723 
Professor Sadtler is here no doubt quoting from memory, and does not 
intend to state what is not true, but as the statement is not only incorrect, 
but by reason of its inaccuracy casts a reflection upon me, I feel bound to 
call for a correction. Professor Sadtler’s letter of December 31st is now 
before me, and the only passage having any reference to the matter reads 
as follows : 
«‘About the formule, I am sorry that my first mistake still stands on 
record uncorrected. I had copied the formule I first used from Foucou’s 
article on analyses of ‘Pennsylvania Natural Gases’ in Comptes Rendus, 
and in my second lot of analyses made for the Survey, I corrected it, and 
corrected the first lot at the same time.’’ This includes every word which 
this letter contains on the matter referred to, and while it may be that Pro- 
fessor Sadtler at the time of writing knew all about the matter, there was 
certainly nothing whatever to imply that such was the case in what he 
here states. On the contrary, when it is known that Foucou’s article, in the 
Comptes Rendus referred to, contains no formule whatever, and that no 
correction of analyses was possible for the simple reason that the correction 
of the error showed any analysts to be impossible except by discovering a 
new method, it will appear that I had good cause to believe that Professor 
Sadtler was entirely in the dark upon the subject. 
As to the assertion that he said in this letter ‘‘that (he) I was proposing 
to rectify the results as first published by the aid of other tests,’’ it is 
simply a lapse of memory on his part, as nothing of the sort exists in the 
letter. 
In a memoir by Fouqué (not Foucou), immediately following that of 
Foucou in the Comptes Rendus, we do find formule in some sort resembling 
those used by Professor Sadtler, but not containing his error. Fouqué’s 
formule are in fact perfectly correct, 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. ~ 
Yours respectfully, 
HENRY MORTON. 
Prof. Sadtler, to whom the letter had been shown previous 
to the meeting, read a written reply to Prof. Morton’s state- 
ments. 
In the letter from Professor Morton just read before the Society, he 
quotes from my paper read here on April 5th, the paragraph relating to the 
correspondence which passed between us about December 31st last, and 
supposes that I was quoting from memory. This is certainly true. I had 
not copied the letter, as it was regarded by me so entirely one of friendly 
correspondence, that I deemed such a step unnecessary. My reco!leciion of 
* As was first pointed out by Mr. Wm. E. Geyer and myself in our paper in the 
Gas-Light Journal, February 16th. 
