Scientific Intelligence. 421 
SCIENTIFIC INTELLIGENCE. 
I. Cuemistry anv Paysics. 
1, article! mension of polychroism in crystallized substances.— 
SENARMONT has communicated to the Academy of Sciences the results 
f acaba upon this subject which are very unexpected and im- 
portant. ‘The capital fact which the ips has discovered is, in his 
own words, expressed a s follows: a coloring matter disseminated 
tallizations in pur ay nevertheless communicate to it in the 
highest degree the properties of polychroism, ane a gy of absorb- 
Ing action comp | not superior to tha substances naturally 
colored in which it shows itself in the most a gp manner.’ 
proof of the correctness of this assertion, 1 the author exhibited large 
crystals of nitrate of strontia formed in a concentrated tincture of cam- 
peachy wood tendered purple by a few rops of ammonia. In these 
crystals white light developed by transmission under certain incidences, 
a red color, and “under others a blue or violet. Observed with a doubly 
refracting prism the crystals gave two images, the one red and the other 
dark violet, according to the thickn ness, and these images exchanged 
their colors, passing through ideatiiys as the crystallized plate was made 
to turn in its own plane. Two similar and perfectly transparent lam- 
ine superposed gi a parallel sian allowed a portion of the inci- 
dent white light to pass with a purple color; superposed with a right 
angled area they arrest the light like tourmalines, or at least re- 
duce it to a violet shade so obscure that we may consider the light as 
extinct. Finally we may detach from these crystals perfectly pure and 
homogeneous plates slightly inclined to the optic axes. By placing 
late very near the eye and using white natural rate we see 
ae. | in the direction of each of the. axes, a brilliant orange spot 
ltaversed by a hyperbolic branch. These open to the right and left of 
the principal section under the form of curved brushes composed of 
two equal parts of violet and sombre blue and dividing the field of the 
Plate into two regions in which the purple tints regularly degenerate on 
th sides of their common limit. The dark tufts interrupted by the 
luminous spot are moreover fringed towards the point with a little yel- 
low and blue, colors which are altogether local, and which arise mani- 
festly from the dispersion of the optic axes corresponding to the differ- 
ent colors. hese phenomena are characteristic of polychroism in 
crystals = a4 optic axes, and perfectly similar to those which Brew 
The Rathoe ened similar results with other coloring matters and 
other crystals, and p romises more ample details hereafter.— Comptes 
» XXXViii, 101, Janvier, 1854. 
[Note.—The results obtained by Senarmont clearly demonstrate that 
the existence of polychroism in crystals by no means necessarily im- 
Plies their chemical SS iecenait, since Bs, polychroism may in any 
Szconp = Vol. XVII, No. 51.—May, 1 54 
