2g2 The Philippine Journal of Science 1923 



placed very firmly in this side hole, was removed temporarily at 

 intervals during the hydrogenation experiments, so that a pi- 

 pette could be inserted into the opening and a sample of the 

 mixture withdrawn without discontinuing the stirring or the 

 flow of gas. The uniform sample of hydrogenated oil thus 

 obtained was not contaminated by small quantities of previous 

 samples; contamination occurs when the hydrogenated oil is 

 siphoned out of the flask. In this method of hydrogenation the 

 safety of manipulation depends upon the mercury trap, a larger 

 diagram of which is shown in fig. 3. The stirring rod, operated 

 by a small electric motor, passed through the tube e, which was 

 inclosed in the mercury trap, /, g. 



As it is somewhat difficult to filter the catalyst out of a 

 small sample of oil which has been hardened, the samples of 

 hydrogenated oil were treated with boiling ether. The ethereal 

 solution containing the extracted fat was then filtered and the 

 ether distilled off in a partial vacuum at 40°. The samples thus 

 obtained were analyzed by determining the iodine value (Hiibl) 

 and the melting point. 



In experiments requiring an unusual length of time, as in 

 the preparation of twenty-hour samples of hydrogenated oil, it 

 was not convenient to continue the hydrogenation and collect all 

 the samples in one day. Therefore, the samples were collected at 

 convenient intervals of time, after which the oil bath was re- 

 moved from beneath the hydrogenation flask and the flow of gas 

 discontinued until the following day. 



In hydrogenating the oils, considerable difficulty was expe- 

 rienced in obtaining uniformly good results. In some experi- 

 ments the catalyst worked excellently, while in others it was 

 not so effective and, although the oil hardened, the iodine value 

 was not greatly reduced. This was probably due to the fact 

 that it was difficult to keep the atmosphere of the laboratory 

 entirely free of obnoxious gases which poisoned the catalyst 

 and decreased its activity. According to Ellis 8 mere traces of 

 halogens or sulphur cause catalysts to lose their efficiency. 



When working with a freshly prepared catalyst it is a good 

 plan to make a preliminary test to ascertain its efficiency before 

 proceeding with hydrogenation experiments. This may be done 

 by using about 2 per cent nickel and hydrogenating an oil, like 

 pili nut or cotton seed, which solidifies readily under favorable 

 conditions and becomes a soft white solid in about an hour. 



'Ellis, C. E., The Hydrogenation of Oils (1919) 113. 



