86 PROCEEDINGS OF THE AMERICAN ACADEMY 



the potash to unite with the oxide of lead, or a basic soluble salt had 

 been formed, in which potash was present. Upon examining the ti- 

 trate of potash employed as a reagent in the first experiment, and 

 which had been purchased for this purpose because it was labelled 

 pure, h was found to contain alkaline chlorides, — a circumstance to 

 which the lead in the first experiment might in part be ascribed. A 

 repetition of it with pure nitrate of potash and the hydrate and carbon- 

 ate of lead, prepared by exposing lead to distilled water in an open 

 vessel, gave but a faint discoloration with hydrosulphuric acid. I am 

 inclined to ascribe to the reduction of the nitric acid much the greater 

 part in the action of nitrates upon lead. 



" Action of Air. — The importance of air in order to the action of 

 a water upon lead has been intimated in the results already recorded. 

 The following experiments confirm the observations of Yorke, Bons- 

 dorff, and others, and, more recently, of Dr. Hayes, as expressed in 

 his Report to the Consulting Physicians.* 



" Experiment 1. — June 17th. An apparatus consisting of a half- 

 gill flask, containing lead scrapings and Cochituate water, filled to half 

 its depth, the lead all below the surface of the water, was connected 

 by a tube, bent twice at right angles, with a vessel of mercury. The 

 cork uniting the tube and the flask was carefully covered with sealing- 

 wax. If, now, in the oxidation of the lead, oxygen should be withdrawn 

 from the space above the water, mercury would rise to occupy its place. 

 The mercury had risen, June 19th, three fourths of an inch ; July 1st, 

 four inches ; July 22d, six inches ; and in August the mercury passed 

 over into the flask. Another similar apparatus prepared on the 16th of 

 May showed, on the 10th of August, mercury at a height of 6^ inches. 



" Experiment 2. — A flask of a half-gill capacity was filled to two 

 thirds its depth with distilled water, and boiled five minutes. While 

 hot, and without delay, bars of bright lead were added, and the flask 

 filled from another flask containing distilled water that had been boil- 

 ing an equal length of time. In this condition a nicely-fitting cork was 

 adjusted to the neck, and expeditiously sealed, so as to prevent the ad- 

 mission of air. Another flask was filled in the same manner with Co- 

 chituate water, and sealed. Both are in possession still. The bar in 

 distilled water is quite as bright as when immersed, except around the 

 end in contact with the glass, which has become a little coated. The 



* Report of Consulting Physicians, Boston, 1848, p. 23. 



