So, cotton has been farmed in the middle east since at least Achaemenid times. The great physician
Muhammad ibn Zakariya al-Razi (lived between 854 and 925 AD) discovered nitric acid and sulphuric acid (though I don't know what methods he used to produce either). The combination of these ingredients is nitrocellulose, which is perhaps most famous as the first smokeless gunpowder, but also found use as a blasting agent in excavation and, with the addition of camphor, as a plastic (called celluloid, the first non-ivory billiard balls were made of this plastic, as was the most popular film base). As an explosive, it has a
relative effectiveness of 1.1, compared to the 0.5 RE of black powder, 1.25 RE of dynamite and 1.54 RE of pure nitroglycerine and is vastly safer to make, store and transport than nitroglycerine. (1 RE is TNT, the basis of the relative effectiveness scale.)
What I've been wondering is if it's possible to have an earlier discovery of nitrocellulose. Perhaps even by al-Razi himself (this seems to me the earliest practical discovery that's practical). It also helps that al-Razi was a pioneer of distillation technology, since storing nitrocellulose wet in alcohol makes it more stable. I'm not sure if al-Razi or one of his successors would be able to produce acids of reliable concentrations (if they can't, the nitrocellulose produced would be of variable sensitivity). I am also unsure how cheap the manufacture could be for pre-industrial people.
Assuming that it can be manufactured reliably, I suspect that the first uses would be medical (dissolving it in alcohol and ether - which may have been first synthesized by
Jābir ibn Hayyān in the 700s - to make collodion, which is an effective liquid bandage solution) and to make celluloid plastic (the necessary plasticiser, camphor was well known in the middle east by the 900s, I expect it would be used especially as lacquer and varnish, though as techniques developed to make objects of a consistent density, whole objects might become practical, though probably not cheap unless the synthesis of camphor from turpentine were also discovered earlier).
Eventually, as with black powder, someone would figure out how to apply the explosive properties of nitrocellulose. For black powder, it took about a century to move from being a medicine to a weapon. I wonder if it would be at all practical for early canons? In OTL, it took decades before the process for making less violently exploding guncotton that could be used as a propellant was found (this involved using less concentrated acids at lower temperatures, so an earlier discovery of nitrocellulose could start with propellant-grade nitrocellulose), before then nitrocellulose was used in explosive shells and the like. But would even propellant grade nitrocellulose crack the best cannons that could be made by Medieval metallurgy? Either way, before the cannon arrives from China, nitrocellulose would still have a use as an explosive charge for arrows and siege engines.
One thought that occurs, is that if nitrocellulose becomes a commonly used propellant for bullets, then battlefields will be much less smoky, meaning there will be more benefit to developing accurate firearms earlier. Also, the much lower amount of fouling left in the barrel after firing a nitrocellulose charge in a gun would mean much faster reloading times, which would likely be the biggest advantage in the early parts of the gun age. (I wonder if for early firearms, the smokelessness would be seen as an advantage or a disadvantage?)
The thing I find most fascinating, however, is the use of nitrocellulose in blasting charges - for mining and excavation. For example, in OTL, when the Portuguesse started muscling in on the Indian Ocean trade routes, the Ottomans considered digging out a canal from the gulf of Suez to the Mediterranean - they abandoned the idea when the engineers did the math and figured it would take 350 years to complete the canal. Modern explosives were THE main invention that made Suez affordable in the 19th Century (though steam engines were also a big help). So do nitrocellulose blasting charges allow the Ottoman state to construct a Suez canal 300 years early?
Better mining technology could potentially alleviate some bottlenecks in stone or metal production. Can this have much impact? Or does it just mean that mines need less labour to be as productive as they were in OTL? The main impact I could see is possibly making the Old World's gold and silver production be higher, which would be beneficial economically. Of course, without steam engines, mines will be limited by how fast muscle power can pump out the mines. I suspect that metal production wouldn't be much different from OTL. Blasting charges might be of more use in quarrying stone. Was anywhere in the world really limited by the availability of stone though?
So what do people think? Can nitrocellulose be developed with the tools of Medieval alchemy? If it can, would the technology be cheap enough to be widely used? Or would it be so expensive to make that it remained a curiosity for centuries? How fast might the technology spread? What does it do to how wars are fought? Can it be used to carve out an early Suez canal?
fasquardon