and its Contact Phenomena. 25 
one and the anhydrous nature of the other being factors modi- 
fying the extent of the effect. 
ny chemical changes that may be connected with these 
modifications are represented in the following table of analyses. 
Bae! sonck etre ph temeomee Sin tegen eons, 
Sid, 72°26 
Al,O3 13°59 12-76 12°34 
Fe.0; 1:16 1°07 2-25 
eO 2°18 4:28 4:92 
MnO tr. “08 tr. 
CaO 113 30 55 
MgO 06 
K,O 5°58 5-10 5°53 
Na,O 3°85 3-16 2-84 
TiO. “45 40 27 
H,O “AT 73 72 
100°73 101°06 100°68 
Sp. Gr. 2°65 2°66 2-68 
Quartz. Orthoclase. Albite. Anorthite. Hornblende. Biotite. Magnetite. Titanic Iron. 
2 32°95 32°61 4°83 1°68 *85 
Or, 26°79 30°76 31°01 5°65 Hclaes 5°44 ree! . 
The biotite has the composition (K,Na),(Fe,Mg),AlSi, 
«(= one molecule K and one M of Tschermak) and the 
hornblende will be 11(R SiO,)+Al1,0,. This calculation can 
not claim to be accurate since there are uo data for dividing 
the lime between the anorthite (which is supposed to be com- 
bined with some of the albite to make a triclinic feldspar) and 
the hornblende. It is introduced to show that the results o 
the chemical investigation do not at all contradict the micro- 
Scopic results, since a recrystallization and a rearrangement in 
the proportions between the feldspars, furnishes all the material 
necessary to convert the hornblende into biotite. 
The schists that occupy the area indicated upon the map, 
form portions of Mts. Tom, Field, Willey and Willard, elevations: 
In the vicinity of the White Mountain Notch. Their age is un- 
known. Their reference to the Silurian on account of a sup- 
posed fossiliferous character being based upon an error, it is only 
certain that they are older than both the Albany and the Conway 
granites, both of which intersect them. In composition they 
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