13(3 On the Composition and Properties of Drinkiny-Watcr, 
washing or cooking purposes, or for supplying steam-boilers, it 
Irequently happens that soft spring and lake-waters, especially 
when much charged with carbonic acid and well aerated, exert 
a corrosive action upon lead, and become contaminated with 
soluble lead-compounds. It is true that the amount of oxide of 
lead dissolved by the action of soft waters upon leaden pipes, or 
the sheet-lead linings of water-tanks, rarely amounts to more than 
one part or less in ten millions of the fluid, but although such 
small quantities of lead probably will not do any positive injury 
to persons who take the water habitually, even traces of lead 
are undesirable in potable waters. The popular notion, that all 
very soft waters act upon lead, I find is not founded on facts ; 
many take up traces of oxide of lead which pass into actual 
solution, others do not become impregnated with soluble lead- 
compounds ; and as it is not always possible to ascertain before- 
hand, or even from the analysis of a soft water, whether it is 
likely or not to act upon lead, it should not be omitted in the 
examination of a soft water to make a few experiments, and 
to test practically its effect upon both new and bright, and dull 
and superficially oxidised sheet-lead. To this end strips of the 
metal should be immersed in the water in question in such a 
manner that a portion of the lead remains uncovered by water, 
and freely exposed to the air. After a week or a fortnight the 
strips of lead may be withdrawn, and the water be examined, 
as well as the strips of lead. Should the latter remain bright, 
and the parts immersed in the water unaltered, and no turbidity 
or deposit have been caused in the water, the probability will be 
that the water has not acted upon the lead, and that it contains 
no appreciable traces of oxide of lead in solution. But should 
the strips of bright metallic lead have been rendered dull, or 
covered with a white powder during the experiment ; .and should 
a whitish deposit have been produced in the water, it will 
appear to have exerted a corrosive action upon the lead, and 
traces of oxide of lead may have actually passed in solution. In 
cither case the water should be passed through white^ filtering- 
paper, and the perfectly clear fluid, after having been slightly 
acidulated with acetic acid, be saturated with sulphuretted 
liydrogen hy passing a current of the gas into it. If there are 
no traces of lead in the clear and filtered water it will remain 
unchanged, but siiould it assume a yellowish-brown colour, the 
presence of lead will be indicated by the colour, which will be 
all the more deep and dccidcxlly brown the more lead has passed 
in solution in the course of the trial. 
Most waters which corrode lead usual! v act more or less ener- 
getically upon metallic iron. The storage of soft water in iron 
\ 
