J 894.] certain Indian Food Stuffs. 63 



6. 1.8012 gm. oil were saponified under the same coaditions as des- 

 cribed above, with 40 c. c. KOH solution — 



40 c. c. KOH = 32'0 c. c. ^ HCl 



Excess of alkali =21'0 „ „ 



c -fl .• • 1 . 0'02805x 11x10' ,„, „ 

 Saponification equivalent =■ ■■ ,.q^,^ = 171'd 



6. Pure mustard oil from Alipur Jail. 



3"493 gm. oil were mixed with 20 c. c. potash solution and the 

 mixture kept immersed in boiling water for over half-an-hour. The 

 mouth of the bottle being closed by a cork fastened by a wire — 



20 c. c. KOH = 30*7 c. c. ~ HCl 



Excess of alkali = 9*2 „ „ 



.. ,. . , ^ 21*5x0-02805x10^ ,„^ 

 Saponification equivalent= oTToq = 1727 



7. Duplicate analysis of the above. 2*195 gm. oil heated to boiling 

 on a water-bath with 20 c. c. KOH solution for 15 minutes, the mouth 

 of the flask being covered with a watch-glass. 



N 

 20 c. c. KOH =30-7 c. c. — HCl (Blank experiment) 



Excess of alkali = 17*2 „ „ 



•n ^' ■ ^ ^ 13*5 X 0-02805x10^ ,„ ^ 

 Saponification equivalent = cTtok. =172*5 



It would thus appear that mustard oil is very easily saponified by 

 alcoholic potash, and that a large excess of the latter is not necessary. 



The oil was in some cases found to have a pale yellow color, in others 

 the tint was somewhat deeper. The soap solutions were tinged 

 accordingly. The want of exact uniformity in the tint sometimes 

 interfered with the exact determination of the conclusion of the 

 reaction during the titrations. It may also be stated that the soap 

 solutions were generally diluted with about 25 c. c. of hot water, fi'om 

 which all traces of carbonic acid gas had been driven off by boiling. 



In the above experiments it will be seen that the saponification 

 equivalent of the samples of mustard oil has varied between 175*5 

 and 171*3, the average of the seven determinations being I73"5. 



Hence it would be safe probably to adopt the saponification equi- 

 valent of mustard oil as lying between 171 — 175. 



