action. By looking at the experiments carried out in corked 
flasks I think it would be altogether unwarrantable to say 
that an increase of surface exposed is generallyassociated with 
an increase in quantity of lead dissolved. From the experi- 
ments carried out in beakers half filled with liquid and 
covered with porous paper I think the conclusion may be 
deduced that there is generally an increase of solvent action 
with increase of exposed surface : this is especially evident 
in the case of those salts which increase the solvent action 
(nitrates, &c.) and after the lapse of considerable periods of 
time — 800 to 500 hours. The results of the experiments 
carried out in basins do not permit me to draw any general 
conclusion on the subject now under consideration : there is 
sometimes an increase, at other times a decrease, in the 
amount of lead dissolved associated with a fixed increase in 
surface exposed. It would almost appear as if exposure of 
the liquid to large surfaces of air was less fitted to promote 
solvent action than exposure to smaller surfaces of air. And 
the experiments carried out in flasks through which a stream 
of air continually passed seem to countenance some such 
conclusion as this. In these experiments there was invariably 
a diminution in the quantity of lead dissolved associated 
with an increase in the surface exposed. It is only in the 
last set of experiments carried out in beakers half filled with 
water, and loosely covered, and having one half of the lead 
immersed in the liquid and the rest exposed to the air,-— 
that an increase in lead dissolved is invariably associated 
with increase of surface exposed. So far as the first enquiry 
is concerned these experiments do not warrant the assumption 
of an invariable increase in the quantity of lead dissolved 
associated with an increase in the surface of lead exposed to 
the action of the solvent. 
5. Does free admission of air to the surface, or passage of 
air through the body of the liquid influence the quantity of 
lead dissolved ? The bearing of the experiments upon this 
question will be best seen by tabulating the results so as to 
bring together the quantities of lead dissolved by the 
same liquid acting on a fixed surface, but under varying 
conditions of exposure to air. 
