676 REPORT— 1892, 



ammonium sulphite were the only products of a volatile nature. The actions 

 were completed at the melting' point of zinc. 



Lead sulphate required a high temperature before any action was visible, and 

 the salt was not completely decomposed by heating for an hour to a red heat. A 

 little lead sulphide was produced. Thallium sulphate acted in a similar manner, 

 bat more sulphide was formed. 



Ferrous sulphate (dry) precipitated by addition of strong acid to the concen- 

 trated water solution of FeSO^j and then dried in vacuo, ordinary crystallised 

 ferrous sulphate, and the ammonium ferrous sulphate were all reduced to metallic 

 iron, which, however, contained 1 to 2 per cent, of sulphur. 



The sulphates of zinc, manganese, cobalt, nickel, magnesium, and chromium 

 were remarkably alilce in their behaviour. 



In all these cases the quantity of material left in the boat after heating corre- 

 sponded very closely with that required if a sulphide of the form M| had been 

 formed. As a matter of fact, the residue consisted of a mixture of the sulphide 

 and oxide in nearly molecular proportions. 



No nitride has as yet been obtained. 



As far as the volatile portion is concerned, the main bulk in all cases appeared 

 to be ammonium sulphite. No trace of sulphate was found. In the hot tube in 

 which the reaction was carried on, the substance which condensed was for the 

 most part ammonium thionamate NH3OHSONH.,. Where this came in contact 

 with water in tlie condensing ilask, or with moisture in the cooler parts of the tube, 

 ammonium sulphite was of course formed. 



Undoubtedly the most interesting salt examined is cupric sulphate. Either 

 dry or with cry,8tal water, the salt absorbed much NII3, and then melted below 

 200° turned black, and as the temperature rose appeared to boil, and finally at 

 somewhere about 400° began to decompose with incandescence, leaving almost 

 pure metallic copper. 



The comparatively low temperature at which an action was observable in the 

 case of copper sulphate suggested the possible formation of a hydrazin compound. 



The white sublimate was therefore examined for its reducing power on Fehling's 

 solution and silver nitrate. As thionamate reduces both silver and copper solu- 

 tions when alkaline, some of the white sublimate was distilled from potassium 

 hydrate solution and the distillate collected in dilute sulphuric acid. This solution 

 also reduced Fehling's solution. There is little doubt but that hydrazin is present 

 along^ with the thionamate sublimate, but the quantity is small, and in several 

 experiments could not be detected at all, probably on account of the temperature 

 being too high when the ammonia comes in contact with the sulphate. 



We are continuing this work in the hope of getting an easy method for the 

 production of hydrazin compounds. 



7. Note on the Action of Dn/ Sulphur Di-oxide on Oxij-salts. 

 Bij Professor W. R. Hodgkinson, Ph.I)., F.B.S.E., and J. Toung, A.B.S.M. 



The behaviour of sulphur di-oxide on solutions of certain oxy-salts, such as 

 nitrates and chlorates, is suiliciently well known, and, in fact, a matter of every- 

 day occurence. The reactions of the dry gas on these salts does not, however, 

 appear to have been very carefully studied. 



Some quantitative experiments have therefore been made with several typical 

 salts. The mode of experiment has been to expose a weighed quantity of the salt 

 to a current of carefully dried SO^ in a tube so arranged that it could, "if necessary, 

 be heated to some definite temperature in an air-bath, or with the naked flame "if 

 desired. 



Nitrates. — A considerable number of nitrates have been examined. As a rule, 

 the action commences at the ordinary temperature coloured oxides of nitrogen are 

 given olf, and when the salt is employed in fine powder the temperature rapidly 

 rises, and the metal in every case completely converted into sulphate. As long as 

 the materials were quite dry no SO3 was formed beyond that necessary to form 

 sulphate with the metal. 



