812 LOEB THE USE OF AKILTNE AS AN ABFORBEKT O F LXVII.-The Use of Aniline as an Absorbent of Cyanogeit in Gas A na lysis. By MORRIS LOEB. In a pa?er published in the Compfes Rerhdus 100 1005 some time ago Jaquemin proposed t h e use of aniline as an absorbetit for cyanogen in quantitative gas analysis without however giving details of any experiments as to the trustworthiness of the method. The proposal is B surprising one considering that hydrogen cyanide is always formed in the preparation of cyananiline; this fact is dis-tinctly stated by Hofmann (Annnlen 66 l29) who accounted for its poduction by certain secondary reactions which he studied. It is also to be noted that Jaquemin in khe same paper describes a very satisfactory method of preparing cyanogen gas in the wet way and that he probably employed t h e moist cyanogen in his experiments with aniline.As the presence of water seems to favour most of the reactions of cyanogen there did not seem to be any conclusive evidence t h a t dry cyanogen would be totally absorbed by aniline. A t all events it seemed worth while to make the experiment with cjanogen prepared in the old way and at the same time to ascertain to what extent the development of hydrocyanic acid would interfere with Jaquemin’s proposed method for gas analysis. For this purpose, cyanogen prepared from dry mercuric cyanide was brought into contact with recently distilled aniline. The gas was indeed absorbed rapidly and completely nor did a bubble of gas appeqr after 24 hours’ standing. But as soon as carbon dioxide was passed in the presenc CYANOGEN IN GAS ANALYSIS.813 of hydrocjanic acid became apparent. It was expelled from the u i l i n e by the carbon dioxide and could now be recognised both hy its odour and by the prussian blue reaction. At tbe same time a considerable quantity of carbon dioxide is absorbed by the aniline and must be held in solution as chemical union is impossible under the circumstances. As the same is said to be the case with carbon monoxide and these two gases are those which generally accompany cyanogen I fail to see how aniline can be generally useful in deter-mining the amount of cyanogen in a mixture apart from the fact that hydrogen cyanide is produced in the reaction and is itself very loosely attracted by anili tie. The experiments by which I satisfied myself of this were made last April in the laboratory of the Physical Association of Frankfort-on-Blain to the director of which Dr.B. Lepsius I am very mnch indebted. The details of a few of the most important tests are given below. I. 38.88 C.C. of cyanogen gas (under standard conditions) wwe absorbed immediately by 12.5 C.C. aniline ; after 25 hours no trace of gas had been evolved. 11. A mixture of cyanogen and dry air was introduced into a U -shaped eudiometer provided with stopcocks and filled with mercury. Aniline was first added and allowed to absorb the cyanogen and dry carbon dioxide was then passed i n ; when no further change took pl:tce the unahsorbed gas was transferred t o a test-t'ube over mercury arid brought in contact with a few drops of sodic hydrate; the alkaline solution gave an appreciable test for hj-drocjanic acid with ferrous and ferric salts.In the followirig table the measurements and the results are given :-1 t. I B. I C.C. 1 Corrected. 1 Volume of cyanogrn and a i r . ' 19 -0" 1 752 -1 ~ 60 I 55.34 ~ -Volume 22 tours after introduc-iiig aniline Polume of cyanogen absorbed After addition of carbon dioxide Volume carbon dioxide After 23.5 hour$ . Volume carbon dioxide absorbed 19.5 '752-1 7 . 7 7.09 - -- 48 -2.5 - 26.75 - 1 - 1 - I - 1 14.51 19.5 I 752.1 1 3F76 33.84 1 -- - -19.5 752.0 21.00 19.33 -111. A similar experiment performed in a somewhat different order and with the use of a straight eudiometer gave an analogous result. H = the height of the column of mercury h = the height of the column of aniline reduced to mercury 814 NILSON AND PETTERSSON NEW CHLORIDES OF INDIUM, C.C. 56.5 108.5 -43.0 -Volume of carbon dioxide. Volume of carbon dioxide and cyanogen. . Volume of cyanogen. . Vol. 22 hours after introduction of aniline . Volume of gas absorbed . Corrected. --52-03 99.91 47 -88 27-32 72-59 t. -19 *5" 19 -5 19'5 --B. '752 *1 '752 *1 '752 * 0 --47.88 C.C. cyanogen gas and 24.71 C.C. carbon dioxide have there-In this case too the residual gas had a decided fore been absorbed. odour of prussic acid