THE SOIL AS AN ASSET 225 



are sensitive enough to weigh the gold lost in 

 this way over a course of months in any con- 

 siderable bulk of metal. 



Gold is soluble in lead, and lead is soluble 

 in gold. This fact can be demonstrated in any 

 laboratory. Place two bars, one of gold and 

 the other of lead, in contact with each other, 

 and raise the temperature to 300 or 400 de- 

 grees F. In the course of a few hours it will 

 be found that minute particles of gold and 

 lead have penetrated the two bars and respond 

 readily to the usual reagents. 



Ordinary glass is more soluble in water than 

 is generally supposed. Water standing in a 

 tumbler gradually dissolves silicates, but in 

 minute quantities. However, if one take the 

 same tumbler and grind it up into flour-like 

 particles, so as to increase the surface pre- 

 sented to the action of the water millions on 

 millions of times, it will be found that the 

 glass enters readily into solution. One can 

 take such a solution after a few hours and 

 evaporate it to dryness and weigh the residue 

 of silicates. It amounts to three per cent., 

 nearly as much as ordinary bichloride of 

 mercury; yet if any one would venture the 

 assertion that glass is as soluble as mercury 



