NITROGEN. ' 67 



These figures by Stas represent weighings in tlie air. Reduced to a 

 vacuum standard, this mean becomes 135.6423. 



The determinations made by Hibbs* differ slightly in method from 

 those of Penny and Stas. He converted the nitrate into the chloride by 

 heating in a stream of gaseous hydrochloric acid. His results were as 

 follows, vacuum weights being given- 



.0026 

 Now, combining, we have : 



Penny, ist series 135-636, ± .001 1 



Penny, 2d " 135.633, dz.ooil 



Stas 135.6423, i .0014 



k Hibbs 135.627, it .0026 



General mean 135.636, ± .0007 



By the same general process Penny f determined how much potassium 

 nitrate could be formed from 100 parts of chlorate. He found as follows : 



82.505 

 82.497 

 82.498 

 82.500 



Mean, 82.500, =b .0012 



For 100 pfirts of sodium chlorate he found of nitrate 



79.875 

 79.882 

 79.890 



Mean, 79.8S23, zb .0029 



For the ratio between the chloride and nitrate of sodium Penny made 

 two sets of estimations, as in the case of ])otassium salts. The subjoined 

 figures give the amount of nitrate equivalent to 100 parts of chloride: 



* Thesis for Doctor's degree, University of Penn.sylvania, 1896. Work done under the direction 

 of Professor E. F. Smith. 

 tPhil. Trans., 1839. 



