168 



S. HA.DA: HOW MERCUROUS AND 



precipitated basic salts, which were visibly mixed with a few minute 

 globules of metal, evidently fallen down from the condenser tube. The 

 basic salts were dissolved in a little very dilate nitric acid, their solu- 

 tion was quickly poured oft" from the mercury and added to the main 

 quantity of solution, and the mercury was weighed with that removed 

 from the condenser. Mercurous chloride was precipitated from the 

 cold solution by sodium chloride and removed, and then mercuric 

 sulphide was precipitated from the nitrate and weighed. It was equal 

 to 0.0378 gram of mercury, while that obtained as metal weighed 

 0.0392 gram, and therefore the same within limits of experimental 

 error. 



The last experiment was repeated but with two modifications. 

 The solution was kept in gentle ebullition by a small gas-flame, and 

 no carbon dioxide was passed through the flask, the steam of the boil- 

 ing solution being relied upon to keep out air» The mercury found 

 as -mercuric salt weighed, this time, 0.0913 gram and that as metal 

 0.0946 gram. 



A third experiment was made, like the last, but with the modi- 

 fication of adding at the beginning just enough nitric acid, (included 

 in the 10 cc.) to keep all the mercurous salt in solution. Everything 

 but precipitation of basic salts went on as before, the mercury volati- 

 lised was 0.03-15 gram, and that of the mercuric nitrate 0.0415, the 

 latter being probably not more than equivalent to the metallic mercury, 

 if all had been collected, only 7 mgm. being wanted. 



Three parallel experiments were then made, the duration of heat- 

 ing being eight hours, and boiling water the source of heat. Through 

 the first flask a gentle flow of carbon dioxide was kept up, and through 

 the other two a gentle flow of air. Just enough nitric acid to prevent 

 basic salt precipitating was added to the contents of the third flask, in 

 place of part of the lOcc. of water alone used in the first and second 



