the cold with a solution of 1.2 grm. of phenol
and 0.4 grm. phosphoric anhydride in 30 c.c. of sulphuric acid. The
mixture is kept well shaken until the solution is complete. From 3 to 4
grms. of zinc-dust is then cautiously and gradually added, the temperature
of the mass being kept down until complete reduction has been effected.
Finally, 0.7 grm. of mercury is added, and the process continued in the
usual way, according to Kjeldahl; that is, the liquid is distilled until
all the ammonia has passed over, and is absorbed in the standard acid. The
distillate is then titrated with standard ammonia.

[Footnote A: J. Kjeldahl, _Zeitschrift Anal. Chem._, 1883, xxii., p. 366.]

[Footnote B: Jodlbauer, _Chemisches Centralblatt_, 1886, pp. 434-484. See
also _Arms and Explosives_, 1893, p. 87.]

The NO_{2} group is at the moment of solution fixed upon the phenol with
the production of mono-nitro-phenol, which is afterwards reduced by the
action of the zinc-dust into the amido derivative. During the subsequent
combustion, the nitrogen of the amido-phenol becomes fixed in the state of
ammonia. M. Chenel is perfectly satisfied with the results obtained, but
he points out that the success of the operation depends upon the complete
conversion of the phenol into the mono-nitro derivatives. This takes place
whenever the organic compound forms a _clear solution_ in the cold
sulphuric acid mixture. Substances like collodion or gun-cotton must be
very finely divided for successful treatment. The following table shows
some of the results obtained by M. Chenel:--

______________________________________________
| | |
| | Total Nitrogen. |
| Substances Analysed. |______________________|
| | | |
| | Calculated. | Found. |
| |_____________|________|
| | | |
| Saltpetre (KNO_{3}) | 13.86 | 13.91 |
| | | 13.82 |
| | | 13.73 |
| | | 13.96 |
| Ammonium nitrate | 35.00 | 35.31 |
| | | 34.90 |
| | | 34.96 |
| Barium nitrate | 10.72 | 10.67 |
| | | 10.62 |
| Nitro-glycerol | 18.50 | 18.45 |
|