VOL. XLVI.] THILOSOPHICAL TKANSACTIONS. 081 



acid are points proportioned to these pores ; these ought to be regarded as so 

 many pegs or pins, which enter into the holes on the surface of the alkali, and 

 fill them up exactly : by which the igneous matter is imprisoned ; and by the 

 preceding principle it bursts the alkaline globule with noise, and scatters around 

 the acid pegs, in the same manner as it bursts the glass drop. 



A mixture of an alkaline and acid liquor being composed of an infinite num- 

 ber of such particles that burst and broke to pieces, the liquor must take up more 

 room, or swell. The particles of contained air being tossed about by all those 

 little explosions, together with the neutral liquors, which area vehicle to the salts, 

 form the scum or froth ; and the igneous matter, which gets out of the alkalis, 

 and is agitated by the shocks of all these explosions, produces heat, drags with it 

 the aqueous and other volatile particles, which form the steam. 



Yet there are cold fermentations, because then, either the motion of the par- 

 ticles of fire, and their burstings are inconsiderable ; or because these particles fly 

 off easily by a direct motion. Further, at this day that we have it in our power 

 to be convinced, that the brush or stream of electric matter is very cold, nobody 

 will be surprised that a stream of the matter of fire may produce cold. 



If all the alkalious corpuscles bursted at once, the fermentation would last 

 but an instant : but as the acid liquor requires a certain space of time, to pene- 

 trate the whole alkaline liquor, and fill the pores of the alkalious corpuscles, the 

 fermentation is performed successively in a certain number of corpuscles at a 

 time, till they are all broken : and this succession constitutes the duration of 

 the fermentation ; which ceases when there are none of the alkalis left entire. 



These principles not only serve to explain the fermentation which results from 

 the mixture of acids and alkalis, but also almost all the motions of this kind, 

 which are occasioned by the mixture or penetration of 2 or more substances. 

 For example ; lime, which we have mentioned above as a body filled with the 

 matter of fire, and which produces an effervescence capable of lighting sulphur, 

 if water be thrown on it ; lime then produces this effect, only because the par- 

 ticles of water, which enter into its pores, have a tendency to shut up the 

 igneous particles more closely. It is by a mechanism entirely similar, that Rom- 

 berg's phosphorus kindles into flame, on being exposed to the air : it is on this 

 principle also that a mixture of spirit of wine and water acquires a new degree of 

 heat ; and so of other phenomena of this nature. 



On the Electricity of Glass, that has been Exposed to Strong Fires. By Mr, 

 Prof. Geo. Matthias Bose of Wittemberg. N° 492, p. I89, 



It seems that a glass ball, which has often been employed for violent distilla 

 tions, and other chemical operations, sends forth the electricity incomparably 

 more strong than any other glass, which never since its making had been ex- 



VOL. IX. 4 S _ 



