tering material, its object being to remove any sediment or floating organic matter which would otherwise clog the converters. From the filters it runs into the generators. The liquid is run through a screen at the top of the generator to break it up into drops and distribute the liquid evenly over the surface of the shavings. The generator consists of a round tank of wood six to ten feet high, with a diameter of 35 inches at the top, and 45 inches at the bottom, thus giving it the form of a truncated cone. The generator is divided into three parts one above the other; the upper one containing a screen to distribute the alcoholic liquor; the center one containing beech shavings, and the lower one serves for the collection of the vinegar. Air is let in by holes bored through the sides of the tank below the false bottom on which rest the beech shavings. The amount of air is regulated by wooden stoppers placed in these holes. After passing through the generator, if it contains any unconverted alcohol, the vinegar is passed through a second time, and then is finished vinegar. Many substances have been prepared for filling the generators, but at present beechwood shavings are considered the best. They are now made especially for this purpose, being cut and curled by machinery. They are prepared for the generator by being washed in water and steamed to remove the woody taste and impurities which they would otherwise give the vinegar. The shavings are dried and saturated with old vinegar and are then ready for use.

Brannt states that the surface exposed in a generator three feet by six, filled with shavings, is over 22,000 square feet.

Material for Vinegar Making.- The substances from which vinegar is made at the present time are beer, wine, glucose, alcohol, molasses, and fruit juices. Wine vinegar is chiefly used in Europe. It is made from grape juice, inferior wines and from the second and third pressings of the grapes called "lees." Wine vinegars vary in color from pale yellow to red, and have a specific gravity of from 1.014 to 1.022. Most of the vinegar used in Great Britain is derived from the fermentation of a wort made

from a mixture of barley and malt. Malt vinegar is of a decided brown color, and in specific gravity varying from 1.017 to 1.019, the strongest known as proof vinegar, containing from 4.6 to 5 per cent. of acetic acid. Glucose vinegar is prepared from a mixture of glucose and water, by allowing it to undergó alcoholic fermentation, and then running it through the generator in the usual way. The vinegar sometimes contains large quantities of dextrine and sulphate of lime, left in the glucose as an impurity during the process of manufacture.

Molasses vinegar is made in the same way as glucose vinegar.

The larger part of the vinegar now on the market is made from a dilute alcohol. This vinegar as it comes from the converters is colorless as water. It is colored by the addition of burnt sugar (caramel) and sold as cider vinegar.

Characteristics of Different Vinegars.- Cider vinegar should have a yellow color and a cider-like odor. Evaporated to dryness on a water bath it leaves a dark brown residue, having a taste of burnt apples. The amount of extract is from 1.5 to 5 per cent., depending on the age of the sample and method of manufacture. Cider vinegar made by the old process contains malic acid, and on the addition of acetate of lead gives a heavy yellowish precipitate of malate of lead. The ash from cider vinegar contains considerable quantities of alkaline phosphate. The residue from wine vinegar contains the salts found in wine. It is distinguished from other vinegars by containing cream of tartar. According to the Edinburgh Pharmacopoeia, it may be distinguished from malt vinegar by adding ammonia in slight excess, which causes in wine vinegar a purplish muddiness and slowly a purplish precipitate, but in malt vinegar no precipitate or only a slight one.

Spirit vinegar made from dilute alcohol should leave only a very small residue; if caramel has been added to color it the residue will be of a dark black brown and leave no ash on burning.

Beer vinegar is yellow and has an odor of sour beer. It

contains as much as 6 per cent. of solids on evaporation. Beer vinegar does not contain more than 2.5 to 3 per cent. of acetic acid and requires to be fortified by the addition of a stronger vinegar. Glucose vinegar has the taste and smell of fermented grain. It usually contains considerable impurities, such as dextrine, sulphate of lime and sometimes sodium chlorides.

Adulteration of Vinegar.- Blythe classifies the adulteration of vinegar as follows:

1, Water; 2, mineral acids, usually sulphuric, rarely hydrochloric or nitric; 3, metallic adulterations; or, more properly, impurities as they are introduced from the apparatus. There are arsenic, derived from the sulphuric acid; copper, lead, zinc and tin from the solvent action of the acetic acid on any metallic surfaces with which they may come in contact; 4, Pyroligneous acid; 5, various organic, such as coloring agents, capsicum, etc.

The chief adulteration is the addition of whiskey vinegar to cider vinegar, or the coloring of whiskey vinegar with caramel, and selling it for cider vinegar.

The analysis of a sample of vinegar consists in a determination of the specific gravity, the amount of acid present and total solids. The specific gravity is taken by a Westphal balance. To determine the acidity 20 c. c. are measured into a beaker, 100 c. c. of water and a few drops of phenol-phthalein (in alcoholic solution) are added, and the acid titrated with a normal alkali solution. The solids are found by evaporating 20 c. c. to dryness at 100° C. (212° F.) Thus far no free acid other than acetic or other impurities have been found in Wisconsin vinegar.

The following table gives the analyses of vinegar examined: