8 PROCEEDINGS OF THE AMERICAN ACADEMY. 



examination of our reagents showed tiiat the purest commercial sodic 

 or potassic hydrate gives an intense color, and even hydrates prepared 

 from the metals are not free from color. Pure sulphuric acid gave no 

 reaction, and pure sodic carbonate only a faint color. We finally 

 obtained a solution that gave not a trace of color by dissolving metallic 

 sodium and boiling the solution for some time with metallic aluminum. 

 With this solution as the absorbent in a combustion of a suljjhur oil, 

 after the analysis the solution was as free from color as before when 

 it had stood half an hour after the addition of the reagents. Since a 

 pink color is distinctly visible in this reaction with one part of nitrogen 

 in the form of nitrous acid in one thousand million parts of solution, 

 it is safe to conclude that nitrous acid is not one of the products in 

 this form of combustion. 



To determine whether nitric acid is formed, after the combustion a 

 portion of the sodic hydrate solution was neutralized, mixed with 

 ferrous sulphate, and concentrated sulphuric acid poured beneath the 

 solution. No color was visible at the junction of the two liquids. 

 In a second test another portion of the alkaline solution was nearly 

 neutralized with sulphuric acid, evaporated to dryness, and a few drops 

 of phenolsulphuric acid added. Ujion diluting to a definite volume, 

 no difference could be perceived between the color of this solution 

 and that given by phenolsulphuric acid alone in a blank experiment. 

 In the combustion of sulphur oils in air, therefore, the atmospheric 

 nitrogen is not affected. 



For efficient aid in studying the details of these methods of analysis, 

 I should acknowledge my obligations to Mr. W. O. Quayle, and to my 

 assistants, Messrs D. B. Cleveland and G. M. Little. 



