212 Scientific Proceedings, Royal Dublin Society. 



this, by assuming that the mean molecular weight of tlie " cerotic " acid 

 of bleached beeswax is 407, and that of the " stearic " acid of commercial 

 " stearine" is 272, the relative quantities of " cerotic" and " stearic" acids 

 in the insoluble " free " acids can be calculated. From the mean molecular 

 weight of the " free " acids in the wax and the Acid Number of the wax, the 

 percentage by weight of the " free " acids, and therefore the percentage of 

 cerotic acid, can be deduced. Taking the percentage of cerotic acid in 

 bleached beeswax as 15'8 (a number higher than that — 13'32 — which I have 

 found for unbleached beeswax by the method described further on), then by 

 multiplying the percentage of cerotic acid found in the wax by 6'3 the 

 percentage of beeswax in the mixture will be obtained. 



In the method used by me the Acid Number of the wax is first found by 

 heating four grammes of the wax with sixty cubic centimetres of neutral 

 absolute alcohol in an Erlenmeyer flask of Jena glass until the alcoliol 

 begins to boil ; a few drops of phenol-phthalein are added, and the acidity 

 of the wax determined by neutralization with N/2 alcoholic potash. To the 

 warm mixture about 40 grammes of clean, dry sand are added, and the 

 contents of the flask are evaporated to dryness in a steam oven. The residue 

 is transferred as completely as possible to a Soxhlet filter-cone, which has 

 been previously dried in a steam oven ; the flask is washed out with some 

 warm dry sand and then with hot low-boiling petroleum-ether (the sand and 

 petroleum-ether being poured into the filter-cone, which has meanwhile been 

 placed in a Soxhlet extractor, to wliich a clean, dry, tared flask has been 

 attached). The " ester " is extracted for about four hours by low-boiling 

 petroleum-ether into the tared flask. The petroleum-etlier is distilled off, 

 and the flask is transferred to a steam oven, where the last traces of 

 petroleum-ether are removed by addition of a little anhydrous ether and 

 reheating until the weiglit becomes constant. The percentage of " ester " 

 (petroleum-ether extract) is calculated; and by subtracting from 100, the 

 percentage by weight of the free acids in tlie wax is obtained. From the 

 latter number and the Acid Number of the wax, the Acid Number of the 

 free acids is calculated. Assuming that the only free acids in the wax are 

 crude cerotic and commercial stearic and palmitic acids, the percentage by 

 weight of the crude cerotic acid can be calculated on the assumption that its 

 mean Acid JSTumber for unbleached beeswax by the method above described 

 is 146, while the corresponding number for commercial stearic acid is 206. 

 By multiplying the percentage by weight of the crude cerotic acid by 7"5, 

 the percentage of unbleached beeswax in the sample will be found. 



In many cases it will be desirable to find the percentage by weight of 

 the unsapouifiable matter in the wax, the number of cubic centimetres of 



