NOTE ON HUBL’S IODINE ABSORPTION METHOD.
There is some difference of opinion as regards the excess of iodine, which should be present after its absorption. Thompson and Ballantyne, who have carefully revised the constants required in the analysis. of some fats and oils, are of opinion that “ at least double the amount of iodine absorbed should be present." Care was taken to fulfil this condition in most of the analyses as recorded above. On reference to sesame and earth-nut oils, it would appear, however, that it is not always necessary that the iodine should be in large excess. Thus in one case the excess of iodine corresponds to only 5'9 c. c. N] 10 Na98303 solution, and in another to only 4'70. 0. NaZSZOs, solution without the results being discordant.
For convenience of reference the results obtained above are pre- sented below in a tabulated form:—
Table of constants in the analyst's of fats and oils.
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Saponifica- G1 . . NATURF or FAT on OIL. tion equi- ycerm loam.“
fluent per cent. absorptlon. Mustard oil 172—176 8'5 970 Niger-seed oil 1900 108 120 Coeoanut oil 258'0 ..., 6-9 Ghee 218—222 335.394 Mowa fat ... 199'3 ... 61-8 MuttOn tallow .. ‘ 199'5-206 10'5 ...... Sesamé ‘ 189'9 ... 104'5 Lard 195‘4: ... 50'0 Earth-nut oil l. 196'0 ... 98'0
SUMMARY AND CONCLUSION.
It Would thus appear that. as the saponifieation equivalents of niger. seed oil, mowa fat, mutton tallow, sesamé oil, lard and earth-unt oil are very close to one another, their admixtures in considerable proportion cannot be detected by Koet-tstorfer’s test. Even the saponification equivalent of ghee is not far removed from that of lard or tallow. The supouification equivalents of mustard oil and cocoanut oil are, however, highly characteristic. The iodine degrees, on the other hand, afford us valuable hints as to the nature of adulteration, the most remarkab|e feature being the exceedingly low numbers for cocoanut oil and ghee. The results of theapplicatiou of Beiehert’s test will be communicated later on.
