on a mineral Production found in Devonshire. i6‘i 
V. General Observations. 
I have made several experiments with the hope of ascer- 
taining the nature of the acid matter in the water ; but from 
the impossibility of procuring any considerable quantity of the 
fossil, they have been wholly unsuccessful. It is, however, 
evident, from the experiments already detailed, that it is not 
one of the known mineral acids. 
I am disposed to believe, from the minuteness of its propor- 
tion, and from the difference of this proportion in different 
cases, that it is not essential to the composition of the stone ; and 
that, as well as the oxide of manganese, that of iron, and the 
lime it is only an accidental ingredient, and on this idea the pure 
matter of the fossil must be considered as a chemical combina- 
tion of about thirty parts of water and seventy of alumine. 
The experiments of M. Theodore de Saussure on the pre- 
cipitation* of alumine from its solutions, have demonstrated the 
affinity of this body for water ; but as yet I believe no alumi- 
nous stone, except that which I have just described, has been 
found, containing so large a proportion of water, as thirty parts 
in the hundred. 
The diaspore, which has been examined by M. Vauquelin, 
and which loses sixteen or seventeen parts in the hundred by 
ignition, and which contains nearly eighty of alumine, and only 
three of oxide of iron, is supposed by that excellent chemist to 
be a compound of alumine and water. Its physical and chemical 
characters differ however very much from those of the new 
fossil, and other researches are wanting to ascertain whether 
the part of it volatilized by heat is of the same kind. 
* Journal de Physique, Tom. LII. p. 280. 
Y 
MDCCCV. 
