ACTION OF WATER UPON LEAD. 185 



is entirely deprived of its nauseous taste by infiltration through 

 powdered charcoal. A siphon-shaped vessel is recommended 

 — the coal to occupy the long arm. (Lond. Athenaeum, 1850.) 

 Action of Water upon Lead. — Horsford (Procdgs. Amer. 

 Acad. Arts and Sciences) classifies drinking-waters, as follows : 



1. Open waters, as ponds, lakes, and rivers, having their 

 sources in rainfalls and surface drainage. 



2. Waters concealed from sunlight, as wells, and certain 

 springs, formed by infiltration through earthy and rocky strata. 



The latter, except in winter, are colder and contain a greater 

 amount of gases than the former. They also hold, in solution, 

 more inorganic matter, especially nitrates and chlorides, but 

 have less organic matter than open waters. 



The results of his experiments authorized the following 

 conclusions. That neither dry air, or water freed of air, have 

 any oxidizing influence upon lead ; that metal being acted 

 upon proportional to the amount of free oxygen in solution. 

 That, the nitrates are partially reduced by lead, and that both 

 they and the chlorides facilitate the solution of the plumbic 

 coating formed in service pipes. That the presence of ani- 

 malcule or vegetable matters does not impart corrosive pro- 

 perties to water ; for these substances being most abundant 

 in summer, the oxygen arising from their decomposition (?) is 

 expelled by the natural heat of the water. Moreover, the 

 escape of gas and air is promoted by the presence of insoluble 

 organic matter, whilst that portion of the latter which maybe 

 in solution consumes the dissolved oxygen and reduces the 

 nitrates. Organic matter, therefore, rather impairs the solvent 

 action of water upon lead. 



Lead does not reduce iron oxide, nor is it corroded by 

 alkaline chlorides, in the absence of air. Pure water, as a 

 general rme, possesses a greater solvent power than when 

 salts are in solution. All natural waters produce more or less 

 corrosion in the interior of load conduits, but the coating at 

 first formed is entirely insoluble ; contact with water and 

 carbonic acid, however, soon increases its state of oxidation, 

 and it then becomes soluble in 7 to 10,000 parts of pure 

 q2 



