92 On the Condensation [1823. 



Carbonic Acid. The materials used irf the production of 

 carbonic acid, were carbonate of ammonia and concentrated 

 sulphuric acid ; the manipulation was like that described for 

 sulphuretted hydrogen. Much stronger tubes are however 

 required for carbonic acid than for any of the former substances, 

 and there is none which has produced so many or more power- 

 ful explosions. Tubes which have held fluid carbonic acid 

 well for two or three weeks together, have, upon some increase 

 in the warmth of the weather, spontaneously exploded with 

 great violence ; and the precautions of glass masks, goggles, 

 &c., which are at all times necessary in pursuing these experi- 

 ments, are particularly so with carbonic acid. 



Carbonic acid is $ limpid colourless body, extremely fluid, 

 and floating upon the other contents of the tube. It distils 

 readily and rapidly at the difference of temperature between 

 32 and 0. Its refractive power is much less than that of 

 water. No diminution of temperature to which I have been 

 able to submit it, has altered its appearance. In endeavouring 

 to open the tubes at one end, they have uniformly burst into 

 fragments, with powerful explosions. By enclosing a gauge 

 in a tube in which fluid carbonic acid was afterwards produced, 

 it was found that its vapour exerted a pressure of 36 atmo- 

 spheres at a temperature of 32. 



It may be questioned, perhaps, whether this and other 

 similar fluids obtained from materials containing water, do not 

 contain a portion of that fluid ; inasmuch as its absence has 

 not been proved, as it may be with chlorine, sulphurous acid, 

 cyanogen, and ammonia. But besides the analogy which exists 

 between the latter and the former, it may also be observed in 

 favour of their dryness, that any diminution of temperature 

 causes the deposition of a fluid from the atmosphere, precisely 

 like that previously obtained ; and there is no reason for sup- 

 posing that these various atmospheres, remaining as they do 

 in contact with concentrated sulphuric acid, are not as dry as 

 atmospheres of the same kind would be over sulphuric acid at 

 common pressure. 



Euchlorine. Fluid euchlorine was obtained by enclosing 

 chlorate of potash and sulphuric acid in a tube, and leaving 

 them to act on each other for twenty-four hours. In that time 

 there had been much action, the mixture was of a dark reddish 



