( *84 ) 
time the End a uppermoft. Then before I took 
‘‘ them out of the Water^ 1 fet the Bolt-head' and 
‘‘ lower part of the cylindrical Glafs y into the ear- 
“ then Veflel pc x full of Water, and having lifted all 
“ out of the great Veflel of Water, I marked the 
“ Surface z of the Water in the Glafs a y , If the In- 
‘‘ gredients in the Bolt-head, upon fermenting, gene- 
“ rated Air, then the Water would fall from z to 
“ and the empty fpace z y, was equal to the Bulk of 
“ theQuantity of Air generated : But if the Ingredients 
“ upon fermentation, did abforbe, or fix the adive 
“ Particles of Air, then the Surface of the Water 
“ would afcend from z to and the Space a », which 
“ was filled with Water, was equal to the Bulk of Air, 
which was abforbed by the Ingredients, or by the 
“ Fume arifing from them ; When die Quantities of 
“ Air, either generated or abforbed, were very great, 
“ then I made ufe oflarge chymical Receivers, inflead 
“ of the Glafs a y: But if thefe Quantities were very 
“ fmall, then inflead of the Bolt-head, I us’d a deep 
“ cylindrical Glafs, or a common Beer*GIafs inverted, 
“ and placed under it a Vial or Jelly-Glafs, taking 
“ care that the Water did not come at the Ingre- 
“ dients in them : Which was eaflly prevented, by 
“ drawing the Water up under the inverted Glafs 
“ to what height I pleafed, by means of a Syphon, 
“ I meafured the Bulk of the Spaces z y or z », by 
“ pouring in a known Quantity of Water, as in 
“ the foregoing Experiment, and making an allow- 
“ ance for the Bulk of the Neck of the Bolt-head, 
“ within the Space 2 y. 
By our Author’s Experiments made upon feveral 
Subftances, it appear’d, that fome by Diftillation, 
and fome by Fermentation, wou’d generate Air, others 
wou’d abforb it ,* and fome again, wou'd abforb 
■ Air 
