so8 Mr. Howard^ Experiments and Observations 
electric by friction. Its specific gravity is from 3263 to 3300. It 
is very refractory : I kept it, for some time, exposed to a degree 
of heat sufficiently strong to oxidize, to a considerable depth, the 
iron crucible in which it was placed, without its having under- 
gone any alteration, except that of having acquired a greater 
degree of intensity in its colour. Its transparency was not at all 
diminished. I think, therefore, there is not the smallest reason 
to allow any probability to the opinion that it ought to be con- 
sidered as a kind of glass. 
Of all substances hitherto known, that with which it seems to 
have the greatest analogy, is the peridot, (the chrysolite of Wer- 
ner,) to which some mineralogists have referred it. The result 
of Mr. Howard’s analysis of it, is nearly the same as that of 
the analysis of the peridot, made by Mr. Klaproth. 
The hardness and infusibility of this substance are nearly 
the same as those of the peridot; but it seems to have a rather 
less degree of specific gravity : that of two very perfect crystals 
of peridot, I found to be from 3340 to 3375. The crystalline 
forms of the substance here described, if ever we should be able 
to determine them, would clear up our doubts respecting the 
analogy between the two substances. If we consider the compact 
part of the specimen now treated of, particularly the strong con- 
nexion that appears to exist between the iron and the transparent 
substance, and the great resistance we experience when we 
attempt to separate them, we cannot help being surprised, that 
almost all the specimens of this mass of metallic iron that 
have been brought to Europe, are in the cellular state already 
d( scribed, owing apparently to the total, or almost total, de- 
struction of the transparent substance. But, besides the fra- 
gility of this substance, the specimen in question helps very 
