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5. CHEMISTRY. 
(Including the Proceedings of the Chemical Society.) 
THE memoirs on subjects relating to pure and applied chemistry 
which have appeared during the last quarter are so numerous, that 
we shall be obliged to confine our notices under this heading to 
such discoveries as are likely to prove of commercial importance or 
are of especial scientific interest. Foremost amongst researches 
which are likely to benefit mankind we may place those which 
have for their object the discovery of a cheap method of preparing 
oxygen gas. ‘T'wo processes haying this object in view have lately 
been brought before the public. The first is by M. Gondolo, who 
has made some improvements in M. Boussingault’s process of ex- 
tracting oxygen from the air by means of baryta. M. Boussingault, 
im 1852, found that on passing a current of air over baryta, heated 
to dull redness, oxygen was subtracted from the air, and binoxide 
of barium formed, and that upon then raising the heat to bright 
redness the oxygen was set at liberty so easily that it might be 
first absorbed and then evolved ad infinitum. M.Gondolo has made, 
in carrying out the detail of the process, certain changes which 
admit of oxygen being prepared upon a manufacturing scale. For 
the porcelain tubes he substitutes iron ones, which may be made 
either of wrought or cast iron. Internally a coating of mag- 
nesia is applied, and externally asbestos, so as to diminish the 
porosity of the tube and the consumption of fuel. These tubes are 
arranged in a brick furnace having dampers, by means of which 
the temperature may be changed at will, and dull redness and 
bright redness easily obtained. To the baryta a mixture of lime, 
magnesia, and a small quantity of manganate of potash is added; 
this prevents fritting of the material. M. Gondolo says that he 
has made 122 alternate operations, and that the atmospheric oxygen 
and nitrogen are easily separated upon an industrial scale; the 
apparatus has been at work during six months, and fulfilled its 
purpose thoroughly. 
The second method by which cheap oxygen can be procured is 
due to M. Mallet, who has just communicated to the Academy of 
Sciences an additional memoir in explanation of a process which he 
published last year. ‘This depends upon the fixation of the atmo- 
spheric oxygen upon protochloride of copper forming oxychloride, 
which again gives out its oxygen at a higher temperature. The 
absorption of oxygen by protochloride of copper is spontaneous ; 
the air being ordinarily moist, it will be complete in a few hours, 
if fresh surfaces be renewed. But elevation of temperature, and 
this is a main pomt, induces a much more rapid absorption: at 
