Why was there no Dynamite in Swedish Sea Mines?

by Petter Wulff

THE MID-19^TH CENTURY was an era of new explosives. The centuries-old gunpowder was replaced by high explosives like dynamite and gun-cotton. Sweden was at the forefront of this revolution with Alfred Nobel long being recognized as the leading figure.1

You might have expected the Swedish military establishment to eagerly exploit the new possibilities appearing. But they did not – or not quite as you might have thought. This will be shown here by comparing the trajectories of Nobel’s explosives and Swedish sea mine development. Although the trajectories came close, they were still separate, and Nobel’s explosives never entered the arsenals of the Swedish navy.

Introducing sea mines – and a new explosive
Alfred Nobel’s military connection came through his father, who had been engaged in mine technology since the 1830s, when he tried to sell ideas for land mines to the Swedish army. Failing in this and other endeavours he tried his luck in Finland. There he came in contact with representatives of a sea-mine committee set up by the tsar and moved to S:t Petersburg.²
Business there went well, but with peace arriving after the Crimean War and a new tsar upon the throne, orders for sea mines and other military equipment were cut back. With the tsar no longer a customer that could support him, Alfred’s father returned to Sweden trying to sell the sea mines to his native country. He asked the Government to set up a mine committee to test the mines he had invented, and in 1863 the request was granted.³ This marked the birth of the Swedish mine weapon.⁴ The Government might have been moved by reports about the successful use of sea mines by the Confederates in the American Civil War⁵, but the reason given for setting up the committee was the request from Alfred Nobel’s father. He can therefore be said to be the father also of the Swedish sea mine weapon.

Where was Alfred in all this? He had been helping his father in S:t Petersburg. Around 1850 he studied for over a year in Paris receiving “Europe’s most distinguished education” in chemistry.⁶ This complemented his father’s knowledge of mine construction. The father was a mechanicus, who knew about mine casing and auxiliary equipment for getting mines into the water. Alfred was knowledgeable about the explosive substance inside, and in S:t Petersburg he had used his knowledge, making experiments with mines. When Nobel the elder returned to Sweden to continue his work on mines, it is not surprising that he asked Alfred to join him. Back in Sweden his son laid the foundation of a brilliant career in explosives with dynamite as his most famous product. But with regard to the Swedish navy, the ambitions of the Nobels came to nothing. How could that be?

A story that wasn’t
Here is what appears to be a great story – a family drama involving the man behind the Nobel Prize. We know that Alfred wanted to break away from the company of a father he found self-centered and unreliable⁷, and there were traits in his father’s character that might have antagonized the committee set up to evaluate his mines.⁸ From this could have followed an aversion of the navy decision-makers to the father’s mines and, by implication, to Alfred and his inventions. Such a story could have ended with the explanation that Albert Nobel’s explosives did not become part of the Swedish sea mine development because of the trail left by Alfred’s father.

Actually, there is more to the story than a product of an inventive genius becoming the victim of personal antipathies from people in power. I hope to be forgiven for having presented an answer to my question along that simple line some years ago.⁹ I now have evidence of other factors at play, and can see that dynamite would not necessarily have been the rational solution for the navy, which its civilian success indicates. In the following I want to present this broader story.

The development of dynamite
In 1863 Alfred obtained his first explosive’s patent with the Swedish Patent Office. The substance was called “blasting oil”, and it was demonstrated to a military commission later that year. The commission found the new explosive to have “tremendous power” but added that it would be “much too hazardous to use in warfare”.¹⁰ This may seem a puzzling comment coming from military quarters, but it is less puzzling when we know that it originates from an artillery commission. They needed an explosive more powerful than traditional gunpowder but not as powerful as to burst gun barrels.

With sea mines it is a different matter. There is no restriction on how powerful their explosive agent should be. The stronger the better. Alfred’s oil was a promising mine explosive, but its safety and chemical stability needed time to assess.

In the following spring Alfred made what many explosives experts consider to be his most important invention – the detonator.¹¹ It is a small charge used for initiating a larger amount of explosive. It represented a significant safety improvement, as quick and easy ignition needed no longer be a property of the bulk of the explosive substance, which could instead be made to resist various shocks from heat or fall; reacting only to the detonator. Mines could thereby be more safely handled. Later in 1864 Alfred formed his first company to produce and sell his blasting oil.

Alfred was now his own master instead of being his father’s assistant and could turn to areas outside of the military that were potentially more lucrative. In an industrializing world there were tunnels to be blasted, iron and other metals to be extracted. Such projects could be greatly helped by a safe and powerful explosive. With outstanding product and sales efforts in Europe and the United States, Alfred satisfied civilian demands and managed to build what came to be a dynamite empire.

