Cooley's Cyclopaedia of Practical Receipts Volume I Part 273

Ordnance Powder. Small Arms Powder.

Nitre 7378 7715 Sulphur 1280 863 {Carbon 1088 1178 Charcoal. {Hydrogen 038 042 {Oxygen 182 179 {Ash 031 028 ------ ------ 9997 10005

2. _Products of Combustion by Weight._

Ordnance Powder. Small Arms Powder.

{ Nitrogen 977 } { 1006 } { Carbonic anhydride 1739 } { 2179 } Gaseous. { Carbonic oxide 264 } { 147 } { Hydrogen 011 } 3058 { 014 } 3418 { Sulph. hydrogen 027 } { 023 } { Marsh gas 040 } { 049 }

{ Ammonic sesquicarbonate 268 } { 266 } { Pota.s.sic sulphate 3695 } { 3617 } { " carbonate 1940 } { 2078 } Solid. { " hyposulphite 285 } 6925 { 177 } 6514 { " sulphide 011 } { 000 } {Charcoal 257 } { 260 } {Sulphur 469 } { 116 } Loss. 017 068 ------ ------ 10000 10000

3. _Products of Combustion by Volume in 100 of Gas._

Ordnance Powder. Small Arms Powder.

Nitrogen 3758 } { 3533 } Carbonic anhydride 4274 } { 4890 } Carbonic oxide 1019 } { 518 } Hydrogen 593 } 100 { 690 } 100 Sulphuretted hydrogen 086 } { 067 } Marsh gas 270 } { 302 }

It will be seen from the above figures that in addition to the generation of a considerable amount of carbonic anhydride (carbonic acid) by the combustion of gunpowder, there is liberated at the same time a large quant.i.ty of solid matter, in the form of sulphate and carbonate of potash, sulphide of pota.s.sium, sulphur, charcoal, &c. This will explain why the air of mines is so prejudicial to the health of the miner, particularly when he is engaged in blasting operations, these being carried on in a more or less confined s.p.a.ce. See AIR, VITIATED.

=Gunpowder, Schultze.= The subjoined account of Schultze gunpowder is a transcription of a report communicated to the editor of the 'Field'

newspaper by Mr F. Toms, A.I.C., F.C.S. After referring to a previous communication on the same subject Mr Toms proceeds as follows:--I have carried out some further experiments, with the aid (by Dr Frankland's kind permission) of apparatus more suited to my requirements than that previously at my disposal; and I now proceed to lay before you the results of these experiments, and the conclusions to which they have led me, respecting the powders formerly received and the new Schultze powder, with a sample of which you have since favoured me.

The main const.i.tuent of the Schultze gunpowder, as you are aware, is wood fibre, which, having first been purified, is then subjected to the action of strong nitric acid (intensified by mixture with sulphuric acid), and thus is converted into a kind of nitro-cellulose or pyroxylin, the ordinary form of which is gun-cotton. The wood fibre undergoes no change in appearance by this treatment; but a change takes place in its chemical composition, which may thus be exemplified:

CELLULOSE NITRO-CELLULOSE (unconverted cotton or (cotton or wood fibre treated wood fibre). with nitric acid).

Carbon 6 parts 6 parts.

Oxygen 5 " 5 "

Hydrogen 10 " 7 " or more.

Nitroxyl (NO_{2}) none 3 " or less.

It will thus be seen that the sole difference between gun-cotton or Schultze powder and ordinary cotton or wood fibre is, that some of the hydrogen is abstracted and has its place supplied by nitroxyl--a substance contained in nitric acid, and composed of one part of nitrogen united with two parts of oxygen. Under the most favorable circ.u.mstances, it is possible to replace _three_ of the ten parts of hydrogen by three of the nitroxyl, when the substance produced is explosive, and is called from its composition _tri_-nitro-cellulose. This is the purest form of gun-cotton. If weaker acid is used, less hydrogen is displaced, and the product is called _di_-nitro-cellulose or _mono_-nitro-cellulose, according as it contains _two_ or only _one_ part of nitroxyl. These derivatives are either feebly explosive or not explosive at all. Such are the compounds known as photographic collodion and soluble gun cotton--the latter name distinguis.h.i.+ng it from pure gun-cotton, which is not soluble in a mixture of ether and alcohol.

The Schultze powder contains both the explosive and the non-explosive varieties of nitro-cellulose.

If the wood fibre, after being carefully purified according to the method described in Schultze's patent of 1864, were thoroughly desiccated and allowed to cool out of contact with air, and then dipped in acid of the strength mentioned in the specification, there seems no theoretical reason why an explosive powder containing at least 90% of true tri-nitro-cellulose should not be produced. As, however, I find on experiment that nothing like that per-centage is arrived at, I can only conclude that, in order to moderate the violence of the explosion, the Schultze Company secure the formation of a large per-centage of "soluble"

or less explosive nitro-compounds by merely air-drying their wood.

