A grist not perfectly malted, or one which contains many hard corns, disappoints the expectation of the computed degree, as the volume cannot be such as was estimated from an equal dryness of true germinated grain. It has been observed, that, in perfect malt, the shoot is very near pressing through the exterior skin. By so much as it is deficient in this particular, must it be accounted only as dried barley, or hard corn. I know no better way of judging what proportion of the corn is hard to what is malted, than by putting some in water, the grains not sufficiently grown will sink to the bottom. Were this to be done in a glass cylinder, the proportion between the hard and malted corn might be found with exactness.--The unmalted parts being estimated with regard to their volume, as barley, a quarter of them will be to the barrel of water as 1,56 to 1[31]. Supposing, therefore, that, in the brown beer grist, before mentioned, the proportion of hard corns is of two quarters out of eleven, to discover the true volume of such a grist, the following rule may be used. 2 quarters of hard malt 9 quarters of true malt 1,56 volume of 1,74 volume at 130° of ---- 1 quarter ----- dryness 3,12 15,66 3,12 volume of 2 quarters of hard corn Total -------- numb. 11) 18,78 (1,70 true volume of one quarter of this malt to one barrel of water, and consequently the eleven quarters will fill a space equal to that of 6,47 barrels. By means of this rule, we may find what increase of heat any proportion of hard corns will occasion, as will be seen in the following table. Proportions of hard corns 1/4 1/6 1/8 1/16 1/32 of the grist Greater heat of the mash 4° 3 2 1 1/2 degrees. But the brewing of such malt ought to be avoided as much as possible, as the hard parts afford no strength to the extract. If a grist is not well and thoroughly mashed, the heat not being uniformly distributed in the different parts of the extract, the liquor of the thermometer, when placed in the running stream of the tap, will fluctuate, and, at different times, shew different degrees of heat. In this case, the best way is to take the mean of several observations, and to estimate that to be the true heat of the mash. If the gauges of the coppers are not exactly taken, a variation must be expected. Though the small and hourly variations in the state of the atmosphere have but little influence upon our numbers, a difference will be observed in any considerable and sudden changes either of the heat or of the weight of the air. Our instruments, and in particular the thermometer, are supposed to be well constructed and graduated. If the water cooled in with is more or less hot than estimated, or if the time of mashing or standing is either more or less than was allowed for, the computation must be found to vary from the event.