22 
We will now proceed to compare this formula with 
those obtained by others for several of the fossil resins 
already mentioned, viz. with Fichtelit analyzed by Bro- 
meis, with Hartit analyzed by Schrotter, and with Te- 
koretin and Phylloretin analyzed by Forchhammer. 
But first we must allude to a matter which has 
given us no little trouble. 
All the above mentioned resins with the exception 
of Hartit were analyzed when the atomic weight of 
carbon was held to be 6.125, hence too much carbon 
was almost always obtained in an analysis. 
Now in books on organic chemistry, and in chemical 
journals when these fossils are alluded to, this fact 
seems generally to have been overlooked. 
We will give two or three instances out of the very 
many which we have noticed. 
Schrotter 1 who analyzed Hartit compares his re¬ 
sults with those obtained by Forchhammer for Tekoretin, 
and remarks that the two substances are very probably 
identical in composition, and only differ in their melting 
points. We give the results as obtained by each: 
Hartit. Tekoretin. 
Carbon 87.47 87.19 
Hydrogen 12.04 12.81. 
Now if we overlook the fact that in the analysis of 
Hartit the atomic weight of carbon was taken as 6., but 
in the analysis of Tekoretin as 6.125, then Schrotters 
remark seems to be correct. The actual difference in 
1 Ann. d. Phys, u. Chem. Vol. LIX, p. 44 
