f 323 ] 
and in order to give a free paffage for the great quan- 
tity of ventilating air to pafs off, and withal, at the 
fame time to prevent the efcaping of much mold: 
vapour with it, it will be proper to fix at the bung- 
hole a long upright pipe of wood, or of any metal. 
I ufed a gun-barrel four feet and a half long ; thro’ 
which fome fmall degree of moifi: vapour efcaped j 
as appeared by the dampnefs of a piece of paper, 
fixed at a little diftance above the mouth of the gun- 
barrel. This vapour became vifible, and much in- 
creafed, when the water in the worm-tub was very 
hot ; at which time, lefs is diftilled into the cafk- 
receiver ; then alfo there is more danger of the fpirit 
of fait arifing. And it was obfervable, that the 
water in the worm- pipe vclTel heated much fooner 
by ventilation than in the common way of diftilling. 
For which reafon that water ought to be changed fo 
much the oftener, which can eafily be done at fea. 
The cocks alfo at the fide of the worm-tub ought to 
be large, in order to let the hot water off the fafter. 
24,. But though the water in the worm-tub 
was fooner heated by ventilation, becaufe a double 
quantity of hot fleam paffed through it more than 
paffed through it in equal times in the common 
way of diftilling ; yet in the ufual way of diftil- 
lation the liquor in the ftill is hotter, with equal 
fire, as is evident by its aptnefs to boil over 
through the worm-pipe ; whereas in the ventilating 
way it did not boil over, notwithftanding a very hot 
fire was purpofely made for a trial. The continual 
ftreams of afcending frefh air, not only in fome de- 
gree abating the heat of the water, but alfo incef- 
fantly carrying off the more rarefied particles of the 
water, which, when expanded into a repelling ftate, 
T t 2 do 
