gravity (pounds) and dividing by the extract yielded per quarter. If materials other than malt are to be employed the extract yielded by them should be deducted from the extract yielded by the malt before dividing by the extract per quarter of malt. Barrels brewers' pounds (L.)

Quarters: =

Extract per quarter

Example 1.-In producing 200 barrels of 18 pounds a malt is employed yielding 86 pounds extract per quarter. How many quarters of malt are required for the brew?

Solution.

200 X 18

= 41.9.

86

Answer.—We employ 41.9 quarters of malt.

Example 2.-The same number of barrels of same strength as in Example I are to be brewed from malt and sugar, using 20 cwt. of glucose (yielding 36 pounds per cwt.). How much malt is required?

In figuring according to English usage it should then be borne in mind that:

1. Brewers' pounds excess of weight, in pounds, of a barrel of wort (or beer) over a barrel of water (360 pounds).

2. Pound beer or pound gravity or saccharometer indication according to Long = L. = brewers' pounds (see 1).

3. Specific gravity or degree of specific gravity excess number over 1,000 (the unit of water).

4. Extract, or brewers' extract, per quarter, generally 80-90 pounds, is an arbitrary figure based upon the extract as indicated by the Long saccharometer.

5. Dry or solid extract = real extract contained in wort or beer.

6. Extract per cent

=

solid extract per 100 pounds of material.

7. Material = quarters of malt.

8. Final attenuation of a beer is the saccharometer indication of the beer according to Long.

THE BREWER'S CHEMICAL LABORA

TORY.

In this chapter are given such analytical methods as are used most commonly in the examinations required to be made in the practice of brewing, when it is desired to examine materials employed, or the product in its various stages, in testing instruments and appliances, or determining the properties of the finished article. Examinations of this character are necessarily confined to what the brewer, in the course of his regular occupation, can attend to, and it is not purposed to go into the more thorough and detailed analytical methods, which are employed in the scientific laboratories.

The object is to aid and refresh the memory of a brewer who has taken a course in scientific brewing, but may not be able, where his mind is taken up in the work of operative brewing, to remember the details of every method and, therefore, will be grateful for a handy reference book to which he can turn and quickly find the necessary information.

Originality is not claimed for all the methods here given. The effort has been to select those which combine in the highest practical degree the two qualities most needed for the work in the laboratory, viz., reliability and dispatch. Some of the methods differ little from those given in the standard treatises. The methods for analyzing beer, wort, malt and barley, are practically identical with those in vogue in Europe, and those for water have also been in common use for a long time. Of the rest, many can be classed as distinctly American, having been evolved under the requirements peculiar to the brewing industry of the United States. They are, in a large measure, the result of patient, careful, and in part, at least, original work on the part of the scientific station of Wahl and Henius of Chicago, devised with a view to supplying the needs of the American brewer.

In regard to brewing materials, this chapter will supplement

that devoted entirely to that subject, as far as methods of examination are concerned.

To make the descriptions more complete, mention is made of the apparatus and chemicals required to equip a chemical laboratory sufficient for a brewer to do his work, and the tests given by which the fitness and accuracy of the appliances may be determined.

ANALYTICAL CHEMISTRY.

Analytical chemistry treats on the determination of the elements of a compound, the proportion of the constituents and the presence of impurities.

If we merely take into consideration the kind of their constituents the analysis is a qualitative one, as testing for starch in wort and beer; iron in water, lupulin and sugars; tannic acid in lupulin.

If, however, the amount of each constituent is determined, then the analysis is a quantitative one.

Volumetric analysis is the analysis by measure.
Gravimetric analysis is the analysis by weight.

SPECIFIC GRAVITY.

To Find the Specific Gravity of Solid Bodies.-The simplest method of finding the specific gravity of solid bodies is based on the principle of Archimedes. According to this principle, a solid body immersed in water apparently loses weight, and this apparent loss is equal to the weight of the water which it displaces, or to its own volume of water.

To determine the specific gravity of a solid body, such body is first weighed in air, next suspended from the balance pan by a fine thread or horsehair and immersed completely in pure water of 60° F. and again weighed while immersed. It now weighs less, the difference being the weight of the displaced water.

Dividing the weight of the body in air by the weight of an equal volume of water we obtain the specific gravity of the body compared to water of 60° F.

