268 PROFESSOR CHRISTISON ON THE ACTION OF WATER UPON LEAD. 



with others of cast-iron ; and this was accordingly done. Reflecting, however, 

 upon what I had observed in many experiments with weak solutions of neutral 

 salts, and remembering that in general, after the action had gone on slowly for 

 some weeks, it gradually became less and less, while, at the same time, a firmly- 

 adhering film formed on the lead, consisting of carbonate mingled with a salt of 

 oxide of lead in union with the acid of the salt in solution, and that, when lead so 

 lined was transferred even into distilled water, no action seemed to take place, I 

 conceived that an effectual remedy might be provided by producing, in like man- 

 ner, an incrustation of the same kind on the inside of the pipe. For this end, it 

 was proposed to leave the pipe for some months filled with a weak solution of 

 phosphate of soda, in the proportion of a 25,000th part, which is somewhat 

 stronger than what had seemed sufficient to prevent the action of distilled water 

 on the small scale. It was hoped that a fine film of mixed carbonate and phos- 

 phate of lead would thus be formed while the water was at rest, which Avould 

 adhere so firmly as not to be swept away when the water was allowed to flow, 

 and which would serve as a lining to prevent the contact of the running Avater 

 with the metal. Circumstances prevented this plan being tried at once ; and in 

 the mean time it was judged right to try the effect of forming a lining of car- 

 bonate of lead, by leaving the water at complete repose in the pipe, so as to 

 allow the carbonate to crystallize slowly and firmly on its interior. This expe- 

 riment was attended with complete success. The pipe was kept full of the 

 spring- water, and without water being drawn from it, for four months. The water 

 was then found to flow without any impregnation of lead, and has done so ever 

 since. 



The other incident I propose to describe occurred last year at Buchan-ness 

 Lodge, a cottage-residence of the EARL of ABERDEEN. It resembles the former 

 singularly in all its leading circumstances. 



In the beginning of June last, Mr JOHNSTON of Peterhead was requested to 

 visit professionally the housekeeper of the Lodge, who was affected with indigestion 

 and constipation ; from which, however, under his directions, she speedily reco- 

 vered on this occasion. Six weeks afterwards he was requested to visit her again, 

 and found her then affected with vomiting, constipation, severe spasmodic pain at 

 the pit of the stomach, retraction of the umbilicus towards the spine, great weak- 

 ness of the limbs, and other symptoms of less note, which it is scarcely necessary 

 to particularize in this communication, but which are proper to the severe form of 

 colic occasioned by slow poisoning with lead. After treating the case judiciously 

 for three days, Mr JOHNSTON was surprised to find, that, notwithstanding frequent 

 temporary benefit, no permanent amelioration had taken place. At last, on the 

 third day, while considering the circumstances of his patient's illness, his atten- 

 tion was drawn to the water-bottle on her dressing-table. It was lined with a 



