13 



TABLE X. Effect of diameter of tube on the liter (R. D. Oilar). 



A. G. Manns makes the following report as to the different meth- 

 ods of preparing the fatt} 7 acids: 



Broadly speaking, the Dalican method gives lower results than the Wolfbauer 

 method, the difference being greater the lower the titer of the sample under exami- 

 nation. Furthermore, the Dalican test gives, in this laboratory, fatty acids the titer 

 of which is higher each time it is retested, presumably because of the loss of moisture 

 caused by the remelting of the sample prior to each test. On the other hand, the 

 Wolfbauer method gives fatty acids, the titer of which is so definite that it can easily 

 be duplicated, and will give very close agreement in different hands if tested in 

 accordance with the method. 



I have repeatedly found this to be true when the same sample of fatty acids was 

 tested at this laboratory and at one or more of our branch laboratories. This is due, 

 however, only to the fact that the method as used in this laboratory, and described in 

 your circular of February 24, 1904, gives a definite point at which to stop stirring. 



I find, further, that the fatty acids from the Wolfbauer method, after having stood 

 for some time, should be heated to 150 C. prior to retesting; if they were simply 

 remelted at a low temperature, the titer was found quite uniformly to be lower than 

 when first tested; if they had been previously heated to 150 C., the titer was found 

 to agree with the first test. This condition is probably due to absorbed moisture. 



A. V. H. Mory sends in the following very interesting results on 

 the effect of incomplete saponification on the titer: 



TABLE XI. Effect of incomplete saponification on the titer test (Mory), 



In every case except that of the brown grease the ammonia-treated alcoholic solu- 

 tions of the acids, obtained by stopping the saponification process short of comple- 

 tion, was less cloudy than that obtained from the mixture containing 1 per cent of 

 fat. It was necessary to stop the evaporation much sooner in the case of the brown 



