426 INTRUSIVE ROCKS OF THE DISTRICT OF MONTREAL. 
TABLE OF OBSERVATIONS—( Continued.) 
Tem- Average | Average 
iad 
fo} 
No.| Date. | Hour. | pera- 3 aa radu, per 0° per| per 0° ez Remarks. 
ture. |S 0 $ ‘| 100 feet. | per foot.| £ 
a s.2 = 
137 Ta 18 |12.0 18° 11 in. Fol MIEN |) loasese alle eas008 NE 
188 cs 2.0 18 aE) Ih. opséao lhe ascosa ans 
Seen 6 AGE | 16 “  {—.0010 -000812 | .00000812% ... 
Feb, 19 19 AM.| 10 «<  }—.0080 -000600 | .00000600) ... 
141| 56 PM.| 16 e —. 0030 -000689 | .00000689% ... 
142 se 9.30 * 10 —.0065 .000750 | .00000750} E 
143|Feb. 20 E FEIN AO) I 23.0] BE AUUSTD I aol dca Sib 
144) =< 9:30) | 27 ONE AOOSOMN S| jicckasen che Ri aeccde w |Moves slowly. 
145 se {12.20 “ 30 SE OOTOM cus Rates E 
146 Ss le°e a og « 1+ .0100 -000750 | -00000750) w 
147 se 6 PM.| 34 € + .0120 .000765 | .00000765) Ww 
148|Feb. 21 {8 A.M.| 20 |121n.}+.0010 -000750 | .00000750) =E 
149 f 12.0 34 ‘id +.0120 -000765 | .O0000765) ... 
150 3 2 P.M. 38 | i po PAY) [= Saciine ore wee 
151 @ Aina’ 37 “ 1+.0140 .000757 | .00000757) ... {Ice dry. 
352|Feb. 22 {12.0 37 # SP OUP fb ssoas HEE 2 Seeciana Sa 
153|Feb. 28 |12.0 32 “ -+.0110 -000750 | .00000750) ... 
154| Feb. 24 )12.0 30 ue +.0100 -000800 | .00000800) ... 
155|Feb. 25 {12.0 24, “ $+.0005 -000600 | .00000600) ... 
156 SF 5 P.M. D4 ss +.0005 -000600 | -00000600) ... 
157 es. LOPS 17 4+ .0004 -001060 | -00001060) ... 
158/Feb. 26 |8 A.M. | 12 t—.0072 -000600 | .00000600) N E 
159 se 9.30 “ 22, | SE eh OOGOM A waseeneeer Hull becctes eid 
160 Sr 5 P.M.| 30 + .0070 -000700 | -00000700) ... 
161\Feb.27 |8 A.M.| 34 | “ + .0120 :000765 | .000007654 S W 
12.0 | 45 Sead PACT OAD IN ep as nee oh secu. ... |Hxposed ice to sun. 
ate 28 {12.0 84 | “ #+.0120 | .000765 | .000007G5] Ss w |Average expansion, 
| “ | | 00000741. General 
average, 00000763. 
ON THE INTRUSIVE ROCKS OF THE DISTRICT OF 
MONTREAL.* 
BY T. STERRY HUNT, F.R.S. 
CHEMIST AND MINERALOGIST TO THE GEOLOGICAL SURVEY OF CANADA. 
At the close of my Report for 1856, I had occasion to call atten- 
tion to the composition of some varieties of intrusive rock, occurring 
n the vicinity of Montreal, and locally known as white traps. These 
rocks, which are sometimes compactly crystalline, at others are por- 
phyritic, the base being dull and earthy in aspect, and enclosing 
crystals of feldspar. My analyses showed these rocks to be essen- 
tially composed of a feldspar approaching orthoclase in composition, 
with occasional admixtures of a silicate of alumina and alkalies 
decomposable by acids, together with carbonates of lime, magnesia, 
and oxyd of iron. These carbonates were sometimes entirely wanting, 
but in other varieties of the rock equalled five or six per cent. In 
2 From the Report of Progress for the year 1858. 
