404 Dr. ingenhousz’s Account of a 
that very hot vapour is capable of occupying almoft 
2000 times the fpace it did in the ftate of cold water. 
The generation of dephlogifticated and inflammable 
air by the inflammation of gunpowder is the reafon why 
this ingredient is almoft the only one known, which does 
not want a free accefs of common air to be confumed by 
fire; and therefore it may be laid to feed, as it were, 
upon its own air. 
This theory of gunpowder induces me to venture a new 
one of the pulvis julminans , which conlifts of three parts of 
nitre, of two of fixed alkaline fait, and of one of fulphur. 
This powder much furpaffes the force of gunpowder in 
exploding, with a very loud report, in the open air when 
it is heated to a certain degree. It is commonly faid, that 
in the heating of this powder the fulphur joins with the al- 
kaline fait and conftitutes an bepar fulphur is , which riling 
up in bubbles confines the air contained in them, which 
air at laft becomes fo powerfully expanded that it over- 
comes and breaks through the refiftance of the coercive 
bubbles of the bepar fulpburis , with all the force of its 
elafticity; which fudden emerfion mult naturally occa- 
fion a proportional found. But I think, that the nitre 
contained in this powder, being heated, yields its dephlo- 
gifticated air when the melting fulphur- yields inflam- 
mable air ; at the fame time the fulphur conftitutes 
with 
