and the Constituents of Well- and River-waters. 203 
Don, from the former of which the supply for the city of Aber- 
deen is obtained, states that he found im yarious samples of 
the Dee water, which had passed through leaden pipes and had 
been stored in leaden cisterns, quantities of lead varying from 
zoodth to jth of a grain per gallon, the quantity rapidly increa- 
sing with the time the water remained in contact with the lead. 
With the view of ascertaining the cause of the Dee water pos- 
sessing such an energetic action on lead, Dr. Smith performed a 
series of experiments on the action of this water upon bright and 
on tarnished surfaces of lead. He found the quantity of lead 
dissolved yaried from ;3,dth to 1th of a grain per gallon; and 
he observed that tarnished surfaces of lead were more readily 
acted upon than those which were perfectly bright. The con- 
clusions arrived at by Dr. Smith are,— 
“st. That the action of water on lead is dependent on the 
aération of the water; since in rainy weather, when the Dee 
water is coloured and contains but little air, the quantity of lead 
it dissolves is less than when the water is bright and well 
aérated. 
“2ndly. That the water at all times acts more strongly upon 
old and tarnished lead than it does upon bright surfaces of the 
metal.” 
The following are the analyses of the waters of the Dee and 
of the Don given in grains per imperial gallon (70,000 grs.) :— 
Dee. Don. 
FRG Brat Veen ois idety <o necnt 14 1:29 
PIR SResIA dil shicy site OHO 0:34 . 
Potash and soda. . . . . 0382 0°58 
Carbonic acid (combined). .. 0°374 0:96 
Nalphuri¢ acu y|.. sis. rn.2r ORTOP 0:76 
Palerige fot An shive ba eli ee 0°74 
BOI aa el seins oy aly at Gl ae 0-60 
Iron, alumina and phosphates 0-080 0-38 
(precipitated by ammonia) . 
Organic matter and loss . . 1°775 3°00 
PUMGIOMMy .. - 6 s,s na BEAR eos 
4.000 8°65 
These waters are remarkable for the small quantity of solid 
matter, and their consequent softness. They contain, however, 
a very large proportion of organic matter, The Dee water con- 
tains, as might be expected, traces of ammonia; but Dr. Smith 
failed to detect any nitric acid by operating on the residue of 
one gallon of the water, although nitric acid, or one of the oxida- 
tion products of ammonia, must undoubtedly have been present. 
