But why aluminum? Why would the US government honor its first leader by making this pyramid out of the metal in which I wrap my peanut butter and jelly sandwiches? The answer
in part is that aluminum was considered a precious metal in 1884, costing about as much as silver. The high price of aluminum was due almost solely to the insane method that Frishmuth used to produce this metal.
In an earlier post I described how aluminum oxide (a.k.a. alumina; Al2O3) is isolated from the ore bauxite. With this metal oxide in hand, all that is left to do is remove the oxygen atoms to produce metallic aluminum. Most metal oxides, such as iron oxide (a.k.a. rust; Fe2O3) can be turned into their pure metal counterparts by treating the metal oxide with coke. Coke is kind of like charcoal, and is essentially a big block of carbon atoms. By heating a mixture of rust and coke, the oxygen atoms move from being bonded to the iron atoms to being bonded to the carbon atoms, producing metallic iron and carbon dioxide. This type of reaction is a big deal, and is in part what led to the bronze age and iron age (more on that in this post).
2 Fe2O3 + 3 C → 4 Fe + 3 CO2
This reaction is contingent upon the fact that oxygen prefers to bond to carbon atoms over iron atoms. However, as was discussed in the previous post on thermite, oxygen atoms really love to be bonded to aluminum atoms, so this reaction doesn't work for aluminum.
Therefore, Frishmuth had to first get rid of those pesky oxygen atoms. Exactly how he did that I am going to guess at, because I can't find any references to this. Given the technology of the time he probably treated alumina with concentrated hydrochloric acid, which gives you aluminum chloride and water:
Al2O3 + 6 HCl → 2 AlCl3 + 3 H2O
After separating the water from the aluminum chloride (not sure how he did that though, any thoughts?), Frishmuth then heated the crap out of water-free aluminum chloride in the presence of the metal sodium.
AlCl3 + 3 Na → Al + 3 NaCl
This strikes me as particularly nuts because sodium burns spontaneously in open air, but is especially violent in the presence of significant quantities of water. Check it out:
That is seriously a LOT of sodium to be dropping into water. Way unsafe.
So Frishmuth used a method like this two-step method to produce around 6 pounds of aluminum for this capstone. He put the capstone on public display in Philadelphia for two days before sending it to Washington DC to be put on top of the monument in 1884. Here is what that apparently looked like:
So everything in Frishmuth's aluminum world was totally cool until in 1886, a new method, now known as the Hall-Héroult process, was invented for the production of aluminum. This method was way cheaper than Frishmuth's method, which meant that by the time the Washington monument was dedicated in 1888, aluminum was no longer such a precious metal.
The Hall-Héroult process is cheap in part because it makes aluminum directly from alumina, without the need to use sodium. It does this by heating the crap out of alumina in a solution of the molten salt cryolite (Na3AlF6) in the presence of coke (carbon). As I said before, the oxygen atoms in this case prefer to bond with aluminum atoms. So in order to coax the oxygen atoms off the aluminum atoms and onto the carbon atoms, energy is added to the system by passing electricity through the solution. Over 100 years after the invention of this process, this is still the way people produce aluminum today.
2 Al2O3 + 3 C + energy → 4 Al + 3 CO2
Having been bested at his own game by the young whippersnappers Hall and Héroult, which meant he was no longer the aluminum king of the united states, Frishmuth eventually took his own life in his Philadelphia apartment in 1893. SO DARK!
So as to not leave you on a down note, check out this wicked video of jupiter taken by Voyager I in 1979. You can even see Jupiter's moons flying by. MESMERIZING! Until I saw this it somehow never occurred to me that the movement of jupiter's atmosphere would be on a timescale view-able by humans.