Hermann Kratzer, of Leipsic, communicates the following practical
information on the clarification and purification of vinegar to the
_Neueste Erfindungen und Erfahrungen_:
If vinegar has an unpleasant odor, which is rarer now that the vinegar
manufacture has reached such a state of perfection, it may be removed as
follows: Well burned and finely pulverized wood charcoal is put into
the bottles containing the vinegar, the proportions being 8 grammes of
charcoal to a liter of vinegar, or one ounce to the gallon. It is shaken
several times very thoroughly, then left standing three or four days,
and the vinegar filtered through a linen cloth. Vinegar treated in this
manner will be found to have completely lost its unpleasant odor.
I have found that when I used blood charcoal or bone coal in place of
wood coal it was still more efficient; but it must be mentioned that
when they are used they must be purified as follows before using:
Charcoal from blood contains potash and hence it is necessary to wash it
with distilled water and dry it before using it. Bone coal (also called
bone black, animal charcoal, etc.) contains on an average 10 per cent.
of nitrogenous and hydrogenated carbon, 8 per cent. of carbonate of
lime, 78 per cent. of phosphate of lime, besides phosphate of magnesia,
sulphate of lime, soluble salts, etc. Before using, it should be treated
with dilute hydrochloric acid until it does not effervesce any more. The
bone coal is then left to stand for 24 or 30 hours and at the end of
this time is washed with distilled water until the wash water no longer
reddens a blue piece of litmus paper, i.e., until every trace of
hydrochloric acid has been removed from the bone coal. Wood charcoal
may be treated in like manner. When this coal is perfectly dry it is
employed in the same proportions as the other, 8 to 1,000, the operation
being exactly the same.
He turns next to the clarification of the vinegar.
It happens everywhere that vinegar instead of being clear is sometimes
turbid. This is due to particles of yeast dissolved in the vinegar that
have not yet settled. To remove this kind of turbidity it is customary
to use oak or beech shavings that have been washed in hot water and then
dried. These shavings, which must be very long and extremely thin, are
put in a barrel with a second and perforated bottom, to a depth of 12
to 34 inches. The vinegar that runs through them deposits its slimy
constituents on the shavings and becomes perfectly clear, and presents
to the eye a pleasing appearance.
To this generally known method I would add a few more:
1. I take a ½ kilo of well pulverized _animal charcoal_ (black burned
bones) to 7/8 of a hectoliter of vinegar (1 lb. to 20 gallons), and stir
it well with a wooden rod; or, if the vinegar is in bottles, I shake it
a long time after putting the animal charcoal in the bottle, and repeat
it several times. After three or four days I finally filter the vinegar
through linen, when the filtrate will exhibit the desired clearness.
2. The best way to clarify vinegar is with _isinglass_. It is first
broken up, then swelled for a day in vinegar (17 or 18 grammes to the
liter), then 2 liters of vinegar are added and the mass boiled until the
isinglass is completely dissolved. Such a solution as this (½ ounce to
3 quarts) is mixed with 10¼ hectoliters (250 gallons) of turbid vinegar
and well stirred through it. After the expiration of five or six weeks
vinegar treated in this way has a beautifully clear appearance.
3. _Albumen_ can likewise be used to clarify it. The vinegar is boiled
with the albumen until the latter is completely coagulated, and then the
vinegar is filtered.
4. And finally _milk_ may be employed. For this purpose the milk is
skimmed, and 1 quart of milk added for every 68 quarts of vinegar,
the mixture well stirred and shaken. After the caseous portion has
coagulated (curdled) it is filtered as before, and in this case, too,
the product is a fine, clear vinegar.
We believe that these few experiments, so easily performed, and at so
small an expense, will prove useful to our readers in enabling them to
put their product in the market in an excellent condition and nicely
clarified.
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