2&8 PFXOMPOSITION OF BORACIC ACID. 



tion of the most instantaneous kind t;;kes place, and the 

 mercury rises with such rapidity half way up the jar, as to 

 raise it forcibly. In this experiment however, the combus-* 

 first oxided, tion of the boracic radical is far from complete. What 

 prevents this is, that the radical is at once converted entirely 

 into the state of a black oxide, the existence of which we 

 then converted think we have perceived ; and the external parts of this ox- 

 acid. C 2CC *^ e P** 8 ' 11 ^ afterwards to the state of boracic acid, they 

 meit, and thus defend the interior parts from the contact of 

 the oxigen. Accordingly to burn them completely it is 

 necessary, to wash them, and place them afr sh in contact 

 with oxigen gas, still at a cherry red heat , but then they 

 burn with less violence, and absorb less oxigen, than the 

 first time, because they are already oxid d : and s + ill the 

 external parts, passing to the state of boracic acid, which 

 melts, prevent the combustion of the interior parts ; so that 

 to convert tliein all into boracic acid, they must be subject-* 

 ed to a great number of successive combinations, and as 

 many washings. 

 Oxigtn fixed, In all these combustions a fixalion of oxigen constantly 

 but do gas takes place, without any gas being disengaged ; and they 

 all afford products so acid, that, in treating these products 

 with boiling water, boracic acid is obtained after suitable 

 evaporation and refrigeration, a specimen of which we pre- 

 sent to the Institute. 

 Bums less vi- Las ly, the boracic radical comports itself in air precisely 

 jjion au-.° m " as ^ n ox, £ eT1 » w i tn tn ^ s difference only, that the combustion, 



is less vivid. 

 The base a From these experiments it follows, that the boracic acid 



« ™ buj,t ' bl « is composed of oxigen and a combustible substance. JKvery 

 »etaiiic. ' thing convinces us, that this substance, for which we pro- 

 pose the name of bore, is of a peculiar nature, and ought to 

 be ranked with phosphorus, carbon, and sulphur : and we 

 presume, that, to acquire the state of boracic acid, it de- 

 mands a large quantity of oxigen ; but, before attaining 

 this state, it becomes a black oxide, 



Note, by the Authors. 

 yermertnals Several chemists have made experiments pn the decompo- 

 sition, 



