The next stage of opacity is _cloudiness_; when the cooper confesses that the distemper exceeds the power of his menstruums, and that his attempts extend no farther than to hide the evil, tournsol and cochineal, were they not so expensive, might in this case be used with success; but what is less known, and would greatly answer the intent of hiding the dusky colour of the drink, is madder;--about three or four ounces of this is the proper quantity for a butt of beer. Calcined treacle, by the coopers called blacking, from its acidity, is of some small service, for, by coloring the drink, it somewhat lessens the grey hue thereon; a quart is generally used in a butt; and, to prevent the defect in the beer being noticed by the consumer, the practice is to put thereon what is called _a good cauliflowered head_. This might be done by using as much pounded salt of steel as will lay upon a shilling; but the difference in price between this salt and copperas makes the last generally to be preferred. The strong froth on the top of the pot, and that which foams about it, together with somewhat of a yellow cast, are often mistaken for the signs of a superior merit and strength, though, in fact, they are those of deceit. A little reflection that the natural froth of beer cannot be yellow, nor continue a long time, especially if the liquor has some age, would soon cure mankind of this prejudice. Cloudy beers, under these circumstances, though not cured, are generally consumed. Beers become _sick_, from their having so large a portion of oils, as to prevent the free admission of the external air into them. The want of this enlivening element makes them appear flat, though not vapid. Such beers should not, if possible, be brought immediately into use, as age alone would effect their cure. But when this cannot be complied with, every means that will put the beer upon the fret, or under a new fermentation, must be of service. By pitching a butt head over head, the lees of the beer, which contain a large proportion of air, being mixed again with the drink, help to bring on this action, and to remove the _sickness_. Burnt hartshorn shavings, to the quantity of two-penny-worth, put into a butt, are often of use. Balls made with eight ounces of the finest flower, and kneaded with treacle, convey likewise air to the drink, and promote its briskness. Beers, by long standing, often acquire so powerful an acid, as to become disagreeable. The means of correcting this defect is by alkaline, or testaceous substances, and in general by all those which have the property of absorbing acids. To a butt of beer in this condition, from four to eight ounces of calcined powder of oyster-shells may be put, or from six to eight ounces of salt of wormwood. Sometimes a penny-worth or two of whiting is used, and often twenty or thirty stones of unslacked lime; these are better put in separately, than mixed with the isinglass.