351 
ance, we perceive, is quite lost; and, in the intervening part, the 
gradual departure from a striped, to quite a plain appearance, may 
be observed : whilst frequently the existence of the soft bituminous 
state will appear, from the wavy and contorted directions of fibrous 
stripes, which are indubitably of a ligneous origin. Nor does any 
difference of physical properties exist between this and the ligniform 
pitch-stone already described. With respect to their chemical pro- 
perties, there exists a very close agreement, as will appear from the 
following experiments. 
Mr. Pepys exposed 50 grains of pitch-stone, and 100 of pure 
nitrate of pot-ash, to the same treatment as he had subjected the 
same quantities of opaline fossil wood and nitrate of pot-ash, and 
reported that the phenomena which resulted were precisely the 
same. 
At Menil le Montant, also at St. Ouen, near Paris, and in 
several other parts of France, have been found a stone which is of 
a greyish colour, sometimes mottled with blue on its surface, opaque, 
generally of a tubercular form, and showing at its fracture a slight 
lustre of the greasy kind. It was first described by Delabre and 
Quinquet, who very properly considered it as a new kind of pitch- 
stone ; its hardness, specific gravity, and fracture, as well as its kind 
of lustre, warranting them in this opinion*. It was named, from 
the place where it was first found, M!enilite, and was considered as a 
variety of the pitch-stone, being therefore termed, by some, blue 
pitch-stone ; but it has been supposed by others to belong rather to 
the magnesian genus of stones, such as the pot-stone, steatites, and 
serpentine. 
The experiments of the justly celebrated Klaproth, which induce 
him to consider this fossil, as a variety of the semi-opal, approach- 
ing to flint (feuerstem ) serve strongly to corroborate the opinion I 
* Journal de Physique, Sept. 1787, p. 219. 