If this supposition be generally true, it seems probable that the sample of Schultze powder supplied by Messrs Blissett may owe its extra explosive force to exceptional care being taken, during the interval between the drying and the dipping, to prevent the absorption of moisture--with the addition, perhaps, of an increased length of exposure to the action of the acid.

That some such variation of the ordinary procedure was carried out seems evident from the different proportions of soluble and insoluble gun-cotton in the specimens of Schuitze powder supplied by Messrs Blissett and Messrs Bland; for it was found that on the washed wood fibre from each being submitted to the action of a mixture of alcohol and ether, about one half of the former powder and two thirds of the latter were dissolved out. This shows that while the "Blissett" specimen contained about one half its weight of insoluble or explosive nitro-cellulose, the "Bland" contained only about one third--a difference which confirms the result obtained by a.n.a.lysis as stated below.

The _soluble_ gun-cotton, ordinarily non-explosive, may, however, be rendered explosive by saturating it with bodies rich in oxygen, which promote the decomposition and complete the combustion of the fibre. Nitre is used for that purpose, because it parts with its oxygen readily; and nitrate of baryta is also used, because, being more stable than the nitre, it renders the combustion more gradual than would be the case if nitre were alone employed. When both are used, the nitre, I should think, would start, and the nitrate of baryta continue and finish the combustion of the powder. The amount used is, I suppose, the result of calculation and experiment; but a powder containing little true tri-nitro-cellulose should require more of these salts than one containing much tri-nitro-cellulose; and an excess of the salts would lower the rate of burning of the powder.

I will now give my a.n.a.lysis in full of the three powders, viz.--(1) the ordinary powder issued last season, being part of a supply obtained from Messrs Bland, gunmakers, of the Strand; (2) some powder furnished by Messrs Blissett, of Holborn, and alluded to in their letter in the 'Field'

of Jan. 19th last, as having damaged a gun made by them; and (3) some of the new powder of 1878, as used at the 'Field' trial of explosives in May last.

1877 1878 Bland's. Blissett's. Trial or New.

Moisture, per cent. 218 239 297 {Nitrate of baryta, per cent. 2150 1659 2232 Extracted { " potash, per cent. 1146 1046 647 by water. {Yellow coloured organic {substance, trace of chlorides, {&c., undetermined

{The converted wood fibre } Insoluble { (nitro-cellulose) then } in water. { remaining contained the } 50 60 295 { following per-centage of } { mineral matter }

The converted wood fibre (after allowing for extraneous mineral matter) possessed the following per-centage composition. I place for comparison Professor Abel's determination of the composition of tri-nitro-cellulose, and two of the impurities found along with it, in a parallel column.

Bland's. Blissett's. Trial or New. Tri-nitro- Impurities.

Cellulose.

Carbon 2875 2807 2812 2424 2920 3050 Hydrogen 349 365 354 236 -- 291 Nitrogen 1080 1560 1166 1414 1185 -- Oxygen 5606 5268 5668 5926 -- --

These powders exploded at a temperature of about 190 C. (374 F.), the different samples varying but slightly. Pure gun-cotton is stated by Professor Abel to explode at 150 C. (302 F.); and black powders are said, by different authorities, to explode at various temperatures between 500 and 600 F., according to the variation in their composition and manufacture.

In addition to the difference in chemical composition of these Schultze powders, I would point out that there is a difference in density--the Blissett being heaviest, the Bland next, and the New the lightest of the three. I think this fact also has some bearing on the violence of the explosion. In black powders, I believe, a dense powder, speaking generally, is stronger than a lighter one; and the Schultze patent states that hard woods make more explosive powders--not, I take it, because the composition is thereby altered, but because a denser powder is produced.

It would appear to me, from the above a.n.a.lyses, that the new trial powder should contain rather more explosive force than the Bland variety, though considerably less than the Blissett. The result may, however, be modified by the difference in density of the powders; and your practical experiments will show how far this agrees with the results of the shooting.

I have hitherto only spoken of the explosive force of the powder; now I will touch on another point--its tendency to spontaneous decomposition.

Knowing that, in the case of gun-cotton, its stability is injured by a small proportion of resin and other organic impurities, and by the presence of free mineral acids. I did not expect to find this powder (made from a less pure kind of cellulose, from which also it must be somewhat difficult to wash all traces of acid) equal in stability to gun-cotton; and on subjecting the three kinds of Schultze powder to the Government 'heat test' of 150 F. (with a minimum of 10 minutes' duration), it was found that the

New or Trial (1878) Powder stood the test 12 m.

'Bland's' sample " 8 "

'Blissett's' sample " 7 "

This shows that the 'new' powder is very stable, as it stood the test for two minutes beyond the Government minimum, while the other two samples were a good way below it. The officials at Waltham Abbey would accept no gun-cotton which did not stand the test for ten minutes; and I have seen the best gun-cotton stand it for fifteen.

