2 P. C. Raj — Constitution of Dimer cur ammonium Salts, [No. 1, 



It is some what surprising that Hof matin and Marburg should have 

 overlooked tbe valuable contributions of Andr6, which throw considerable 

 light on the constitution of the compounds in question. The French 

 chemist has carefully studied the interaction of corrosive sublimate and 

 ammonia under varying conditions and degrees of dilution, 1 and finds, 

 moreover, that a solution of the sublimate and ammonium chloride when 

 treated with potash (I.e. p. 1110) yields a compound which may be 

 viewed as made up of equal molecules of dimercurammonium and dimer- 

 curoxy ammonium chlorides : NHg 2 Cl+NH 2 0Hg 2 Cl. It should be noted, 

 however, that this rather complex formula admits of being simplified as 

 2NHg 2 Cl + H 2 0. 



Judging from analogy, I was naturally led to expect that mercuric 

 nitrite solution with ammonia would yield a compound of the formula 

 NH 2 -Hg-N0 2 . The expectation was in a way realised, only in place of 

 the mono-, a di-substitution product was invariably obtained, viz., N.Hg» 

 Hg.N0 2 or dimercurammonium nitrite with a semi-molecule of water. 

 When this nitrite is treated with hydrochloric acid and gently warmed, it 

 dissolves to a clear solution, evolving nitrous fumes. On evaporation a 

 crystalline double chloride of the formula 2 Hg01 2 -f NH 4 C1 is obtained ; 

 hydrobromic acid also yields a compound of analogous constitution. The 

 aqueous solutions of these double salts again, when treated with an excess 

 of alkali, throw down precipitates of the type NHg 2 X : where X repre- 

 sents a halogen atom. 8 



The haloids as obtained by me, however, seem to conform to the 

 general formula 2 NHg 2 X.H 2 0. The water is obstinately held by these 

 salts — even at 160° 0.; and hence this water may be regarded as " water 

 of constitution." 



It may be urged that the hydrated compounds, in view of their high 

 molecular weights, may all be taken to have one instead of a sewn-molecule 

 of water, and the percentages of mercury and nitrogen, &c, may still fall 

 fairly within the range of "errors of experiment;" but the concurring 

 testimonies of the analyses of the different compounds under the respec- 

 tive heads speak in favour of a semi-molecule. 



As regards the question whether these salts should be regarded as 

 of the type mercuroxy — or mercurammonium derivatives, my answer is 

 in favour of the latter. On treating the double salt 2 HgBr 2 .NH 4 Br» 

 with an alkali I have succeeded in preparing not only the hydrated bromide 

 2NHg 2 Br.H 3 0, but also a salt of the formula 2 NHg 2 Br.HgBr 2 which 

 is absolutely wow-hydrated. A corresponding chloride has been described 

 by Kane, though prepared under different conditions. [Ann, Chem. Phys* 



1 Compt. Bend. T. 108, pp. 235, 290, 1108, 1164. 

 8 Trans. Chem. Soc. (1902), Vol. 81, p. 644. 



