The distribution of the heated air in the kiln is rarely as uniform as is supposed, the temperature of the malt on drying floor being very different at different parts. In illustration of this, the following may be taken from a statement by Mr. Stopes of the results of an examination of the temperatures at different parts of a drying floor in a kiln in Norfolk: "A malting steeping 105 qr. every four days has a kiln 75 feet by 36 feet; an average drying area of under 26 feet per qr. The consequent depth of green malt when loaded is over 10 inches. The total area of air inlets is less than 27 feet super. The air outlet exceeds 117 feet, a ratio of 13 to 3. The capacity of head room equals 44,550 feet cube. The area of each tile is 144 inches, with 546 holes, giving an effective air area of some 32 inches. The ratio of non-effective metallic surface to air space is thus 9 to 2." The Casella anemometer gave no indications at several points, and fluctuating up and down draughts were observable at many others, especially at two corners and along the center. "The strongest upward draught pulsated with the gusts of wind and ranged from 30 feet to 54 feet per minute, a down draught of equal intensity occurring at intervals at the same spot, notwithstanding the fact that the air was rushing in at the inlets below the floor at the high velocity of 785 feet per minute. The temperatures of the drying malt and superimposed air consequent upon the conditions thus indicated were naturally as follows: At B, the place supposed to be hottest: Heat of malt touching tiles, 216 deg.; heat of malt 1 inch above tiles, 167 deg.; heat of malt 3 inches above tiles 154 deg.; heat of malt 4 inches above tiles, 152 deg.; heat of malt 5 inches above tiles, 142 deg.; heat of malt on surface, 112 deg. At A, the place supposed to be coldest: Heat of malt next tiles, 174 deg.; heat of malt 2 inches above tiles, 143 deg.; heat of malt 4 inches above tiles, 135 deg.; heat of malt on surface, 104 deg.; the heat of the air 3 feet above tiles, 84 deg.; the heat of the air 5 feet above tiles, 82 deg. Fig. 9 shows the temperature at twenty-six points close to the tiles, taken with twelve registered and accurate thermometers in the space of fifteen minutes." These and other similar tests have led to the conclusion that the best malt drying cannot be done on a single floor.
Fig. 10 is a similar diagram showing the temperatures on a drying floor of kiln at Poole, Dorset, altered to Stopes' system of drying. The temperature at different depths of the drying grain was as follows: Malt at surface of tiles, 142 deg.; malt at 1 inch above tiles, 142 deg.; malt at 2 inches above tiles, 142 deg.; malt at 4 inches above tiles, 141 deg.; malt on surface, 140 deg.
The advantages of the Saladin system over that hitherto working in Britain are numerous, and are thus enumerated by Messrs. Stopes & Co. who are agents for M. Saladin: The area occupied by the building does not equal one-third of that otherwise required. The actual growing-floor space is only about one-seventh, and the number of workmen is ruled necessarily by the size of the house, but on an average is reduced two-thirds; but the employment of much more power is necessary, and the power is used at more frequent intervals. The use of plant and premises is continuous, the processes of malting being equally well performed during the summer months. The further advantage of this is that brewers secure entire uniformity in age of malt. By the English system the stocks of finished malt necessarily fluctuate largely. All grain is subjected to the same conditions of surrounding air, exposure, and temperature. The volume of air supplied to the germinating corn is entirely under control, as are also its temperature and humidity. When germination is arrested and the green malt is drying, the double kilns insure control of the temperatures of the corn in the kilns. The infrequency of turning the germinating grain benefits the growth of the roots and the development of the plumule, besides saving much labor. No grains are crushed or damaged by the feet or shovels of workmen. The air supplied to the corn can be inexpensively freed from disease germs and impurities. The capital needed for malting can be reduced by the diminished cost of installation, and the reduced stocks of malt on hand. The quality of the malt made is considerably improved. The percentages of acidity are much reduced. The stability of the beer is increased, and a greater percentage of the extractive matter of the barley is obtainable by the brewer.--The Engineer.
NON-SPARKING KEY.
Profs. Ayrton and Perry lately described and exhibited before the Physical Society their new ammeters and voltmeters, also a non-sparking key. The well known ammeters and voltmeters of the authors used for electric light work are now constructed so as to dispense with a constant, and give the readings in amperes and volts without calculation. This is effected by constructing the instruments so that there is a falling off in the controlling magnetic field, and a considerable increase in the deflecting magnetic field. The deflections are thus made proportional to the current or E.M.F. measured. The ingenious device of a core or soft iron pole-piece, adjustable between the poles of the horseshoe magnet, is used for this purpose. By means of an ammeter and voltmeter used conjointly, the resistance of part of the circuit, say a lamp or heated wire, can be got by Ohm's law. Profs. Ayrton and Perry's non-sparking key is designed to prevent sparking with large currents. It acts by introducing a series of resistance coils determined experimentally one after the other in circuit, thereby cutting off the spark.