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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 beings 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 was 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 })eaty 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 



