116 MASON— ACTION OF WATER UPON METALS. [April 19, 



casioiially given a gentle motion and is kept at 15 degrees for one 

 hour, after which time the metal in solution or suspension is de- 

 termined. One hour is sufficient time to allow of the watching 

 of metallic solvency, and let it be added, the limiting of the time 

 of action to the standard period is important, for the rate of action 

 of the same water is not only variable but the ratio of the total 

 action during different lengths of time is not a simple one. Thus, 

 the quantity of metal attacked in ten hours is by no means ten times 

 that acted upon during one hour. 



In conclusion, let it be said that although we know in a general 

 way that softness, acidity, dissolved gases and the presence of much 

 chloride or nitrate will tend towards metallic action, while alkalinity 

 and hardness are rated as protective agents, yet it is far better 

 to actually test a water with reference to its behavior towards metals 

 than to attempt any prophecy of its action based upon analytical 

 knowledge of what the water may contain. 



Troy, N. Y. 

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