Sweden was an origin, although not the centre, of this empire. Alfred had moved his business to Germany when dynamite was invented in 1867, and in the 1870s almost half of the quantity of Nobel explosives sold came from Germany, with also Great Britain selling more than Sweden. But the rapid expansion of Sweden’s dynamite market – which in the three last decades of the 19th century saw a tenfold increase in production volume – is typical of what happened in other parts of Europe (Figure 1).

Fig 1. The rise of new explosives. Production in Sweden. From: Sjöstrand, Albert, Krut, dynamit och andra sprängämnen, Studentföreningen Verdandis småskrifter, nr 240, Bonnier, Stockholm 1921, p. 51.

 
From 1870 Sweden produced explosives enough to have sufficed for thousands of mines per year, if all production had been directed toward the military customer.¹²

Early navy explosives experiments
A Norwegian naval officer, after visiting a number of European countries, reported that they all looked for a more powerful mine explosive than gunpowder. His opinion was that through this, “considerable cost reductions would be achieved”.¹³ Sweden was one of those countries.

The Swedish navy was in the latter half of the 1860s open to novelties, and experiments were carried out both with Nobel’s blasting oil and his dynamite.¹⁴ In 1868, just a year after production of the explosive had started, the navy bought enough to fill half a dozen mines. They were exploded and the effects studied. The main finding was that dynamite was an extremely strong and, under certain conditions, suitable explosive, but there could be a problem. In temperatures below +10^o Celsius it was said to become more and more difficult to ignite, and at 0^o or below “extremely difficult”. In the same report it was mentioned that an alternative ammonium-based explosive was said to be both cheaper and less dangerous to handle.¹⁵

Alfred Nobel’s blasting oil and dynamite were not the only new explosives to be developed in the 1860s. There were many others, one of which was gun-cotton. It was being experimented with in Austria and Great Britain. In 1863 a British expert committee reported favourably on its application to “warlike purposes”,¹⁶ noticing that the substance was unaltered after years of storage and could be manufactured without danger.¹⁷ Still, manufacturing safety could be improved and in 1865 the British Woolwich arsenal claimed to have found “the patent safety gun-cotton”.

The Norwegian officer, referred to above, mentioned dynamite and gun-cotton among what he saw as main candidates for a new naval explosive. We have seen that dynamite was used in mine experiments, but there is very little mention of gun-cotton in the Swedish archival material for these years. This can be interpreted as a signal that Sweden chose to rely on what was done to develop and test gun-cotton (for mines) in Great Britain.

Gun-cotton chosen and retained
A mine committee was set up in 1870 with the task of “arranging the mine system”.¹⁸ Later that year a requirement for mine materiel was formulated. This time it was not for experimental purposes, but for the protection of the major sea-lanes to the capital. Hundreds of mines should be acquired and supplied with an explosive. The requirement here was for 5 tons of gun-cotton. This, together with various pieces of mine equipment, was to be supplied by England. The requirements were described by an officer on the mine committee as an order from the minister for sea defence. The committee had no say in this or any comments. Soon after it had been agreed that Sweden should use gun-cotton on a larger scale, an officer was sent to England with the task of acquiring, among other things, over three tons of gun-cotton.

A new mine committee began work in 1873. This time the ambition was great involving officers also from the Norwegian side and from Denmark, with numerous experiments carried out, formulas presented, and the results printed and published. Experiments were made during both summer and winter, with some of the experiments involving exploding mines under ice.

This time, dynamite was accepted as an explosive to use in the committee’s experiments. It was provided by Sweden as a typical new explosive, which was to be compared to traditional gunpowder. In the end, however, the committee concluded that gun-cotton had a considerable advantage over dynamite, in that it could absorb 20-30 % (fresh) water without deterioration.¹⁹ No further explanation was given; the committee concentrated on contrasting the new explosives to the traditional gunpowder with regard to physical impact. From what the committee said there was no reason for the navy to abandon gun-cotton.

