on the Nature of certain Bodies. \\5 



the synthetical proofs of its nature involve more complicated 

 circumstances. 



I found that when equal weights of potassiutJi and boracic 

 acid WL-re healed together in a green glass tube, which had 

 been exhausted after having been twice filled with hydrogen, 

 there was a most intense ignition before the temperature was 

 nearly raised to the red heat ; the potassium entered into 

 vivid inflamination, where it was in contact with the boracic 

 acid. When this acid had been heated to whiteness, before 

 it was introduced into the tube, and powdered and made 

 use of whilst yet warm, the quantity of gas given out in the 

 operation did not exceed twice the volume of the acid, and 

 was hydrogen. 



I could ouly use twelve or fourteen grains of each of the 

 two substances in this mode of conducting the experiment; 

 for when larger quantities were employed, the glass tube 

 always ran into fusion from the intensity of the heat pro- 

 duced during tlie action. 



When the film of naphtha had not been carefully removed 

 from the potassium, the mass appeared black throughout; 

 but when this had been the case, the colour was of a dark 

 olive-bro\\ n. 



In several experiments, in which T used equal parts of 

 the acid and metal, T found tliat there was always a great 

 quantity of the former in the residuum ; and by various trials, 

 I ascertained that twenty grains of patassium had their in- 

 flammability entirely destroyed by about eight grains of bo- 

 racic acid. 



For collecting considerable portions of the matters formed 

 in the process, I used metallic tubes furnished with stop- 

 cocks, and exhausted after being filled with hydrogen. 



When tubes of brass or copper were employed, the heat 

 was only raised to a dull red ; but when iron tubes were 

 used, it was pushed to whiteness. In all cases the acid was 

 decomposed, and the products were Scarcely difilrent. 



When the result was taken out of a tube of brass or cop- 

 per, it appeared as an olive-coloured glass, having opaque, 

 dull olive- brown specks difi'used through it. 



It gave a very slight rflervHscence with water, and par- 

 tially dissolved in liot water, a dark olive-coloured powder 

 separatmg from it. 



The residts from the iron tube, which had been much 



more strongly heated, were dark olive ni some parts, and 



ahnost black iii others. They did not efiervcscc with warm 



water, but were rapidly acted upon by it, and the particles 



II 2 separated 



