174 INTRODUCTION TO GENERAL SCIENCE 



References : 



1. 1601 : 252. Hydroscopic Moisture. 



2. 1703:53-54. Water of Crystallization and Mechani- 



cally Inclosed Water. 



3. 1703 : 55-56. Efflorescence, Deliquescence, etc. 

 a. 1701 : 54-55. Water of Crystallization. 



6. 1706 : 46-47. Efflorescence and Deliquescence. 



c. 1707 : 56-57. Water of Crystallization, Efflorescence, 



and Deliquescence. 



d. 1708 : 154-155. Crystallization, Efflorescence, and Deli- 



quescence. 



e. 1709 : 47. Efflorescence and Deliquescence. 



/. 1712:67-68. Water of Crystallization, Efflorescence, 

 and Deliquescence. 



Experiment 66. Efflorescence and Deliquescence. 



Apparatus : Balance, set of weights, watch glasses. 



Materials : Sodium carbonate crystals, sodium sulphate 

 crystals, granulated calcium chloride, sodium hydrate (solid). 



a. Weigh about 5 g. of sodium carbonate crystals on a 

 watch glass, and expose to the air for twenty-four hours. 

 Then weigh again. Do the same with sodium suphate. 

 Describe the results, and state your conclusions. 



6. Perform a similar experiment with calcium chloride and 

 sodium hydrate. 



123. SOAP 



Soap is made by the combination of organic acids with 

 sodium hydrate (caustic soda) or potassium hydrate (caustic 

 potash). The process of soap making may be considered as 

 the neutralization of the hydroxide by the acid contained in 

 the oil or grease. Glycerine is formed at the same time, and 

 is usually saved. Sodium hydrate produces a hard " soap, 

 while potassium hydrate is used to manufacture soft soap. 



