795 
of kaolin shown by the calculation has therefore been added 
to the nepheline in extending the table. 
No. I takes the following position in the Quantita- 
tive Classification: 
Class II, Dosalane. 
Order 5, Germanare. 
Rang 3, Andase. 
Subrang, 4, Andose (grad—polmiric.) 
No. II, however, belongs to the next order and is 
domalkalic. Its position in the Quantitative Classification 
is as follows: 
Class I,, Dosalane. 
Order 6, Norgare. 
Rang, 2, Essexase. 
Subrang 4, Essexose (grad—prepolic). 
It is therefore seen that the essexite from the central 
portion of Mount Johnson (No. II) is practically identical 
in character and composition with the essexite of the 
original locality of Salem, Mass. (Analysis IV), while 
the outer andose is poorer in nepheline and has a somewhat 
larger proportion of lime as compared with the alkalies. 
Dykes—A feature in connection with Mount Johnson, 
and one possibly connected with its somewhat peculiar 
structure, is the almost entire absence of dykes. Only five 
small dykes, each only a few inches wide, have been found. 
Some of these are camptonite, while the others, although 
much altered, are apparently solvsbergite. 
Structure—The structure of the mountain and the 
character of the rocks composing it throw some light 
on the question as to where the differentiation took place. 
In course of conversation with the foreman of one of the 
quarries in the essexite on the flank of the mountain, 
the writer was informed by him that Mount Johnson 
consisted of three layers of horizontal rock; a fine grained 
one on top, below which was the coarser grained rock 
of the quarry, and beneath this a spotted variety. Each 
of these layers, he considered went through the mountain 
horizontally and could be seen outcropping at their respect- 
ive levels on every side. The three rocks referred to were, 
as will be recognized, the fine grained essexose, the andose, 
and the transitional rock below the latter, respectively. 
The pulaskite zone he had not noticed, it being at the base 
of the mountain and in many places more or less covered 
