142 Miscellaneous Intelligence. 
When taken from the camera the proof is to be placed upon a plate 
placed between. 
The paper for the positive proof should be very stout and as smooth 
as possible. Prepare a solution of 3 parts water saturated with com- 
mon salt and 10 pts. distilled water; upon this float the paper for two or 
irected. In this way a quantity may be prepared in a short time. 
The positive paper is to be preserved in the way directed for the other, 
but must not be kept more than one or two weeks, or it will lose its 
delicacy and become discolored. 
may now GX- 
amined by daylight, and the action of the hyposulphate watched. 
Gradually the lights become more brilliant, and the shades pass from a 
dirty red to a bistre and finally come to resemble those of an aquatint., 
When the desired tint is reached, the operation is stopped and the salt 
removed by soaking in water for five or six hours to a whole day. 
Several proofs can be immersed at the same time in the hyposulphate, 
and those which do not stand its action for two hours must be rejected. 
The operations although in appearance complicated, are in reality quite 
simple and of easy execution. .C.5. 
7. Report on the Aurora Borealis.—Aurores Boréales, 1 vol., 8vo. 
Accompagné d’un Atlas de 12 planches in folio; par MM. Lorrin, 
Bravais, Lin.iend6k, et SrtsestROM.* 
see following notice of this great work is from M. Bravais. He re- 
marks :— 
- [have divided my general review of the subject into eight paragraphs. 
In the first, | examine the much controverted question, as to the nature 
-*This is one of a series of twenty-six volumes of large Svo, and seven folio 
atlases, published as the results of Voyages de la Commission Scientifique du 
Nord, en Scandinavie, en Laponie, au Spitzburg et aux Ferée, pendant les annees 
