its surface. So although the water is too cool to 



