318 



] !', K U 



gentleman connected -with another groat London brewery, had the kindness to 

 inform me that their average product from a quarter of malt was a barrel of 84 Ibs. 

 gravity. It is obvious, therefore, that by taking the moan operation of two sucli great 

 establishments, I must have arrived very nearly at the truth. 



' It ought to be remarked that such a high density of wort as 1-234 is not the result 

 of any direct experiment in the brewery, for infusion of malt is never drawn off so 

 strong ; that density is deduced by computation from the quantity and quality of 

 several successive infusions ; thus, supposing a first infusion of the quarter of malt to 

 yield a barrel of specific gravity I'll 2, a second to yield a barrel at 1-091, and a third 

 a barrel at 1-031, we shall have throe barrels at the mean of these three numbers, or 

 one barrel at their sum, equal to 1-234. 



1 1 may hero observe that the arithmetical mean or sum is not the true mean or sum 

 of the two specific gravities ; but this difference is either not known or disregarded by 

 the brewers. At low densities this difference is inconsiderable, but at high densities 

 it would lead to serious errors. At specific gravity 1-231, wort or syrup contains 

 one-half of its weight of solid pure saccharum, and at 1-1045 it contains one-fourth 

 of its weight ; but the brewer's rule, when here applied, gives for the mean specific 



gravity 1*1155 = . The contents in solid saccharine matter at that 







density are, however, 27^ per cent., showing the rule to be 2| Ibs. wrong in excess on 

 100 Ibs., or 9 Ibs. per barrel. 



' The specific gravity of the solid dry extract of malt-wort is 1-264 ; it was taken in 

 oil of turpentine, and the result reduced to distilled water as unity. Its specific 

 volume is 0'7911, that is, 10 Ibs. of it will occupy the volume of 7'911 Ibs. of water. 

 The mean specific gravity, by computation of a solution of that extract in its own 

 weight cf water, is 1-1166 ; but, by experiment, the specific gravity of that solution is 

 1-216, showing considerable condensation of volume in the act of combination with 

 water. 



' The following Table shows the relation between the specific gravities of solutions 

 of malt-extract and the percentage of solid extract they contain : 



The extract of malt was evaporated to dryness, at a temperature of about 250 F., 

 without the slightest injury to its quality or any erapyreumatic smell. Bate's tables 

 have been constructed on solutions of sugar, and not with solutions of extract of malt, 

 as they agree sufficiently well with the former, but differ materially from the latter. 

 Allen's tables give the account of a certain form of solid saccharine matter extracted 

 from malt, and dried at 175 F., in correspondence to the specific gravity of the 

 solution ; but I have found it impossible to make a solid extract from infusions of malt, 

 except at much higher temperatures than 175 F. Indeed, the numbers on Allen's 

 saccharometer-scale clearly show that his extract was by no means dry : thus, at 1 ] 00 

 of gravity he assigns 29-669 per cent, of solid saccharine matter ; whereas there is at 

 that density of solid extract only 25 per cent. Again, at 1-135, Allen gives 40 parts 

 per cent, of solid extract, whereas there are only 33^ present." 



The Table (p. 319) shows the origin and effect of fermentation in the reduction of 

 gravity, in a number of practical experiments. 



The second column here does not represent the solid extract, but the pasty extract 

 obtained as the basis of Mr. Allen's saccharometer, and therefore each of its numbers 

 is somewhat too high. The last column, also, must be in some measure erroneous, on 

 account of the quantity of alcohol dissipated during the process of fermentation. 

 It must be likewise incorrect, because the density due to the saccharine matter will bo 

 partly counteracted by the effect of the alcohol present in the fermented liquor. In 

 fact, the attenuation does not correspond to the strength of the wort ; being greatest 

 in the third brewing and smallest in the first. The quantity of yeast for the alo 

 brewings given in the Table was, upon an average, one gallon for 108 gallons ; but it 

 varied with its quality, and with the state of the weather, which, when warm, permits 

 much less to be used with propriety. 



The good quality of the malt, and the right management of the mashing, Jnay be 

 tested by the quantity of saccharine matter contained in the successively drawn worts. 



