10 OPTICAL ACTIVATION 



bottles W;-, and W 4 ; and dried with concentrated sulphuric 

 acid in W. v The last traces of carbon dioxide were removed 

 with soda-lime in the tube U r From this the nitrogen passed 

 into the reaction flask R, where it mixed with the carbon dioxide 

 liberated from the acid. On passing out of the reaction flask 

 most of the solvent vapour that was carried along with the 

 nitrogen condensed in the cooler Kj and ran back again into 

 the flask ; the last traces of solvent vapour condensed in the 

 three small condensors K 2 , which were immersed in a freezing 

 mixture of ice and salt. After leaving K 2 the gas passed 

 through the three way tap T\ to either of the sets of soda-lime 

 tubes U,IL and U 4 U 5 , where the carbon dioxide was 

 absorbed. Each of these sets of tubes was connected with a 

 soda-lime tube Rj or R 2 and a bubble counter bj or b 2 . The 

 reaction flask, the coolers, and the soda-lime tubes were all 

 attached to a small wooden frame. To immerse the reaction 

 flask in the thermostat it was simply necessary to lower the 

 wooden frame. At fixed times the current of gas was cut off from 

 one set of U-tubes and passed through the second set by means 

 of the three way tap ; during the interval the first set of tubes 

 was weighed. This operation was repeated as often as was 

 necessary. The influence of the rate of the nitrogen stream 

 on the velocity of decomposition of the bromcamphor-carboxylic 

 acid was investigated, and it was found that the velocity of 

 evolution of CO 2 apparently increased slightly with increase 

 in the velocity of the nitrogen stream up to four liters per 

 hour, probably owing to small traces of carbon dioxide remain- 

 ing in supersaturated solution; but when the nitrogen stream 

 was over four liters per hour, however, no further increase in 

 the velocity of CO 2 evolution, with increase in the velocity of 

 the nitrogen steam, was observed to occur. In the experiments 

 which follow the current of nitrogen was usually 6-8 liters 

 per hour. A more rapid current of gas was not used on account 

 of the evaporation of the solvent, With a nitrogen stream of 

 8 liters per hour traces of acetophenone vapour were usually 

 carried over into the first two tubes of the cooler K 2 ; but 

 seldom was a trace of acetophenone ever found in the third 