Example-A stone weighs in air..........

...108 lbs.

... 70

When suspended in water the same stone
weighs ......

Difference, being the weight of an equal volume of water, 38 lbs., and 10838 2.84, the specific gravity of the stone.

To Find the Specific Gravity of Gases.-Gases are compared to air as standard. The specific gravity of a gas is found in the same way as that of a solid, that is, by weighing equal volumes of the gas and air, and dividing the weight of the gas by the weight of the air. Example.-One cubic foot of carbonic acid gas weighs....1.976 oz. One cubic foot of air weighs ..... .....1.3

1.976 ÷ 1.3 = 1.52; hence the specific gravity of carbonic acid gas is 1.52, that is, carbonic acid gas is 1.52 times as heavy as air.

To find the specific gravity of liquid with an ordinary flask.Weigh a flask, first, empty; next, full of water; then, full of the given liquid. Subtract the weight of the empty flask from each of the other two weights; the remainders represent the weights of equal volumes of water and the other liquid. Divide the weight of the liquid by the weight of the water, and the quotient is the specific gravity of the liquid.

Example. A flask filled with water weighs....

Same flask filled with wort weighs.

Empty flask weighs

.55.9 oz. ..58.2 oz.

..24.I OZ.

Subtracting 24.1 oz. from 55.9 oz. gives weight of water 31.8 oz. Subtracting 24.1 oz. from 58.2 oz. gives weight of wort 34.1 oz. Divide 34.1 oz. by 31.8 oz., and the quotient of 1.07 indicates that the wort is 1.07 times as heavy as an equal volume of water, or, that the specific gravity of the wort is 1.07.

Another and simpler way of finding the specific gravity of a liquid is to let a body lighter than the liquid float in it. The denser the liquid is, the less deep does the floating body sink into it.

Water at 15° C. has been accepted in the brewer's laboratory as a convenient standard of specific gravity for worts, beers and other liquids, the specific gravities of which vary with the amounts of alcohol, sugar or other substances held by them in solution.

The picnometer is the only strictly reliable instrument for the determination of the specific gravity of a liquid, from which the quantity of sugars and other solids, or of alcohol, present in a wort or beer, can be found by referring to proper tables.

Balling's extract tables give, in convenient columns, the amounts of extract corresponding to specific gravities. After the latter has

been obtained by the instrument, the corresponding weight per cent of extract will be found in the table.

Alcohol tables give the weight per cent of alcohol in beer for a certain specific gravity of an alcoholic solution.

THE PICNOMETER,

This instrument should hold very nearly (within a decigram) 50 grams of distilled water at 15° C. Before using, the picnometer should be dried completely, which can be most easily effected by rinsing with 96 per cent alcohol, which, in turn, is reinoved by air from the bellows. The instrument is then accurately weighed, together with its capillary stopper. A quart pail, or dish, is filled with hydrant water, and some pieces of ice are added to hasten the cooling. The picnometer is filled with distilled water and immersed in the pail. A clean, dry, thin and accurate centigrade thermometer is used to indicate the temperature in the picnometer, and as a stirring rod. When the distilled water has a uniform temperature of 15° C., the picnometer is drawn from the pail, filled to the brim with distilled water and closed with the stopper containing the capillary tube, care being taken to avoid bubbles between stopper and liquid. The top of the plug is dried with a soft, clean, dry towel, and the whole instrument immersed so as to be almost covered by the cooling bath. The cooling liquid should not show more than 4 or 5° C., and in a warm room the cooling must be continued longer than in a cold room, so that the liquid in the picnometer may not expand and escape from the capillary stopper, while weighing the instrument. The plunging of the picnometer in the cold water causes the glass to contract, and a small drop of water is forced out at the top of the stopper; it sinks back again, however, as soon as the water in the picnometer begins to cool below 15° C. When the water has contracted to the bottom of the capillary tube of the stopper, draw the instrument from the cold water, dry it carefully with a soft, clean, dry towel, and weigh to milligrams. From this weight of the full picnometer, deduct the weight, previously obtained, of the empty picnometer. The difference will be the weight of the distilled water contained in the picnometer.

After finding the weight of the picnometer and the weight of the water it can hold at 15° C., we ascertain the weight of a wort, beer, or alcohol solution, in precisely the same manner as that of distilled water, the same precautions being observed. Suppose