purify further by repeated washing with cold water and decantation. Digest the starch with 0.5 per cent. caustic potash solution for twenty-four hours, wash well, and drain the starch on a filter. Transfer to an unglazed porcelain plate and air-dry at the temperature of the room.

Determination of the Moisture in Barley and Other Cereals.-This determination must be conducted on a ground sample of the corn. First clean the mill by grinding through it some of the corn to be tested. Reject this sample. Then grind from 3 to 5 grms. of the corn and transfer the whole to a stoppered drying-tube the weight of which has been previously ascertained. Weigh the tube and its contents, transfer to a water-oven, remove the stopper and dry at 100° for four or five hours. Replace the stopper, transfer to a desiccator until cool and weigh. Return the tube to the water-oven for an hour or two, cool and weigh again, as before. These operations must be repeated until the weight remains constant within one or two milligrams. Now calculate from the weights obtained the percentage of moisture lost.

A more rapid estimation of the moisture may be obtained by drying in a hot-air oven kept at a constant temperature of 102° C., but care must be taken that this temperature is not exceeded.

The student should determine the moisture in kiln-dried as well as undried samples of barley, in order to demonstrate that an apparently perfectly

dry barley contains from 10 to 12 per cent. of moisture. It is important that he should recognise that this amount of moisture is natural to a barley in perfect "condition," and that it is the presence of moisture in excess of this amount which produces the different degrees of "want of condition " in barley.

66

Determination of the "Vitality" or Germinative Power of Barley.—The student should experiment with Coldewe's, or other form of germinator, on various samples of barley. The germinative power of barley is often regarded from two points of view -its germinative energy and its germinative "capacity". Germinative energy is expressed by the percentage number of corns which vegetate in a definite time, generally taken as three days. Germinative capacity is expressed by the percentage number found capable of germinating, irrespective of time.

Determination of the "Weight" of Barley.In this country the term "weight" as applied technically to barley is understood to refer to the weight in pounds of a bushel measure of the grain. The student can gain some experience in the laboratory of the bushel weights of different kinds of barley by weighing them in the miniature bushel of the instrument known as the "chondrometer ". But the results obtained must be regarded more as comparative values than reliable determinations of the actual bushel weight of the corn.

Another meaning of the expression "weight as applied to barley refers to the weight of a certain number (usually 1,000) of corns. This method of comparing the weight of different barleys, is employed more frequently on the Continent than in this country, and has the merit of giving the true average weight of the corns, which is not expressed accurately by the bushel weight. The latter is much influenced by the shape of the corns, and, consequently, by the different manner in which they arrange themselves in the measure.

Count out 200 average corns from several samples of different barleys, including English Chevalier and Smyrna, or other "light foreign barley, and weigh them. Express the results as weights in grams of 1,000 corns. Compare the weights of the English and Smyrna barleys, and note that the relation they bear to each other differs very considerably from the relation of their bushel weights found by the chondrometer.

Determination of the Specific Gravity of Barley.-In a well-matured, mealy barley its white friable endosperm is permeated with minute spaces containing air, which diminish its specific gravity. In a badly matured, steely barley the hard endosperm contains fewer air-spaces, and consequently its specific gravity is greater than that of the mealy endosperm. A comparison of the specific gravities of the endosperms of different barleys is therefore a measure of their relative tenderness. But in technical work it is not practicable to obtain a sufficient number of skinless endosperms in order to determine their specific gravity, and recourse must therefore be had to a determination

of the specific gravity of the whole barley corns. This may be effected by observing their displacement-volume in a liquid like toluene which does not readily penetrate the interior of the corn.

Weigh out accurately about 50 grms. of the barley, and after noting the exact weight, transfer the corns to a dry 100 c.c. flask. From an accurately graduated burette run toluene slowly into the flask, shaking it to disentangle any air which may be confined in the mass of barley corns. When the toluene reaches the 100 c.c. mark, note the volume of toluene which has been run into the flask. If the temperature of the toluene in the flask and in the burette is kept constant, the difference between the volume of toluene run into the flask and 100 c.c. represents the displacement volume of the barley. Divide the weight of this volume, considered as water, into the weight of the barley taken, and the specific gravity of the barley will be obtained. But it should be noticed that the specific gravity of the barley obtained in this manner is influenced by the air confined within the skins of the barley and that the proportion in volume of this air is liable to vary in different types of barley. Hence the above method of experiment is not reliable if used for comparing different types of barley, and can only be used with advantage for the purpose of comparing the relative mealiness of samples of barley of the same type.

As toluene is a volatile, easily inflammable liquid, experiments with it must not be conducted near a flame.

Technical Examination and Valuation of Barley for Malting Purposes.-This is a convenient time for the student to gain some experience in the valuation of barley for malting purposes. Personal instruction by an expert is absolutely necessary.

PART IV.

THE CHANGES IN BARLEY DURING GERMINATION.

Steep about 100 grms. of English barley in water for forty-eight hours, and change the steep water twice each day.

Keep the first highly coloured steep water in a beaker, and note how rapidly it commences to decompose on standing. Water extracts from barley matter which readily putrefies, and hence arises the necessity to change the steep water in the malthouse frequently.

After the barley has been steeped for about two days, examine the corns. If they are moistened throughout, but not saturated with water, the barley is sufficiently well steeped.

Determination of Moisture in the Steeped Barley. -Weigh about 10 grms. of the steeped barley in a drying bottle. Place in a water-oven and dry very slowly with the door of the oven open until most of the moisture is evaporated. Finally dry at 100° until the weight is constant. Calculate the percentage of water lost. This will give some idea of the amount of water retained by barley when steeped in the malt-house.

Study of the Changes in Barley during Germination. Spread the rest of the steeped barley (see above) in a thin layer in some suitable form of germinator to start it into growth. Proper