Whether the loose granulated condition of the Schultze powder, when stored, is sufficient to neutralise this inferiority in purity, and render a sample of Schultze, which only stands the test of seven minutes, as little liable to spontaneous combustion as gun-cotton which stands the test for ten minutes, there is at present no evidence to show.

To carry out this 'heat test' properly, some practice is required; so, in order to put the matter beyond doubt, I called in the a.s.sistance of my friend Mr Arthur Linnell, F.C.S., chemist to the Gun-Cotton Company, Stowmarket, a gentleman who uses the test daily, and who carried out the above three experiments strictly after the manner adopted by himself and by the Government officials.

In addition to Mr Linnell's experiments, I noted that the aqueous extract of 'Blissett' was very faintly acid; that when heated in a chest at 195 F. moist blue litmus was very quickly reddened.

I think this serious defect (want of stability) is due to want of care in the was.h.i.+ng; and I base this opinion on the following facts:

(1) The 'Bland' and 'Blissett' samples (the powders of least stability) are of a deeper tint than the 'new' (due to the soluble yellow impurity before mentioned). By continued was.h.i.+ng in warm water they become pale, like the more carefully prepared new powder, and the yellow substance is dissolved away. Hence the lighter colour of the 'new' (and most stable) indicates it has less of this organic impurity.

(2) Sulphuric and nitric acids are used in the dipping of the powder, but should be entirely washed out, as they promote spontaneous decomposition.

If left in, the sulphuric acid will, when the salts are added, decompose the nitrate of baryta, forming insoluble baric sulphate and free nitric acid.

On experiment I ascertained that the abnormally large quant.i.ty of mineral matter or ash (5 and 6 per cent.) found in the insoluble part of the 'Bland' and 'Blissett' powders _is_ due to baric sulphate, and I think the acidity of the aqueous extract is due to the nitric acid thus set free.

Had this baric sulphate been present in the new powder, I should have thought it was purposely formed in all to prevent access of moisture; but, not finding this substance in this carefully prepared sample, I attribute its presence in the other cases to carelessness on the part of the workmen.

I should state that all these powders consisted of a granulated and consolidated pulp. This improvement must, I think, have considerable advantages over the sawdust form previously adopted by the Schultze Company in as much as it facilitates a more thorough purification being carried out, and produces a more h.o.m.ogeneous and equal powder. It is possible, too, that working with pulp may be of advantage, inasmuch as the company may now, by varying the pressure in forming the cake, obtain grains of any required density.

In conclusion, I may say that, in my opinion the most difficult task which the Schultze Company have had to encounter is that of obtaining uniformity of strength in their explosive; and the 'Blisset' sample of their powder may he looked upon as an experimental batch in which (by altering the mode of procedure in some such manner as I have indicated) they made a powder with a large per-centage of tri-nitro-cellulose, thus producing a more rapidly burning substance, and consequently a more violent explosion.

Taking all things into consideration, I think the Schultze Company, in manufacturing a nitro-explosive which gives the uniformity of shooting power shown in your recent experiments, have worked out a most troublesome problem with remarkable success. The difficulty of obtaining such results is evidenced by the fact that so many inventions of a somewhat similar character have been abandoned for sporting purposes from a deficiency in this respect.

But, however difficult it may be to manufacture a powder giving uniform shooting, it is evidently possible, with suitable care to produce (as the 'new' Schultze shows) a wood powder which is perfectly safe and stable, as far as spontaneous decomposition is concerned. The company, therefore, if they have not already done so, ought to take means to prevent powder of the low stability of the 'Bland' and 'Blissett' samples being again issued from their works.

P.S.--Since writing the above I have examined cursorily a sample of the 'Dittmar' wood powder, an American variety of 'Schultze,' used by Captain Bogardus in some of his recent shooting compet.i.tions. The powder is somewhat darker in tint, and of slightly larger grain, than the Schultze.

In density it is intermediate between 'Bland's' and the 'new' powder; and the charge in a twenty-bore cartridge was forty-two grains. This powder would seem to be made from solid cubes of wood (not a pulped ma.s.s like the present 'granulated' Schultze, or of sawdust splinters like the old so-called 'cube' Schultze). It contains no nitrate of baryta, but has a small quant.i.ty of nitrate of potash and soda. Possessing, as it would seem, therefore, a much smaller proportion of oxidizing salts than the English Schultze, it should contain, to make up for this loss of force, a larger proportion of explosive pyroxylin; but this is a point I have not experimentally determined. ('Field,' August 3rd, 1878, No. 1336, p. 143.)

=Gunpowder, White.= _Syn._ BLASTING POWDER. _Prep._ 1. See BLASTING POWDER, No. 3.