the city of Lowell. The first examination was made from a sample of water taken from the source or spring-head before it had entered the leaden pipes, when the specific gravity was found to be 1,000,18. The pint, on evaporation to dryness, yielded 2.37 grains of solid matter. The solid contents of an imperial pint were found to be, Grains. Chloride of Sodium, - 1.54 Chloride of Magnesia, - - - 0.71 Sulphate of Lime, - - - 0.128 A trace of Carbonic acid, Grains, 2.378 Excess in the course of analysis - .008 The second examination was made of water taken from the leaden pipes when the specific gravity was found to be 1.000.42. Upon a pint of this water being evaporated to dryness it yielded two grains of solid matter, (viz.) Carbonate of lead - 164 Grains, Organic matter ana salts 036 „ 202 Excess in analysis, - 002 - ,, It therefore has been calculated that every gallon of the water used after pass- * 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. 37 146 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 square feet of lead before being discharged ; and it would not therefore be at all remarkable, if the water were found contaminated with the lead. In this city, however, the pipes are rarely more than 50 feet in length, generally not more than 25, and therefore cannot exert so deleterious an influence as in those of greater extent. Dr. Chilton, recently inspected the Croton water drawn from the leaden pipes, by which it is introduced into the house of Mr. G. D. Coggeshall. No 421 Pearl-street in this city, and found the water evidently affected by the lead. He has also obtained similar results in several other instances. If the precaution be used, of not employing the water first drawn from the pipes for dietetic and culinary pur- poses, no injurious consequences would probably attend the use of water conveyed in this metal, but as this is not likely to be attended to generally, it is expedient to employ other measures to guard against its deleterious effects. For this pnrpose, various means have been suggested, such as the substitution of block -tin and other metals not acted upon by water; but the most efficient, scien- tific, and useful, as well as the most economical, of all the plans hitherto proposed, is that introduced by Thomas Ewbank, Esq., of coating the lead-pipes with tin both inside and out. The process, which has been patented, consists simply in drawing an ordinary lead-pipe through a bath of melted tin, coated with a layer of melted rosin, which leaves a continuous deposit of tin upon both sides of the pipe, of sufficient thickness, to effectually prevent any oxidation of the lead. These * Containing 4.05 grains of solid matter to the gallon, or about one 18,000 part. 147 pipes have been highly recommended by our first chemists, and other men of sci- ence, as furnishing an effectual safeguard against the corroding effects of pure water This highly ingenious process, strengthens the pipe, without diminishing its elas- ticity, and although some small portions of the lead should escape being coated, yet the proximity of the tin, will, from galvanic action, probably prevent oxidization of the lead. As these pipes are furnished at about eight cents per pound, the