A New Method for the Examination of Coffee.
BY F. M. RIMMINGTON.
I think it will be generally admitted that the methods in use for estimating the degree of adulteration in coffee are far from satisfactory as regards definiteness and certainty, and that something approaching nearer to chemical accuracy is very desirable. Little has been done in this direction since the days of the "Lancet" Sanitary Commission.
It may, possibly, not be generally known to analysts that chicory, dandelion and probably some other substances that are used for mixing with coffee, are readily deprived of color by a weak solution of chloride of lime (hypochlorite), and that this agent has very little action on the coffee. When this method is adopted a portion of the coffee should be gently boiled a short time in water with a little carbonate of soda, so as to remove extractive as much as possible; after subsidence the liquor should be poured off, and the residue washed with distilled water. When this has been sufficiently done, a weak solution of the hypochlorite of lime is to be added and allowed to remain, with occasional stirring, until decoloration has taken place, which will probably be in two or three hours. The coffee will then form a dark stratum at the bottom of the glass, and the chicory a light and almost white stratum floating above it, and showing a clear and sharp line of separation.
The chicory after this operation is in the very best condition for microscopical examination, and it is not difficult to discriminate between chicory, dandelion or other substances. Although the lower stratum may be dark, and have all the appearance of coffee, other substances may be present and should be sought for. I have recently met with a substance which is entirely new to me, as a coffee substitute, that is not affected by this treatment.—Phar. Jour. and Trans., Jan. 1, 1881.