724 
my words must therefore have been an incorrect one when I supposed that 
with my acknowledgment of the error I mentioned the test proposed by me 
in September last here before the Society. I certainly have been under the 
impression that I alluded to them in writing to him at that time. In this 
point then, I have done Professor Morton an injustice. I must still rely on 
my recollection of what I wrote in that letter, but I do not think I alluded 
to Foucou’s article at all in writing to him. I think, if Professor Morton 
would look at my letter again, he will see that I alluded to Fouqué’s 
article. It would have been absurd for me to have appealed to 
Foucou’s article as that was a geological one, and dealt only with the 
matter of the occurrence of these natural gases. The article of Fouqué, 
which follows it in the Comptes Rendus, on the other hand speaks of the 
analysis of these gases, and gives equations for such analysis. So what Pro- 
fessor Morton says in italics, viz.: that the article of Foucou referred to 
‘‘contained no formule whatever,’ is true, but has no bearing upon the 
question at issue. I have alluded in every paper which I have published 
on this matter, including those in Professor Morton’s hands at the time of 
his first writing, to Fouqué’s formulas and his article, found in Comptes 
Rendus, Vol. 87, p. 1048, and not to Foucou’s article, found just before it 
on;page 1041. In my last paper, read here on April 5th, I quote Fouqué’s 
language on the subject just as it appears in the original French, and 1 
think the words are capable of but one interpretation, viz.: that which J 
gave them. That Fouqué was in error, and that I fell originally into the 
same error, does not make me guilty of a willful prevarication in this matter 
of quoting Fouqué. 
Professor Morton says that ‘‘ Fouqué’s formule are in fact perfectly cor- 
rect, and so are his results, his only fault lay in failing to perceive that 
hydrogen might be regarded as a lower member of the marsh-gas series, 
and thus find a place in his general equation.” 
Professor Morton, in calling attention tomy errors, seems to me to be 
willing to let Fouqué off much too easily. His fault is greater than that 
here indicated. Fouqué literally translated says, ‘‘a mixture of these car- 
bides with free hydrogen prevents this condition from being realized. It is 
therefore easy to recognize if a mixture of gaseous hydrocarbons consist ex- 
clusively of carbides of the formula Cn H2n + 2.’ He therefore not only 
‘fails to perceive that hydrogen might be regarded as a lower member of 
the marsh-gas series,’’ to use Professor Morton’s words, but says distinctly 
that its presence interferes with the realization of an equation character- 
istic of the marsh-gas hydrocarbons as a series. 
I have no desire to shield myself behind Fouqué’s faults, but I wish to 
be given credit for a faithful interpretation of his language, and for a wil- 
lingness to acknowledge my errors when they are pointed out. 
The Secretary exhibited by permission of Mr. Lorenz, 
Chief Engineer of the Reading R. R., the stone slab from 
the Ellengowan Colliery shaft, bearing the Batrachian foot- 
