J. D. Dana on the Green Mountain Quartzite, 179 
cyanogen derivatives are still unknown, I shall try if it be 
possible to obtain a similar series of reactions among the chlo- 
rine derivatives. Monochloracetic acid should give ethylene di- 
CH 
chloride }_* , and, by a precisely analogous reaction, we 
might expect from the electrolysis of dichloracetic acid acetylene 
tetrachloride | *, In the same manner the electrolysis of 
trichloracetic acid would probably yield dicarbon hexachloride 
Ocl,” 
Art. XXIL—Green Mountain Geology. On the Quartzite; by 
JAMES D. DANA. 
THE quartzite of the Green Mountain region is the most 
remarkable of its rock formations. It has a wide distribution 
The outcrops are smallest to the south, in Connecticut, and 
largest in the southern half of Vermont. In the latter region, 
the quartzite departs somewhat from its habit of isolation, and 
forms, according to the geological map of Vermont in the Report 
of 1861, a ridge, with but small interruptions, over one hun 
miles in length, rising near Bennington, in Bald Mountain, to 
a height of 3100 feet. 
The quartzite has still another peculiarity in usually crop- 
ping out in the vicinity of the great metamorphic limestone of 
* Proc. Amer. Phil. Soc., Jan. 1, 1841; also, Trans. Assoc. Amer. Geol. and Nat., 
1842, p. 482; and Address before the Assoc. in 1844, Am. Jour. Sci., xlvii, 150, 1844 
