256 



CASSAVl. 



the tar and grease combine and soften ; and when 

 soap is added, the compound is soluble in water, and 

 the spot is removed. 



Limestone or marble may be heated in the dry 

 fire, till it become quick-lime ; and while that lime 

 is hot in the kiln, it has an increased action of heat 

 in it ; and it parts with water and with carbonic acid. 

 After it is removed from the kiln, the action of heat 

 is communicated to the surrounding atmosphere, till 

 that and the lime have the same temperature ; and 

 if the atmosphere is moist enough, the lime takes 

 water back again out of that. So also some vege- 

 table substances (such as the Jatropha manihot, 

 of the tuberous roots of which the Indians of Central 

 America make their cassavi bread, and which in its 

 raw state is a poison) may, by moist heat, have both 

 the water and the poison, or other offensive ingre- 

 dients, boiled out of them. 



* 



CASSAVI (JATROPHA MANIHOT). 



