134 Van Helmont and the Rise [lect. 



not air, not the air of the atmosphere. This appears when 

 wood is burnt, when the must of grapes or of malt ferments in 

 the making of wine or beer, and on other occasions ; and this 

 he calls ' gas.' 



He gives it that name, because the sound is not so far from 

 that of ' (jjhaos,' the unformed womb of all things. 



Here is an experiment giving a quantitative proof of the 

 existence of gas in wood or charcoal : 



" Charcoal moreover, even if heated in a closed vessel for 

 "nine days in a burning furnace, though it is exposed to 

 " combustion— for the fire has access to the charcoal in the 

 "closed vessel just as it does when charcoal is burnt in the 

 "open — nevertheless is not at all consumed. It cannot be 

 "consumed because its effluvium is prevented. Charcoal there- 

 " fore, and we may say generally all things which do not directly 

 "change into water, and are not fixed, necessarily give forth 

 "the spirit of wood (spiritum sylvestre). Consider that of 

 "62 lbs. of charcoal of oak, 1 lb. only remains as ash when it is 

 "burnt. The remaining 61 lbs. therefore consist of that spirit 

 " of wood which, even though the charcoal be exposed to fire, 

 " cannot escape from a closed vessel. This spirit, hitherto un- 

 " known, I call by the name of ' gas.' * * * 



" Many bodies indeed contain this spirit, and some are wholly 

 " changed into it. Not indeed that it is present in these in its 

 " actual state of gas, but as a condensed spirit, solidified to suit 

 " the fashion of the body in which it resides ; and it may be set 

 " free by the action of a ferment as in wine or bread." 



This idea of a ferment setting free gas by its action was one 

 of which, as we shall see, he made great use. He says : 



" A grape uninjured may be dried and kept without change 

 "for an indefinite time; but if once its skin be broken, it 

 "presently receives the ferment of ebullition, and hence the 

 " beginning of change. 



" The juice of grapes, apples, berries, honey, and even bruised 

 " flowers and twigs, a ferment having been laid hold of, begin to 

 " bubble and effervesce, whence gas. 



" When I was a student, misled by the authority of ignorant 

 "writers, I thought that the gas of grapes was the spirit 



