V 



64 PROCEEDINGS OF THE AMERICAN ACADEJir 



ing paper. By filtering for some time through the same paper it be- 

 came saturated, and the lead in solution passed without detention. 



" Christison, to whom we are indebted for a careful record of the 

 principal conflicting opinions upon this subject, repeated and extended 

 the experiments of Guyton Morveau, to ascertain the effect of solutions 

 of certain salts in water. He came to the conclusion that arseniates, 

 phosphates, sulphates, tartrates, and even chlorides, acetates, and ni- 

 trates, possess the power of protecting lead from the action of the wa- 

 ter. Of the nature of this protecting power he acknowledges that he 

 has no clear conception. He assured himself that it does not in all 

 cases arise from the formation of an insoluble coat consisting of the 

 acid of the employed salt united to the oxide of lead, by finding that 

 the coat, which for the most part, in his experiments, consisted of car- 

 bonate of lead, readily dissolved in acetic acid. This author has sug- 

 gested that leaden pipes, before being laid down for service, should be 

 exposed a length of time to solutions of some of the salts, denominated 

 protecting ; having observed that leaden pipes, which poisoned certain 

 waters when first served, after a time became coated, and passed the 

 same waters without injury to the health of those who drank them. 



" The city of London has long been supplied with water distributed 

 through lead, and though occasional excitements upon this subject have 

 sprung up in Great Britain from individual cases of poisoning, the pre- 

 vailing public sentiment is in favor of lead. Professor Graham states 

 that in London lead only is used for service-pipes. The exemption of 

 Paris from illness derived from this cause is asserted by Tanquerel.* 

 This is believed to be true of all the larger European towns whose in- 

 habitants are supplied with water from public reservoirs. On the other 

 hand, the inhabitants of Amsterdam were poisoned by drinking rain- 

 water that had fallen on leaden roofs ; and on replacing the lead with 

 tiles, the maladies ascribed to the former disappeared. 



" We find ourselves at the conclusion of the literature of the Old 

 World upon this subject with these impressions : — 



" 1st. That some natural waters may be served from leaden pipes 

 without detriment to health. . •2d. That others mav not ; and 3d. That 

 we have no method of determining beforehand whether a given water 

 may or may not be transmitted safely through lead. 



" Professor Silliman, Jr., in his able report on the various waters sub- 



* Tanquerel on Lead Diseases, edited by Dana, App., p. 396. 



