and the Constituents of Well- and River-waters. 49 



Nitrate of ammonia in contact with the lead of cisterns forms 

 quadribasic nitrite of lead, with evolution of binoxide of nitrogen. 

 The binoxide of nitrogen is converted into nitrous acid, which 

 combines with the ammonia, forming again nitrite of ammonia. 

 The quadribasic nitrite of lead is decomposed by the cai'bonic 

 acid of the atmosphere. Three equivalents of the oxide are pre- 

 cipitated as carbonate of lead, while the monobasic nitrite of lead 

 remains in solution. This monobasic nitrite in contact with the 

 metal forms again quadribasic nitrite, and by the decomposition 

 of water, ammonia. 



Assuming, as we justly may, that decaying organic matter and 

 •its products of decomposition are present in the water supplied 

 to our houses, that the active products of decomposition consist 

 chiefly of ammonia and nitrous acid, and remembering the 

 energetic and continuous action of nitrous acid upon lead, we 

 have a ready and easy explanation of the rapidity with which 

 water so circumstanced acts as a powerful solvent of lead*. 



The mutual reactions of the organic matter of water and lead 

 appear, as far as my experiments allow me to offer an opinion, 

 to occur in the following order. By the action of the metal, and 

 partly by other influences, the nitrogen of the organic matter is 

 converted into ammonia. 



The ammonia in contact with the metal is partially converted 

 into nitrous acid, which combines with another atom of ammonia 

 and forms nitrite of ammonia. 



The nitrite of ammonia by further oxidation may be converted 

 into nitrate of ammonia. 



Nitrates in contact with metallic lead form quadribasic nitrite 

 of lead, with evolution of binoxide of nitrogen. 



The binoxide of nitrogen is instantly converted into nitrous 

 acid. 



Nitrous acid attacks the lead and forms again quadribasic ni- 

 trite of lead. The quadribasic nitrite is decomposed by the car- 

 bonic acid of the atmosphere, three equivalents of the oxide are 

 precipitated as carbonate, while monobasic nitrite of lead remains 

 in solution. 



Monobasic nitrite of lead in contact with metallic lead decom- 



* The accidental omission of a sentence in my last paper renders my 

 meaninf^ liable to misconstruction. The sentence as printed stands as fol- 

 lows: — "Thus, although the quantity of nitrogenous organic matter in 

 water may be very small, and the nitrous acid directly resulting from the 

 oxidation of ammonia may be in very minute quantity, yet it will be evi- 

 dent from the foregoing remarks that the quantity will rapidly increase from 

 a process of self-manufacture which is constantly going on." After the 

 words " foregoing remarks that," ought to have been inserted the words 

 " with the daily accession of more putrescible organic matter to our cis- 

 terns" the quantity, &c. 



Phil. Mag. S. 4. Vol. 15. No. 97. .Tan. 1858. E 



