CHEMISTRY. 



65 



(81) THE "HARDNESS" OF WATER. 



On Clark's scale each degree of hardness corresponds to one grain 

 of calcium carbonate in a gallon (70,000 grains) of water. 



On the scale used by Professor Frarikland and in France, one 

 degree of hardness corresponds to one part of calcium carbonate in 

 100,000 parts of water. 



On the scale used in Germany, one degree of hardness corresponds 

 to one part of caloium oxide in 100,000 of water. 



Clark. 



1 



07 

 1-25 



French. 

 1-43 

 1- 



1-79 



German. 

 0-8 

 0-56 

 1- 



Each part of calcium carbonate in solution occasions a waste of , 

 from 8-12 times its weight of the best hard soap. 



(85) MULTIPLES OF ROME ATOMIC AND MOLECULAR WEIGHTS. 

 12 345 o 7 8 9 



