Pkideaux. — On Kauri-resin. 373 



leading-tube. The resin softens at a low temperature, and 

 gives off a good deal of vapour. It shows a disposition when 

 the temperature is quickly raised to swell up and froth over 

 into the leading-tube. I collected all the oils together and 

 redistilled them from a flask containing a bulb apparatus and 

 a thermometer. When the temperature began to go up 

 steadily I substituted a fresh receiver, and left it there while 

 the thermometer stood still at a fixed point until the tempera- 

 ture began to rise again. I distilled a second time on the 

 same principle and with the same apparatus, and again a 

 third time. (See Plate XVII., fig. 1.) 



Descriptions of Oils. 



After the first of these distillations the oils fell into seven 

 broad classes — 



(1.) Below 100°; colourless; aromatic odour, with very 

 slight smell of resin-oil. 



(2.) Light-yellow ; strong smell of resin-oil ; 100° to about 

 200°. 



(3.) Eeddish-yellow ; strong smell of resin-oil ; 200° to 

 about 280°. 



(4.) Light-green ; slight smell of resin-oil ; 280° to about 

 300°. 



(5.) Greenish-brown ; slight smell ; 300° to about 310°. 



(6.) Greenish-brown ; blue fluorescence ; slight smell ; 

 310° to about 380°. 



(7.) Dark-red: green fluorescence; slight smell; 380° to 

 about 390°. 



The temperatures are only approximate, being taken during 

 the distillation. After the third distillation the light-green 

 fraction disappeared. 



The boiling-points were now obtained by putting the 

 fractions successively into a small flask fitted with a cork 

 containing a thermometer and a simple glass tube for a re- 

 flux condensor. I washed the flask out with CS 2 after each 

 determination. (See Plate XVII., fig. 2.) 



The temperature when the thermometer-bulb was im- 

 mersed in the liquid was usually 2 or 3 degrees above that 

 taken when the bulb was just above the surface of the 

 liquid. 



For the readings given I took the temperature of the va- 

 pour just above the liquid, and applied a correction for the 

 length of the mercury column in the air. I took the tem- 

 perature just outside this by means of a smaller thermo- 

 meter attached. 



The following is a description of the oils obtained after 

 the third distillation : — 



