1820.J of different inorganic Bodies. 279 



grammes, must be ascribed to the ammoniacal gas. Thus borate 

 of ammonia is composed of 



Boracic acid 37-95 100-000 



Ammonia 30-32 79-895 



Wa(er 31-73 



100-00 



This qiiantity of water contains 28 of oxygen ; and the ammo- 

 nia, on the liypothesis that it contains a quantity of oxygen 

 proportional to the quantity of acid which it saturates, compared 

 with the other saline bases, contains 14'07 of oxygen, which, 

 multiplied by 2, gives 28-14 ; so that in this salt, as well as in 

 the sulphate and oxalate of ammonia, the water of combination 

 contains twice as much oxygen as the base. The 79-895 of 

 ammonia, with which 100 parts of boracic acid are saturated, 

 contain 37-085 of oxvgen ; and if liorncic acid contain twice as 

 much, it is composed of 74-17 per cent, of oxygen and 25-83 of 

 boron, which comes very near the determination of Davy. The 

 result furnished by the analysis of borate of ammo-iia is still fiu'- 

 iher confirmed by the late analyses of the biborate of magnesia 

 (borucite of mineralogists) in which 100 of boracic acid saturate 

 a quantity of base which contains 18*54 of oxygen ; that is, half 

 tlie number found above. 



I was desirous to contirni this experiment by the analysis of 

 the borates of barytes and lead ; but these salts always gave 

 variable results after a hxiviation continued for a longer or 

 shorter time, by means of which these borates are decomposed, 

 the water carrying off a portion which is at a different degree of 

 saturation from that wliich remains. Besides, the borate ot" 

 barytes precipitated by borax contains always a greater propor- 

 tion of acid than the boiate of soda ; so that this last precipitate 

 is a mixture of borate and biborate of barytes. 



I could have wished to verify these experimeiits on the coni- 

 position of boracic acid by synthesis ; but having no boron nx 

 my possession, 1 was obliged to give up the project. 



Experiments on the 'prohahh,' Conipos/lion cif' Fhiniic Acid, cnlru- 

 fitted J'ro/ii i!s Capaciii/ of Salniuiivn. 



Different chemists have endeavoured to determine the capa- 

 city oi' saturation of fluoric acid by analysing fluate of lime, i 

 may mention Wenzel, Richter, Klaproth, Dalfcon, Thomson, and 

 Davy ; but their experiments have given results so variable that 

 Klaproth, for example, found the capacity of saturation of this 

 acid a third greater than Dalton. Sir Humphry Davy obtained 

 from 100 of the fluate of lime of Derbyshire,' by digesting it 

 fight times successively with sulphuric acid, 175-2 of gypsum. 

 in an analysis of a iluate of lime from the iron mine of Ko,>berg, 

 100 parts <jf the Huate gave me 173 of sulphate of lime. 1 wat. 



