406 Correspondence of J. Nickleés. 
at the end of some time, lost its standard value without having lost its 
bleaching power, these chemists examined the liquid and found that a 
part of the bypochlorous acid was changed to chlorous acid, which 
therefore every way preferable to the arsenous acid. 
Excepting this substitution, the process resembles that of Gay Lus- 
‘TT grammes of crystallized hyposulphite of soda dissolved in 
1 litre of water, constitutes the test-liquor, Corresponding to the arsen- 
ical solution of Gay Lussac. After having taken 10 cubic centimeters 
of this normal liquor, 100 parts of water are added and some drops © 
sequence of the slight excess of sulphuric acid added. ae 
This hyposulphite is also an excellent antidote of bromine and iodine 
which are largely in use through the operations of photography. — 
Illuminating gas—An important change has just been made in the 
six gas works from which Paris is lighted, in consequence of the dis- 
cussions that have been going on the past two years, and large reduc- 
tions have been made by the company in their charges. urea 
From the Ist of January, 1856, the cubic meter of gas, which till 
then had cost the people 35 centimes, has been put at 15 centimes. 
The contract made with the company is for fifty years; but at the 
end of sixteen years, if the annual profits exceed ten per cent, half 
the surplus will go to the city; and if a new mode of illumination less 
expensive should be discovered, it may be put in practise without any 
indemnity to the contractors. 
ing been constructed in the park of St. Cloud, nothing was neglect 
that would put the investigation under the best possible conditions for 
accuracy. : 
The results set forth by the company as having been obtained in the 
period between 1844 and 1853 are the following :— 
