T. S. Hunt on Lithology. 103 
xi }, xiv 6. 
Silica, - . - - - - - - - 59°70 6090 
Alumina, - - - - - - - - ae 24 os 
nme. - - - “ « é é s é E 
Potash, —- - - . - - - - Hn undet, 
Soda, - - - - - - « a a 9° “ 
olatile, - - - - - - - . 993 210 
cero of soda is very small. In xX, on the contrary, the 
arge predominance of soda indicates a composition approaching 
gone a commencement of decomposition, which consists in the 
loss of a portion of silica and alkali, and the combination of 
, Somewhat to the south of Burlington, on the west side of 
ake Champlain, and near to Essex, there is a great mass of in- 
‘vusive rock, found in the slates of the Hudson River formation. 
As described by Emmons, it is interstratified in an irregular 
‘Manner among the layers of the unaltered sedimentary rocks, 
