from the RIVER DEE. 257 
of the 6 grains in muriatic acid, a portion of black matter fepa- 
rated. It weighed 0.2 grains, and was totally diffipated before 
the blow-pipe in a white fmoke. Hence, it muft have been ar- 
fenic. Thefe 1.5 gr. are equivalent to rather more than 1 
grain of metallic arfenic. Thus, it appears, that the 6 grains 
contained 1 grain of arfenic, which explains the whitenefs of 
their colour. The reft was iron. It can fcarcely be doubted, 
that the proportion of arfenic prefent was originally greater. 
Some of it muft have been driven off when the iron oxide was 
heated with oil. 
10, THE infoluble refidue, (No. 4.), was with great difficul- 
ty diffolved in fulphuric acid. When the folution was mixed 
with ammonia, a white powder fell, which weighed 0.8 grains. 
It was accidentally loft, before I examined its properties. But 
I have no doubt, from its appearance, that it was oxide of tita- 
nium. 
11, Tuus, from the roo grains of iron-fand, the following 
conftituents have been extracted by analyfis : 
Black oxide of iron, - ' 98.70 
White oxide of titanium, 12.65 
Arfenic, - - 1.00 
Silica. and alumina, - 1.50 
Total, 113.85 
Here there is an excefs of néarly 14 grains, owing, without 
_ doubt, to the combination of oxygen with the iron and the 
titanium during the analyfis. 
Hap the iron in the ore been in the metallic ftate, the ex- 
cefs of weight, inftead of 14, could not have been lefs than 30. 
For the black oxide is known to be a compound of too metal 
and 
