2 
(5) Water charged with carbon dioxide exercises no very 
marked solvent action upon lead, but when the water is 
charged with the gas under pressure the solvent action is 
very greatly increased. 
2. These or similar general conclusions had been arrived 
at by previous experimenters ; but I have been able to give 
a considerable series of actual measurements of the amount 
of action exercised by the various solutions upon given sur- 
faces of lead under stated conditions. 
8. In carrying out the experiments alluded to above I 
was often struck by apparent discrepancies in the results 
obtained; hence I was led to the belief that the action of 
dilute saline solution upon lead is one which may be very 
materially altered by what appear at first sight to be slight 
alterations in the conditions of the action. The object of the 
experiments detailed in the present paper was, if possible, to 
determine more narrowly what these conditions are. The 
questions to which I shall endeavour at present to give 
answers, partial though they must be, are these — Does the 
amount of lead dissolved increase with increase of surface 
exposed to the action of the solvent ? Does the free admis- 
sion of air to the surface, or the passage of air through the 
body of the liquid influence the qiiantity of lead dissolved ? 
Do the solvent actions of dilute saline solution upon lead 
continue during lengthened periods, or is there a limit 
reached after which little or no further action is exercised 
upon the lead ? 
4. And in the first place, does the amount of lead dissolved 
increase with increase of surface exposed to the action of the 
solvent ? In order to obtain an answer to this question 
experiments were carried out with the same solvent but 
with varying surfaces of lead exposed and under somewhat 
varying conditions of action. 
The results of these experiments are presented in Table L 
