CHAPTER IV 



THE VARYING EFFECTS OF HIGH TEMPERATURES 



UPON THE SOLUTIONS 



THE varying effects of high temperatures are shown 

 best in regard to the yellow solution. The changes 

 produced in it have been found to differ in a re- 

 markable way even when the solutions contain only 

 very slightly varying amounts of sodium silicate 

 to the ounce of distilled water. 



Thus the tubes Nos. 80, 81, 82, and 92, 93, 94, 

 were all heated together in the can to 125 C. for 

 ten minutes; and the result was that in each of 

 the first three tubes the solution was decomposed, 

 all the iron silicate being thrown down in the form 

 of a copious reddish yellow deposit, while the fluid 

 above was perfectly clear and colourless. But in 

 each of the other three the deposit was very scanty, 

 and the fluid itself was reddish and opalescent. 

 Yet the only difference was that the first three 

 tubes were each charged with a solution contain- 

 ing six drops of the dilute sodium silicate, and 



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