The fact that the explosive was an important part of the mine weapon was underlined when the navy employed a chemist in the 1880s. His first job was to control the gun-cotton imported and stored, but he also came to investigate some new explosives available on the civilian market.
The wisdom of importing such a central ingredient of the naval defence had not been questioned until and in the early 1890s when the navy administration asked the chemist to find out “which of the violent explosives produced within Sweden would be most suitable, in case of a shortage of gun-cotton, to use instead of that?”²⁰

Here was a new chance to have a Nobel explosive introduced into the navy. The navy chemist came out in favour of a Nobel product of the 1870s, called blasting gelatin, and found that it had many advantages: the simplicity of its production, its heaviness, its greater safety against blows compared to gun-cotton, its insolubility in water, its simplicity to insert in a mine, its usefulness in all kinds of powder receptacles without prior configuration. Blasting gelatin also had a 20 to 30% greater effect than gun-cotton, and a further advantage was its low price. According to the navy chemist, there was no other explosive to match it.²¹

The substitute asked for had been found better than the original. What was the military reaction? The year after the chemist had declared his preference for blasting gelatin, the navy solved the gun-cotton problem in a very different way, as it invested in a factory for the domestic production of gun-cotton. The factory was built in 1894 and started production the year after.²²

This surprising decision was backed up by a new mine commission in 1896, which found the product lauded by the navy chemist inferior to gun-cotton both with regard to safety and power. The safety criteria of the commission were that the explosive should not become dangerous if hit by a gunshot, and it should be unaffected by variations in temperature. Experiments showed that the blasting gelatin “exploded violently” when hit by projectiles from a 57 mm quick-firing gun, whereas the (wet) gun-cotton’s reaction to this was “entirely without danger”. Resistance to temperature variations seems to have been less investigated, and here the committee was content to find gun-cotton unaffected after being stored for three months. The chemist’s conclusion was reversed also with regard to the destructive power of the explosive. The finding that the power of blasting gelatin was stronger, was now found to be true only for large distances to the target (45 metres or more), while gun-cotton was found “considerably superior” at lesser distances. The commission on these grounds recommended that gun-cotton should be only a navy explosive, with its wet form to be used as a main charge, and its dry form as detonator.²³

The long reign of gun-cotton in Swedish sea-mines is illustrated in Figure 2. The last mines with gun-cotton were not decommissioned until the early 1950s.²⁴

Fig 2. Explosives for the Swedish sea mine weapon. Gun-cotton dominant from 1870s till after 1900, and the most powerful explosive till 1940s. From: Mine department, Ö III, Taube (picture page 40).

Why was dynamite discarded?
Dynamite was a hugely successful product in the latter half of the 19^th century. Upon it Alfred Nobel established an explosives empire covering most of Western Europe. But the navy of Sweden – the country where it all started – did not make dynamite part of its inventory. It makes one wonder why.

In Sweden, 1863 marked the start of years of experiments in sea-mine technology. One part of that technology consisted of the explosive inside the mine ­– a field where Alfred Nobel was engaged. In the 1860s and 1870s he patented three explosives that came to be tested by naval representatives in Sweden. Beside dynamite it was blasting oil and blasting gelatin.

Blasting oil was Alfred’s first contribution to the explosives field. It was developed for use in the mines his father had constructed, but Alfred also presented his explosive to civilian customers, and after his father’s mines had been found inadequate for mass production, Alfred’s connection to the military sector seems to have been severed. However, the navy cannot be blamed for not acquiring his blasting oil. It was too new and too little tested to be entirely relied on as a mine explosive.

Alfred soon came up with dynamite as a more stable and safe substance. Only a year after its introduction in 1867 it was tested in Swedish sea mines. Its explosive power was found impressive, but there was a suspicion that the substance would be difficult to initiate at low temperatures. This was obviously a drawback for an explosive in such northerly waters as Sweden’s. Neither was dynamite seen as the cheapest among the new high-explosives.

The suspected poor performance at low temperatures can have been a reason for dynamite not to have been chosen, when in 1870 mine materiel was acquired for the protection of sea-lanes to the capital. A mine committee had been appointed earlier that year but was not consulted. Instead, what was to be acquired was decided upon in a dialogue between a mine officer on the committee and the ministry for sea defences. The explosive decided on for the mines was gun-cotton. Whether it was a decision from below (the officer) or from above (the ministry) is unclear.

A geographically broader and more active mine committee was set up soon after. It was a Scandinavian collaboration with Denmark involved beside Sweden/Norway, which provided the high explosive to be used in the committee’s experiments. Somewhat surprisingly it was dynamite. It was found cost-effective enough to use, which meant that the price argument against it had disappeared. Neither did there seem to be any problems using dynamite at low temperatures, as part of the experiments meant exploding mines under ice. But with two of the arguments against dynamite gone, a third argument turned up, which made the committee express a preference for gun-cotton. It was said to have a considerable advantage in that it could be used when wet. The implication was that dynamite was more problematic in this respect.

