Caveman Chemistry

A group of twelve intrepid teens traveled through time in the name of Science by recreating 28 key developments in the history of Chemistry.  Their fearless leaders Buddha Buck and Claire Fox used the engaging, entertaining, and eccentric book Caveman Chemistry by Kevin Dunn as a guide:

“Half a million years ago our ancestors learned to make fire from scratch. They crafted intricate tools from stone and brewed mind-altering elixirs from honey. Their descendants transformed clay into pottery, wool into clothing, and ashes into cleansers. In ceramic crucibles they won metal from rock, the metals lead to colored glazes and glass. Buildings of brick and mortar enshrined books of parchment and paper. Kings and queens demanded ever more colorful clothing and accessories in order to out-class clod-hoppers and call-girls. Kingdoms rose and fell by the power of saltpeter, sulfur, and charcoal. And the demands of everyday folk for glass and paper and soap stimulated the first round of chemical industrialization. From sulfuric acid to sodium carbonate. From aniline dyes to analgesic drugs. From blasting powder to fertilizers and plastics. In a phrase, From Caveman to Chemist.”

Here are some pictures and notes from some of our labs:

Students learned that when yeasts are in an anaerobic environment, they eat sugar, fart out carbon dioxide, and pee out ethyl alcohol. We experienced this firsthand by observing mead brewing. Lesson learned: don’t forget to put your airlock on right away….otherwise, you will wake up to a shower of yeast and honey water all over your kitchen! You can improvise one out of household materials (as shown here) if you don’t have time to get to the brewing supply store. Also, younger siblings are magnetically attracted to brewing projects.

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We formed and fired our own crucibles out of earthenware clay. That is just awesome.

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Textiles — the smell of raw wool is so memorable!  Those polymers smell like a barnyard.

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Potash – It’s tricky business, making potash. The ashes do not want to fit into the neck of a 2-liter bottle – doubtlessly this is a problem that has been plaguing people since antiquity! We did not document the vigorous shaking, or the tedious filtering. Some of us succeeded in producing alkaline crystals, yay!

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Using our homemade crucibles, we measured out powdered malachite (copper ore) and tin oxide, plus a liberal dose of soda ash to act as a flux. We filled in the remaining space with crushed charcoal (our reducing agent which combined with the oxygen in the ores and leave as carbon dioxide) and sealed the lid tightly. The crucibles were heated to cone 05, or 1915 degrees F. The two oxides were reduced into elemental metals which co-mingled and formed golden nuggets at the bottom of the crucible, covered by white ash and crusty slag. We dug out our smelted metal and polished it. Students experimented with different proportions of ores, and some of the resulting metal was silver rather than bronze in color, but were assuredly still an alloy. It was exciting to discover the metal, and see the large volume of powdered ore transform into a dense golden and silvery treasure.

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Yes, we fermented our own urine in an attempt to try traditional indigo dyeing! Many of us bravely tended to vats of stinking pee secreted away in far corners of our house. We didn’t have much luck with that method, sadly. But we did succeed in using thiorea dioxide as a reducing agent for the indigo. It was spectacular watching the pale green wool, saturated with leucoindigotin, transform before our eyes into deep blue indigo as it hit the air and oxidized.

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We created glass by mixing finely ground silica with borax (to act as a flux, and reduce the melting temperature) and firing to 1915 degrees F. The mixture was placed in a mold that each student made themselves by making a shape from clay, and placing it in wet plaster at the bottom of their crucible, allowing it to harden, then removing the clay and packing in the silica. Some people colored their glass with malachite. I don’t know how that deep blue and black was achieved, as no one claimed that crucible – it will remain a mystery.

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Who thought papermaking would involve touching maggots? We made paper by boiling cattail heads (from the marsh plant) in caustic soda, a.k.a lye. The black lignin separated from the pale cellulose. The resulting fiber was floated in water and scooped up on a mold and deckle made of old picture frames and window screen, and turned out onto couching cloths to dry. This was super easy because the fibers were so small that we didn’t need to do any blending. However, we were not expecting that the cattail heads would be an overwintering home to dozens and dozens of little larvae! They all floated to the surface of the water and got stuck in our paper. Some people picked them out, and others left them in! We also tried our hands at hand-pounding hemp fiber which had also been boiled in lye for many hours. It is a seriously tough fiber.   IMG_6080 IMG_6081 IMG_6024

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Distilling (strictly for experimental purposes, to produce a few ounces of fuel) was an exciting experience! Students watched as their meat thermometers swung suddenly from rare to well-done, and we all gathered around to see if our hard-earned product would light – and indeed it did, burning with an eerie blue light.

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Soap – each pair of students tried a different recipe, and took the results home to cure and use. The most successful seemed to be a mix of coconut oil, palm oil, and olive oil. Thank god for immersion blenders – or we would have been there all night, especially with the 100% olive oil!

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Volta! Homemade batteries using aluminum foil as the anode, and activated charcoal as the cathode, plus paper towels and stainless steel bowls. We lit up some LED’s and felt special.

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Buddha still has a 40lb bag of coal on his porch because we had a half-baked plan to destructively distill coal to produce coal tar, the basis for some shockingly bright mauve and turquoise dyes that were employed widely in the Victorian era (and made a fortune for their inventor!). Instead, we did a chromatography lab using pre-made analine dyes, and dyed some silk while we were at it.

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Albumin printing was magical and amazing, and also challenging!  First students learned the fine art of separating egg whites, a task relished by some and dreaded by others. The egg white was mixed with table salt and painted on watercolor paper and left to dry. The prepared paper was then sensitized using silver nitrate in a dark room (this is where a subterranean hackerspace lair really comes in handy!). Silver nitrate is, as you might expect, shockingly expensive. Dunn has instructions on how to reclaim the silver, which sounds interesting. Using negatives printed on acetate, we exposed the sensitized paper under incandescent lights. When the image had turned a rich chocolate brown, we put it in a hypo bath and rinsed it in water. Not all of the images turned out, but the ones that did were something to behold. Oh, and the hypo created some interesting crystals.

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The Ammonia lab was an epic fail! It was too cold to work outside and it turned out that we didn’t have adequate ventilation and we had to evacuate. But, can’t say we didn’t try! You can see that  the students are getting well acquainted with safety gear. This is the point at which we put the program on hold, until it was warm enough to work outside — it took forever for the evening temps to rise above freezing this year!

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We turned a penny into silver, and a nickle into gold! Well…. not quite. We substituted an electrolysis lab borrowed from Cornell in place of the Chloralkalai cell lab, and electroplated coins in zinc and copper. It was fun to watch the transformation and goggle at the weird looking coins.

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Nitrocellulose! This one was done as a demo, because the fumes were really awful – I prepared it the day before by mixing sulfuric acid with sodium nitrate to produce nitric acid, mixed in a couple of cotton balls as a cellulose source, stirred, then rinsed and rinsed and rinsed. Let it dry overnight and the students got to do the fun part – watching it ignite and burn in a big bright flash of light!

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I just want to say one word to you… Plastics! Last but not least, we created polyester out of antifreeze (ethylene glycol) and phthalic acid. Heated gently over a test tube and then repeatedly tested and re-heated, students pulled the sticky liquid into long thin threads. The gossamer strands that were stretched and held aloft for inspection were seemingly impossible to capture on camera in the darkness, but they really did exist.

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