COLORATION OF ANILINE: II. 431 



heating, and on treating with a few drops of potassium hydroxide gave a strong 

 and unmistakable odor of ammonia. The small amount of aniline salt present 

 did not interfere at all with the tests. 



A third portion was heated in a distilling flask very slowly and carefully 

 until 0.5 cubic centimeter had passed over. This distillate on nitration developed 

 the characteristic odor of. nitrobenzene. A control experiment in which an 

 equal quantity of pure aniline was treated in the same way developed no odor of 

 nitrobenzene. 



A fourth portion was distilled in the same manner and the first three drops 

 collected. The refractive index of the distillate was decidedly lower than that 

 of aniline and on nitration the odor of nitrobenzene was quite strong. 



A fifth portion of 2 cubic centimeters was evaporated in a vacuum desiccator 

 over sulphuric acid at 3Q degrees. Crystals of azophenine separated after ten 

 days. 



ANILINE, METHYLANILINE, AND DIMETHYLANILINE SEALED IN ATMOS- 

 PHERES OF HYDROGEN AND CARBON DIOXIDE AT DIFFERENT PRESSURES. 



Since I have shown that one can not be certain of preparing pure 

 aniline by distillation in contact with atmospheric air or in the light, an 

 apparatus was designed to avoid these sources of undesirable influences. 

 This apparatus is pictured in figure 2. 



The hydrogen made by the action of pure, dilute sulphuric acid on 

 pure zinc was purified by passing through alkaline pyrogallol, a wash 

 bottle of concentrated sulphuric acid, and then into the chain of apparatus 

 shown in figure 2. 



A is a wash bottle of concentrated sulphuric acid, J3s are tubes of phosphorus 

 pentoxide with plugs of glass wool at the ends. The hydrogen, thus purified, 

 then comes in contact with the aniline in the flask C. The purified aniline, 

 which finally has been dried by distillation over sodium, is distilled into C through 

 the tube at the top, a small amount of metallic sodium in a glass rod 32 is 

 introduced and the tube sealed. The hydrogen current is then turned on and 

 the entire apparatus thoroughly dried. With a slow current of hydrogen passing 

 through the apparatus the analine in is distilled. The first fraction is 

 passed into E by means of the three-way stopcock D and only the middle 

 fraction is collected in F. From F it is again distilled into the tubes 

 Gf, H and /. Two fractional distillations, one over sodium and one without, in 

 a hydrogen atmosphere are thus obtained. The tube G is then sealed off at 

 atmospheric pressure. A Sprengel mercury pump sealed on at L was then started 

 and the tube H sealed off at 200-millimeter pressure and the tube I at the best 

 vacuum obtainable under the conditions, about 1 millimeter as shown by the mano- 

 meter K. The entire apparatus shown in the figure from mercury pump to 

 hydrogen generator was connected by glass seals. No outside air could possibly 

 enter. The only possible opening was the stopcock D. This, however, was 

 exceptionally tight and was always subject to a pressure which was greater on 

 the inside than the outside. 



The carbon dioxide atmosphere was employed in the same manner. The gas, 

 made by the action of hydrochloric acid on marble, was purified by passing 

 through a wash bottle of distilled water, two bottles of pure, concentrated 

 sulphuric acid and then into the chain of apparatus shown in the figure. 



32 The method of handling the sodium has been described in a previous paper. 

 99667 5 



