text: pharmacist's carboy - what is the coloured liquid? hi, i have 3 victorian pharmacist's glass carboys with red, green and yellow coloured liquid in them - they were left to my husband by his father (a pharmacist).  could anyone please tell me what the special coloured liquid is and where i could get some more?  i rang the royal pharmaceutical society of great britain and they were unable to help.  i would also need to know what i should clean the glass out with, to avoid adding bacteria to the vessel before re-filling with the new coloured liquid.  many thanks for your time for display perposes the liquid is just water with a dye. perhaps if food colouring fades (these are also just dyes) you could try a haberdashery shop that sells fabric dyes which may be longer lasting.  it may have been luck that the red dye lasted.  to clean the glass we use detergent. bacteria is removed with a solution of sodium metabisulphite which is available from wine making shops this is then washed out with distilled water and then dried by adding a little acetone, swirling it around and emptying it. the bottle is left in a warm place for the acetone to evaporate. (no naked flames as acetone is flammable)