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° 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° to 25° 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