Casks are almost universally made of oak, though other material has been tried, but generally to be abandoned in favor of the first named. Large, covered tanks of redwood are used to some extent in California for storing red wine, being first well steamed to extract the coloring matter of the wood, but they are not considered desirable, and had better be replaced by oak casks.

Oak Wood.—In France very nice distinctions used to be made as to the kind and nationality of the wood used, the shook from the north, Dantzig, Lubeck, Memel, Riga, and Stettin, taking the first rank, that from America the second, and that known as Bosnian, from the southern provinces of Austria and the north of Turkey in Europe, the third, and that of France the fourth. That from America is the most pliable, but is liable to be found worm-eaten.

All kinds of oak wood contain in different proportions fourteen different principles, several of which are dissolved by wine, and among the most important of which are tannin, gallic acid, a bitter extractive, mucilage, vegetable albumen, and several of pronounced smell and taste. The Bosnian oak contains the most tannin and soluble matter, and is suitable for highly colored wines. But now-a-days there is not so much stress laid upon the quality of the wood as formerly. Their extracts serve often to correct some of the defects of the wine, and many of them are neutralized by the ingredients of the latter. By the introduction of their tannin and albumen the clarification of wine is facilitated; but none but new wine whose insensible fermentation is not yet completed should be put into new casks, for they cause older wines to lose their transparency, and give them a woody flavor which may last a long time. Therefore, temper your new casks with new wine.

Storing Casks.—Casks should be kept in a closed place, not so dry as to cause much shrinkage, nor so damp as to cause mould. In California during the summer, there is no danger from the latter, but the former should be guarded against. In winter, the reverse is the rule. Where casks are to be kept a long time empty, they should be sulphured and tightly bunged, and the sulphuring should be repeated every six months. But they must be carefully washed before putting wine into them. They are less liable to be attacked by the borer if stored in a dark place.

New Casks.—Before putting wine into a new cask, it is ordinarily sufficient to give it a thorough washing with boiling water. Pour in one or two gallons of hot water, bung it up, and roll it and shake it about till it is thoroughly rinsed, letting it rest awhile on each end, and not only will this sufficiently cleanse the cask, but will show if there are any leaks. When the water is nearly cold, let it run out, and thoroughly rinse with cold water, and turn down the bung-hole and leave till well drained.

Mr. Maigne recommends that a couple of pounds of salt be dissolved in the first water, and that the second washing be made with a decoction of peach leaves. Often the casks are soaked for a day with cold water, then washed with lime water, prepared by adding four pounds of lime to two gallons of boiling water for a 100-gallon cask. After thorough agitation, it is washed with cold water. Sometimes, too, the cask is washed with a gallon or so of boiling wine, but it is an unnecessary waste.

Mr. Boireau says that when it is necessary to put old or very delicate wines into new casks, the greater part of the soluble matters can be extracted in the following manner: Pour in about two gallons of boiling lye made from ashes or potash, or other alkaline substance, such as slacked lime or pulverized chalk, etc., for they will dissolve out more of those soluble matters than pure water. After thoroughly agitating the cask, pour out the lye, and repeat the process; afterwards rinse with boiling water, and run it out before cold; then wash with cold water acidulated with one-tenth part of sulphuric acid, which enfeebles the solubility of these matters; finally, rinse with cold water and drain.

These latter operations may be avoided by first washing with hot water, and then filling the casks with common wine of the color of that intended to be put into them, and leaving them for about two weeks.

And before filling them with a grand red wine, it will be well to moisten the inner walls of the cask with a glass or so of good, old brandy.

Old Casks, or those which have been in use, should be well washed as soon as emptied, and the washings should be repeated with clean water until it runs out perfectly clear. Oftentimes the cask will have more or less lees adhering to its inner walls, which cannot be removed by an ordinary washing, but it will be necessary to make use of the rinsing chain. This chain is about six feet long, consisting of links made of square iron whose corners will more readily detach the lees. One end is attached to a long conical bung to keep it from falling into the cask, and the other is armed with a square block of iron of a size to easily go into the bung-hole (fig. 11). After pouring in two or three gallons of boiling water, leave the cask for a while so that the lees may become softened, then introduce the chain by the bung-hole, and close it with the bung at the other end of the instrument. Thoroughly roll and agitate the cask until the chain and its iron block have removed the lees so that they will run out with the water. Repeat the operation with clean water as often as necessary, and rinse till the water runs out limpid, and let the cask drain.

