The Mexican gunpowder dilemma

[yulzari]

The risk in using small arms powder in artillery is that the smaller grains cause a more rapid burn which gives a higher pressure and the cannon barrel may fail. If it does hold together (for a while at least) then the cannon ball will be projected faster rather than slower so it does not match the reported behaviour of Mexican artillery.

BTW the powder cannot be transported in it's constituents for mixing when needed. That would give you, at best, very bad firework powder. The incorporation of them needs much time and pressure. To get past transport shaking the constituents parts apart corning was developed generations before this war. The powder being pressed under high pressure into solid cakes which are then broken up and sorted through sieves into solid grains which will not break up if well made. It burns better than the earlier powdery 'meal' as the flash can pass through the interstices between the grains. I will spare you issues about adiabatic heating etc. By this time meal is only made for fireworks, rockets and some blasting purposes. Never for firearms but it would match the observed performances of Mexican powder.

I conclude it was probably made as badly made powder, badly corned, badly packaged, roughly transported and badly stored. Based upon low quality firework powder and deteriorated since making. Soft corning and poor incorporation will result in friable grains which will crumble in transport and be more hygroscopic in storage. I do doubt that even the most venal buyer and military would expect to get away with buying actual meal firework powder.

[Jim McDougall]

Originally Posted by yulzari

The risk in using small arms powder in artillery is that the smaller grains cause a more rapid burn which gives a higher pressure and the cannon barrel may fail. If it does hold together (for a while at least) then the cannon ball will be projected faster rather than slower so it does not match the reported behaviour of Mexican artillery.

BTW the powder cannot be transported in it's constituents for mixing when needed. That would give you, at best, very bad firework powder. The incorporation of them needs much time and pressure. To get past transport shaking the constituents parts apart corning was developed generations before this war. The powder being pressed under high pressure into solid cakes which are then broken up and sorted through sieves into solid grains which will not break up if well made. It burns better than the earlier powdery 'meal' as the flash can pass through the interstices between the grains. I will spare you issues about adiabatic heating etc. By this time meal is only made for fireworks, rockets and some blasting purposes. Never for firearms but it would match the observed performances of Mexican powder.

I conclude it was probably made as badly made powder, badly corned, badly packaged, roughly transported and badly stored. Based upon low quality firework powder and deteriorated since making. Soft corning and poor incorporation will result in friable grains which will crumble in transport and be more hygroscopic in storage. I do doubt that even the most venal buyer and military would expect to get away with buying actual meal firework powder.

An absolutely brilliant synopsis Yulzari!! thank you so much.
I think your conclusion perfectly sums up the Mexican powder situation and well illustrates the circumstances that were faced with powder production in wider scope of these times.
Very much appreciated.

[fernando]

My ignorance of experimental or even theoretical knowledge is overwhelmed by my curiosity ... and nonconformism (in lack of a better term). Furthermore my mediocre english impedes me to understand the following paragraph

Originally Posted by yulzari

...BTW the powder cannot be transported in it's constituents for mixing when needed. That would give you, at best, very bad firework powder. The incorporation of them needs much time and pressure. To get past transport shaking the constituents parts apart corning was developed generations before this war.The powder being pressed under high pressure into solid cakes which are then broken up and sorted through sieves into solid grains which will not break up if well made. It burns better than the earlier powdery 'meal' as the flash can pass through the interstices between the grains...

Note that i was diverting from the specific problematic of Mexican gunpowder both because what i had to (or managed to) learn about it is exhausted and because i found ambiance grounds to bring the gunpowder per se to the table, a subject often mentioned in chronicles ... Portuguese for one . This to say that i am perplex at your technical rejection on the possibility (probability) of gunpowder components (constituents) being taken to spots to mixed in opportune occasions. Does the fact that i am quoting events occurred in early periods (XV-XVII) puts things in a different scenario than in the XIX centuries, a period where discussed Mexican powder problems took place ? The thing is that, i keep reading (or inferring) that such procedure was feasible.

" 1626, June 10, letter of the Governor of Sao Tome, to the king about the state of the island ... warning that in the next contract the contractor would have to bring gunpowder, refined saltpeter, sulfur, aguardente (brandy) and lead to the fortress ".

Now, if he had a need for ready gunpowder, why would he also ask for the three separated constituents ?

On the other hand and later in the XVIII century, Alpoim weaves considerations on how to preserve gunpowder using the 'pães' system. Pães translates as breads, as or bread rolls; is this the same you mention as cakes ?

" By spraying the powder with brandy and mixing well, you can mold it into breads that, after drying should be stored in glass vases. Although, according to him, there are those who use vinegar instead of brandy, he prefers brandy, and says, "I and some of my disciples know what it is for, with the Prince's use." The advantage of gunpowder in bread is “it never gets corrupted, even with moisture; It is very good when you grind it in the fires, and you need to be careful in grinding it ".

... And he follows:

" However, it is even better to store saltpeter, sulfur and charcoal ready in the barrels, not prepared gunpowder, “because time wastes it,” as well as being a risk factor. For this, however, it is necessary to have mills to prepare the gunpowder when it is needed ".

Earlier in the XVII centuries in Macao, an interesting passage involving the deteriorated gunpowder problematic may be read:

" In June of the same year (1639), an agreement is made with the Spanish gunpowder maker João de Mosqueira, to repair gunpowder 'danada' (condemned, damaged), so that it can be used again ".

[yulzari]

Oh dear. This could get very technical and involve wide digressions. So, in a short version.

Corning (making the gun powder into grains) used to be done by drying the gun powder into 'cakes' and then rubbing them through sieves or graters into irregular grains. It was only later with improving mechanical technology that the powder was pressed under high pressure in hydraulic presses into rock like cakes that had to be broken up into hard grains which were then sieved into size grades.

The older soft grains were liable to crumble in transport and storage. In 17th century Sao Tome they were probably getting soft grains so the governor was asking for either the cakes, un-sieved, in waterproof containers or for the ingredients to combine and corn in Sao Tome.

I think it quite possible that Mexican powder was of the soft corned variety in our period.

It was, and is, quite normal for the finer dust powder left in processing to be reintroduced into the next batch and damaged powder also. If too damaged, especially by damp, gun powder would be reused as a source of saltpetre for new production.

To me all of this points to Mexican production being of low quality meal powder for the civilian market which was soft corned for firearms use.