Important: Safety Warning
This page describes trade processes that use dangerously toxic materials such as cyanide solutions, mercury amalgams, or strong acids. These processes require training, equipment, and precautions far beyond what the text describes.
This information has been left in for historical purposes but should not be acted upon.
Yeast
of its weight of sulphuric acid (oil of vitriol), and let this be shaken for some time; this is to be poured out, the cask well washed, and then rinsed with a few gallons of lime-water or sal soda. It is needless to say, that it ought likewise to be washed out.
The theory is, that sulphuric acid has the property, when used alone, of charring wood, and when diluted has sufficient strength to destroy must, etc., with the additional advantage of entering into every crevice. The lime in solution seizes any particle of acid which the first washing might leave, and converts it into an insoluble, inoffensive, neutral salt, such as, if left in the cask, would not in the least injure the most delicate liquor. London Coopers' mode of Sweetening Casks.
It is their system to take out the head, place the cask over a brisk fire, and char the inside completely. The head is then put in again, and the cask, before used, is filled 2 or 3 times with hot liquor, bunged down and well shaken before it is used again.
Method of Seasoning New Casks.
Put the staves just cut and shaped, before they are worked into vessels, loose in a copper of cold water, and let them heat gradually so that they are well boiled, and in boiling take out a handbowl of water at a time, putting in fresh till all the redness is out of the liquor, and it becomes clear from a scum of filth that will arise from the sap so boiled out; also take care to turn the staves upside down, that all their parts may equally have the benefit of the hot water. Observe also that in a dry, sultry summer the sap is more strongly retained in the wood, than in a cool and moist one, and therefore must have the more boiling. Then, when the vessel is made, scald it twice with water and salt boiled together, and it may be readily filled with strong beer without fearing any twang from the wood.