on the Nature of certain Bodies. 79 
If it be excluded from air and heated to whiteness in a tube 
of platina, exhausted after having been filled with hydrogene, 
it is found very little altered after the process. Its colour is a 
little darker, and it is rather denser ; but no indications are 
given of any part of it having undergone fusion, volatilization, 
or decomposition. Before the process its specific gravity is 
such that it does not sink in sulphuric acid ; but after, it ra- 
pidly falls to the bottom in this fluid. 
The phenomena of its combustion, are best witnessed in a 
retort filled with oxygene gas. When the bottom of the 
retort is gently heated by a spirit lamp, it throws off most 
vivid scintillations like those from the combustion of the bark 
of charcoal, and the mass burns with a brilliant light. A sub- 
limate rises from it, which is boracic acid ; and it becomes 
coated with a vitreous substance, which proves likewise to 
be boracic acid ; and after this has been washed off, the 
residuum appears perfectly black, and requires a higher tem- 
perature for its inflammation than the olive coloured sub- 
stance ; and by its inflammation produces a fresh portion of 
boracic acid. 
In oxymuriatic acid gas, the peculiar inflammable substance 
occasions some beautiful phenomena. When this gas is brought 
in contact with it at common temperatures, it instantly takes 
fire and burns with a brilliant white light, a white substance 
coats the interior of the vessel in which the experiment is 
made, and the peculiar substance is found covered by a white 
film, which by washing affords boracic acid, and leaves a 
black matter, which is not spontaneously inflammable in a 
fresh portion of the gas ; but which inflames in it by a gentle 
heat, and produces boracic acid. 
