and Polarization of Heat. 161 
riments, of which the following is a brief summary, seem to in- 
dicate. The coincidence has generally been more perfect, as the 
steadiness of the source of heat admitted of more accurate com- 
parison. The indications in the same line are alone intended to 
be compared, as they are expressed in degrees of the multiplier, 
the absolute amount of which would vary in different experi- 
ments. The interposed film of mica No. 1., is that mentioned in 
(54), as giving a red of the second order when placed between 
the polarizing and analyzing plates crossed ; the film No. 2. gave 
a plum-red of the first order under the same circumstances. 
Increase of Intensity of Extra- | Decrease of Intensity of Ordi- 
Mica ordinary Pencil, by the De- nary Pencil, by the Depolariz- 
Plate polarizing Action of the In-|ing Action of the Interposed 
* | terposed Crystal. Crystal. 
E2 
Source of Heat. 
F202 
Number of Number of 
5 D f 5 Degrees of 
pitge? Multiplier. poner Multiplier. 
Mercury below 500°, No. 2 5 0.23 6 0.26 
No. 1 4 0.46 4 0.82 
No. 1 4 0.35 0.55 
No. 1 4 0.51 4 0.52 
No. 1 4 0.5 5 0.78 
Brass about 700°, No.2| 4 Daa 5 ie 
No. 2 q 0.75 7 0.70 
0.545 
2.14 
2.52 
: 2.13 
Incandescent Platinum, 2.50 
232 
: 1.00 
Argand Lamp (with 1.74 
chimney.) pace a ee 
1.37 
VOL. XIII. PART I. x 