To Examine the Inside of a Cask, an instrument called a visitor is used. This is simply a piece of heavy wire bent into a loop or handle at the upper end, with the lower end turned up and bent around into the form of a small ring into which a candle can be inserted (fig. 12). Put a piece of a candle into this candlestick or socket, light it, and lower it into the cask through the bung, and the interior can be inspected.

Empty Casks should not be allowed to remain long without Washing; as soon as the lees are removed, they should be rinsed as already mentioned, and they should not be put to drain in the sun, for the heat will transform the alcohol remaining into vinegar in a few hours.

Sulphuring Casks.—If the cask is to be kept empty for some time, after it has been washed and then drained for a few minutes, it should be sulphured by burning in it a piece of sulphur match about an inch square, and it should then be left to drain dry. After twenty-four hours, burn in it three or four inches of the match, and bung it up with the gas in it. Store it in a suitable place as described for new casks, and sulphur it every three months. (See Sulphuring.)

Condition to be Examined.—In using an old cask, as well as a new one, the first thing to ascertain is if it leaks. If the hoops are loose, they should be driven; then pour in two or three pails of water, and stand the cask alternately on each end, and if it is found to leak, soak it till it is tight. If the leaks cannot be stopped by driving the hoops and by soaking, it must be repaired.

The next thing to ascertain is, if the cask has become sour, mouldy, or has been otherwise injuriously affected, as it is liable to be if put away without being carefully washed and cared for. This can be ascertained by examining with the visitor, or by smelling. If, when the candle or a piece of lighted sulphur match is lowered into the cask, it ceases to burn, the cask probably contains a noxious gas, which must be expelled. This may be done by blowing in the bung-hole with a hand-bellows till the air is changed, or by standing the cask on its lower end with the hole in the upper head open, and the open bung turned towards the wind. If, however, it is in the condition which the French call eventé, which corresponds with that diseased condition of wine called by the same name and which we call flatness, the gas being carbonic acid, and heavier than air, will run out of its own accord if the open bung is turned down and the cask left for a while in that position.

Flatness in the Cask, as we will call it for want of a better term, Boireau says, consists in the disengagement of carbonic acid gas which is produced in the interior, and is generally found in casks which have been bunged up without washing, and which gives them an odor of stagnant lees with slight acidity, and will extinguish the sulphur match. After the bad air has been expelled the cask should be well washed with the use of the chain. A cask which has contained wine that has become flat should receive the same treatment. If a large tun is to be treated, the foul air should be expelled, and a man should not enter till a light will burn in it. (See the disease, Flatness.)

Acidity will be found in the cask if it is left for several days uncared for; the alcohol contained in the wine remaining on the inside of the cask acidifies in contact with the oxygen of the air, and is soon changed into acetic acid, and the change is much more rapid in a high temperature. Instead of being simply flat, the cask is now really sour, and smells of vinegar. The treatment consists in either removing or neutralizing the acid. The first can be done by steam. Turn the bung-hole down, and conduct a jet of steam into the cask either through the faucet-hole or the bung; the water condensed from the steam charged with acid runs out at the bung-hole, and the process must be continued till the water no longer has an acid flavor.

Where it is not convenient to use steam, rinse the cask by using the chain, and scald it out with hot lye made from wood ashes or potash, or with quicklime dissolved in hot water. Give it several rinsings with the alkaline solution without allowing it to cool, and, if possible, fill it with cold water and let it soak three or four days, and rinse as usual. If the water is allowed to remain longer in the cask it may become stagnant.

Mouldy Casks.—Casks may become mouldy inside when left in a damp place, if the bungs are left out, or if they are leaky through defective staves or hoops, sometimes even when they have been sulphured, and much more if they have not been. This condition is recognized by a mouldy smell. The surest way to treat a mouldy cask is to take out the head, and give it a thorough scrubbing with a stiff broom and water. If after removing the mould the staves resume the color of wine-stained wood, it is proof that the wood has not been affected, and the head may be replaced, and the cask rinsed in the usual way. If, however, after removing the mould, the wood is found to be of a brown color, it is more or less rotten.

