* Where water contains a large quantity of carbonic acid, there are some facts which appear to prove, that it may act on lead, to an injurious extent, though there may be present a large amount of neutral salts.

ing through the leaden pipes, contains 1.312 grains of the carbonate of lead. Such water, although it would not speedily destroy life, would undoubtedly be attended wtih injurious consequences, should its use be habitually continued. On the other hand, Dr. Hare of Philadelphia, in reply to a letter requesting his opinion as to the action of the Schuylkill water* on lead pipes, states that after

using the Schuylkill water for 25 years in his laboratory, he has never perceived the slightest indication of the presence of lead ; and that if there had been any in

the water, the re-agents which he has been accustomed to use must have rendered the impurity evident. Ifitbetrue that the Schuylkill water does not act upon the lead pipes, it would follow as a matter of course, if the doctrines above laid down be correct, that the Croton, which contains very nearly the same quantity of saline ingredients, would also exert no influence upon this metal. In cases, however, where injurious consequences have resulted from the agency of lead, the pipes through which the water was conducted, were of considerable length ;

suppose for example that the pipes are 4000 feet long, and three fourths of an inch in diameter, each portion of water will pass successively over no less than 784