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And I have been informed that some of the lead of commerce 

 is in fact much more easily corroded than other samples. 

 Even the difference in density between rolled and cast lead 

 may produce some difference in effect. 



I met with an instance but a few years ago of how little the 

 knowledge of the true action of water on lead had become 

 known, and of the danger attending ignorance on the subject. 

 A gentleman of some fortune, education, and general intelli- 

 gence, at whose house I had occasion to call on other chemical 

 business, showed me with great glee a leaden cistern in a 

 dark cellar, into which was conducted the water arising from the 

 condensation of the steam of his cooking apparatus, and in which 

 this water so distilled, was stored for his own special drinking. 

 Suspecting that the usual process must take place, I examined 

 the state of the cistern more closely than he had done, and 

 found at the bottom a deposit of nearly half an inch in thick- 

 ness of carbonate of lead in loose glistening crystals ; the 

 water at the same time showing to the proper tests, decided 

 proof of the presence of some of the carbonate in solution. 



I proceed to the case in question, as the immediate subject 

 of this essay. I was applied to in order to discover the cause 

 of, and if possible to provide a remedy for, the corrosion of 

 certain cisterns at a gentleman's mansion. One had to be 

 provided with a new bottom about five years after its erection, 

 and others threatened a like result. The corrosion was not 

 general, like that of a sheet of lead in pure water, but on 

 certain spots there were fungous or efflorescent deposits of 

 carbonate of lead. These were easily removed, and under 

 each the lead was black, without metallic lustre, and so soft 

 as to be easily scraped with the nail into a hollow. When 

 left to themselves, the lead in these spots, in the cistern which 

 perished, was acted on more and more deeply, until they 

 became holes, which caused it to leak. These spots upon the 

 lead were confined to the bottom, but upon the solder they 



