small scale, that although the water of Edinburgh does not contract a sensible impregnation of lead on remaining a few days in contact with it, yet a sufficient action ensues in the course of a few months, to show that it might be dangerous to keep that water long in a lead cistern. After coming to this conclusion, I had an opportunity of verifying it on a large scale. A cistern in my laboratory in the University having been left undisturbed for four or five months with about six inches of water in it, I found so large a quantity of pearly crystals lying loose on the cistern and diffused through the water, that when the whole was shaken up and transferred to a glass vessel, the water appeared quite opaque. Mérat observes that at the laboratory of the Medical Faculty of Paris there was procured by evaporating six loads, or probably about 1000 pounds of water, which had been kept two months in a leaden pneumatic trough, no less than two ounces of finely crystallized carbonate of lead.[1] Water in such circumstances has proved eminently poisonous. Thus, the crew of an East-India packet having been put on short allowance of water, in consequence of being delayed by contrary winds, the men got their share each in a bottle; but the officers united their shares and kept it all in a lead cistern. In three weeks all the officers began to suffer from stomach and bowel complaints, and had the lead colic for six weeks; while the men continued to enjoy good health. The surgeon detected lead in a tumbler of water without the process of concentration, by adding to it the sulphuret of potass.[2] A similar accident has been briefly alluded to by Van Swieten. He mentions, that he was acquainted with a family who were all attacked with colica pictonum in consequence of using for culinary purposes water collected in a large leaden cistern and kept there for a long time.[3] The composition of the water has not been mentioned in any of these instances; but the water of Paris is so strongly impregnated with calcareous salts, that in ordinary circumstances its action on lead must be trifling.
It was probably from confounding the consequences of keeping the same water long in a lead cistern with the action in ordinary circumstances, that Dr. Lambe was led into the error of supposing that all spring waters whatever act on lead so powerfully, as to render it in his opinion advisable to abandon the use of this metal in the fabrication of pipes and cisterns. It must be admitted, however, that in all likelihood many waters will contain a trace of lead, without being kept more than the usual time in the pipe or cistern. For Dr. Lambe's results correspond to a certain extent with the more recent and accurate researches of Dr. Thomson, who mentions many instances where a faint trace of lead was found in the residue of the evaporation of a large quantity of spring water by himself, as well as by Dr. Dalton, Dr. Wollaston, and Mr. Children.[4] But, as Dr. Thomson properly
