84 PROCEEDINGS OF THE AMERICAN ACADEMY 



decomposition with the saltpetre. The decision of this point rested up- 

 on the following experiments. 



" 1. A solution of saltpetre, the usual laboratory reagent, was pour- 

 ed upon a quantity of common white lead, and, after repeated agitation 

 and alternate rest, filtered off and tested with hydrosulphuric acid for 

 lead. There followed an instantaneous, distinct, though not large, pre- 

 cipitate of sulphide of lead. There was an objection to the experiment. 

 White lead prepared from the acetate might not be altogether free from 

 acetate of lead. This, if present, might be brought into solution by the 

 nitrate of potassa. 



" 2. To settle this point, a portion was carefully ignited upon plati- 

 num. Had there been appreciable acetic acid, the mass would have 

 more or less blackened, or would have revealed to the sense of smell 

 some evidence of its presence. It gave no indication whatever. 



" 3. A quantity of the white lead was then treated with sulphuric 

 acid and alcohol in a test-tube, in the usual manner for detecting acetic 

 acid by the formation of acetic ether. This failed to give a trace of 

 acetic acid. The quantity of white lead was small. 



" 4. Four ounces of white lead were then boiled three hours with a 

 large measure of diluted soda, filtered, concentrated, and treated with 

 sulphuric acid and alcohol as before. It yielded no distinct trace of 

 acetic acid. 



" 5. To meet the question fully, and give to the experiment the ad- 

 vantage of the nascent state which in actual practice must occur, and 

 to give to the view an entirely unobjectionable foundation, I added to a 

 solution of nitrate of lead, first, potassa, which threv\^ down a hydrate 

 of lead, and then carbonate of potassa, which threw down a carbonate 

 of lead, until the solution yielded an alkaline reaction. There were 

 then hydrate and carbonate of lead in the precipitate, and nitrate of 

 potassa, carbonate of potassa, and if any lead, a nitrate of lead in so- 

 lution. The liquor was filtered, and, upon adding hydrosulphuric acid 

 to the filtrate, I obtained a precipitate of the black sulphide, more 

 voluminous than in the first experiment with white lead and a solution 

 of sahpetre. 



" 6. Soda and carbonate of soda gave the same reaction. 



" 7. Nitrate of lime in solution gave the same reaction as nitrate of 

 potassa. 



" My attention has been drawn by a friend to the following sen- 

 tence in Berzelius : — ' When nitrate of lime is boiled with carbonate 



