[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 |
| Di-nitro-benzol[A]    |    16.67    |  16.78 |
|                       |             |  16.57 |
| Para-nitro-phenol     |    10.07    |  10.03 |
| Picric acid[A]        |    18.34    |  18.42 |
|                       |             |  18.43 |
| Ammonium picrate      |    22.76    |  22.63 |
|                       |             |  22.67 |
| Di-nitro-ortho-cresol |    14.14    |  14.10 |
|                       |             |  13.98 |
| Tri-nitro-meta-cresol |    17.28    |  17.57 |
|                       |             |  17.27 |
|_______________________|_____________|________|

[Footnote A:  Dr. Bernard Dyer obtained 18.39 per cent. for picric acid and 16.54 per cent. for di-nitro-benzol.—­Jour.  Chem.  Soc., Aug. 1895.]

When Chenel endeavoured to apply Jodlbauer’s modification of Kjeldahl’s process to the examination of the tri- and tetra-nitrated naphthalenes, he found that good results were not obtainable, because these compounds do not dissolve completely in the cold sulphuric acid.  It may, however, be used if they are previously converted into the naphthylamines, according to the plan proposed by D’Aguiar and Lautemann (Bull.