17.2.

Perfect Balance is achieved through the marriage of sulfur and mercury. The secret which I am about to impart brought not only gunpowder, but the entire modern age into being.

I don't believe it. Is the Author insane?

From the Mongol bombard to the blunderbuss, from the cannon to the steam engine, from the Ford Model T to the Boeing 747, this secret has been instrumental in shaping the world.

From dynamite to C4, from the V2 rocket to the ICBM, from farm kids blowing their fingers off to Timothy McVeigh calling around for the best price on fertilizer, your "secret" has been instrumental in killing innocent people. Look, I kept my mouth shut about the distillation of alcohol, but this is going too far. Given the rise of terrorism, wouldn't we be better off skipping gunpowder and moving on to something less inflammatory?

You imagine that terrorists are going to make their own gunpowder? I have news for you; it is easier to buy gunpowder than it is to buy saltpeter and sulfur.

But this is dangerous! You can't go around teaching people to make explosives as if they were some kind of toys. After all, as a Taoist you must know the teachings of Lao-tzu:

 

Now arms, however beautiful, are instruments of evil omen, hateful, it may be said, to all creatures. Therefore they who have the Tao do not like to employ them. [1]

And as a figment of the "Author's" imagination, you must know that Lao-tzu continues:

 

The superior man ordinarily considers the left hand the most honourable place, but in time of war the right hand. Those sharp weapons are instruments of evil omen, and not the instruments of the superior man;—he uses them only on the compulsion of necessity.

Is it a necessity for cowboys to shoot Indians, for cops to shoot robbers, or for little kids to shoot their playmates?

You are the one who has laid the foundation; Absolute Harmony comes through the application of stoichiometry to oxidation and reduction.

Hey, that was for educational purposes only!

You probably need not concern yourself; your vacuous little jingles have probably filled no heads with wonder; your breezy little games have probably blackened no hands with charcoal; your tedious little exercises have probably whitened no faces with ash. But just in case,

 

He who has killed multitudes of men should weep for them with the bitterest grief; and the victor in battle has his place (rightly) according to those rites.

Join me in weeping, Figment, for your I-deas are as tinged with blood as my own.

Alright, alright you two; knock it off. It seems that I am of two minds in this matter. On the one hand, gunpowder manufacture was an important predecessor to modern chemical industry. To ignore it would make the subsequent chapters less comprehensible. On the other hand, it would be irresponsible to encourage the public to engage in dangerous and destructive activities. So I will stop short of giving the formula for gunpowder. I will explain the chemical principles involved and the astute reader will be able to calculate the formula for herself. I suppose that the lazy reader will look up the formula in any encyclopedia and the budding terrorist will buy her explosives ready-made. My intention here is simply to give the student of chemistry a tactile introduction to this important material; if you are lazy or evil-minded, let me suggest that you will find more practical information elsewhere.

Perfect balance is achieved through the marriage of sulfur and mercury. I think that what Tu Tzu-Chhun was getting at was the careful balance of oxidation and reduction which is required for an explosion to take place. In Chapter 1 you were introduced to the oxidation of charcoal by oxygen. You observed that when you blow on a glowing coal, it gets brighter. The rate of combustion is limited by the rate at which fresh oxygen can be provided to the fuel. In Chapter 5 you learned the principle of the furnace, in which a steady draft of air allows the fuel to burn at a faster-than-normal rate, thereby increasing the temperature attainable in the kiln. The draft can only be so strong, however, before the extra heat produced by the draft is simply carried away by the increased flue gases. This is what happens when you blow out a match.

