318 The American Geologist. November, i»97 
Silica Si O2 41.16 per cent. 
Alumina AI2O3 6.60 " 
Iron Calculated as Fe 24.26 " 
Magnesia Mg O 19.03 " 
Lime CaO 4.34 " " 
Nickel Calculated as Ni 2.26 " 
Sulphur S traces 
Total 97.65 per cent. 
In the above analysis all of the compounds appear in tjjo 
correct chemical combination with the exception of iron and 
sulphur. Sulphur should appear as FeS, but the small amount 
obtained made such estimate impracticable. A part of the 
24.26% of iron -should be estimated as FeO and also a part as 
FesOa which will then bring the analysis to the proper total 
amount. 
The lacking 2.35% should properly be accounted for in this 
way. 6.89% of iron disposed of in this way satisfies the chem- 
ical proportions. 
EDITORIAL COMMENT. 
The Geological Chronology of Renevier. 
There is published in the Compte Rendu of the sixth ses- 
sion of the International Congress of Geologists, Zurich, 
April, 1897, an extended review of geological stratigraphy, 
by Prof. E. Renevier, of the University of Lausanne. This 
paper is a re-edition of a previous scheme of the sediment- 
ary formations, and hence it embodies the results of long 
study on a subject to which the author has devoted much 
labor. It deserves, therefore, to be received with a cordial 
welcome, and despite its errors, if such it has, the geologists 
of the world will render their gratitude to Prof. Renevier for 
a sincere and persistent attempt to systematize the strati- 
graphic nomenclature of their science. 
It goes without saying that it is vain to attempt to satisf}^ 
all, in such a work. There are so many special phenomena, 
viewed by so many different geologists, from so many points 
of view and under so varied opportunities of reaching the 
truth, that much confusion and even of contrariety of opinion 
have arisen, a fact w^hich sometimes is plainly reflected from the 
