172 DR. FARADAY’S EXPERIMENTAL RESEARCHES IN ELECTRICITY. (SERIES XXX.) 
3405. It so happens, that the size of the bismuth and the force of the magnet 
place the observations between those of the crystal before obtained, and the results 
show how parallel the three are in their direction and nature. These seem, also, to 
be in a line, straight or nearly so. The force is at 70° equal to 159, and at 210° only 
to 105, being a loss of 54 for the 140° of difference between the two temperatures. 
If we take the loss of power for equal differences, at the same temperature, the 
results are very accordant. 
Torsion force. 
Loss of power. 
At 90° 
At 207° 
0 
Bismuth crystal, A . . 
135 
90 . 
. 45 or ^ of the power at 90 
Bismuth crystal, C , 
167 
112 . 
. 55 or ^ of the power at 90 
Bismuth compressed, D. 
149 
107 . 
. 42 or ^ of the power at 90 
3406. The compressed bismuth data are few in number, and do not afford so good 
an indieation as those obtained with the crystal; but the results are such as to 
give an additional reason to those advanced by Tyndall, that the magnetic force 
in compressed bismuth is of precisely the same nature in disposition, &c. as in cry- 
stallized bismuth. I have endeavoured to obtain some additional physical evidence, 
of another kind but in the same direction, by subjecting crystallized and compressed 
bismuth to the slow dissolving aetion of dilute nitric acid; but though signs of 
crystalline structure appear in both cases they are not clear or satisfactory. 
3407 . Tourmaline . — This substance, as a paramagnetic crystal, was then submitted 
to the action of heat, the crystal employed being that already described (3377-) ; 
its upsetting angle was 90°. A series of observations with the crystal in water was 
made, extending from 39° to 206°, which are entered in the plate of measurements as 
“Tourmaline crystal I.” A second series was made with this crystal in oil, the 
temperatures reaching from 79° to 289°; they are entered as “Tourmaline crystal K.” 
A third short series with the crystal in brine and extending from 7° to 69°, is entered 
as “ Tourmaline crystal L.” These results are recorded, not with the torsion numbers 
obtained, which, though occurring with the silver torsion wire, ranged from 640 to 
1200 degrees of force, but in other numbers which conveniently entered within the 
range of the table adopted, and which were obtained by reducing the experimental 
results proportionately. It will be understood, of course, that the different entries in 
the diagram offer no absolute comparison between one body and another, that not 
being possible for equal bulks or weights of the substances, in a table like the present ; 
but only a result for each particular body during change of temperature, the source of 
magnetic power and the measure of torsion force remaining irivariable for the time. 
3408. The precedence which the tiiermometer takes of the body (3397.)3 'S here 
very manifest in the first observations of K. The progression of the numbers is 
generally good, either with rising or falling temperatures. The magnetic force in 
the crystal diminishes continually with increase of temperature ; there is no change 
of sign. The loss of force between 7° and 289° is nearly half the force possessed by 
the crystal at the lower temperature; and, therefore, almost as much as that left at 
