149 
covered with porous paper : after 5 or ^6 days the liquids 
contained only traces of lead in solution. From the liquids 
containing Ammonium Nitrate the lead was precipitated 
more slowly than from any of the others. The precipitate 
consisted of hydrated carbonate of lead 2 PhC 03 , Ph(OH) 2 . 
11. These results are apparently contradictory of those 
previously obtained, inasmuch as it has been already shewn 
that in most cases more lead is dissolved when the air has 
free access to the surface of the liquid, and that the larger 
the surface of liquid exposed the greater is the amount of 
solvent action. I believe that the explanation of the results 
is to be sought for in the mechanical state of the samples of 
lead experimented upon. 
12. With regard to the influence of hammering and rolling 
upon lead, so far as concerns the power of the lead to withstand 
the action of dilute saline solutions, I have meanwhile only 
a few experiments to bring before the Society. I propose, 
however, to investigate this subject in a more systematic 
manner, and hope, at a future date, to record the results. 
Table VII. 
Effect of Hammering and Kolling on Lead. 
Experiments in Beakers half-filled with liquid (SOOcb.c. in each) 
COVERED WITH UNSIZED PAPER. 
Surface 
Lead dissolved. 
Salt. Grams 
of Lead. Nature of Lead. 
in Mgms., after 
per litre. 
sq. cm. 
11 days. 
21 days. 
Potassium Nitrate... 0*20 . 
„ „ 0-20 . 
.. 50 ...Thin Lead' 
foil “pure.” J 
.. 50 ...4 or 5 sheets" 
1-50 .. 
. 1-80 
of same lead 
rolled to- 
trace . 
. 0-30 
gether into 
compact 
*26 days.. 
. 0-30 
piece ^ 
So far as these experiments go, rolling several sheets of 
“pure” lead foil into one compact sheet, very materially de- 
creases the solvent action exercised upon that lead by a 
liquid containing nitrates. 
