146 
extent. Generally I conclude that the solvent action of 
saline solutions continues throughout very lengthened 
periods ; certainly that it does so if the liquid be removed, 
and fresh liquid, holding the same or other salts in solution, 
be put in its place. In some cases however a maximum 
point appears to be reached after the expiry of 14 days or 
so, after which, if the liquid be undisturbed, little or no 
further solvent action occurs. 
7. In some of these experiments a remarkable result is 
obtained, viz. : the quantity of lead in solution is found to 
decrease after a certain point has been reached. In order to 
determine whether the same result could be obtained when 
the solvent liquids were not exposed to the air, the following 
experiments were carried out in corked flasks each con- 
taining 500 cb.c. of water, the surface of lead exposed 
amounting as before to 50 sq. cm. 
Table Y. 
Salt. 
Grams 
per litre. 
Total Lead, in Mgms., dissolved after 
15 days. 32 days. 38 days. 
Potassium Carbonate.. 
0-20 ... 
... 0-40 ... 
... 0-30 ... 
... 0-30 
„ Nitrate 
0-20 ... 
... 090 ... 
... 0.70 ... 
... 060 
Ammonium „ 
0-20 ... 
... 1-50 ... 
... 1-00 ... 
... 0-80 
8. Here again we have a slight decrease in the solvent 
action of Solutions of Potassium and Ammonium Nitrates 
upon lead taking place after the expiry of lengthened 
periods. The lead would appear to be precipitated from 
solution after a time. A remarkable instance of such pre- 
cipitation will be detailed in a future paragraph. 
9. I must now consider the question of the purity of the 
lead itself as influencing the quantities of this metal dissol- 
ved by various liquids. 
The experiments were carried out in flasks and beakers. 
The sample of “pure” lead was found to contain very 
small traces of Manganese, Iron, and Zinc : the “ commercial” 
