What does the manganese dioxide do? It contributes no oxygen. At the conclusion of the reaction it 'is all still there, unchanged. Its mere presence seems sufficient to hasten the evolution of oxygen. It is a haste-maker or, more properly, a catalyst.
And how can one explain influence by mere presence?
Is it a kind of molecular action at a distance, an extra sensory perception on the part of potassium chlorate that the influential aura of manganese dioxide is present? Is it telekinesis, a para-natural action at a distance on the part of the manganese dioxide? Is it, in short, magic?
Well, let's see…
To begin at the beginning, as I almost invariably do, the first and most famous catalyst in scientific history never existed.
The alchemists of old sought methods for turning base metals into gold. They failed, and so it seemed to them that some essential ingredient was missing in their recipes. The more imaginative among them conceived of a substance which, if added to the mixture they were heating (or what ever) would bring about the production of gold. A small quantity would suffice to produce a great deal of gold and it could be recovered and used again, no doubt.
No one had ever seen this substance but it was de scribed, for some reason, as a drv, earthy material. The ancient alchemists therefore called it xenon, from a Greek word meaning "dry."
In the eighth century the Arabs took over alchemy and called this gold-making catalyst "the xerion" or, in Arabic, at-iksir. When West Europeans finally learned Arabic alchemy in the thirteenth century, at-iksir became "elixir."
As a further tribute to its supposed dry, earthy prop erties, it was commonly called, in Europe, "the philos opber's stone." (Remember that as late as 1800, a "natural philosopher" was what we would now call a "scientist.")
The amazing elixir was bound to have other marvelous properties as well, and the notion arose that it was a cure for all diseases and might very well confer immortality.
Hence, alchemists began to speak of "the elixir of life."
For centuries, the philosopher's stone and/or the elixir of life was searched for but not found. Then, when finally a catalyst was found, it brought about the formation not of lovely, shiny gold, but messy, dangerous sulfuric acid.
Wouldn't you know?
Before 1740, sulfuric acid was hard to prepare. In the* That's all right, though. Sulfuric acid may not be as costly as gold, but it is conservatively speaking-a trillion times as in trinsically useful.
ory, it was easy. You bum sulfur, combining it with oxygen to form sulfur dioxide (SO2)- You burn sulfur dioxide further to make sulfur trioxide (SO3)- You dissolve sulfur trioxide in water to make sulfuric acid, (H2SO4) - The trick, though, was to make sulfur dioxide combine with oxygen.
That could only be done slowly and with difficulty.
In the 1740s, however, an English sulfuric acid man ufacturer named Joshua Ward must have reasoned that saltpeter (potassium nitrate), though nonflammable itself, caused carbon and sulfur to burn with great avidity. (In fact, carbon plus sulfur plus saltpeter is gunpower.) Con sequently, he added saltpeter to his burning sulfur and found that he now obtained sulfur tri'oxide without much trouble and could make sulfuric acid easily and cheaply.
The most wonderful thing about the process was that, at the end, the saltpeter was still present, unchanged. It could be used over and over again. Ward patented the process and the price of sulfuric acid dropped to 5 per cent of what it was before.
Magic? - Well, no.
In 1806, two French chemists, Charles Bernard Ddsormes and Nicholas C16ment, advanced an explanation that contained a principle which is accepted to this day.
It seems, you see, that when sulfur and saltpeter bum together, sulfur dioxide combines with a portion of the saltpeter molecule to form a complex. The oxygen of the saltpeter portion of the complex transfers to the sulfur dioxide portion, which now breaks away as sulfur tri oxide.
What's left (the saltpeter fragment minus oxygen) pro ceeds to pick up that missing oxygen, very readily, from the atmosphere. The saltpeter fragment, restored again, is ready to combine with an additional molecule of sulfur dioxide and pass along oxygen. It is the saltpeter's task simply to pass oxygen from air to sulfur dioxide as fast as it can. It is a middleman, and of course it remains un changed at the end of the reaction.
In fact, the wonder is not that a catalyst hastens a re action while remaining apparently unchanged, but that anyone should suspect even for a moment that anything "magical" is involved. If we were to come across the same phenomenon in the more ordinary affairs of life, we would certainly not make that mistake of assuming magic.
For instance, consider a half-finished brick wall and, five feet from it, a heap of bricks and some mortar. If that were all, then you would expect no change in the situation between 9 A.m. and 5 P.m. except that the mortar would dry out.
Suppose, however, that at 9 A.M. you observed one fac tor in addition-a man, in overalls, standing quietly be tween the wall and the heap of bricks with his hands empty. You observed matters again at 5 P.m. and the same man is standing there, his hands still empty. He has not changed. However, the brick wall is now completed and' the heap of bricks is gone.
The man clearly fulfills the role of catalyst. A reaction has taken place as a result, apparently, of his mere pres ence and without any visible change of diminution in him.
Yet would we dream for a moment of saying "Magic!"?
We would, instead, take it for granted that had we ob served the man in detail all day, we would have caught him transferring the bricks from the heap to the wall one at a time. And what's not magic for the bricklayer is not magic for the saltpeter, either.
With the birth and progress of the nineteenth century, more examples of this sort of thing were discovered. In 1812, for instance, the Russian chemist Gottlieb Sigis mund Kirchhoff…
And here I break off and begin a longish digression for no other reason than that I want to; relying, as I always do, on the infinite patience and good humor of the Gentle Readers.
It may strike you that in saying "the Russian chemist, Gottlieb Sig7ismund Kirchhoff" I have made a humorous error. Surely no one with a name like Gottlieb Sigismund Kirchhoff can be a Russian! It depends, however, on whether you mean a Russian in an ethnic or in a geographic sense.
To explain what I mean, let's go back to the beginning of the thirteenth century. At that time, the regions of our land and Livonia, along the southeastern shores of the Baltic Sea (the modem Latvia and Estonia) were in habited by virtually the last group of pagans in Europe. It was the time of the Crusades, and the Germans to the southeast felt it a pious duty to slaughter the poorly armed and disorganized pagans for the sake of their souls.
The crusading Germans were of the "Order of the Knights of the Sword" (better known by the shorter and more popular name of "Livonian Knights"). They were joined in 1237 by the Teutonic Knights, who had first established themselves in the Holy Land. By the end of the thirteenth century the Baltic shores had been conquered, with the German expeditionary forces in control.
The Teutonic Knights, as a political organization, did not maintain control for more than a couple of centuries.
They were defeated by the Poles in the 1460s. The Swedes, under Gustavus Adolphus, took over in the 1620s, and in the 1720s the Russians, under Peter the Great, replaced the Swedes.
Nevertheless, however the political tides might shift and whatever flag flew and to whatever monarch the loyal in habitants might drink toasts, the land itself continued to belong to the "Baltic barons" (or "Balts") who were the German-speaking descendants of the Teutonic Knights.