194 E. DIVEES AND M. OGAWA : 



colourless, and gives, when recently prepared, the reactions 

 mainly of a mixture of ammonium sulphate and trithionate, but 

 to a small extent those of a sulphite also ; and, lastly, that when 

 the solution is of certain concentration it gives a transient red- 

 dish coloration with hydrochloric acid. 



Forchhammer {Comyt. reiid., 1837, 5, 395) found that, be- 

 sides the orange- coloured substance, crystals of ammonium sulphate 

 are produced by the union of the gases, which can sometimes be 

 seen apart from the other product in some spots of the mass, 

 though often indistinguishably mixed up with it. (That the 

 crystals observed in the product were those of sulphate, could 

 only have been a supposition of Forchhammer's). The mass 

 when moistened is alkaline and evolves ammonia, yielding other- 

 wise the reactions recorded by Rose. Absolute alcohol dissolves 

 out of it a substance which takes a rose colour, soon disappear- 

 ing. Indirectly, he represented the mass to be derived from two 

 mois, ammonia to one mol. sulphur dioxide, as did also Doe- 

 berenier. 



The views advanced as to the nature of the orange body 

 have been, that it is a compound of ammonia with an isomer 

 of sul^^hurous anhydride, which changes at once with water 

 into ammonium sulphate and trithionate, just as ammonium pyro- 

 sulphite slowly changes in hot solution (Kose) ; that it is amido- 

 gen sulphide, S(NH2)2, mixed with ammonium sulphate (Forch- 

 hammer) ; that it is, partly, thionamic acid, NHs'SO'OH, partly, 

 ammonium thionamate, both volatile, being its colour due to 

 impurity (H. Watts) ; and that it is ammonium pyrothionamate, 

 NHo'SaO^-NHj (Joergenssen). 



Interaction of the gases. — We have repeated Hose's experi- 

 ments of measuring over mercury the volumes of the gases which 



