30 DECOMPOSITION OF PLTlORlC ACIB. 



Attempts to Our first care, say they, was to obtain pure fluoric acid ; 



procure pure but ag tn j g ^jj €X j sts on ] y CO mbined with lime, and no one 

 iiHoric acid J ' 



has yet been able to separate it, without its entering into 



combination with some other body, we were obliged to 

 make a great number of trials, that procured to us the ad- 

 vantage of observing several facts, the most remarkable of 



Gas procured which are the following. When air is placed in contact 



tromfluatfiof w j tn the fl UO) .; c cr a8 disengaged from a redhot iron tube 



lkne and bo • « ' • ? 1 ■ 



racic ur d pro containing filiate of lime and glacial boracic acid, vapours 



daces vapour are formed as dense as those arising from muriatic acid gas 

 •with all gasses , . T . ° . . , 



containing an " ammonical gas. It produces the same with ail the 



water. other gasses, except the muriatic acid gas, provided those 



gasses have not been dried. But it does not alter the trans- 

 parency of any of them, if they have remained some time in 

 contact with lime, or muriate of lime. In the first case, where 

 there is a production of strong vapours, the volume of gas 

 diminishes equally, and only a few hundredths at the tem- 

 perature of 7° [44-6° F.]. In the second case, where the 

 gasses retain their transparency, their bulk does not alter. 

 Hence we may infer, that fluoric acid gas is an excellent 

 mean for indicating the presence of hygrometrieal water in 

 gasses ; and that all contain some, except the muriatic acid 

 No water pre- gas, fluoric gas, and probably ammoniacal gas. For this 

 cipitated from reason, if we expose fluoric gas to a cold of 15° or 19° [5° 

 above or 2*2° below F.], we find no trace of liquid sepa- 

 rated ; while on exposing sulphurous acid gas, carbonic acid 

 gas, &c, to the same degree of cold, water is suddenly de- 

 posited. 

 It hasagreat T\\e dense vapours, produced by fluoric gas in the gasses 

 affinity for that contain hygrometrical water, announce in it a great 

 affinity for this fluid: and indeed it is no exaggeration 

 to say, that water can absorb more of it than of muriatic 

 acid gas, and probably more than two thousand times its 

 Propertiesof bulk. When water is thus saturated with it, it is limpid, 

 water saturated fnnnug^ arK l exceedingly caustic. About a fifth part of 

 what it contains may be abstracted from it by heat ; but, do 

 what we 1 will, it is impossible to get more. It then resem- 

 bles concentrated sulphuric acid : it has its causticity and 

 appearance : like it its boiling point is much above that of 

 water, and it condenses entirely in striae, though it contains 



still 



