108 
they became bands. At the end of the experiment the pres- 
sure had increased to 2f inches mercury. 
To 101 c.c. hydrogen at inches pressure 
•04 c.c. air was added, but no nitrogen lines appeared. 
•16 c.c. air „ „ 
•26 C.C. air „ „ „ „ 
•1 c.c. air the nitrogen green line appeared at the edges only, 
•2 c.c. air the nitrogen green line became much clearer. 
Thus •SG c.c. air =*29 nitrogen in 11-8 c.c. hydrogen 
= 2-5%. 
Therefore at inches of mercury pressure the smallest 
amount of nitrogen that must be present in hydrogen in 
order that it may be detected in the spectroscope is 2-5%. 
Complete Results. 
a. Nitrogen in hydrogen at atmospheric pressure.. Tl% N. 
Nitrogen in hydrogen at 10 J inches „ 3*6% N. 
Nitrogen in hydrogen at 3| „ „ 2-5% N. 
h. Hydrogen in nitrogen at atmospheric „ -25% H. 
c. Nitrogen in oxygen „ „ *8% N. 
d. Oxygen in nitrogen „ „ 4^5% 0. 
“Lower New Red and Permian — Stockport,” by J. W. 
Gray, Stockport Society of Naturalists, and Percy F. 
Kendall, Berkeley Fellow of Owens College. Communi- 
cated by Thomas Kay, Esq. 
These notes are offered as a contribution to the literature 
of a subject which has I'eceived considerable attention from 
Geologists for man}^ years, viz., the relations between the 
Triassic and the so-called Permian rocks. 
The subject is of great interest, by reason of a supposed 
interval of greater or shorter duration between the Palaeozoic 
and Mesozoic Periods occurring between the lower New Red 
Sandstones and the Permian rocks, and corresponding to the 
undoubted organic break which marks the close of the 
Palaeozoic Period. 
The Permian (? Lower New Red) Sandstone is estimated 
