JUNi:. 1011. 



KNOWLEDGE. 



221 



more rapid method of acetification, his apparatus 

 was speedih- adopted in Europe, and more slowly in 

 this country. 



The acetitiers emplo\-ed in w liat was then termed 

 the quick process consisted of large vats holding 

 from two thousand to three thousand gallnns each. 

 About two-thirds of the way down they were 

 provided with a perforated false bottom, and the 

 whole of the space above was filled with beech 

 shavings, while holes for the admission of air were 

 made in the side of the vat, just above the false 

 bottom, and smaller holes for its escape in the top. 



The g\"le was constantly pumped over from the 

 bottom of the vat to the top. and trickling down 

 through the shavings met with a current of air, 

 which was drawn into the vat, under the influence 

 of the heat promoted by the reaction. About three 

 weeks were required for the complete conversion 

 of the alcohol into acetic acid. 



The acetifying apparatus used at the present da\', 

 is essentialh- the same as that of Schiitzenbach, the 

 chief differences being in the nature of the packing 

 material placed in the vat, and in the method of 

 distributing the g\-le over the surface at the top, so 

 as to insure its reaching all parts of the aerating 

 medium. 



In most acetifiers a sparger is used for sprinkling 

 the li(]uid over the material, and basket work is 

 commonl}" emplo\-ed in place of wood shavings. 

 The principle of the sparger is shown in P'igure 6, 

 which represents a section of the upper portion of 

 an acetifier. 



The liquid is pumped from the bottom of the \at 

 and discharged into the funnel at the top, this 

 funnel being boxed in to prevent loss by evaporation. 

 Thence it flows down through the tube G. into the 

 sparger R, which revolves smoothly upon a pivot S. 

 In the arms of the sparger are a number of small 

 holes through which the liquid passes, and thus 

 causes the sparger to re\dl\e steadily and to sprinkle 

 uniformh- the whole of the surface of the basket 

 work, which is also shown in the figure. 



A thermometer inserted through a hole in the 

 side of the acetifier shows the temperature within 

 the apparatus, and affords an indication whether the 

 acetification is following a normal course. 



No more striking illustration of the manner in 

 which scientific text-books will copy errors from one 

 another can be found than in the assertions that are 

 put forward as to the temperatures at which acetic 

 bacteria thrive the best. 



This is commonly given as about 90'' to 95 F.. 

 and according to Brannt, " the formation of \'inegar 

 ceases entirely at 104" F." Yet the writer has 

 frequentK' seen the thermometers record a tem- 

 perature of 110- F., and there is no doubt that in 

 this country, at all events, the bacteria are most 

 active at a temperature of about 105 F. Possibly, 

 this may be the result of ada[)tation to the sur- 

 rounding conditions, since in Continental vinegar 

 works the temperature of the acetifiers seldom 

 exceeds 95° F. 



The conditions for successful working are, firstly 

 a regular and uniform supply of air, and secondly 

 the right temperature. If too much air is 

 admitted the bacteria w ill oxidise part of the acetic 

 acid the\- have produced and a weak vinegar will 

 result. If too little air is available the acetification 

 proceeds ver\- slowly, the bacteria fonii themselves 

 into the zoogloeal condition mentioned above, and 

 the acetifier becomes clogged with slimy masses 

 which still further stop the passage of the air, so 

 that it forms currents in one portion instead of 

 effecting uniform aeration. 



However carefulh' the process may be carried out, 

 the reaction never proceeds quantitatively in practice, 

 and the loss of acidit\', due to evaporation of the 

 alcohol and irregular aeration resulting in the 

 destruction of acetic acid, usually ranges from ten 

 to twenty per cent., and may, in very faulty apparatus, 

 reach as much as thirt\' per cent. 



Most of the modern patents have had for their 

 object the remed\ing of these defects. Thus, in 

 some types of acetifiers, the air issuing from the 

 apparatus is carried back again into the vat, the idea 

 being, that the volatile constituents of the vinegar 

 w ill thus be prevented from escaping. 



In others, attempts have been made to accelerate 

 the speed of oxidation, and thus reduce the period of 

 loss, by the introduction of ozonised air, but these do 

 not appear to have met with much success. 



The key to the problem appears to be the provision 

 of a sufficiently large aerating medium through which 

 the air can circulate with absolute uniformity, and 

 experiments on a large scale, made by the present 

 w riter, have show n that so long as these conditions 

 can be maintained, the conversion of alcohol into 

 acetic acid proceeds almost in accordance with the 

 theoretical requirement. 



After the vinegar leaves the acetifiers it is stored 

 ioT some time to form the ethers to which it owes its 

 aroma, and is then clarified by filtration through 

 large vats containing a suitable filtering medium, such 

 as fine sand. Finally it is diluted to the required 

 strengths, and is sent out to the trade. 



From the davs i)f Charles II. to the reign of 

 William I\'. vinegar was under the control of the 

 Excise, and paid duty in accordance with its acetic 

 strength, \\hich was determined b\- the Excise 

 Officers by means of a special hydrometer, the vine- 

 gar being first neutralised b\" the addition of pure 

 calcium carbonate. Not until the year 1836 did 

 \inegar cease to be tested by the Excise Officials. 



As it leaves the filtering vats, vinegar has an 

 acetic strength of 6 per cent., and upwards, and is 

 termed '' 24 \'inegar." Originally this name indicated 

 that one fluid ounce required 24 grains of sodium 

 carbonate to neutralise its acidity, but in the trade 

 the name is now applied to vinegars containing 

 5 • 5 }>er cent, of acetic acid and upwards. In like 

 manner, the lower strengths of vinegar are known 

 as ■• 16," " 18," " 20," and " 22," the lowest of these 

 containing 4- 1 per cent, of acid. 



There is no legal standard as to the permissible 



