On the composition of food and how it is adulterated : with practical directions for its analysis / by W. Marcet.

  • Marcet, W. (William), 1828-1900.
Date:
1856
Catalogue details

Licence: Public Domain Mark

Credit: On the composition of food and how it is adulterated : with practical directions for its analysis / by W. Marcet. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    the precipitate thus induced will possess a bottle-green colour, more or less dark, according to the natural hue of the wine; if colour has been artificially obtained, the results will be as follows : Tournesol will give a precipitate of a bright violet colour, Brazil-wood will occasion a brownish- red precipitate, elderberries or privet a brownish-violet precipitate, whortleberries a precipitate of the colour of dirty wine lees, with logwood the precipitate will be coloured lake-red. Vogel recommends, for the same pur- pose, the use of acetate of lead ; in genuine wines, it pro- duces a greenish-gray precipitate, which is not the case with coloured wines. Prout gives ammonia, as a test for the determination of artificial colours in wines; this re- agent occasions in genuine wines an olive-green colour, and a precipitate containing phosphate of ammonia and mag- nesia or triple phosphate; in those artificially coloured, the precipitate forms more gradually, in less quantity, and is free from admixture with triple phosphate.^ Alcohol.—This fluid is added in large proportion more especially to Port and Sherry, but also to most of the wines sold in the London market, for the purpose of making them stronger to the taste, and preventing their decom- position. The wine reserved for exportation at Oporto is mixed with a considerable quantity of brandy, and when it arrives in this country possesses a dark, purple, or inky colour, with an astringent, bitter-sweet taste, and a strong flavour and odour of brandy ; and it is only after being kept for ten or fifteen years in bottle, that the odour of the brandy is completely subdued, and the genuine aroma of the wine developed. During the process of melioration, a considerable portion of the extractive and colouring matter ^ Henderson's 'History of Wines.'