374 Mr. J. N. Furze on Fermentation. 



5 oz. of the original 45 gallons were distilled with baryta 

 in excess, to combine with any acids that might be present, 

 and the product was redistilled with hydrochloric acid ; chlo- 

 ride of platinum and sodium was then added, and the whole 

 carefully evaporated to dryness ; the soluble parts having been 

 removed by alcohol left 1 *9 gr. of ammonio-chloride of plati- 

 num, which indicates by calculation 0'146 grain of ammonia. 

 It follows, therefore, that 4 - 672 grains of ammonia were con- 

 tained in the original bulk per gallon, or 21 0*24 grs. on the 

 whole volume. 



The residue, after the distillation with barytes, was exa- 

 mined for acetic and formic acids, but without success. 



Respecting the volume of carbonic acid eliminated during 

 the process of fermentation, I have not yet had the opportu- 

 nity of using an apparatus capable of measuring the amount 

 set free from so large a quantity of wort as 180 barrels. On 

 a small brewing of ale the quantity of gas measured by a very 

 large metre was 7900 cubic feet. The meter having been 

 charged with great care, the relative quantities were as fol- 

 lows: — 43£ barrels of ale wort attenuated 16'5lbs. per barrel, 

 and gave off 7900 cubic feet of carbonic acid, or about 1 1 

 cubic feet of gas for every pound of attenuation. Again, 91 

 barrels of ale wort attenuated 1 5 lbs. per barrel, and gave off 

 11,700 cubic feet of carbonic acid, or about 11*66 cubic feet 

 of gas for every pound of attenuation. 



It being manifestly inconvenient to distil so weak a spirit 

 on a large scale, from the necessity of apparatus and arrange- 

 ments totally different from the usual machinery of a brewery, 

 the means of preventing the saturation of the gas by the va- 

 pour of alcohol was the next object. This is accomplished in 

 a most simple manner. The tun being air-tight, the exit- 

 pipes for the carbonic acid were allowed to dip into a vessel 

 of water to the depth of three feet, and by the pressure of the 

 confined gas upon the surface of the fermenting worts the 

 power of holding the vapour of the alcohol in the carbonic 

 acid gas is checked, and a very large proportion of spirit thus 

 retained, which would otherwise have been lost. The effect 

 was tested as before by distillation, and although the retention 

 was not complete, a most extraordinary reduction was made, 

 amounting in some instances to 80 per cent, of the before- 

 stated produce. The depth of 3 feet is of course an ar- 

 bitrary number, but in practice a greater pressure is inconve- 

 nient from the difficulty of keeping large tuns air-tight by 

 common means. The difference of the quantity of vapour 

 dependent upon pressure will be confirmed by the following 

 experiments, in addition to the test of distillation. 



175 barrels of porter wort were fermented in a close tun, 



