276 



"A coat of greater or less permeability forms in all natural waters, to 

 which lead is exposed. The first coat is a simple sub-oxide, absolutely 

 insoluble in water, and solutions of salts generally. This becomes con- 

 verted in some waters into a higher oxide ; and this higher oxide, uniting 

 with water and carbonic acid, forms a coat, soluble in from 7,000 to 

 10,000 times its weight of pure water. The above oxide unites with 

 sulphuric and other acids, which sometimes enter into the constitu- 

 tion of the last coat ; uniting with organic matter and iron inst, it forms 

 another coat, which is in the highest degree protective. 



Dr. Horatio Adams, in a lengthy and very able report, before the 

 American Medical Association, at its Annual Meeting in 1852, depre- 

 cates the use of lead pipe for the conveyance of water under any cir- 

 cumstances. Having shown, both by analysis, and its effects on the 

 system, that lead is present in the Cochituate water drawn through lead 

 pipes, also in the Croton water, the New Orleans water, the Cincinnati 

 and Louisville water, he concludes : " That it is never safe to use wa- 

 ter drawn through lead pipes, or stored in leaden cisterns, for domestic 

 purposes ; and that any article of food or drink is dangerous to health, 

 which, by any possibility, can be impregnated with saturnine matter." 



Gmelin, a distinguished German Chemist, does not differ from 

 Christison. 



On the whole, as it is at least, doubtful, whether the solid matter 

 contained in any of the varieties of natural water, will effectually 

 protect lead from dissolving, and especially as the water of Detroit river 

 contains less solid matter than either Christison or Gmelin consider ne- 

 cesaary for that purpose, I am inclined to discourage the use of lead ser- 

 vice pipe, at least until it can be clearly shown that no evil results there- 

 from. Block tin service pipe, or lead pipe, lined with tin, would not be 

 liable to the same coiTosion. I would, therefore, recommend it as a 

 substitute for the lead pipe. 



SILAS H. DOUGLASS, 



Prof, of Chemistry, dc. 



