[Footnote A:  “On the Oxidation of Cellulose,” by C.F.  Cross and E.J.  Bevan, Jour.  Chem.  Soc., 1883, p. 22.]

MISCELLANEOUS NITRO-EXPLOSIVES.

Nitro-Starch.—­It is only recently that, by means of the process introduced by the “Actiengesellschaft Dynamit Nobel,” it has been possible to make this explosive upon the manufacturing scale.  Nitro-starch has been known since 1883, when Braconnot discovered it, and called it xyloidine.  Its formula is C_{6}H_{8}O_{3}(NO_{3})_{2}, but Dr Otto Muehlhaeusen has lately succeeded in preparing higher nitrated compounds, viz.:—­

(a.) C_{6}H_{7-1/2}O_{2-1/2}(NO_{3})_{2-1/2}.

(b.) C_{6}H_{7}O_{4}(NO_{3})_{3}.

Or doubling the molecule of starch:—­

Nitrogen.
i.   Tetra-nitro-starch   C_{12}H_{16}O_{6}(ONO_{2})_{4} 11.11 per cent.
ii.   Penta-nitro-starch   C_{12}H_{15}O_{5}(ONO_{2})_{5} 12.75    "
iii.   Hexa-nitro-starch    C_{12}H_{14}O_{4}(ONO_{2})_{6} 14.14    "

He regards them as true ethers (esters) of nitric acid.  Thus on treatment with sulphuric acid, these compounds yield NO_{3}H, the residue O.NO_{2} thus appearing to be replaced by the sulphuric acid residue.  On treatment with a solution of ferrous chloride, nitric oxide and “soluble” starch are regenerated.  On shaking with sulphuric acid over mercury, all the nitrogen is split off as NO.

Tetra-nitro-starch is prepared upon the large scale as follows:—­A quantity of potato-starch is taken and exposed in some suitable desiccating apparatus at a temperature of 100 deg.  C. until all the moisture which it contains is completely driven off.  It is then reduced to a fine powder by grinding, and dissolved in nitric acid of specific gravity 1.501.  The vessel in which this solution is accomplished is made of lead, and must be provided with two jackets, cooled by means of water.  It should further be fitted with a screw-agitator, in order to keep the nitric acid circulating freely.  The charge of starch is introduced through an opening in the cover of this digesting vessel, and the proportions of acid to starch are 10 kilogrammes of starch to 100 kilos. of acid.  The temperature is kept within the limits 20 deg. to 25 deg.  C. When the solution of the starch is complete, the liquid is conducted into a precipitating apparatus, which is also provided with a cooling jacket, for the purpose of regulating the temperature.  The bottom of this vessel is double and perforated, and here is placed a layer of gun-cotton to act as a filter.  This vessel is filled with spent nitro-sulphuric acid obtained as a waste product from the nitro-glycerine manufactory, and the solution of starch in nitric acid is sprayed into it through an injector worked by compressed air, whereby the nitro-starch is thrown down in the form of a fine-grained powdery precipitate.