SCIENTIFIC SUMMARY. 
233 
CHEMISTRY. 
The Density of Ozone has recently been considered in detail by M. J. L. 
Soret, who sums up our actual knowledge of the volumitive relations of this 
body as follows : — 1st. Ordinary oxygen diminishes in volume when 
ozonized, that is to say, when a part of it is converted into ozone, by elec- 
tricity, for example. 2nd. When oxygen charged with ozone is treated with 
iodide of potassium and other oxiaizable bodies, the ozone dissappears with- 
out the volume of the gas changing. 3rd. Under the action of heat, oxygen 
charged with ozone suffers an expansion equal to the volume of the quantity 
of oxygen that the gas would have been capable of yielding to iodide of 
potassium. These facts, he says, lead to the supposition that ozone is an 
allotropic state of oxygen, consisting in a molecular grouping of several atoms 
of this body. One of the simplest hypotheses in this matter is that in which 
the molecule of ordinary oxygen is regarded as formed of two atoms, and the 
molecule of ozone as formed of three atoms. 
A New Method for preparing Aniline Blach. — In the Bulletin of the 
Industrial Society of Mulhouse, M. Paraf describes a new method for pre- 
paring aniline black. This method simply consists in preparing hydro- 
fiuosilicic acid of a specific gravity of 8°, and of dissolving in this, hydro- 
chlorate of aniline. When fabrics which have been prepared with chlorate 
of potash are washed with this, an exquisite black is produced in the fixing. 
The black thus obtained may be associated with any kind of madder- colour, 
and in the subsequent processes may be treated exactly like a logwood 
black. 
How to separate Cobalt from Nickel. — A method for this purpose, and also 
for the separation of manganese from both these metals, has been pointed out 
by M. Terreil in a paper read before the French Academy of Sciences, Jan- 
uary 1st. To a solution of the two metals he adds ammonia until the oxides 
are redissolved. He then heats the liquor, and to the hot solution adds a 
solution of permanganate of potash until the mixture remains violet from an 
excess of permanganate. He then boils for a few minutes and redissolves 
the oxide of manganese with a slight excess of hydrochloric acid. The 
liquor is kept hot for some hours, and then set aside for twenty-four hours. 
At the end of this time all the cobalt is deposited in the form of a crystalline 
powder of a beautiful reddish-violet colour. Of this precipitate, 100 parts 
correspond to 22*761 of metallic cobalt or 28*929 of the protoxide. For a 
very accurate determination, however, a known weight of the compound 
may be reduced by dry hydrogen, and the pure metal weighed. 
Who discovered Ozone ? — M. Labord has published a note in a late num- 
ber of the Comptes JRendus clearly with the intention of showing that some of 
the credit of the discovery of ozone is due to him. He says, “ Some years 
ago I called attention to the beneficial action of electricity in purifying air 
which is charged with the miasmata which produce epidemics. Now, since 
ozone is only oxygen modified by electricity, it is seen that ozonometric 
observations fully confirm my views.” 
YOL. Y. — NO. XIX. 
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