the Nitrates and Nitrites of Lead, 403 
maximum : nevertheless, after having exposed it in a retort to a 
temperature of 100° (centigrade), as well as to the rays of the 
sun, | obtained water from it which I heated in an elongated tube. 
M. Berzelius says that this salt crystallizes in small scales of 
a brick-coloured red: that which I have described was in needles 
of a flesh colour; and what led me to think that the salt of 
M. Berzelius was not so well saturated with base as mine, was, 
that I obtained erystals similar to these which he has described, 
when the solution of octohedral nitrate had not been long enough 
boiled over the lead: besides, in my experiment, 100 parts of 
octohedral nitrate dissolved 134°5 of lead, whereas in that of 
M. Berzelius they only dissolved 116-5: and finally, I obtained 
to the very last needles of flesh colour from the solution of ni- 
trate boiled over lead, whereas M. Berzelius obtained subnitrite 
at the minimum with his subnitrite at the maximum. 
M. Berzelius prepared the subnitrite at the minimum by 
M. Proust’s process; but, according to mine, the salt thus pre- 
pared is not a pure nitrite: it contains nitrate of lead. I think 
that my experiments ought to leave no doubt on the subject: 
for (a) when we dissolve this salt’ in water, we obtain subnitrate 
at the minimum; (l) when we treat its solution by the carbonic 
acid, we separate from it a part of the oxide, and by evaporating 
the liquor we obtain, Ist, scales of a yellowish white, formed 
of subnitrite and subnitrate at the minimum ; 2d, white needles 
of subnitrate at the minimum ; 3d, yellow crystals, resembling 
in form the octohedral nitrate of lead. (c) When we decom- 
pose the subnitrite at the maximum by the carbonic acid, and 
evaporate the solution in the sand-bath, there are separated 
yellow crystals of subnitrite at the minimum*, which being re- 
dissolved.in water yield only yellow scales of subnitrite at the 
minimum, whether we concentrate the solution, or treat it by 
the carbonic acid, and afterwards evaporate it in the sand-bath. 
Now if the nitrate of lead which we get from M. Proust’s nitrite 
is formed during the treatment given to this salt, why should 
it not be formed, also, when we submit to the same treatment 
the subnitrite at the minimum coming from the subnitrite at the 
maximum ? d 
M. Berzelius, in treating the subnitrite at the minimum with 
a quantity of sulphuric acid sufficient to separate from it the 
half of the oxide, obtained octohedral crystals of a citron yellow 
which he regarded as neutral nitrite. It is evident that these 
crystals are the same with those which | have extracted fron 
* Notwithstanding all this, there may be a little nitrate of lead in these 
crystals: [ have even tried to account for their formation. See the note 
to No, 43 of my memoir. I have had no other evidence, however, of this 
formation, except the pale colour assumed by the scales in soine operations, 
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