New Publication. 281 



powder, into a leaden retort; pour over it three parts of ful- 

 phuric acid, and adapt to the retort a leaden receiver half 

 full of water. The operation is performed with a balneum 

 mariae ; and fnr this purpofe you put the retort into a cop- 

 per or iron veflel containing water, or into a falt-bath ; you 

 then expofe the apparatus to a gentle heat, and the fluoric 

 Ticid, in proportion as it is difengaged, will be abforbed by 

 the water in the receiver. 



For this purpofe, inftead of a receiver, you adapt to the 

 orifice of the retort a bent tube of lead, the extremity of 

 which is introduced under a mercurial pneumatic apparatus. 



2d, When this acid is made by means of a glafs appara- 

 tus, you employ a retort, having adapted to it a tube iu- 

 fcrted in a bottle containing diftilled water. 



As this acid has the property of diflblving glafs, it feizes 

 on the filex, which appears under the form of white flakes. 



Care mull be taken to employ large tubes, efpecially when 

 you operate with glafs, as for want of a fufficient paflage the 

 gafeous acid is comprefled in the retort, and its a6tion on 

 the glafs is augmented, fo that the retort will be foon cor- 

 roded through. 



The filex depofits itfelf in the water, becaufe the latter 

 has more affinity for the acid than the acid has for the filex. 



If you preferve fome of this gas under a glafs bell, it will 

 diflblve the filex of the glafs. 



If you plunge into it an extinguiflied taper, an incrufta- 

 tion will be formed on the wick, becaufe the water which 

 iffues from it diflblves the unrounding acid charged with 

 filex, and the filiceaus earth is precipitated upon it from this 

 folution. 



This gas is heavier than atmofpheric airj it extinguishes 

 a lighted taper, kills animals, reddens blue vegetable co- 

 lours, and has a penetrating fmell, which approaches near 

 to that of muriatic acid gas. 



It corrodes the fkin : it undergoes no alteration from light. 



In contact with the air it emits white fumes. If you ex- 

 pofe to the vapour of this gas in an earthen veflel animals, 

 bits of fponge a little moiflened, charcoal, &c. the moifture 



Vol. VIII. O o they 



