GUNPOWDER 



471 



in.-,.ip..i;iied : i in- meal powder tluiH made was first 

 in KiijJ.-md as a propelling agent by Edward 

 III. in hi* war against the Scotch in 1327, the tubes 

 from which he propelled thoHhot being called r;W.i//\ 

 nf' n-iir. Tin- >ame king subsequently used cannon 

 at the battle of Crecy in \'.U(\. From that date the 

 use of gunpowder throughout Europe Hoon became 

 general, the Russians, \\ ho in 1889 celebrated the 

 .MX nil anniversary of its introduction into Russia, 

 IM-III- tlu; last to adopt it. Until the reign of 

 < t >ueen Elizabeth by far the larger quantity of 

 powder required by the English was obtained from 

 abroad ; Imt in ner reign it* manufacture was 

 introduce.] into England. The earliest English 

 powder-mills of which there is any record were 

 established at Long Ditton and Godstone, in 

 Sin icy, by George Evelyn (John Evelyn's grand- 

 father) in 1590; the Faversham mills were started 

 soon after this date, as were also those at Waltham 

 Abbey. The mills at Faversham subsequently lie- 

 came the government powder-factory, and in 1787 

 the government also bought the mills at Waltham 

 Abbey, which have remained in its hands down 

 to this day. The Faversham mills were given up 

 by the government after the peace of 1815 ; they 

 were soon after bought by Messrs John Hall & Son, 

 who still retain them. 



The mode of manufacture adopted in England 

 when these several powder-mills were all 

 thoroughly established remained practically un- 

 changed up to within the last thirty-five years. 

 But before proceeding with a description of the 

 manufacture and of the different powders now in 

 use, it will l>e desirable to consider very briefly the 

 part played by the several ingredients of which 

 gunpowder is composed, and the chemical action 

 which takes place on ignition. The saltpetre or 

 nitrate of potash, KNO 3 , acts as a magazine of 

 oxygen, with which it readily parts when raised to 

 a certain temperature. When the powder is h'red, 

 the oxygen of. the saltpetre converts most of the 

 carbon of the charcoal into carbonic acid, CO 2 , a 

 portion of which combines with the potash of the 

 nitre to form carbonate of potash, KC0 3 , the 

 remainder existing in the state of gas, and the 

 nitrogen is liberated. The sulphur, which performs 

 the part of a second combustible in gunpowder, is 

 for the most part converted into sulphuric acid, SO 3 , 

 and forms sulphate of potash. The reaction on 

 firing the gunpowder may be expressed by the 

 equation KO,NO 5 + S + 3C = 3CO, + N + KS. 

 Tne heat generated by the explosion evolves a large 

 quantity of elastic gases, the expansive power of 

 which is greatly increased by the heat. The pressure 

 being equal in all directions, the work done on the 

 projectile in the bore of the gun is due to this 

 elasticity and expansive force. The method adopted 

 for measuring the amount of pressure in the bore 

 of the gun will be dealt with hereafter. 



Sir Frederick Abel, K.C.B., F.R.S., and Sir 

 Andrew Noble, K.C.B., carried out two series of 

 most exhaustive and complete experiments on fired 

 gunpowder, and the conclusions they arrived 

 at were communicated by them to the Royal 

 Society in two papers (1875-80) under the head 

 of 'Researches on lired (JunjKnvder.' The results 

 are summarised as follows : when fired in a con- 

 fined space ( 1 ) the products of combustion are 

 about 57 per cent, by weight of ultimately solid 

 matter and 43 per cent, of permanent gases; (2) 

 the permanent gases occupy alx>ut 280 times the 

 volume ..f the original powder; (3) the tension of 

 the products of combustion when the powder 

 entirely fills the space in which it is fired is about 

 6400 atmospheres, or 42 tons per square inch; (4) 

 the temperature of explosion is about 4000 F. ; 

 (5) the chief g.-iseous products are carbonic acid, 

 nitrogen, and carbonic oxide; ( 6 ) the solid residue is 



mainly composed of potassium carbonate, sulphide, 

 and MI I phut . 



From the foregoing description of the part 

 played l.\ the nitrate of potash it might he thought 

 that it would be highly advantageous to make 

 gunpowder with some nitrate containing a 

 larger percentage of oxygen than nitrate of potas- 

 sium; and as a matter of fact there are a large 

 11 u m l>er of nitrate mixtures other than gunpowder 

 in which nitrate of sodium, barium, or ammonium 

 are substituted for the nitrate of potassium. But 

 unfortunately they are extremely hygroscopic, so 

 that gunpowder made with them would, under 

 ordinary circumstances, soon become useless on 

 account of the damp it would absorb from the 

 atmosphere. In a hot dry climate nitrate of soda 

 powders would doubtless be valuable, besides being 

 much cheaper to manufacture than nitrate of 

 jK)tash powders : indeed such powders were used 

 to a considerable extent in the construction of the 

 Suez Canal ; but, as these powders are not in 

 general use, it is unnecessary to refer to them 

 further. 



Process of Manufacture. The method of manu- 

 facture of gunpowder at the Royal Gunpowder 

 Factory at Waltham Abbey ( fully explained in the 

 official handbook ) may be briefly described. As in 

 all other explosives, it is essential that the ingredi- 

 ents of which the powder is composed should ue as 

 pure as possible. The selection ana preparation of the 

 charcoal is of the greatest importance ; for, without 

 any change in the proportions of the components, 

 the properties of the gunpowder are capable of 

 great variation from the quality of the charcoal used 

 in its manufacture. The ingredients are first 

 reduced to a fine powder by grinding. They are 

 then mixed by hand in the proportion of 75 per 

 cent, by weight of saltpetre, 15 of charcoal, and 10 

 of sulphur, and are next thoroughly incorporated 

 in a wet state in a powder-mill into a cake called 

 a mill -cake. This cake is then broken down 

 between copper-plates into meal. From this meal- 

 powder all granulated powders are made. The meal 

 is compressed in a press-box, the amount of com- 

 pression it undergoes being dependent on the 

 density of powder required. After compression the 

 press-cake is broken into pieces ready for granulat- 

 ing, which is done in the granulating machine, the 

 powder passing between gun-metal rollers till it is 

 broken into grains of the required size, different 

 powders being made to pass through sieves whose 

 meshes are of the size of tl e grain required. There 

 is a considerable amoun of dust formed by the 

 granulating process, so t'.at after granulating it is 

 necessary to dust the pr ,vder previous to glazing it, 

 which is the next oper tion. It is glazed in glazing 

 drums, which, revotvi.ig rapidly, impart a glaze to 

 the powder simply by the friction set up. The 



Sowuer is now stoved or dried in copper- trays in a 

 rying room, which is heated to a temperature of 

 about 100 F., and the powder is left in this room 

 from one to two hour- according to the amount of 

 moisture that it contains. Formerly all powder was 

 granulated, but the enormous increase in the size 

 of the guns now used necessitated the introduction 

 of other descriptions of powder viz. cut and 

 moulded powders. In the cut powders, after the 

 process of pressing, the press-cake, instead of being 

 granulateu, is first cut into strips, and these strips 

 are then cut into cubes, and the powder so made 

 is called cubical or pebble powder ; there are at 

 present two sizes viz. jj-inch and lA-inch cubes. 

 In the moulded powders, as is implied in the name, 

 each grain or piece of powder is moulded or pressed 

 in a separate mould. This is done in a hydraulic 

 machine. The exact quantity of granulated powder 

 required to form each prism is deposited in a block 

 containing sixty-four moulds ; the powder in these 



