1894.] certain Indian Food Stuffs. 61 



test. The amount of iodine absorbed by different fats and oils also lies 

 within wide ranges. The iodine absorption test has been employed with 

 remarkable success by Baron Hiibl in deciding cases of adulteration. 

 The following processes have been made use of : — 



1. Direct titration of the fats and oils by alcoholic potash — 



Koettstorfer's test. 



2. Estimation of the amount of glycerin. 



3. Iodine absorption test of Hiibl. 



4. Estimation of the volatile fatty acids — Reichert's test. 



The detailed results obtained by each of these methods as applied 

 in the present inquiry will now be described. 



KOETTSTORFER'S METHOD. 



Most of the oils, when recently expressed, contain suspended im- 

 purities derived from the seeds, &c., in a very fine state of division. 

 These settle down in course of time. The oils thus clarified by sub- 

 sidence were filtered through bibulous paper to remove any traces of 

 adherent moisture which might be present. The application of even a 

 gentle heat cannot be resorted to for this purpose. Mustard oil, which 

 is classed among the non-drying oils, was found to gain in weight con- 

 tinually when placed inside the chamber of a water-oven and weighed at 

 intervals of 15 to 20 minutes. 



Preparation of Alcoholic Potash. — The alcoholic solution of 

 potash, approximately of semi-normal strength was prepared by dissolving 

 sticks of potash in pure alcohol. The solution, filtered off the 

 insoluble residue, is generally found to have a reddish-yellow color. 

 It has therefore to be decolorised by shaking with pure animal 

 charcoal. 



Oil op Mustard. 

 Sinapis nigra, S. alba (Nat. order — Cruciferse.) 



Different samples of mustai'd seeds were found to yield a fixed oil 

 varying from S2°/^ to 367o oi the air-dried seeds. 



1. 2*534 gm. oil were weighed into a bottle of about 12 oz. capa- 

 city, and 20 c. c. of alcoholic potash solution were added. The mouth 

 of the bottle was closed with an India-rubber cork, fastened by means 

 of wire. The bottle was kept immersed in boiling water for 45 

 minutes. A blank experiment under exactly similar conditions was 

 made side by side to detei^mine the strength of the potash. The 

 indicator used was phenolphthalein — 



20 c. c. KOH=20-7 c. c. ^ HCl. 



