Editorial Comment. 379 
most cases impossible to determine, and even observers like 
Rosenbusch and Zirkel have recognized the hopelessness of 
the attempt by applying to these vitreous components such 
vague names as "undeveloped ground-mass," "amorphous ma- 
trix," interstitial paste, etc. 
We enter here upon a department of petrographical science 
which presents much that is strange and mysterious. These 
incipient forms have been carefully studied by a number of 
able observers, but though a great deal has been written about 
them — from the time of Vogelsang's splendid monograph to 
recent treatises and devitrification-processes — we are still 
very much in the dark as to their real character. The mode 
of their origination is part of the great secret of crystal life, 
and when once we thoroughly understand the laws which gov- 
ern the formation of these remarkable bodies, one of the most 
important tasks of petrographical philosophy will be accom- 
plished. 
EDITORIAL COMMENT. 
The Philadelphia Meeting of the International Con- 
gress OF Geologists. 
The following official record of the history of the choice of 
Philadelphia, by the International Geological Congress as the 
place for the next meeting, and the subsequent attempt to sub- 
stitute Washington, is inserted in the view of an unfortunate 
misunderstanding which has recently developed. It is hoped 
that it will enable every reader to form an independent opinion 
as to the nature of the considerations and influences brought 
to bear by the representatives of the United States Geological 
Survey, as well as the actual facts regarding the willingness 
and ability of Philadelphia to pro]3erly entertain the congress. 
C. L. Herrick. 
Early in 1885 the year of the last session of the International Geolog- 
ical Congress a form of invitation was signed by the greater number 
of large American institutions of learning and original research, asking 
the International Congress of Geologists to fix the next after the Lon- 
don session in the United States. 
Another form of invitation to hold its sessions in the city of Phila- 
delphia was signed by mayor Fitler, the heads of all the scientific and 
educational institutions in the city and its neighborhood ; the U. S. 
Govt. Officers stationed there, the principal judges, lawyers, bankers, 
merchants, prominent citizens to the number of several hundred, and 
