13 



about 100 c. c. capacity, closed by a stopper through which passed the 

 long neck of a cylindrical funnel holding about GO c. c., the neck hav- 

 ing an interior diameter of but 1 mm. and separated from the wider 

 cylindrical reservoir by a well ground glass stopcock. There also 

 passed through the same stopper the stem of a thermometer reading 

 to one-tenth of 1 degree with accuracy, a small tube with stopcock for 

 the introduction of gas to displace the air of the apparatus, and a sec- 

 ond small tube to carry off the nitrogen evolved. The capacity of the 

 flask was carefully gauged with the tubes and thermometer in position 

 and the stopper inserted to a marked depth in the neck, so that after 

 the introduction of any known volume of solid or liquid material a 

 simple subtraction would give the volume of gaseous matter remaining 

 included. A gas measuring cylinder, connected with the flask by a 

 tube of very small bore and immersed in water in a larger cylinder 

 which could be raised or lowered, provided for collecting and measur- 

 ing the evolved nitrogen. The flask was supported in a water bath, 

 so that it could be heated or cooled at pleasure. 



In order to give time for action upon the organic material under 

 experiment, and to keep down to conveniently small limits the evo- 

 lution of nitrogen dioxid. it was found. important to work with the 

 nitrous acid in a sufficiently diluted condition. With the same object 

 in view it was found desirable to raise the temperature of the flask 

 very gradually. In carrying out an experiment the particular amidic 

 or proteid material was fluely pulverized, weighed off, and introduced 

 into the flask, either in the dry state or with as little recently boiled 

 water as possible, and with the necessary amount of silver nitrite, as 

 a fine crystalline powder. This powder was contained in a small, thin 

 glass cylinder which could be easily upset in order to mix its contents 

 with the other materials in the flask. A current of nitrogen gas was 

 next run through the flask until all air was expelled. In the case of 

 substances dissolving in water with difficulty the flask was now allowed 

 to stand closed for some time to permit of solution taking place. Com- 

 munication was established with the gas-measuring cylinder and the 

 proper quantity of standard hydrochloric acid made by diluting very 

 strong aqueous acid with boiled water and kept in small well closed 

 bottles, was gradually introduced through a funnel with capillary bore. 

 Care was taken that no air was admitted. After all action in the cold 

 had ceased the temperature of the flask was gradually raised by means 

 of the water bath up to a maximum of about 06 or 97 C. As soon as 

 all action was over and the apparatus had cooled down to atmospheric 

 temperature the flask was nearly filled up with recently boiled water, 

 introduced through the capillary funnel, and a small measured volume 

 of nitrogen was run in to displace any remaining nitrogen dioxid. 

 The gas in the measuring cylinder was then treated with oxygen in 

 sufficient excess to dispose of all nitrogen dioxid and with caustic 

 potash and pyrogallol to remove excess of oxygen. Alter standing at 



