278 Scientific Intelligence. 
enumerated, it became interesting to ascertain what effect was pro- 
duced by each of these forces acting separately, and which of them 
was chiefly influential in developing the doubly refracting arrangement 
exhibited by the substances that possessed it. 
The force of compression was undoubtedly the agent in forcing the 
i m 
& question has no bearing upom our present subject, I have not at- 
tempted its solution. 
Without expecting any very interesting result, I submitted to exam- 
ination several of the soft solids which possess double refraction, such 
as bees’ wax, oil of mace, tallow, and almond soap. The last of these 
substances, though in common use, is a very remarkable one. Owing 
to its particles not being in optical contact, it has a fine pearly lustre, 
and may be drawn out into long and slender strings. Upon laying a 
portion of it on glass, it hasa quaquaversus polarizing structure, with @ 
tendency to form circular crystals; but when it is drawn out into 
strings, and laid upon glass, these strings have neutral and depolarizing 
axes, like the streaks formed by compression and traction. In the 
present case it is by traction alone that this crystalline arrangement of 
the particles is produced. ‘ , 
In oil of mace and tallow a similar effect is produced by compression 
and traction. With bees’ wax the de olarizing lines are still better 
displayed, and the effect is considerably increased by mixing the bees 
f rosi 
the preceding experiments place it beyond a doubt that the opti- 
cal or crystallographic axes of a number of minute particles eo 
e i to ac 
d e traction into the same direction, so as to 
upon light like regular erystals, it became interesting to discover r 
of phe which certainly could not have been anticipate 
from theoretical principle with which we are a ed. T 
primary force, and ji d the only apparent one exerted in 
experiments, is a mechanical force; but it is not improbable that @ 
but ev 4 
electricity was the agent in producing the phenomena under ee 
eration. In subjecting asparagine to compression and traction, 
he experiments with soft solids, but especially those made < 
the almond soap, exclude the supposition that the electricity of beats ; 
is the cause of the crystalline arrangement of its particles; thoug 
is not improbable that the sliding of the particles upon one another; af 
produced by traction, and their mutual separation, as in the ease 
