DECOMPOSITION OF BORACIC ACID. ]<5 



the magnifier, appeared vitreous at the surface, and evidently- 

 contained a fixed acid. 



These circumstances seemed distinctly to show the de- The combust^ 

 composition and recomposition of the boracic acid ; but as Jfj^J 8 "^ 

 the peculiar combustible substance was a nonconductor of in thin films, 

 electricity, I was never able to obtain it, except in very thin 

 films upon the platina. It was not possible to examine it3 

 properties minutely, or to determine its precise nature, or 

 whether it was the pure boracic basis ; I consequently en- 

 deavoured to apply other methods of decomposition, and to 

 find other more unequivocal evidences upon this important 

 chemical subject. 



I have already laid before the Society an account of an 

 experiment*, in which boracic acid, heated in contact with 

 potassium in a gold tube, was converted into borate of po- 

 tash, at the same time that a dark coloured matter, similar 

 to that produced from the acid by electricity, was formed. 

 About two months after this experiment had been made, 

 namely, in the beginning of AHgust, at a time that I was 

 repeating the process, and examining minutely the results, 

 I was informed, by a letter from Mr. Cadell at Paris, that 

 Mr. Thenard was employed in the decomposition of the bo- B • ., 

 racic acid by potassium, and that he had heated the two decomposed 

 substances together in a copper tube, and had obtained bo- by Thenard * 

 rate of potash, and a peculiar matter concerning the nature 

 of which no details were given in the communication*!". 



That the same results must be obtained by the same me- 

 thods of operating, there could be no doubt. The eviden- 

 ces for the decomposition of the boracic acid are easily 

 gained ; the synthetical proofs of its nature involve more 

 complicated circumstances. 



I found, that, when equal weights of potassium and bo- Potassium and 

 racic acid were heated together in a green glass tube, which boracic acid 

 had been exhausted after having been twice filled with hi. th e ,! r te tos ** 

 drogen, there was a most intense ignition before the tempe- 

 rature was nearly raised to the red heat ; the potassium en- 

 tered into vivid inflammation, where it was in contact with 



• Phil. Trans. Part II, 1803, p. 343 ; or Journal,, vol. XXI, p. 375. 

 t Gay Lussac and Thenard's paper is given in our last volume, p f 260, 



the 



