KIRSCHNER PROCESS. 249 



Coconut oil gives a Reichert-Wollny figure of 7 to 9 c.c., 

 and a Polenske value of 16 to 18-5, and palm-kernel oil R-W 

 5 6, and P 9 10. 



Should the Polenske figure exceed the maximum given in the 

 table the quantity of coconut oil present may be deduced from 



p P' 



the formula C = -r^- - X 100. 

 144 



C = percentage of coconut oil. 



P = Polenske figure. 



P' mean Polenske figure from the table for a figure 

 equal to the Reichert-Wollny figure found + half the Polenske 

 figure. 



Should palm-kernel oil be known to be present or detected by 

 Burnett and Revis' test, the figure 8-5 may be substituted for 

 144. 



To distinguish between coconut and palm-kernel oils Burnett 

 and Revis filter off the insoluble barium salts obtained by neutral- 

 ising the alcoholic solution of insoluble volatile acids in the 

 Polenske process, on a hardened filter paper under pressure, 

 and wash 3 times with 3 c.c. of 93 per cent, alcohol (vol.), the 

 funnel being kept covered. After all alcohol has been sucked out, 

 the salts are dissolved in 10 times the Polenske value in c.c. of 



93 per cent, alcohol (%p. gr. -8235 at - ) , and the flask boiled 



under reflux till the barium salts are dissolved. About 5 c.c. 

 are placed in a strong test-tube, and a cork carrying a thermometer 

 and an aluminium stirrer fitted, and the turbidity temperature 

 determined. Coconut oil becomes turbid at 52 1*5. Palm-kernel 

 at 68-5. Cohune oil behaves in all ways as coconut oil. 



Kirschner's Modification. To the 100 c.c. of the distillate 

 of volatile fatty acids obtained in the Polenske process, which 

 has been neutralised, 0-5 gramme of finely powdered silver 

 sulphate is added, and after standing for an hour with occasional 

 shaking, the liquid is filtered. 100 c.c. of the filtrate are placed in 

 the distilling flask, 35 c.c. of water, which has been well boiled, 

 and 10 c.c. of the sulphuric acid solution previously used added ; 

 a long piece of aluminium wire is placed in the flask, and 110 c.c. 

 distilled as in the Polenske method ; of the distillate 100 c.c. are 



N 

 titrated with alkali, and after correction for the figure obtained 



in a blank experiment, the Kirschner figure is calculated by 



j^ 100 i x 



multiplying the number of c.c. of r-r- alkali by 1 '21 and by ^-. 



10 luu 



(where x = the number af c.c. of alkali added to the first distillate 

 for neutralisation). 



