ON FLUOR 43 



SECTION VI. 



In order to prevent this, I distilled half an ounce of 

 fluor with 1 oz. of oil of vitriol for five hours. The crusts 

 were separated from the water ; they weighed, after being 

 well washed and dried, 11 grs. ; they were white and very 

 fiocculent ; 32 grs. of siliceous earth were precipitated from 

 the filtered water ; the ley was then evaporated in a leaden 

 vessel, and yielded 80 grs. of salt. 



Glass vessels were no longer to be trusted ; a piece of a 

 gun-barrel furnished with a cover and terminated by a bent 

 tube, intended to serve instead of the neck of a retort, 

 was used in the following experiments, and the distillation 

 was performed in a sand-bath. In this apparatus, to half a 

 drachm of the newly procured ammoniacal salt I added 

 2 drms. of oil of vitriol, and distilled for two hours into a 

 glass receiver containing 1 oz. of water. 



No vestige of a crust could be perceived on the water ; 

 but I saw some earth in the receiver, where the vapours 

 having ascended through the tube came into contact with 

 the wet glass ; and here the surface was become sensibly 

 rough. 



On the addition of volatile alkali, a few flocculi of 

 siliceous earth, amounting only to one-fourth of a grain, were 

 thrown down out of the water. 



Again, I added 1 drm. of oil of vitriol to 1 J drm. of the 

 salt in the same apparatus ; but I now used a receiver of 

 lead containing 1 oz. of water. 



At the close of the distillation, I found no crust on the 

 water which had an unpleasant smell ; and, on the addition 

 of spirit of sal ammoniac, let fall a little grey earth that 

 weighed half a grain. 



