VINEGAR 



1079 



drive off the alcohol ; and agitation in contact with air, though it removed the carbonic 

 acid, would tend to the formation of acetic acid, by which the gluten would be kept in 

 solution more decidedly than before, and thus lead to the production of a turbid, ropy, 

 and impure vinegar, extremely liable to decompose and undergo the putrefactive 

 fermentation. It is obvious, therefore, that the theoretical conditions needed in the 

 treatment of fermented wort by the vinegar-maker are precisely those which we have 

 shown to be in use at Worcester. That is to say, the gluten, when insoluble, should 

 be removed by a filter, and when held in solution by carbonic acid gas, this must be 

 slowly expelled by keeping at a temperature too low for acetification to take place, 

 and which may be assumed at less than 55 Fahr. Fermented wort stored away at this 

 temperature for six months will flow to the acetifier perfectly limpid and bright ; it 

 will cause no deposition of gluten upon the birch-twigs, and thus secure complete oxida- 

 tion ; it will rapidly take on the grateful flavour of acetic ether, and never become 

 tainted by the formation of that noxious product aldehyde, which so frequently con- 

 taminates ill-made vinegar. 



Presuming, however, that all the necessary precautions "with respect to care in 

 washing, fermenting, and keeping the wort, have been attended to, we may now pass 

 on to the acetifier, that is to say, Ham's acetifier. 



This is a wooden vat or vessel (figs. 2089, 2090) about 12 feet in height and from 



2089 



2090 



7 to 8 feet in diameter, closed at top and bottom, except at the opening for the introduc- 

 tion of the wash and the exit of the vinegar. The sides are perforated by a few small 

 holes for the admission of air, and within are tiiree floors or partitions perforated with 

 numerous holes for the passage of the wash through them. Upon these floors are laid 

 bundles of birch-twigs, to favour the dispersion and division of the fluid which passes 

 through the acetifier, and is thus brought into the most immediate contact with the 

 oxygen contained in the vessel, or admitted through the openings in its sides. The 

 fluid or wash is admitted at the top of the acetifier, and suffered to trickle slowly 

 through the masses of birch-twigs and through the partitions, thus causing a 

 rapid absorption of oxygen, and consequent production of vinegar, which with any 

 undecomposed wash flows out at the bottom of the vessel, and is again pumped up to 

 the top, and so on until the process is finished. If we examine the circumstances 

 connected with the formation of vinegar in this way, we shall perceive that it is a 

 case of partial combustion, or, in other words, an example in which an organic com- 

 pound undergoes oxidation at a temperature and under conditions which prevent the 

 completion of the change. 



Every one must have observed that when common coals are thrown upon a fire, a 

 volatile portion immediately bursts into flame, while copious particles of soot or carbon 

 are thrown off unburnt ; though of the other constituent of the coal, that is to say, the 

 hydrogen gas, no particle escapes unoxidised. This .arises from the fact, that, except 

 at very high temperatures, hydrogen has a greater affinity for oxygen than carbon 

 has ; consequently, as the supply of oxygen from atmospheric air in the imrncdiata 



