166 



Trans. Acad. Sci. of St. Louis. 



screw top carrying a brass inlet and outlet tube. The thread 

 of the cap is made air tight with a little white lead and oil.) 

 The protector is put into the air bath and the temperature is 

 raised to 85 degrees C. and allowed to remain at about this 

 point for 20 minutes. Then a slow current of air is drawn 

 through the apparatus and the temperature raised to 185 

 degrees. The air is freed from carbon dioxide and moisture 

 by passing through the potash bulb and calcium chloride tube 

 A and £ as shown in the figure. After drying in this way 

 for 30 minutes the apparatus is disconnected, the protector 

 removed from the air bath and the crucible taken out and 



placed in a desiccator and when cold is weighed. The in- 

 crease of weight is the weight of water taken up by the quick 

 line to form calcium hydroxide. 



The method and apparatus was first tested by hydrating 

 pure lime obtained by the ignition of Iceland spar. A 

 weighed quantity of Iceland spar was heated from 5 to 10 

 minutes in a platinum crucible with the blast lamp. After 

 cooling in a desiccator the weight of quick lime ^vas deter- 

 mined. The hydration was then carried out as above de- 

 scribed. The following results were obtained: — 



