DECOMPOSITION OF DIMERCURAMMONIUM NITRITE HP HEAT, 3.23Ry PRAFULLA CHANDRA RAY and ATUL CHANDRA GHOSH.THE preparation of dimercurammonium nitrite has been alreadydescribed at some length (Trans., 1902, 81, 644), and evidence hasbeen adduced in support of the view that it is a derivative ofammonium nitrite.The solution of sodium mercuric nitrite, from which it is obtainedby the action of ammonia, does not contain mercury as cation,but as part of a complex anion; it does not, therefore, undergo thehydrolysis so characteristic of oxylic mercuric salts, and has presumablya non-oxylic constitution. Two samples of the salt were prepared, anddried a t 95' for analysis :VOL. XCVII. 324 RAY AND GHOSH: DECOMPOSITION OFFound : Hg= (I) 84.74; (11) 84.61. N = (I) 6.33 ; (11) 6.16,NHg,N02,&H,0 requires Hg = 85.29.N = 5-97 per cent.Method of Experiment.-From 0.2 to 0.6 gram of salt was placed ina small bulb, the drawn-out stem of which was connected with aSprengel pump. A preliminary trial proved that the salt commencedto decompose, although very slowly, a t about 140°, and that even at210’ a portion of it remained undecomposed. The bulb was thereforecautiously and gradually immersed in a bath of molten sodium andpotassium nitrates, mixed in about equal proportions (m. p. 21s’).The temperature mas slowly raised to 260°, when no more gas wasevolved, the ‘‘ click ” in the fall-tube remaining persistent. Raisingthe temperature to 280’ made no difference i n this respect. The gaswhich was evolved was found to consist of a mixture of nitrous oxide,nitrogen, and oxygen ; nitrous fumes were not noticed ; in fact, themercury in the fall-tube was not in the least tarnished, nor couldeven a trace of nitric oxide be detected.I f , however, the bulb wassuddenly plunged in a bath previously heated to 2 2 5 O , the mode ofdecomposition was slightly different. Mercury in the shape of finedust was at once deposited on the glass, and in the gaseous mixturenitric oxide could be recognised.The nitrous oxide was removed by alcohol, and sometimes byrepeated shaking with cold water, until no more absorption tookplace. The oxygen was in some instances removed by alkaline pyre-gallate, but generally by means of phosphorus. The residue in thebulb was of a greyish-yellow colour; it consisted mainly of mercuricoxide with a small proportion of mercuric nitrate.This was provedby boiling the mixture with a solution of sodium hydroxide. Thefiltrate indicated the presence of nitrogen in the form of nitrate.Metallic merciiry, both as a mirror and in fine globules, was depositedin the stem of the bulb. More than a dozen experiments wereperformed, the resdts of- some of which are tabulated below :Total 0“Free” N as N as in the H ~ a s Hg as “Frec”N. N,O. Hg(NO,),. Oxygen. salt. Hg(h0,)p HgO. Hg.I. 3’21 1.55 1.21 0-21 6.82 5-64 57‘20 19-4511. 3-17 1-48 1-32 0.17 - 9.43 55.31 20.55- 6 .OO 62-65 16’68V. 3.73 1.52 0.72 0% - 5-14 83’31 16’84- - - 111. 3-43 1-44 1‘10 0‘22 -IV. 3’53 1‘60 0‘84 0 ‘34I n those experiments in which nitric oxide was obtained, thenitrogen was distributed as follows :“ Free ” N.N as N,O. N as Hg(NO,),. N as NO.I. 2.54 1 ’03 2 ’31 0.0911. 3’23 2 ‘24 0’29 0 ’42111. ‘L.ti9 I .06 0.95 0.3DIMERCURAMMONIUM NITRITE BY HEAT. 325Discussiorn of Resuh.--It has already been pointed out that thehalogen derivatives of the mercurammonium group (NHg,-) may beregarded as non-oxylic in constitution, since they decompose under theaction of heat according to the equation :2NHg2X = N, + 2Hg + 2HgX,*where X = C1 or Br.series should decomposelas follows :and that the mercurous nitrite thus formed, being unstable a t thistemperature, would yield its own products of decomposition (compareRBy and Sen, Tram., 1903, 83, 491).We have repeated theexperiment on the decomposition of mercurous nitrite. The initialtemperature of decomposition has been found to be almost the sameas that of dimercurammonium nitrite, namely, 1 40°, and it is completedat 247O. I n order to protect the mercury in the Sprengel pump frombeing soiled, a glass spiral, packed with glass beads and moistenedwith sodium hydroxide solution, mas interposed, as in some of theprevious experiments (compare Trans., 1905, 87, 180). The gaseousproduct which was collected was found to be nitric oxide. Moreover,had dimercurammonium nitrite decomposed according to the equationgiven above, exactly half the nitrogen would have been given offas “free” nitrogen, but it varies from 3.2 to 3.7 per cent. Theformation of nitrous oxide is rather remarkable. The reactionevidently seems to proceed in three or four directions simultaneously,which may be expressed by the following equations :From analogy, one would naturally expect that the nitrite of the2NHg,N02 = N, + 2Hg + 2HgN02,. . . . . . . NHg,NO, = N, + 3Hg0 (1)NHg,NO,=N,O+HgO+Hg (2)NHg,N0,=N2+2Hg+0, (3)3NHg2N02 = Hg(NO,), + 3N, + 5Hg. . . . (4).(compare NH,NO, 5 N, + 213,O) . . . . . .. . . . . .We are at present engaged in studying the decomposition ofdimercurammonium nitrate, in the hope that further light may bethrown on these points.CHEMICAL LABORATORY,PRESIDENCY COLLEGE, CALCUTTA.* RAY, “ Studien uber die Konstitution der Dinierkuramnioiiium Sake ’’ (Zeitsch.anorg. Chem., 1902, 33, 193; also, Sen, ibid., 197).2