92 Capt. P. Yorke's Experiments and Observations 



by G. de Morveau, has been so much more fully investigated 

 by Dr. Christison that I shall not dwell further on it. Dr. 

 Christison found that T^r.-oo-ffth of phosphate or hydriodate of 

 potash was an almost perfect preventive of the action of distilled 

 water. This author, however, gives it as his opinion that an 

 unusual quantity of carbonic acid in natural water is the most 

 common counteracting cause which impairs the power of sa- 

 line bodies to protect lead, and he supports this opinion by 

 an experiment made with the Edinburgh water (" Poisons," 

 p. 465). The few facts that I have observed which bear on this 

 part of the inquiry do not accord with this view of the matter, 

 at least so far as the dissolving power of water is concerned. 



38. I mentioned in the first paragraph a spring water 

 which had the power of holding a portion of lead in solution; 

 I found also that when drawn from the spring head, and made 

 to act on lead, as in the before-mentioned experiments, it gave 

 indications in a few days of holding a minute portion of lead 

 dissolved. 



A portion of this water was brought from the spring head 

 in a well stopped bottle, and examined. It remained perfectly 

 transparent when an excess of lime was added, and after be- 

 ing boiled 32 measured ounces were evaporated to dryness 

 in a silver crucible at a heat a little above 300°. The residue 

 weighed 1*75 grain: of this T 6 oths of a grain was soluble in 

 strong alcohol, and proved to be chloride of manganese with 

 chloride of aluminum, and the remainder sulphate of lime with 

 some sulphate of iron and a little silica. Both this spring and 

 the one mentioned rose on the same hill, which consisted of 

 the upper conglomerate beds of the old red sandstone, and 

 contained occasionally thin veins of oxide of manganese. 



It is somewhat remarkable that Dr. Lambe* has attributed 

 the power of spring water to dissolve oxide of lead to a 

 " compound salt, the basis of which is manganese and iron, 

 with, perhaps, a little nickel." He thinks that the acid of this 

 salt is the muriatic, and that such a compound is diffused 

 through all common spring water ; but this is surely general- 

 izing the matter more than his or any other experiments 

 warrant. It seems clear, however, that he did detect manga- 

 nese in some of the specimens of spring water which he ex- 

 amined. 



On the Electric Relation of Lead to Iron, fyc. 



39. In the course of these researches I was led to make 

 some experiments on the electrical relation of lead to other 



• Researches on Spring Water, p. 158 el seq. 



