ARTICLE XIX. 



On the Change effected in the Nitrates of Potash and Soda by the limited Appli- 

 cation of Heat, with the View of ohtaining pure Oxygen, hy which they are 

 only partially convertible into Hypo-nitrites: also on a Liquid and a gaseous 

 ethereal Compound, resulting from the reaction of nascent hypo-nitrous Acid 

 with the Elements of Alcohol. By Robert Hare, M. D., Professor of Chemis- 

 try in the University of Pennsylvania. Read July 17, 1840. 



It is well known that when either nitrate of potash, or nitrate of soda, is 

 subjected to heat, as is usual in the process for obtaining oxygen, the first 

 portions of gas extricated are nearly pure. When the fire is carefully regu- 

 lated, the residue, after cooling, is a white indurated mass. If this mass be 

 dissolved in as much boiling water as its solution requires, a large deposition 

 of crystals of nitrate will take place after the resulting liquid becomes cool. 

 On boiling down the solution, a further portion of crystals of the same nature 

 will be obtained. 



The mother water being evaporated to a certain point, begins to yield crystals 

 of hypo-nitrite. Thus the superior solubility of the hypo-nitrites of potash and 

 soda renders it practicable to separate either of them from the nitrate having 

 the same base. Of course repeated crystallization is requisite to obtain either 

 of the salts in question free from the other. It is inexplicable that about a third 

 of the salt employed should be reduced to the state of hypo-nitrite, while the 

 remainder is not decomposed. It would seem as if there were a reaction be- 

 tween the nitrate and hypo-nitrite, which, having co-operated to expel a portion 

 VIT. — 3 u 



