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DR. B. D. STEELE, DR. D. McINTOSH AND DR. E. H. ARCHIBALD 



the limb of a transferrer was passed through k, and the whole apparatus made air- 

 tight by means of a piece of rubber tubing, e. 



The object of the cap k was to prevent the limb of the transferrer from coming into 

 contact with the rubber grease, with which the stoppers were lubricated, and it was 

 constructed so that when in position its narrow portion was exactly in the axis of 

 the tube g. 



The transferrer was then packed with the carbon dioxide and ether mixture, and 

 the hydrogen bromide blown into A by means of a small indiarubber bellows. The 

 rubber tube e was then cut away, after which the transferrer and then the cap k 

 were removed, and the stop-cock f was re-inserted. 



The tube A was finally removed from the cold bath and the hydrogen bromide 

 allowed to boil off. This always took place steadily, provided the vessel contained 

 moist beads or garnets ; in the absence of these, or if they were dry, the violent 

 bumping which resulted was liable to blow out one or other of the stoppers. The 

 hydrogen bromide as it boiled off passed through C, and was almost completely 

 absorbed at the surface of the water in the outer portion of B ; a small quantity ot 

 gas bubbled through the hole h and was absorbed inside ; very occasionally a few 

 bubbles passed through b, where any traces of acid which might have passed through 

 the larger portion of the apparatus were absorbed. After all the hydrogen bromide 



had evaporated the stop-cock e was closed, the 

 apparatus immersed in distilled water, carefully 

 wiped and again weighed, the necessary correction 

 being made for the increase of volume of the liquid 

 contained in it. The increase in weight gave the 

 amount of solution that had been used. The 

 contents of the absorber were next washed into a 

 large beaker and the hydrogen bromide determined 

 by titration with a twice normal alkali solution, 

 which had been carefully standardised and was free 

 from carbonate. The difference between the amount 

 of acid found in this manner and the amount of 

 solution actually weighed gave the weight of the 

 dissolved substance. The alkali was contained in 

 a weighing burette of the pattern shown in fig. 4. 

 In order to deliver from this burette, the cap 6 was 

 removed and the stop-cock opened, when by blowing through the side tube d the 

 liquid was forced through the tube c. The burette was weighed to 0-002 gramme, a 

 glass counterpoise of approximately the same volume being used. 



Phenolphthalein was used as indicator, and an excess of one or two drops of alkali 

 added, the exact amount of excess being determined by titration with a twentieth 

 normal solution of hydrobromic acid. 



d. 



Fig. 4. 



