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The Gun - Gunpowder

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Without a propellant the gun could not have been born, so we must first look at the story of gunpowder, the sole propellant in use up to the 19th century.

From ancient times throughout the known world men had used incendiary mixtures for warlike purposes. They were well-acquainted with saltpetre (potassium nitrate), the most potent of the three ingredients of gunpowder, its effect when burned with charcoal and sulphur, the other two, as well as with other substances. That someone would eventually chance upon a mixture which exploded when ignited was inevitable.

However, while mixtures involving the crude saltpetre dug from the ground or scraped from the walls of cellars by the ancients can be made to burn quite fiercely, they cannot be made to explode. To make an explosive mixture the saltpetre must first be refined.

The earliest known reference to the refining of saltpetre appears in an Arabian text dated 1240. Therefore it is extremely unlikely gunpowder was discovered prior to that year. Among the many claims to have discovered it are the Chinese, Hindus, Greeks, Arabs, Germans and English. Within the well-recorded histories of the first four there is no written evidence which would satisfy a historian that any of them discovered or used gunpowder before it came into use in Europe. If one of their people had discovered it some writer doubtless would have mentioned the fact.

For over 500 years military historians attributed both the discovery of gunpowder and the invention of the gun to one Berthold Schwarz (Black Berthold), a German monk so-called because he dabbled in the 'black art' of alchemy. They based their beliefs on an entry allegedly made under the year 1313 in the records of the city of Ghent, but a study carried out in 1923 by Sir Charles Oman revealed the entry was a marginal note, not a contemporary entry, inserted not in 1313 but in 1393, by which time guns were in general use throughout Europe. The entry was therefore declared invalid.

Extensive research produced not one scrap of evidence that Schwarz ever existed. He is now seen as a legendary figure, rather like Robin Hood - or perhaps Friar Tuck! It is thought the entry, made in a foreign hand, may have been made by a German scribe anxious to credit his countrymen with both discovery and invention.

Roger Bacon

In the early years of this century attention focussed upon the work of Roger Bacon (1214-94). After graduating MA at Oxford he lectured for some years in Paris but in 1247 returned to Oxford where he later became a Franciscan Friar. Bacon was an intellectual giant, ages ahead of his time. At Oxford he concentrated on mathematics and scientific investigation on which subjects he wrote several learned treatises. In one of these, written about 1249, appears a chapter which had puzzled readers for centuries, but which in 1904 was found by LtCol HWL Hime RA (1840 - 1929) to be an anagram or cipher for the preparation of gunpowder. Bacon not only named the ingredients and the proportions then used (saltpetre:charcoal:sulphur 7:5:5) but also described the explosive properties of the mixture. He gave no indication it could be employed as a propellant.

Bacon's reason for the anagram is not hard to find. In 1233 Pope Gregory IX had founded the Inquisition, an organisation designed to ensure the faithful adhered to official religious doctrine - by torture and death if necessary. It hierarchy frowned upon scientific study almost as much as they did the black arts of magic and witchcraft. In the anagram Bacon had said the explosive effects of gunpowder resembled thunder and lightning. To say as much in plain language - and so tell the world - would have condemned him in the eyes of the Church as being in league with the devil, the penalty for which was to be burnt at the stake. Brother Roger had already been in trouble with his superiors over his scientific teachings; no doubt he did not wish to 'push his luck'!

Note that Bacon did not claim that he himself discovered gunpowder; he merely recorded its composition and described its explosive properties. There is a belief - but no proof - that he obtained the recipe from Arabian sources, possibly the same which described the refining of saltpetre mentioned above. Until further evidence comes to light, whoever actually discovered gunpowder will remain a mystery.

The Original Powder

Early makers simply pounded quantities of the three ingredients into powder and mixed them according to their own particular recipes. No finite method of proving the product existed; quality was judged by the loudness of the bang it made! Such a method of 'proof' seems funny to us today, but it was not quite so funny 500 years ago; 14th century Gunners were well aware of the effect of the sound of guns on an uninitiated enemy. They frightened not only the horses but also the ignorant and superstitious soldiery who saw guns as instruments of the devil - and Gunners as his henchmen!

Known as 'serpentine' (in allusion to an early type of ordnance) or 'meal' early gunpowder possessed several faults; firstly, jolting during transport caused the ingredients to separate, the heaviest ending up on the bottom of the barrel, the lightest at the top. The ingredients were therefore often carried separately and mixed on the gun position, creating in the process a highly explosive dust easily ignited by spark or friction.

Serpentine also absorbed moisture from the air to a degree which greatly reduced its efficiency, or in bad cases rendered it useless.

Loading presented more problems. To load, the Gunner simply filled a ladle with powder - hoping to put the same amount into it each time - inserted it into the gun, turned it over, then withdrew it, probably spilling some of its contents along the way. His assistant then rammed wad and shot. Now if these were rammed too hard, the powder was compressed, thus slowing the rate of burning. On the other hand, if they were rammed lightly the powder burned faster. Obviously any consistency in the shooting was purely a matter of luck.

Fouling, ie the residue consisting of unburnt or partially burnt powder, was excessive and made loading difficult. It was one of the reasons for the windage of a quarter inch (6.35mm) allowed in all natures of early British ordnance.

Old-time Gunners were well aware of serpentine's faults. As time went on they tried to improve its quality by varying the proportions of saltpetre, charcoal and sulphur, and by adding other substances, eg camphor, sal ammoniac, gum, etc, without much success.

Improvements to Powder

The most important breakthrough came in 1429 when corning was first carried out in France. Briefly the process consisted of moistening the mixture, pressing the paste so formed into 'cakes', drying them, then breaking them up into smaller particles called 'grains'. Various moistening agents were tried, including wine, vinegar and urine. Monks' urine was said to be the best, with bishops' the 'creme de la creme'.

This was a typical example of mediaeval thinking. Because the clergy generally enjoyed a higher standard of living than other folk, therefore their urine was thought to be of higher quality. Eventually pure water was found to be the best moistener.

Corning thus formed a much more intimate mixture with the following advantages:

  1. Vibration had little effect on it; the ingredients no longer separated out during transport.
  2. The grains were less susceptible to the effects of moisture.
  3. The gaps between the grains enabled flame to pass more freely, making the rate of burning more consistent.
  4. Variations in loading conditions did not affect the rate of burning to the same extent.
  5. Corned powder was found to be at least 30% more powerful than serpentine.

Apparently not at first realising its added strength, 15th century Gunners loaded charges of corned powder of the same weight as used with serpentine, so bursting a number of old bombards. For this reason serpentine continued to be used in these guns until heavier and stronger types superseded them.

Polishing the powder grains by tumbling them in a wooden barrel improved their moisture-resisting properties, while the addition of a small amount of graphite made the process even more effective. Corned powder came into use in England in 1520.

Minor improvements to powder continued to be made chiefly by increasing the purity of its constituents and by experimenting with their proportions. In 1781 Richard Watson DD FRS, Bishop of Llandaff, who was also a professor of chemistry, ordained that for general purposes the proportions be saltpetre 75%, charcoal 15%, sulphur 10% - and for British gunpowder they have remained the same ever since. Later, in 1786, when asked by the Government for advice on improving the strength of powder he recommended the charcoal be made by 'distilling' the wood in closed vessels, and his recommendation was adopted.

WL Ruffell, September 1992
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