14 THE ROYAL SOCIETY OF CANADA 



and washed with hot water to remove the excess of glycol. 

 The uncombined acid present in this mixture was determined 

 and the calculated amount of sodium bicarbonate added to neutralize 

 the free acid. This was fused in a porcelain dish on the water bath for 

 one hour. The ester was washed out with hot ether, using a hot 

 filter. This was allowed to crystallise at room temperature, and 

 filtered, the residue dissolved in 95% alcohol and crystallized 

 at about 0°C. From their relative solubilities thes^ crystals could 

 be separated into the di and mono compounds for purification. A 

 series of fractional recrystallisations were made until the mono 

 and di esters were obtained pure, as shown by their constant melting 

 points. When these esters had been prepared by this method and 

 purified, their physical properties were determined. 



The melting points were taken in the usual way. 



The refractive indices were determined by the Abbe Zeiss re- 

 fractometer at various temperatures, slightly above the melting 

 points of the esters, and from these the refractive index at the melting 

 point was calculated. 



The solubility of each of the purified fats was found by saturating 

 a solution of absolute alcohol at a temperature slightly above that at 

 which the solubility was wanted. These saturated solutions were 

 kept for sixteen hours first at a constant temperature of 15°C. About 

 10 c.c. of the clear supernatant solution were drawn off by means of 

 a warm pipette and weighed accurately in a closed weighing bottle. 

 After the alcohol had bsen evaporated very slowly on a hot plate, 

 the residue was dried to constant weight at 95°C. The rest of the 

 saturated solution was placed in a mixture of melting ice and kept at 

 zero in a refrigerator for several hours, when the solubility at this 

 temperature was determined in a similar way. 



The specific gravity of a solid fat was determined by the dilato- 

 metric method which was found to be most satisfactory as well as 

 very exact. The dilatometer was first carefully calibrated with pure 

 mercury. To fill it with the fat to be studied the tube was heated 

 in the electric oven, and then suspended in hot water and the 

 melted fat was drawn in through a very fine capillary, with aid 

 of a suction pump. When the bulb of the dilatometer was filled 

 with the fat, the whole apparatus was quickly transferred to the 

 inner tube of a double walled glass vessel. To prevent the fat from 

 solidifying, this tube was previously heated by boiling in the 

 outer jacket, connected to a reflux condenser, some pure liquid 

 such as ethyl alcohol, chloroform or benzol, whose boiling 

 point was above the melting point of the fat. A number of 

 readings were taken; in most cases it required about two hours for 



