A carboy is a large glass vessel for containing a big quantity of liquid.


CarboyFour decorative carboys were displayed in the chemist shop windows and are again in the reconstruction in the Museum. Of a distinctive shape, they form part of the identification of a chemist shop; even today small versions can be seen at the dispensing counters of large shops. Once they may have been functional, but they turned into trade signs containing coloured water. Where there are four, traditionally they stand for the four elements: earth, fire, air and water.

According to a book of pharmacy recipes, red was produced with a mixture of iodine, potassium iodide and hydrochloric acid; or of potassium sulphocyanide and a tincture of ferric chloride. Blue was generally copper sulphate with ammonia solution; green- copper sulphate, common salt and hydrochloric acid, or nickel sulphate with sulphuric acid; yellow- potassium bichromate and sodium carbonate; purple- potassium permanganate and sulphuric acid.
Modern-style aniline dyes were also used instead.

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