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Chemistry and Physics. A15 
Four discs and one square were next taken from two transparent 
crystals of the spar, and suspended successively between the poles. 
e were by no means prepared for the reply given to these experi- 
= in each of the five cases the optical axis set itself distinctly 
axial, 
— 
The balance sheet of our inquiries up to the present time is this; out 
Projection of the optical axis lies in the same direction as the bar; both 
therefore work together, and both strive, in virtue of the two properties 
mentioned, to attain the equatorial position; they do not attain it, how- 
ever; the bar stands almost axial. 
Structure, we thought it might be destroyed by reducing the mass to 
powd 
4 straw horizontally, into each end of which a bit of crystal was thr 
d nosafe conclusion. Co 
te 
exactly suited to our purpose ; 
