260 Chronicles of Science. [April, 
position of an important class of minerals; and in another paper 
offers some remarks “On the Scheelite of the Reisengebirge” in 
Silesia, a new locality, which yields this rare mineral in crystals of 
surpassing beauty.* 
Professor vom Rath’s “ Mineralogical Contributions” to ‘ Poggen- 
dorff’ relate to the antimonio-sulphide of lead, called Meneghinite, 
from the silver-lead mine of Bottino in Tuscany ; and to some new 
and rare forms of calcareous spar.} 
The zeolitie mineral called Lerderite, found in the trap rocks of 
Nova Scotia, has been shown by Professor Marsh to be identical in 
composition with Gmelinite.{ Mr. EK. W. Roots announces a new 
locality for the Canadian mineral, Wilsonite;§ and Von Hanthken 
describes the occurrence of Meerschawm in the Lyubicer mountains, 
in Bosnia, where it is found in large fragments associated with 
serpentine, embedded in a conglomerate.|| 
11. PHYSICS. 
Licut anp Heat,—The action of light on chloride of silver has 
been studied by M. Morren. He arranged an experiment in the 
following way. Two bulbs, one containing nitrate of silver, the 
other, chloride of potassium, in equal equivalents, were placed in 
a tube sealed at one end. The tube was then filled with water 
saturated with chlorine gas, and sealed before the blowpipe. By 
agitation, the bulbs were broken, and chloride of silver was thus 
formed in an excess of chlorine water. Exposed to the rays of the 
sun for several days, the chloride of silver remained white as long 
as the liquid retained the yellow colour given to it by the chlorine. 
When the colour disappeared, owing to the action of chlorine on 
the water, under the influence of light, the chloride of silver slowly 
assumed a red-brown tint. The tube being then placed in obscu- 
rity (or in the diffused light of the laboratory), the brown colour 
gradually disappeared, and the chloride of silver reassumed, in all 
its intensity, its original white aspect. Replaced in the sun’s rays, 
the coloration returned, disappearing as before when screened from 
the light. 
Mr. J. Browning, F.R.A.S., has published a paper in the 
‘Chemical News,’ “On the Influence of Aperture in Diminishing 
the Intensity of the Colour of Stars.” Mr. Browning, during 
the late lunar eclipse, had failed to detect either the coppery or the 
* « Zeitsch. d. Deutsch. Geol. Gesell.’ Bd. xix., Heft 3, pp. 493, 496. 
+ ‘Pogg. Ann.,’ 1867, No. 11, p. 372. 
} ‘Silliman’s Journal,’ 1867, No. 132, p. 362. § Ibid., Jan. 1868, p. 47. 
|| Verhand. d. geol. Reichsanst, 1867, No. 10, p. 227. 
