1870.] 



Acids of the Sulphur Series, 



511 



and sulphochlorides ; it may then be possible to separate the products of 

 the reaction by means of distillation under reduced pressure. 



The formation of phosphoric oxychloride in this reaction can be con- 

 sidered as the result of the simple addition of oxygen to phosphorous chlo- 

 ride, the triatomic phosphorus becoming pentatomic*. 



On the Properties and several Reactions of Pyrosulphuric Chloride. 



Pyrosulphuric chloride was first obtained by H. Rose by the action of 

 sulphuric anhydride on chloride of sulphur S 2 C1 2 , and later on by simple 

 distillation of chloride of sulphur saturated with chlorine with Nordhausen 

 sulphuric acid. 



Rosenstiehl prepared it by heating sodic chloride with sulphuric anhy- 

 dride, ! 



3S0 3 + 2NaCl = S 2 0 3 C1 2 + Na 2 SO,. 

 According to him, acetylic chloride is formed by heating it with sodic 

 acetate, and chlorochromic acid by its action on potassic chromate, sodic 

 and potassic pyrosulphates being formed at the same time, as he proved 

 by analysis, — 



K.CrO, + S 2 0 5 C1 2 = Cr0 2 Cl 2 + S 2 0 7 K 2 . 

 On passing its vapour through a tube heated to dull redness, I have 

 found the following decomposition to take place : — During the whole 

 operation chlorine and sulphurous anhydride escaped, and in the receiver, 

 which was kept cold by ice, sulphuric anhydride and a liquid layer were 

 condensed. The latter yielded on distillation two products, the one boiling 

 below 100° and the other consisting of the pyrosulphuric chloride which 

 had escaped decomposition. The first portion was found to be sulphuric 

 anhydride contaminated with traces of pyrosulphuric chloride; for on 

 passing a stream of dry carbonic anhydride through it the whole solidified. 

 The decomposition is therefore expressed by the equation — 



S 2 0 5 C1 3 = S0 3 + SO, + Cl 3 . 

 The result of a vapour-density determination, according to Dumas's 

 method, also speaks for the above decomposition. The following are the 

 observations recorded : — 



mm. 



Weight of globe + dry air at 14°'/ and 758*9 .... 50-513 



Weight of globe + vapour at 202° and 758-6 50732 



Capacity of globe 249cub.centim. 



Residual air 1 ,, „ 



which gave a specific gravity = 5 "06. 



The calculated number for S 2 O ft Cl 2 =2 vol. is 14*89 ; a splitting up into 



SO.. + S0 2 C1 2 being admitted, it is 7*44 ; and if the decomposition go further, 



* Experiments were also made to oxidize carbonic oxide ; but the anhydride was found 

 to be without action on it up to a temperature of 200°. I have no doubt, nowcver, that 

 the employment of a somewhat higher temperature will effect the combination. 



2 Q 2 



