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400° _ Foreign Literature and Science. 
ing it off, and another, for which the first may easily be sub- 
stituted, for receiving a bent tube which conveys the steam 
out of doors. The exterior vessel does not rise higher 
than the interior, but it descends lower and rests upon the 
grate. ie & 
From an experiment of the reporters, one part of char~ , 
- coal is sufficient to vaporize 9.42 parts of water from the 
freezing point. Now, according to theory, charcoal can 
evaporate only 10.8 times its own weight of water, neuge it 
appears, that, taking into consideration the heat communica- 
ted to the vessels themselves, the actual loss of heat is only 
;'s which is very trifling. “ , 
The superiority of this instrament for culinary purposes, 
especially for soups, vegetables, &c. is attested by these sei- 
entific reporters, who assert that they intend habitually to 
use it, as itis attended with an economy of time, and fuel, 
an improvement in the quality of the food, and a certainty 
of success. 
46. Sait Petre.—M. Baffi, an able chemist, born at Per- 
gola, has received from the mee Roy of Egypt, a present 
of 100,000 crowns, and the title of Bey, for having discover-_ 
eda method of making salt-petre by the sun’s a alone, 
without the aid of fire. ore this discovery every cwt. 
of salt-petre cost the Vice Roy ten crowns, an expense 
which is reduced by the new method to one crown. he 
manufactory erected by M. Bafli on the great plain of Mem- 
phis furnished last year, to the Egyptian army, 3,580,000 
ibs. of salt-petre. 
% 
47. Dr. Brewster bas published (in the Trans. of the 
Cambridge Philos, Soc.) an interesting paper on certain 
peculiarities in the structure and optical properties of the 
Brazilian topaz illustrated by colored figures:—also (in the 
Trans. of the R. Soc. of Edin.) a description and drawings 
of a Monochromatic lamp with remarks on the absorption 
of the prismatic rays, by coloured media—also an account 
of the native hydrate of Magnesia discovered by Dr. Hib- 
bert in Shetland, and, in a separate pamphlet, additional ob- 
servations on the connexion between the primitive forms of 
minerals and the number of their axes of double refraction. 
r. Brewster’s researches on the optical properties of min- 
erals continue to present very extraordinary results. 
oii — ~ Pe 
MM, 
