Soc.  Chim., vol. iii., new series, p. 256).  This is rapidly effected as follows:—­Twelve grms. of iodine are gradually added to a solution of 2 grms. of phosphorus in about 15 or 20 c.c. of bisulphide of carbon, this solution being contained in a flask of 250 c.c. capacity.  The flask and its contents are heated on the water bath at 100 deg.  C. with constant attention, until the last traces of the carbon bisulphide have distilled away.  It is then cooled, and the iodide of phosphorus is detached from the sides of the flask by shaking, but not expelled.  The next step is to add about 0.5 to 0.6 grm. of the substance that is to be analysed, after which 8 grms. of water are introduced, and the flask is agitated gently two or three times.  As soon as the reaction becomes lively, the contents of the flask are well shaken.  It is usually finished about one minute after the addition of the water.  The flask is now cooled, and 25 c.c. of sulphuric acid, together with 0.7 grm. of mercury, are gradually added; hydriodic acid (HI) forms, and the temperature of the flask must be raised sufficiently to expel it.  The remaining part of the operation is as in the ordinary Kjeldahl process.

M. Chenel has found this process the best for the analysis of the nitro-naphthalenes, and for impervious substances like collodion or gun-cotton.  Personally, I have never been able to obtain satisfactory results with this process in the analysis of nitro-cellulose, and I am of opinion that the process does not possess any advantage over the nitrometer method, at any rate for the analysis of gun-cotton.

Table giving the Percentages of Nitrogen and Oxide of Nitrogen in Various Substances used in or as Explosives: 

     Name FORMULAE NITROGEN NO_{2}
                                                       per cent. per cent.

Nitroglycerine C_{3}H_{5}(ONO_{2})_{3} 18.50 = 60.70
Hexa-nitro-cellulose C_{12}H_{14}O_{4}(ONO_{2})_{6} 14.14 = 46.42
Penta-nitro-cellulose C_{6}H_{8}O_{5}(ONO_{2})_{5} 11.11 = 36.50
Nitro-benzene C_{6}H_{5}NO_{2} 11.38 = 37.39
Di-nitro-benzene C_{6}H_{4}(NO_{2})_{2} 16.67 = 54.77
Tri-nitro-benzene C_{6}H_{3}(NO_{2})_{3} 19.24 = 63.22
Nitro-toluene C_{7}H_{7}NO_{2} 10.21 = 33.49
Nitro-naphthalene C_{10}H_{7}NO_{2} 8.09 = 26.53
Di-nitro-naphthalene C_{10}H_{6}(NO_{2})_{2} 12.84 = 42.12
Nitro-mannite C_{6}H_{7}(NO_{3})_{6} 23.59 = 77.37
Nitro-starch C_{6}H_{8}O_{4}(HNO_{3}) 6.76 = 22.18
Picric acid
  (Tri-nitro-phenol) C_{6}H_{2}OH(NO_{2})_{3} 18.34 = 60.15
Chloro-nitro-benzene C_{6}H_{3}Cl(NO_{2})_{2} 13.82 = 45.43
Ammonium nitrate NH_{4}NO_{3}