OF ARTS AND SCIENCES. 293 



position by a piece of platinum wire projecting from its upper end 

 and resting against the neck of the flask. The apparatus was then 

 filled with carbonic dioxide from a heated tube containing mag- 

 nesite, after which by shaking the flask the sulphuric acid was 

 added to its contents in small quantities at a time, and the nitrogen 

 given off collected over a solution of potassic hydrate, and measured 

 in the usual way. It is necessary to heat the flask gently toward 

 the end of the operation to drive off all the nitrogen. One half 

 of the nitrogen collected is derived from the sodic nitrite. To test 

 the accuracy of the method two determinations of the nitrogen in 

 commercial sodic nitrite were made by it which gave, — 



Found. 



Nitrogen 18.09 18.11 



and as they agreed with each other, and came tolerably near to the 

 usual percentage of nitrogen in commercial sodic nitrite (between 

 19 and 20 per cent), it was evident that the method was accurate 

 enough for our purposes. A third portion of the aqueous liquid 

 was in two experiments used for the determination of the trini- 

 trophloroglucine, but we give our results with a great deal of hesi- 

 tation, as we were unable to find any satisfactory quantitative 

 method; methods based upon extraction with an organic solvent, 

 or the precipitation of the barium salt, which Benedikt says is in- 

 soluble, led to no result. We were therefore driven to determining 

 the amount of nitrogen in the residue obtained by evaporating to 

 dryness a portion of the aqueous solution acidified with sulphuric 

 acid, and calculating from this the amount of trinitrophloroglucine, 

 on the assumption, which at best can be but approximately correct, 

 that this was the only substance containing nitrogen left in the 

 residue. 



Experiments in ivhich Alcohol was the only Solvent used. — 

 I. Weight taken, 10.556 gr. Weight of aqueous solution, 135.4 gr. ; 

 8.6 gr. of the solution gave 16.9 c.c. of nitrogen from the sodic 

 nitrite under a temperature of 23° and a pressure of 763.8 mm. ; 

 28.2 gr. of the solution gave 1.1718 gr. of argentic bromide ; 

 20.8 gr. of the solution gave after the nitrous acid had been ex- 

 pelled by sulphuric acid 8.2 c.c. of nitrogen at a temperature of 

 23° and a pressure of 767.8 mm.; 54.4 gr. of the solution gave 

 0.808 gr. of the diethylether of trinitrophloroglucine. The organic 

 matter insoluble in water weighed 6.97 gr. 



II. Weight taken, 10.1582 gr. Weight of aqueous solution, , 

 164.55 gr.; 15.95 gr. of the solution gave 24.65 c. c. of nitrogen 



