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be hurtful until it contained one-fortieth of a grain. We 
have little idea of the extreme susceptibility of some persons, 
and it is better to avoid lead as much as possible. Short 
lead pipes may be used without fear in Manchester, especially 
if the water which has stood over night be thrown away. 
Long lead pipes should be avoided, and lead cisterns are 
extremely dangerous, especially with soft waters, including 
Manchester water. (Here, instances were given.) Soft water 
dissolves lead more readily than many hard waters, and if the 
hardness be due only to the earthy carbonates, the lead becomes 
coated instead of being dissolved. But if the hardness be 
due to chlorides or nitrates, the water dissolves lead much 
more rapidly than pure water (referring to what he had 
written on this). He gave an instance of water from a cess- 
pool obtaining, by oxidation of its impurities in a porous soil, 
much nitric acid, which, along with the chlorides always 
found in such cases, caused the adjacent water, when drawn up 
by a lead pump, to have a very strong taste of lead salts. It is 
remarkable that this water wa^ drunk for some years, but 
ultimately caused the death of two or three persons. It is a 
mistake to suppose that pure water dissolves lead more than 
all impure waters. Some very pure natural waters dissolve lead 
simply because they contain chlorides, although in small 
quantities. Such waters sometimes come from clay slates and 
similar formations. As to peaty water, it was of two kinds, 
occasionally acid, with some action on lead, but in most cases 
alkaline, the peaty matter not dissolving lead. Some lead pipes 
were more easily affected than other. Dr. Smith gave an in- 
stance of a lead pipe, nearly an inch in thickness, with holes 
pierced through the sides in various places by the action of the 
water; others are much more equally corroded. He had spent 