To use gun-cotton as the first high explosive in Swedish sea mines in the 1870s was probably not a bad idea. Three arguments can be raised in favour of such a decision: first, experiments and development work had gone on for more years with gun-cotton than with dynamite. Second, a British expert commission had found it suitable for military applications and much work had gone into achieving its safe production. A third argument is that with as large and leading a customer as the British navy, gun-cotton was a substance likely to be in production for many years to come, and one that would possibly continue to be improved. These arguments can be inferred from the logic of the situation. They are not made explicit in the archival material, where, instead, appear the more specific techno-economic arguments noted above

Why was dynamite’s successor discarded?
Gun-cotton may have been good enough technically, but there was a potential problem. There was no indigenous supply from where the navy could get it. If a rise in political tensions would occur or a threat of war, Sweden might find itself cut off from its supply of mine explosives. Sweden later became sensitive to such foreign dependence, leading in the Cold War period to avoidance of imported commodities in areas as different as nuclear engineering and agriculture.²⁵

For most of the 19^th century foreign dependence was not an issue. But in the century’s last decade – possibly in reaction to a more aggressive German naval policy after 1890²⁶ – the Navy Authority (Marinförvaltningen) formulated a question directly addressing the problem. It was asked if there was a domestic back-up explosive in case Sweden should be cut off from its gun-cotton supply. The question was sent to the navy chemist to investigate, and his answer was affirmative. There was a very good substitute; so good, indeed, that he saw it as superior to the long established gun-cotton. It could be easily produced, and easily filled into mines, it was more chock-resistant than gun-cotton, and 20 to 30 % more powerful. In short, there was nothing to compare to it. The explosive in question was “blasting gelatin”, a Nobel explosive introduced in the 1870s as a successor to dynamite.

But blasting gelatin fared no better than dynamite with the navy. A few years after the chemist had recommended it, a mine commission came to a totally different conclusion. Now it was gun-cotton that was the superior substance with regard to both safety and destructive power. Where the chemist had found blasting gelatin to be more shock resistant, the commission now found it that it could not resist the shock of a hit from a 57 mm projectile, something which gun-cotton was found to do quite well. The superior explosive power of blasting gelatin, found by the chemist, was now reduced to superiority only at very large distances. At distances where mines were supposed to work – up to a few metres from the target – gun-cotton was found to be the stronger of the two.

This is quite confusing. If blasting gelatin “exploded violently” when hit by a projectile, it is more or less what we would expect, as it should explode through the shock from an activated detonator. Was the impact of a 57 mm projectile really less of a shock? If it was not, how could we trust a substance not affected by the projectile to explode at all? There is no hint in the commission summary that here was a major problem: Under what conditions could and should an explosive be expected to go off and under what conditions should it not? We get to know nothing about that and are left wondering about the experimental set-up, the shooting distance or which part of the mine was hit.

No less confusing is the reported result that an explosive measured to have had considerably less destructive power – that is, gun-cotton – could come out in the new trials with more power (at most distances) than its competitor. How could that be accommodated with the earlier results favouring blasting gelatin? There appears to have been something more than normal technological testing practice involved in the commission’s work.

One way of seeing the commission’s recommendation is as a confirmation of a decision already made and implemented. Some years earlier, the problem of foreign dependence regarding sea-mine explosives had been solved by the building of a Swedish gun-cotton factory. The commission showed this step to have been motivated, but it cannot be ruled out that the experiments were arranged so that this conclusion could be drawn; in other words that it was a rigged procedure. Lending some support to such a conspiracy theory is the curious fact that the findings of the commission have only survived in the form of an undated and unsigned summary, and that the date given for when the commission was set up is not correct (there is no corresponding information in the ministry records).²⁷ If there was never a formal ministry decision to set up the commission, there might not have been a full report written. With just a summary to describe experiments and conclusions, it would have been harder to scrutinize and criticize their validity.

Its price, which had been seen as one of the factors favouring blasting gelatin compared to gun-cotton, was not commented on in the summary. It is possible that, with a domestic gun-cotton factory already built, gun-cotton could be seen as price-competitive; but if the factory investment had been included in the calculus, the choice of gun-cotton would probably have turned out to be a costly affair.

One thing was to start using gun-cotton, another to continue using it for decades. Nobel’s dynamite was succeeded by blasting gelatin, made safer and more user-friendly through much development work and experience from civilian projects. It was more available and cheaper than gun-cotton, where the possibility of having the supplies cut off, when they were most needed, surfaced as a problem in the 1890s. Blasting gelatin appeared far preferable to gun-cotton, but with some curious experiments and/or conclusions from a mine commission gun-cotton stayed as the mine explosive preferred by the Swedish navy for another decade, and it remained part of the country’s mine weapon till as late as the early 1950s. The Nobel competitor, blasting gelatin – like its forerunner dynamite – got no further than the experimental stage.

Notes