EXPLOSIVE COM PO U INDS OF TOE NITRIC DERIVA TIVES. This group of explosives consists of nitric derivatives either of cellulose or gelatin. In the first case the cellulose is treated with nitric acid. forming guncotton, mid in the second case glycerin yields, by the action of nitric acid, nitroglycerin. According to the proportions used the mono-, di-, or tri-nitro derivatives of glycerin or a multiple of them for cellulose may be obtained. This class is by far the largest one, and too numerous to admit of a general de ipt ion, in consequence of which the peculiar properties of each will be found described under their special headings.
Guncotton is an important member of this class. IL consists of cellulose such as pure cot ton treated with nitric acid, although in actual practice the best results are obtained from a. mix ture of nitric acid and sulphuric acid. It is em ployed chiefly for military purposes and is re garded as the safest explosive known. (See GUN COTTON.) Among the various guncotton prepara tions, which differ from each other only by the proportions of their ingredients and methods of preparation, are the following, which are now seldom used, although valuable on account of their safety: G/yoxi/inc, a guncotton pulp which is mixed with potassium nitrate, converted into porous pellets which are saturated with nitro glycerin and afterwards coated with varnish to I rotect them from moisture; potentitc, a mixture of 62.2 parts guncotton and 33.8 parts potassium
nitrate compressed into cartridges; t on ite or cotton powder, a preparation consisting of 52.5 parts of finely divided or macerated guncotton with •7.5 parts of barium nitrate, which are made up into cartridges coated with paraffined pa per.
The value of guncotton as an explosive led to its adoption for use in the manufacture of blasting-gelatin, invented by Nobel in IS75, which is accomplished by dissolving the soluble variety of guncotton in nitroglycerin. This has been made up variously, and also combined with absorbents, forming ge/ot in which have been largely used for blasting mirposes, notably in the case of the Saint Gotthard tunnel. In this class should be included forcitc, consist ing of blasting-gelatin (nitroglycerin OS parts, collodion cotton 2 parts), 50 parts, and absorb ent (sodium nitrate 76 parts, sulphur 3 parts, wood tar 20 parts. wood pulp I part), 50 parts; and gelignite, consisting of blasting-gelatin (ni troglycerin 96 parts. collodion cotton 4 parts) 65 parts, and absorbent (sodium nitrate 75 parts, sodium carbonate 1 part, wood pulp 24 parts), 35 parts.