|Table of Contents for Caveman Chemistry: 28 Projects, from the Creation of Fire to the Production of Plastics|
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To make ammonia from nitrogen and hydrogen we require a vessel which can withstand high pressures. For this, we shall use the container that has served us so faithfully in previous projects, the 2-liter soft-drink bottle.
That's it, then; I am living in the head of a madman.
Are you talking to me?
Sorry, I didn't realize you were going to write that down. Apparently, I am talking to you. It seems like a literary device which can only confuse the reader, but what do I know? I'm just a figment of your twisted imagination, after all. But you can't be serious about using a soft-drink bottle to make ammonia. The Haber-Bosch process requires pressures which would turn a pop bottle into a cloud of plastic confetti. Then again, the temperatures required would have turned it into a puddle of goo long before you could fill it with gas.
What do you suggest?
There's a nifty demonstration of the Ostwald process which can be done on a small scale, in a soft-drink bottle, if you like. You put some concentrated ammonium hydroxide into the bottle, heat a piece of platinum wire until it glows red-hot, then plunge the wire into the bottle. It will catalyze the oxidation of ammonia, continuing to glow for a half an hour.
This is a private party, if you don't mind.
Pardon me. I am sure that readers will have no problem laying their hands on some platinum wire. Then they will have everything they need to turn household ammonia into nitric acid.
Well, not exactly. It won't make enough acid to actually collect. But the wire will glow, demonstrating—
—the catalytic oxidation of ammonia. Yes, I got it the first time. Figment, you disappoint me. Your early projects were the most boring in the book because there was nothing to make. I thought that you had come to your senses with soap and photography, but now you want to revert to ethereal projects that make no hands—
—black with charcoal. Yes, I got it the first time. I suppose you have a better idea.
I was thinking of producing nitroglycerin. The glycerine could be distilled from the soap made in one of your previous chapters. It could be nitrated with nitric acid, one of the main subjects of this very chapter, and it would make for an unforgettable demonstration of the importance of nitrogen fixation.
Nah, nitroglycerin is too unstable for the beginner to make. There's no profit in blowing half your reading public to kingdom come.
Finally, the voice of reason—
I think nitrocellulose would be much safer.
I should have known.
Actually, nitrocellulose has a lot going for it. From it, we can make collodion, the material mentioned in Chapter 23 for making glass photographic negatives. Collodion, of course, is a solution of nitrocellulose in ethanol and ether, still used in medicine as artificial skin. Mix collodion with a little camphor and you have celluloid, the first plastic, which foreshadows the subject of Chapter 28.
I suppose it would be too much to ask for the Author to step into the conversation to bring a little order to this literary diversion.
As much as I would like to make chemicals from air, I'm afraid that the engineering concerns are too demanding for us at this point; I think that nitrocellulose is probably a pretty good compromise.
Let's start again. To make nitrocellulose you need to get some concentrated nitric and sulfuric acids.
Folks are going to have a hard time getting nitric acid. You can't just go down to the local hardware store for that.
Hmm. That is a problem. Sulfuric acid can be bought in the form of industrial drain opener, but there's no household use for nitric acid.
You could have them make it from saltpeter, the old-fashioned, pre-Ostwald way.
Instead of making fertilizer from nitric acid, we make nitric acid from fertilizer. Yes, there is a certain poetry in that. So, to make nitrocellulose you need to get some saltpeter, either potassium nitrate or sodium nitrate, and some concentrated sulfuric acid. Saltpeter fertilizers are often in the form of "prills," small balls about a millimeter in diameter; if so, you will need to grind your saltpeter to a powder using a mortar and pestle. Weigh 15 grams of sulfuric acid into a small beaker and 10 grams of ground saltpeter into another container. In a fume hood or other area with adequate ventilation, add the saltpeter to the acid and stir it with a glass rod to form a uniform paste. The paste will become warm and if you sniff it cautiously, you'll detect the acrid aroma of nitric acid. Allow the paste to cool while you weigh your cotton.
You'll need about 0.5 grams of cotton. In the US cotton is sold as balls weighing about 0.25 grams each. Select two balls as close to this weight as possible and record their exact weights in your notebook. In the following procedure, try to keep each cotton ball intact. When your saltpeter/acid paste has cooled to room temperature, add both cotton balls to the beaker and, using your glass rod, mash them into the paste until they are both thoroughly and uniformly wet with acid through and through. Allow them to sit in the acid for two minutes. Next we need to wash the acid from the cotton. Using your glass rod, fish the cotton balls out of the acid and drop them into a large beaker of water. Use the glass rod to swirl them around in the water, poking them and prodding them as necessary to cleanse them of acid. Dump the acidic wash water from the large beaker into a sink, retaining the cotton with the glass rod. Refill the beaker with fresh water, swirl the cotton thoroughly, and add a spoonful of baking soda, sodium bicarbonate, to neutralize any remaining acid. Test the water with pH test paper; if it still acidic (red or orange) add another spoonful of baking soda and test again. When the water is neutral, pour it down the drain, retaining the cotton once again with the glass rod. Refill the beaker a third time, swirl the cotton to wash out the bicarbonate, pour the third rinse down the drain, and place the cotton on some paper towels. Press as much water from the cotton as possible and separate them from one another. Allow one ball of your "guncotton" to dry overnight and use the other to make collodion.
To make collodion, we will dissolve our nitrocellulose in a suitable solvent. The traditional solvent consists of 1 part ethanol to three parts ethyl ether. If you don't have access to ether, you can use acetone or ethyl acetate, available as a paint thinner or nail-polish remover (check the label on the bottle). Whatever your solvent, use 10 mL of it in a Petri dish to dissolve one of your cotton balls. Stir the cotton with a glass rod, poking and prodding it to dissolve as much as possible. When it appears that no more will dissolve, fish the remaining cotton from the solvent and dispose of it. Your collodion solution might be used to make photographic emulsion but for now simply allow the solvent to evaporate overnight.
The next day, both your guncotton and your collodion should be dry. Note the resemblance of the collodion film to modern cellophane, also derived from cellulose. Weigh your guncotton and compare its weight to that of the cotton ball from which it was made. Does it weight more or less? Why? Take your guncotton to a suitable location, one free from flammable materials, and carefully light it with a long match. It should burn very quickly, leaving very little ash.
Ether, acetone, and ethyl acetate are flammable solvents. Pay attention to possible sources of ignition when you are handling them or allowing them to evaporate.
Guncotton is a fire hazard and should be stored only in small quantities for as short a time as possible.
Your collodion film should be transparent and flexible. Tape it into your notebook and note the similarity of your film to the tape you are using. Unlike modern cellophane tape, collodion film is quite flammable.
Reference , page 214.
Be sure to check the label. Household drain openers are usually sodium hydroxide, but hardware stores often carry drain opener that consists of 95% sulfuric acid.