402 Prof. B.Weber on a new Oxide of Sulphur and an 



of sulphur dioxide. The conclusion arrived at from Schweig- 

 ger's experiments, viz. that the sulphur is merely dissolved 

 in the anhydride without any true chemical action taking 

 place, is not a legitimate conclusion. 



This compound decomposes but slowly in a cool place when 

 protected from the action of moisture ; quantities required for 

 analysis may therefore be readily weighed out. The sub- 

 stance readily withdraws water from moist air, and forms a 

 clear brown liquid, which by taking up more water becomes 

 turbid through the deposition of sulphur. On the addition of 

 cold water to this body rapid decomposition ensues with the 

 production of sulphur (which appears partly in the plastic 

 state, partly in the finely divided form in which it is known 

 as milk of sulphur), sulphuric and sulphurous acids, and thio- 

 sulphuric acid or one of the polythionic acids analogous in its 

 reactions to thiosulphuric acid. 



On the addition of silver solution to the liquid, a precipitate 

 is obtained which, from being at first yellow, changes to red, 

 then to brown, and finally to black. 



Absolute alcohol, and also anhydrous ether, decompose the 

 blue compound with precipitation of sulphur ; the behaviour 

 of the compound towards sulphuric acid varies in accordance 

 with the concentration of the acid. 



Many of the older observations on this compound are ex- 

 plained by these reactions. 



Composition of the Blue Compound. 



In order to obtain a quantity of the compound for analysis, 

 the freshly prepared substance was placed in a small thin glass 

 tube provided with a glass stopper and previously weighed. 

 After weighing, the stopper was withdrawn, and the tube was 

 placed in a glass about 80 millims. in height, which was fur- 

 nished with a properly fitting glass stopper ; in this glass a 

 thin layer, about 1 millim. deep, of a mixture of pure and of 

 fuming nitric acid had been previously placed. After inserting 

 the stopper the glass was inclined so that the acid came into 

 contact with the substance, whereupon violent decomposition 

 ensued. The stopper was firmly held in its place until the 

 liquid had entirely absorbed all the red fumes ; the absorption 

 was only complete after 12 or 24 hours. The contents of the 

 glass w T ere then diluted with water, and the liquid separated 

 from sulphur by filtration. The sulphuric acid in the filtrate 

 was precipitated as barium sulphate, while the separated sul- 

 phur was collected and weighed. The results of analyses carried 

 out in the way described are as follows : — 



