which becomes a violet coloured Gas by HM, 87 
substance and a gas which is not inflammable, and which does 
not support flame ; and unless the substance is moist, I have 
never been able to discover any other product ; but the minute 
quantity I have employed prevents me from being confident 
on this point. 
It was an object of considerable interest to ascertain the 
proportion in which the new substance combines, as compared 
with that in which the other substances that form acids by 
their action on inflammable bodies enter into union. 
I made several experiments on this subject. 4 grains of 
hydrate of potassa, I found, were saturated by 6.25 of the new 
substance, and 2.8 the quantity of potassium in 4 grains of 
hydrate of potassa is to 6.25 the quantity of the substance, as 
75, the number representing potassium, is to 166. Again, 1 
grain of hydrate of soda required 2.1 grains of the new sub- 
stance for its saturation, and 1 grain of hydrate of soda con- 
tains .578 of sodium, so that supposing the combination of the 
new substance with sodium to contain a double proportion of 
the substance, the number representing the proportion in which 
it combines will be nearly 160. 
Two grains of the compound of the substance with sodium 
decomposed by sulphuric acid afforded 128 of dry sulphate of 
soda, and calculating on this experiment the number is 165.5. 
I have made some experiments on the quantity of the sub- 
stance absorbed by tin, mercury, and lead. Mercury absorbs 
nearly of its weight of the new body to become the crimson 
substance ; from which it appears that it must absorb two 
proportions. 
My experiments have been made upon quantities too small 
to afford very exact results; but they shew that the new 
