402 Dr. ingenhousz’s Account of a 
fee how far this computation agrees with the analyfis of 
gunpowder. Abbe fonttana, fo advantageoufly known 
by his important diicoVeries in natural philofophv,more 
efpecially by thofe he has made on the various kinds of 
air, favoured me with the following refult of his experi- 
ments. An ounce of nitre, expofed to a great degree of 
heat for the purpofe of extraditing its air in the ufual 
way, yielded about 800 cubic inches of dephlogifticated 
air. An ounce of charcoal, treated in the fame way, 
gave about 150 cubic inches of air, partly fixed, partly 
inflammable, mixed with fome common air. 
Let us now calculate (without, however, being too 
fcrupulous about the accuracy of the refult) what quan- 
tity of elaftic permanent fluid a cubic inch of folid 
gunpowder will give in the moment of deflagration: a 
cubic inch of folid gunpowder contains in weight 442 
grains (which is 38 grains fhort of an ounce Troy 
weight) of which 33 if grains is nitre, 5 5-) charcoal, 
and as much fulphur (fuppofing the proportion of the 
ingredients of the powder to be fix parts of nitre to one 
of charcoal and one of fulphut); 33 if grains of nitre 
will give about 552 cubic inches of dephlogifticated air; 
55? grains of charcoal will produce about 17 cubic 
inches of air, chiefly inflammable, according to the 
calculation of Abbe fontana. 
By 
