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lead to an uniform cause. Free carbonic acid, atmospheric air in 

 solution, organic matter, earthy chlorides, saline nitrate, alkaline carbo- 

 nates, and, more lately, lower oxides of nitrogen resulting from the 

 oxidation of ammonia, have been, by different authors, considered 

 as the special solents of lead under the varied circumstances in which 

 that metal is found to be corroded. A recent government report, 

 by Professors Graham, Miller, and Hofmann, contains the following 

 conclusions, arrived at by these able investigators : — 



1st. That the protecting coat of sulphates is not uniformly reliable. 



2nd. That the presence of certain chlorides and nitrates increases 

 the power of solution. 



3rd. That bicarbonate of lime is the most effectual protective. 



In the experience of the authors numerous instances have occurred 

 in which hard water had attacked and dissolved lead, and exhibited 

 upon analysis serious contaminations of that metal. In some cases the 

 solution of the lead might be ascribed to extreme softness, in others to 

 the presence of chlorides of magnesium and calcium, and Dr. Nevins 

 has shewn, on a previous occasion, that a large proportion of sulphate 

 of lime was favourable to the solution of the lead, although a small 

 proportion of that salt protected it. 



The properties of the water obtained from the wells round Liverpool 

 have been frequently ascertained by several able chemists, and the 

 uniform result has been that these waters have been found to possess 

 no solvent property upon lead. 



The experience of practical plumbers, however, has been to the effect 

 that leaden cisterns containing rain water appear never to suffer loss or 

 decay, while those in which hard water is stored are corroded with 

 greater or less rapidity, become eaten into holes, and leak, notwith- 

 standing the production of an adherent and regular crust upon the 

 surface. The action of hard water, therefore, appears to be continuous, 

 and instances were quoted in which the bottoms of thick leaden cisterns 

 were corroded through in periods of two mouths, six months, eighteen 

 months, and two years respectively, by the action of the supply from the 

 well water of Liverpool. 



It would thus at first sight appear that the plumber is at issue with 

 the chemist upon this question. 



It appears to be established, however, by confirmed observation, that 

 the well waters of Liverpool, with rare exceptions, whilst they attack 

 and corrode the cisterns, do not hold the lead in chemicnl solution, and 

 no evil has therefore arisen from the use of lead for storing this water. 

 A careful examination of the old cistern lead and the deposit, throws 

 some light upon the cause of corrosion. 



