1824.] On the Liquefaction of Gases. 125 



Dissatisfied both with the deductions drawn, and the means 

 used previously, that philosopher proceeded to fire gunpowder 

 in cylinders of a known diameter and capacity, and closed by a 

 valve loaded with a weight that could be varied at pleasure. By 

 making the vessel strong enough and the weight sufficiently 

 heavy, he succeeded in confining the products within the space 

 previously occupied by the powder. The Count's object in- 

 duced him to vary the quantity of gunpowder in different 

 experiments, and to estimate the force exerted only at the 

 moment of ignition, when it was at its maximum. This force, 

 which he found to be prodigious, he attributes to aqueous 

 vapour intensely heated, and makes no reference to the force of 

 the gaseous bodies evolved. Without considering the phe- 

 nomena which it is the Count's object to investigate, it may be 

 remarked, that in many of the experiments made by him, some 

 of the gases, and especially carbonic acid gas, were probably 

 reduced to the liquid state. The Count says, 



" When the force of the generated elastic vapour was suffi- 

 cient to raise the weight, the explosion was attended by a very 

 sharp and surprisingly loud report ; but when the weight was 

 not raised, as also when it was only a little moved, but not suffi- 

 ciently to permit the leather stopper to be driven quite out of 

 the bore, and the elastic fluid to make its escape, the report was 

 scarcely audible at a distance of a few paces, and did not at all 

 resemble the report which commonly attends the explosion of 

 gunpowder. It was more like the noise which attends the 

 breaking of a small glass tube, than anything else to which 

 it could be compared. In many of the experiments, in which 

 the elastic vapour was confined, this feeble report attending the 

 explosion of the powder was immediately followed by another 

 noise totally different from it, which appeared to be occasioned 

 by the falling back of the weight upon the end of the barrel, 

 after it had been a little raised, but not sufficiently to permit the 

 leather stopper to be driven quite out of the bore. In some of 

 these experiments a very small part only of the generated elastic 

 fluid made its escape ; in these cases the report was of a pe- 

 culiar kind, and though perfectly audible at some considerable 

 distance, yet not at all resembling the report of a musket. It 

 was rather a very strong sudden hissing, than a clear, distinct 

 and sharp report. " <* ;.< 



