70 REPORT— 1840. 
sulphurous and arsenious acids, and have been found to destroy all 
vegetation for miles around the copper works, without affecting animal 
life in the slightest degree. By bringing the escaping fumes in contact 
with steam, and forcing it through burning charcoal, or subjecting it 
only to a great pressure in contact with steam, the new solid compound 
was deposited on the cool surfaces of the chambers connected with the 
calcining furnace. It was deposited in beautiful erystallized leaves or 
tables, perhaps belonging to the same class as Wohler’s dimorphic 
modification of the crystallization of arsenious acid, the regular form 
of which belongs to the octahedron. It was found to consist, in 100 
parts, 
of 68:250 Arsenious acid. 
27°643 Sulphuric acid. 
3°029 Protoxide of iron. 
0-420 Oxide of copper. 
0°656 Oxide of nickel. 
99:998 
Corresponding to 51-741 Metallic arsenic. 
11:095 Sulphur. 
2°339 Iron. 
0°336 Copper. 
0°516 Nickel. 
33°971 Oxygen. 
99-998 
These crystals attracted moisture from the air with great rapidity and 
with evolution of heat, corroding animal and vegetable substances as 
powerfully as concentrated sulphuric acid. Their taste was pure, but 
powerfully sour, similar to sulphuric acid, and, dissolved in water, the 
remainder of 100 parts of these crystals was 17-436 grains only. The 
shape of the crystals was perfectly retained, only their appearance was 
changed from transparent into opake. Their chemical composition 
was found to be, 
16°778 grains of Arsenious acid. 
0°656 Oxide of nickel. 
17°434 
What the water had dissolved consisted of 
51°472 Arsenious acid. 
27°643 Sulphuric acid. 
3:029 Protoxide of iron, 
0-420 Oxide of copper. 
82-564 grains. 
One of the remarkable changes during the formation of this com- 
pound, was the conversion of sulphurous acid into sulphuric acid, as 
well as the presence of iron, copper, and nickel in a deposit from 
gaseous matter. No other definite compound of arsenic acid with 
another acid seems to be known, except those with the organic tartaric 
and paratartariec acids. 
