on different Coml'mations of Fluoric Acid. 385 



^fcen made, barom. 30-5, therm. 50, -J^ of a cubic inch of 

 Water were introduced intd a tube over mercury, and the 

 gas, in portions of 5 cubic inches at a lime, was added until 

 100 cubic inched had been absorbed, when the water was 

 apparently saturated. This acid was of the sp. erav. 1-77. 



The property which sulphuric acid has of absorbmg fluo- 

 boracic acid gas has already been noticed. I found that 

 I cubic inch of sulphuric acid, of the specific gravity 1'85, 

 Condensed 25 cubic inches of the gas, or SO tiineS its 

 volume. The compound acid was strongly fuming, and 

 appeared more tenacious than pure sulphuric acid, y'et not 

 nearly so much so as that compound of the two which di- 

 stds over durmg the latter part of the operation of making 

 fluoboracic gas. 



This latter compound has some peculiarities. It is so 

 tenacio;is that it flows very slowly. Jt appears to be 

 far more volatile than pure sulphuric acid. When poured 

 into water, a dense white precipitate is formed, the exact 

 nature of which I have not yet satisfactorily ascertained ; 

 but which is not produced by the direct compound of sul- 

 phuric acid, and the fluoboracic. 



Sect. IV. On the Comhinaticns of Fluoboracic Acid Gas 

 and Ammoniacal Gas. 



M. Gay Lussac has combined fluoboracic acid eas with 

 ammonia. He states, that equal volumes of the two gases 

 condense each other*. This I have found to be the case, 

 and I have also found that fluoboracic acid gas condenses 

 twice and even three times its volume of the volatile alkali. 

 The compound observed by M. Gay Lussac is solid, white, 

 and opake, like the ammoniacal salts. The combination* 

 I have obtained are liquid, transparent, and colourless, like 

 water, though they are entirely free from this fluid. They 

 were made by the direct union of the two gases. Five 

 cubic inches of ammoniacal gas were added lo the same 

 volume of the fluoboracic gas contained in a small jar over 

 dry mercury. There was a complete condensation of both, 

 and the solid salt was the result. Five cubic inches more 

 of ammonia were introduced. The whole was quickly 

 absorbed, and the solid salt was converted into the trans- 

 parent fluid. Five cubic inches more were added, which 

 too were slowly absorbed, but without any change of 

 form. 



The solid salt volatilizes in close vessels unaltered, oa 

 the application of a gentle heat. 



• Vide M^m. d'/lrtueil, tome ii. 



Vol. 40. No. 175. Nov. 1812. B b Both 



