23 
composition will be seen if we in both cases take the 
atomic weight of carbon as 6. 
Hartit. Tekoretin. 
87.47 85.89 
12.04 12.81. 
Again Gerhardt 1 commits the same error, but in 
a different way. On noticing Scheererit (Konlit) he gives 
the composition in one hundred parts as obtained by 
Kraus, who took the atomic weight of carbon as 6.125, 
but affixes to this a formula in which it is taken as 6: e. g. 
nC 2 H 
Carbon 92.45 92. 3 
Hydrogen 7.42 7. 7 
Tekoretin, Phylloretin and other resins are noticed 
in the same way by Gerhardt. 
Lowig in his ^Organic Chemistry” has many similar 
errors. The same oversight is also common in works 
on mineralogy. 
COMPARISON WITH OTHER SIMILAR 
FOSSIL RESINS. 
Let us now compare the result which we have ob¬ 
tained with the composition of several similar fossil re¬ 
sins. Those analyses which were made when the atomic 
weight of carbon was held to be 6.125 we have recal¬ 
culated. 
The four substances which bear perhaps the nearest 
relation to that which we have analyzed, are Fichtelit, 
Hartit, Tekoretin and Phylloretin. Their composition in 
one hundred parts is 
1 Traite de Chemie Organique, Tome quatrieme. p, 398, 
