54'2 PHILOSOl'HICAL TRANSACTIONS. [aNNO 1779. 



same time a new light upon some powerful agents, \vh<«e mischievous force was 

 known, though their nature was still in the dark. 



Being at Amsterdam in Nov. 1777> Messrs. ^neae and Cuthbertson, two 

 ingenious philosophers of that city, showed me some curious experiments with 

 explosive and inflammable airs of different kinds. They produced an inflam- 

 mable air, by mixing together equal quantities of oil of vitriol and spirit of wine 

 and applying heat, to the pliial containing the compound. A great quantity of 

 white vapour was extricated, which, passing up the inverted receiver tilled with 

 water, settled at the top and depressed the water, as other airs do. This air soon 

 became clear, the white fumes being absorbed by the water. This air was easily 

 lighted in an open cylindrical glass, and burnt almost as clear as a candle, the 

 flame descending gradually lower and lower till it reached the bottom. A very 

 little quantity of this air mixed with common or dephlogisticated air, for instance, 

 a 14th or a 10th part, and kindled by an electrical spark, exploded with a very 

 loud report, and shattered the glass to pieces in which it was kindled, when it did 

 not find a ready vent. 



They had contrived a kind of pistol for tl\e purpose, consisting of a strong 

 cylindrical glass tube with a piston adapted to it. To the end of this tube was 

 fixed a brass barrel, like that of a common pistol: into this barrel a brass bullet 

 was put loose, so that the barrel was placed a little above the level, to prevent 

 the bullet rolling out. The barrel was directed to a board of oak at 8 or 10 feet 

 distance. A proper quantity of common and inflammable air, produced in the 

 manner abovementioned, being drawn into the glass tube by means of the 

 piston, it was fired by directing an electrical explosion through it. The ex- 

 plosion was very loud: the ball struck the board with such a force that it made a 

 strong impression in it, and recoiled with a considerable force, so as to strike 

 the wall behind us, and to put us in some danger of being hurt by its rebounding 

 force. 



The same gentlemen told me, that this inflammable air had in some respects 

 the advantage over the inflammable airs extracted from metals by the vitriolic or 

 marine acid, and that extracted from mud or marshes; because this air, being- 

 heavier than either of these airs, and even than common air, is not so easily 

 lost out of an open vessel; and, that when it escapes into the open air, it 

 agreeably perfumes the room with the smell of spiritus vitrioli dulcis or aether; 

 whereas the other inflammable airs, which from their less specific gravity escape 

 easily into the common air, ) ield an offensive, disagreeable stench. 



Mr. yEneae, having examined the specific gravities of the difterent inflammable 

 airs compared with common air, favoured me with the following result of his 

 inquiries. A vessel, which contained the weight of 138 grains of common air, 

 contained 25 grains of inflammable air extracted from iron by vitriolic acid, and 



