714 PROCEEDINGS OF THE AMERICAN ACADEMY. 



also, that the boiling point of a mixture containing 18 to 30 per cent 

 chlorsulphonic acid is within close limits and lower than that of either 

 component. 



The Action of Water on Pyrosulphuryl Chloride and Chlorsulphonic 

 Acid and the Separation of the Two Bodies. 



Both pyrosulphuryl chloride and chlorsulphonic acid are decomposed 

 by water, the latter far more quickly, according to the equation : 



(1) SO2OHCI + H2O = S02(0H)2 + HCl. 



The formation of chlorine in small quantity from this reaction is evi- 

 dent from the color of the product and its action with potassic iodide. 

 This is probably due to a slight dissociation from the heat of reaction, 

 and a consequent oxidation of the hydrochloric acid by the sulphur 

 trioxide (reactions (1) and (3), pages 703 and 704). 



The action of water upon pyrosulphuryl chloride might take place in 

 two ways : either a direct conversion to sulphuric acid and hydro- 

 chloric acid according to 



(2) S2O5CI2 + 3H2O = 2S02(OH)2 + 2HCI 



or with intermediate formation of chlorsulphonic acid, according to 



(3) S2O5CI2 4- H2O = 2S02(0H)C1, 



the chlorsulphonic acid being then decomposed according to equation 

 (1). The observed formation of chlorine in this reaction also might be 

 ascribed to dissociation of either body under the heat of reaction. 



Konovaloff,33 who added to 100 parts of pjo-osulphuryl chloride 4 

 parts of water (theory for equation (2), 25.1 parts; for (3), 8.4 parts), 

 obtained a mixture of the two bodies. Billitz and Heumann,*^ who 

 used 7.5 parts to 100, found that chlorsulphonic acid was the chief 

 product. Prandtl and Borinski,*® with the proportion of 100 of sub- 

 ctance to 8.3 of water, obtained a product which still reacted quietly 

 with water and gave no color with tellurium, tbus showing, according 

 to our results in Table III, at most a small amount of chlorsulphonic 

 acid. They concluded, therefore, that the reaction took place accord- 

 ing to equation (3), but was very gradual and, in that instance, in- 

 complete. This opinion would seem to be substantiated by their 

 method of separation of the two bodies, which depends upon the selec- 

 tive attack of water in the form of ice upon the ice-cooled mixture, the 

 chlorsulphonic acid being completely broken down and but little of the 

 pyrosulphuryl chloride. 



