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On the Action of Water upon Lead. By ROBERT CHEISTISON, M.D., F.R.S.E., 

 Professor of Materia Medica in the University of Edinburgh. 



(Read 7th February 1842.) 



IN an experimental inquiry into the action of water on lead,* published by 

 me in 1829, in continuation of some previous researches by GUYTON-MORVEAU, it 

 was stated as the general result, that all very pure waters, such as distilled wa- 

 ter, rain, and melted snow, act upon lead, dissolving a trace of it, and causing 

 the formation of an insoluble carbonate of lead in large quantity. It was like- 

 wise shewn, that this action is prevented by the existence of neutral salts in solu- 

 tion ; so that most terrestrial waters, as they contain saline matter, act feebly 

 and only in circumstances favourable in other respects. Farther, it appeared to 

 flow from comparative experiments, that this preventive power depends upon the 

 acids of the salts, and not upon their bases ; and that their energy as preventives, 

 that is, the minuteness of the proportion required to annihilate the action, is in. 

 the ratio of the insolubility of the compounds which the acids of the salts are 

 capable of forming with oxide of lead. 



Since the time when the investigations now referred to were first made pub- ' 

 lie, my attention has been repeatedly recalled to the subject by divers interesting 

 facts connected with the economic use of lead, which have illustrated practically 

 the conclusions drawn from experiments conducted in the laboratory. Two of 

 these facts, which relate to the employment of lead as the material for water- 

 pipes, are so remarkable in their circumstances, that I am induced to lay them 

 before the Society. On the one hand, they shew that the action of water on lead, 

 notwithstanding its serious consequences, and all that has been written respect- 

 ing it, does not seem to have attracted the attention among such professional men 

 as engineers, architects, and others, which it unquestionably deserves. And on 

 the other hand, when taken along with the general principles formerly established 

 by me, they point out the risk of the action of water on lead-pipes being unex- 

 pectedly developed, where due care is not taken, but at the same tune fix the 

 conditions in which the action may be foreseen, and likewise provide a simple 

 and efficacious remedy. 



As an appendix to this communication, I propose also to take notice of a 

 topic of more purely scientific interest, namely, a question which has arisen 



* Treatise on Poisons, first edition, 1829, p. 384. 

 VOL. XV. PART II. 4 C 



