78 
Sir H. Davy on a new Substance 
I exposed the body to the action of chlorine in a small glass 
tube ; it absorbed the chlorine, and a substance formed which 
was volatile by heat, and which appeared as a yellow solid ; 
it was soluble in w^ater, and rendered the water of a yellowish 
green colour and strongly acid, the solution when acted upon 
by solution of potassa not in excess effervesced, and afforded 
the peculiar substance. 
The acid formed by the solution of the substance united to 
chlorine reddened vegetable blues by its immediate contact, 
and soon after destroyed them. 
When the new substance was heated in oxygen gas, or 
brought in contact with red hot hyperoxymuriate of potassa, 
it seemed to undergo no change. 
M. M. Desormes and Clement had stated, that, when the 
substance is combined with the metals, metallic oxides could 
be obtained from the solutions ; I suspected that this depended 
upon the presence of moisture, or upon oxygen derived from 
the air, and experiment justified my suspicion. 
I heated the substance with iron, mercury, tin, zinc, and 
lead, out of the contact of air ; it united to them without any 
violence of action, and formed compounds fusible at a mode- 
rate heat, and volatile at a higher temperature. All the com- 
pounds, except that of zinc, which was white, were coloured 
of different shades of red brown, red and orange ; the com- 
pound it formed with tin was of a deep orange, that with iron 
of a bright red brown, that with lead a bright orange, that 
with mercuiy an orange still more approaching to red, and 
which, when crystallized, was bright crimson. 
The compound of iron and the substance, when exposed to 
an alkaline solution, immediately deposited black oxide of iron ; 