To make an explosive, what we really need is a solid or liquid oxidant which can be intimately mixed with the reductant, or fuel, thus eliminating the need for atmospheric oxygen. The first material to be used in this way was saltpeter, or potassium nitrate. A sort of gunpowder can be made from charcoal and saltpeter alone:

Given the balanced equation, we can use stoichiometry to determine the relative weights of charcoal and saltpeter:

That is, for every 1 gram of charcoal, we require 6.74 grams of saltpeter. If there is too little saltpeter, charcoal will remain after the saltpeter as been used up, which means that there was charcoal that could have burned, but didn't. The residue which remains will be black, from the leftover charcoal. If there is too much saltpeter, the charcoal will be consumed and some unused saltpeter will remain. The residue will be white, from the leftover saltpeter. But if mercury and sulfur, oxidant and reductant, are perfectly balanced no salt at all will remain from their union and the maximum energy will be delivered from the available fuel.

While a saltpeter-charcoal gunpowder will burn without air, the production of potassium oxide consumes much of the energy available from the combustion of the charcoal. Potassium sulfide consumes much less energy, leaving more bang for the buck. This becomes possible with the addition of sulfur to the saltpeter-charcoal mix—not esoteric, alchemical sulfur—but the ordinary, yellow element. Equation 17-1(a) gives a skeleton reaction for the saltpeter-charcoal-sulfur mixture. Balance it using the method of Chapter 11 and then answer the following stoichiometric questions using the method of Chapter 15:

Q: How many grams of saltpeter are needed to react with each gram of sulfur?
Q: How many grams of charcoal are needed to react with each gram of sulfur?

Charcoal is not the only reductant from which gunpowder can be made. A popular alternative for amateur rocket fuel is powdered sugar, sucrose. Balance Equation 17-1(b) and then answer the following stoichiometric questions:

Q: How many grams of saltpeter are needed to react with each gram of sulfur?
Q: How many grams of sucrose are needed to react with each gram of sulfur?

Equation 17-1. Skeleton Equations for Two Gunpowder Mixtures

WarningMaterial Safety
 

Can there be any doubt in your mind that making fireworks is dangerous work? It is not for the lazy, the timid, or the careless. If you are unprepared to make careful calculations and measurements; if you are unwilling to accept responsibility for your own safety and that of others in your vicinity; if you are not able to observe all appropriate safety precautions, you would do well to skip the Salt section and retire to some less demanding exercise, like spinning or dyeing or whistling. But if your hands are black with charcoal and your face is white with ash, welcome Comrade to the fellowship of those who are not afraid to keep in the heat and withstand it.

Locate an MSDS's for saltpeter (CAS 7757-79-1), sulfur (CAS 7704-34-9), charcoal (CAS 7440-44-0) or sucrose (CAS 57-50-1). Summarize the hazardous properties in your notebook, including the identity of the company which produced each MSDS and the NFPA diamond for each material.[2]

The most pressing hazard in this project is the danger of fire. Sources of ignition, including sparking from static electricity or iron utensils should be avoided. Fireworks should be handled according to federal, state, and local laws. For more information on firework safety see, for example, Practical Introductory Pyrotechnics.[3]

You should wear safety glasses while working on this project. Any leftover gunpowder should be carefully burned. Leftover sulfur, charcoal, or sugar may be thrown in the trash. Leftover saltpeter can be flushed down the drain with plenty of water.

NoteResearch and Development
 

You should not remain ignorant if you are to proceed in the Work.

  • Know the meanings of those words from this chapter worthy of inclusion in the index or glossary.

  • You should have mastered the Research and Development items of Chapter 13 and Chapter 15.

  • Be able to balance the redox reactions of charcoal or sucrose with saltpeter and sulfur.

  • Be able to work out the stoichiometry for either of these reactions.

  • Know the systematic names and formulae for sugar and saltpeter.

  • Know the hazardous properties of charcoal, sugar, saltpeter, and sulfur.

  • Be familiar with local laws concerning fireworks.

Notes

[1]

Reference [16], Tao Te Ching 31 (or 75).

[2]

The NFPA diamond was introduced in Section 15.2. You may substitute HMIS or Saf-T-Data ratings at your convenience.

[3]

Reference [48].