Rottenness is due to the same causes as mouldiness, and when the inside of a cask is decayed, it is no longer fit for wine. If, however, the mouldy cask is brown only in spots, they should be entirely scraped off, and then it may be used. But it is best not to put good wine into such casks, for there is danger of spoiling it.

Brandy Casks, when emptied, should simply be bunged up, without washing, as the alcohol remaining will have a preservative effect. They should not be kept in a place which is too damp.

Do not Sulphur Old Brandy or Whisky Casks which have recently been emptied or in which any alcohol remains, or you may cause a disastrous explosion. In preparing new casks for the reception of brandy, they should be washed and left to drain for twenty-four hours and until they are dry, and if they are to be kept some time, throw in a glass or two of brandy, bung tightly, and roll and shake till the inside is moistened with the liquor. If they are to be used at once, they ought to be first soaked with water for three or four days to remove the woody taste.

Boireau says that common wines may be put into brandy barrels, or even oil barrels which have not become rancid (olive oil barrels, I presume), but that fine wines should never be put into them. He also adds that wine should not be put into casks which have been used for rum, kirsch, vinegar, absinthe, vermouth, or any other liquor having a strong odor, traces of which will be preserved in the pores of the wood, even after the staves have been scraped.

Cask Borers.—There is a beetle which is very destructive of casks in California, which Mr. J. J. Rivers, curator of the museum of the University, describes as Sinoxlylon declive of the family of Bostrichidae. In a paper read before the Anthrozoic Club, and reported in the Rural Press, Vol. XX, p. 153, 1880, he states that at the request of Mr. Schram, of Napa county, he experimented with the insect in order to ascertain a remedy for the ruin caused by it. He says that “Its primary mischief is caused by the habit of the parent insect boring a hole three or more inches for the purpose of depositing eggs. As casks are usually much less than three inches in thickness, the beetle taps the liquid contents, and loss accrues by leakage. The remedy I first thought of was to select some species of wood suitable for cask making that would be unpalatable to this insect. My endeavors in that way have resulted in failure for the reason that this beetle appears to have no particular dislike to oak, chesnut, pine, whitewood, and several of the eucalypti. The next step was to saturate the outside of the cask with a strong solution of alum water applied hot, and when dry, a coat of linseed oil, this latter to prevent the alum from being washed out, as it would be in time. This proved a success, for all the examples treated with the solution were untouched, while the unprepared were riddled by the borer.” The insect is more destructive to casks stored in light places; it is therefore better to keep them in the dark.

The Size of the Casks is a matter of a good deal of importance. For shipping, the ordinary pipe or puncheon holding from 150 to 200 gallons is of a convenient size for handling, but for storing it is better to use as large a vessel as possible, and where the quantity stored is large, tuns of from 1000 to 3000 gallons or more in size are far preferable. In the first place, it is a well known fact that wine made at the same time, of grapes of like varieties, from the same vineyard, and under the same apparent conditions, turns out quite differently in different casks, and the contents of one cask may far excel in quality that of another. In order to insure uniformity in a large quantity of wine, it is necessary to store it in large receptacles.

Another, and perhaps still more important consideration, is that there is much less loss by evaporation when the wine is stored in large casks. The evaporation in a small barrel will be almost as great as in a cask three or four times the size, and to keep the small one full will require about the same amount of wine at each ulling, which must be performed nearly as often. There are two reasons for this: first, because the staves of small casks are thinner, and secondly, because in them a greater surface of wine is exposed to evaporation, according to the volume, than in the case of the larger vessel.

Guyot says, however, that the larger the receptacles, other conditions being equal, the more rapid the development of the wines, and the sooner they go through the periods of their life, and arrive at decrepitude. He says that the greater part of wines, especially light wines and white wines, cannot endure a long sojourn in tuns, vats, and cisterns. They go through the phases of their life with a rapidity fatal to their good qualities; nevertheless, this fact may be utilized to hasten the epoch when wine may be used or put upon the market; also to produce dry wines, to vinify sweet ones, and to age those of good body. If, therefore, his theory is well founded—and we know that fermentation once established is more active, if the mass is great—the intelligent man will act in this behalf as circumstances require. It would seem, however, that a large mass would be less affected by sudden changes of temperature, and therefore, better protected from their consequent ill effects.

And Boireau recommends that white wines be stored in tuns, when mature, as already mentioned. (See Aging.)