87 
have, when in solution, very differenj^ actions upon lead. 
Nitrates undoubtedly very largely increase the solvent 
action of water upon lead : the other salts generally diminish 
this action. ^ 
The general conclusion which I would draw from these 
results are 
(1.) Nitrates if present alone even in srnaJl quantity 
cause water to exert a very marked solvent action upon lead. 
(2.) The presence of other salts — sulphates, carbonates, 
and chlorides — along with nitrates, greatly decreases, or even 
stops, this solvent action : • carbonates especially exercise a 
deterrent action. 
(8.) Carbonates, sulphates, and chlorides, when added to 
distilled water, greatly dmiinish the solvent action of that 
water upon lead. 
(4.) A small quantity— -about 15 grains per gallon— of 
these last mentioned salts exercises almost as great a 
deterrent action as a comparatively large quantity, about 35 
grains per gallon, 
(5.) The amount of lead dissolved increases but slightly 
after the lapse of twenty-four hours, in the presence of these 
salts which exercise a deterrent action upon the solvent 
power of water on lead. In the presence of salts which 
increase this action — notably of nitrates— the amount of lead 
dissolved increases with the length of time during which 
the water remains in contact with the lead. I cannot speak 
with certainty upon this point for a greater length of time 
than 72 hours. 
In these experiments the lead was uniformly clean and 
bright. Inasmuch as natural waters, even if contaminated 
with nitrates, usually contain small quantities of soluble 
carbonates, sulphates, or chlorides, the solvent action of these 
waters upon leaden pipes and leaden cisterns may, I think, 
be said to be, under ordinary circumstances, exceedingly 
small. I would especially draw attention to the experiment 
