x:°- Proceedings. {January igth, igo^. 



by A. D, Michael (8vo., London, 1903), purchased from the 

 Ray Society. 



The Secretary announced that the Council had decided 

 to photograph some of the apparatus belonging to Dalton, and 

 used by him in making his researches. Mr. C. L. Barnes, M.A., 

 read a letter from the late Dr. Schunck stating how the apparatus 

 came into the Society's possession. 



Mr. R. L. Taylor, F.C.S.,F.I.C.,communicated the following 

 " Note on a Method of preparing Hydrobromic Acid." 



It is well known that when a bromide is acted upon by 

 strong sulphuric acid, a mixture of hydrobromic acid and free 

 bromine is produced, the formation of the bromine being due to 

 the action of the hydrobromic acid and sulphuric acid upon each 

 other, sulphur dioxide being produced at the same time : — 



H^SOi + 2HBr = SO, + 2HP + Br,. 

 If however a little amorphous phosphorus is mixed with the 

 bromide, and a little water added, strong sulphuric acid liberates 

 hydrobromic acid which is quite colourless and contains no 

 free bromine. By this method the acid may be prepared in 

 quantity just as easily as hydrochloric acid can be obtained 

 by the action of strong sulphuric acid upon common salt. 



The hydrobromic acid prepared in this way is not perfectly 

 pure; it always contains a small quantity of sulphur dioxide. 

 For most purposes the presence of this impurity would not 

 matter, but, if the acid is required to be perfectly pure it may 

 be first passed into water, the small amount of sulphurous acid 

 oxidised by a little solution of potassium permanganate, and the 

 solution redistilled. 



Ordinary Meeting, January 19th, 1904. 



Professor W. Boyd Dawkins, D.Sc, F.R.S., President, 

 in the Chair. 



The thanks of the members were voted to the donors of the 

 books upon the table. 



