26 
ON PYROXYLIN. 
All the samples heated in this way to 100° were sooner or later decomposed, and in a 
few minutes a disengagement of nitrous vapours took place. 
The decomposition takes place in different ways, and cannot be reproduced at will. 
Four methods of decomposition at 100°, having the common characteristic of the disen¬ 
gagement of nitrous vapours, may be,given:— 
1. The pyroxylin detonates violently. 
2. It decomposes without detonating, leaving a white, pulverulent, acid residue, par¬ 
tially soluble in water, containing no nitrogen, and forming about half the weight of 
the pyroxylin. 
3. It leaves a yellow, amorphous, inexplosible residue, partially soluble in water, and 
reducing, like glucose, the double tartrate of copper and potash. 
4. It gives a small residue (only 8 to 10 per cent, of its weight), and a black matter, 
in appearance like charcoal. In this case the matrass is entirely covered w r ith a yellow 
powder, which dissolves in alkali with considerable disengagement of ammonia (this 
matter is apparently ulmate of ammonia). From this solution acids precipitate a dirty 
yellow body, also soluble in alkalies. The charcoal-like residue disengages ammonia 
under the action of potash. This production of ammonia by the simple action of heat 
from a matter formed of nitric acid and cellulose is very remarkable. 
Other experiments made on various pyroxylins at 90° and then at 80° gave exactly 
the same results, except that decomposition took place after several hours instead of a 
few minutes. 
At 60°, and even at 55°, pyroxylin is still decomposed. After a few days the matrass 
becomes full of dense reddish vapours, and the same non-nitrogenized pulverulent residue 
of which we have already spoken is obtained. No combustion was observed in these 
latter experiments. 
We moreover produced detonation by putting about one gramme of pyroxylin into 
one of Gay-Lussac’s copper stoves containing oil at only 47°. The pyroxylin thus 
decomposed was from a specimen prepared by forty-eight hours’ immersion, and washing 
by Lenk’s process. 
These experiments plainly show that, contrary to General Lenk’s assertion, his pyroxy¬ 
lin does not offer more resistance to the action of heat than that of Bouchet, the Austrian 
silicated pyroxylin having under all conditions behaved itself in the same manner as the 
others. 
From its decomposing at about 50°, it may be asked whether pyroxylin is not liable 
to decompose even at the ordinary temperature. Is it, for instance, likely to detonate 
spontaneously when kept in large masses in magazines? Several chemists have given 
examples of the decomposition of pyroxylin at the ordinary temperature. They have 
generally mentioned as products of this decomposition nitrous vapours and several oxi¬ 
dized bodies like formic, oxalic, and acetic acids, and residues of gummy or saccharine 
substances, and have endeavoured to ascribe these instances of the alteration of pyroxylin 
to imperfect washing. 
We. will in the first place remark that it is easy to wash small quantities of materials, 
and that as the destructive action of sulphuric acid on pyroxylin is perfectly established, 
it is evident that the greatest care should be taken to eliminate every trace of it, and 
that consequently the most careful washing is necessary. 
YV ithout entering into the details of the known cases of the decomposition of py- 
roxylin at the ordinary temperature, we will describe the decomposition we observed in 
some specimens made in 1847, which had been washed with especial care either in pure 
or alkaline water. 
Of twenty-eight samples placed in small stopped flasks, and a few grammes in weight, 
sixteen underwent alteration of some kind. 
We took at hazard one of the altered specimens, and examined it. It was originally 
composed of six. grammes of pyroxylin which had been washed in potash water and left 
since March 17, 1850, or fourteen years, in a flask imperfectly stopped. It had left a 
residue representing 79 per cent, of a dark yellow colour, and considerable amount of 
acid, but no sulphuric acid. This residue dissolved completely in water, and like glucose 
reduced tartrate of copper and potash. Its boiling solution gave a decided odour of 
vinegar, and, what was very remarkable, disengaged ammonia under the action of potash. 
There are, then, under the ordinary atmospheric conditions, incontestable instances of 
the spontaneous alteration of pyroxylin, which, moreover, had been washed in alkaline 
water. 
