If Hansel and Gretel Were Chemical Engineers

“A Thermodynamic Approach to Estranged Female Practitioners of the Occult”, or, “If Hansel and Gretel Were Chemical Engineers”

Adapted from the fairy tale by Jacob and Wilhelm Grimm

Jessie Stewart

4/24/06

Next to a great forest there lived a poor woodcutter with his wife and his two children. The boy’s name was Hansel and the girl’s name was Gretel, both recent graduates of Chemical Engineering at North Carolina State University who, unsure of what they wanted to do with their lives, had returned home to Germany to live with their father.  The woodcutter had but little to eat, and once, when a great famine came to the land, he could no longer provide even their daily bread.

One evening as he was lying in bed worrying about his problems, he sighed and said to his wife, “What is to become of us? How can we feed our children when we have nothing for ourselves, especially after paying for their out-of-state tuition?”  “Man, do you know what?” answered the woman. “Early tomorrow morning we will take the two children out into the thickest part of the woods, make a fire for them, and give each of them a little piece of bread, then leave them by themselves and go off to our work. They will not find their way back home, and we will be rid of them.  Maybe then they’ll actually get jobs, who knows?”  “No, woman,” said the man. “I will not do that. How could I bring myself to abandon my own children alone in the woods? Wild animals would soon come and tear them to pieces, and I just spent all that money on graduation invitations!”  “Oh, you fool,” she said, “then all four of us will starve. All you can do is to plane the boards for our coffins.” And she gave him no peace until he agreed.  “But I do feel sorry for the poor children,” said the man.

The two children had not been able to fall asleep because of their hunger, and they heard what the stepmother had said to the father. Gretel cried bitter tears and said to Hansel, “It is over with us!  I didn’t make it through senior design to go die in the woods two weeks later!” “Be quiet, Gretel,” said Hansel, “and don’t worry. I know what to do—remember, we’re engineers—we can solve this problem.”  And as soon as the adults had fallen asleep, he got up, pulled on his jacket (it was down to 273 K that night), opened the lower door, and crept outside.  The moon was shining brightly, and the white pebbles in front of the house were glowing like bands on an electrophoresis gel.  Hansel bent over and filled his jacket pockets with them, as many as would fit. Then he went back into the house and said, “Don’t worry, Gretel. Sleep well.” Then he went back to bed, and fell asleep.

At daybreak, even before sunrise, the woman came and woke the two children. “Wake up, you lazybones, this isn’t your 8am class!  We are going into the woods to fetch wood.”  Then she gave each one a little piece of bread, saying, “Here is something for midday. Don’t eat it any sooner, for you’ll not get any more.”  Then all together they set forth into the woods.  Hansel dropped the shiny pebbles from his pocket onto the path. When they arrived in the middle of the woods, the father said, “You children gather some wood, and I will make a fire so you won’t freeze.”  Hansel and Gretel gathered together some twigs, a pile as high as a T-S diagram.  They set it afire, and when the combustion reaction occurred, the mother said, “Lie down by the fire and sleep. We will go into the woods to cut down trees. Wait until we come back and get you.”  Hansel and Gretel sat by the fire until midday, and then ate their bread.  They sat on until evening, but the mother and father did not return, and no one came to get them.  After the full moon had come up, Hansel took his little sister by the hand.  They followed the glistening pebbles, and as morning was breaking, they arrived at the father’s house.  The father was overjoyed when he saw his children once more, for he had not wanted to leave them alone. The woman pretended that she too was happy, but secretly she was angry.

Not long afterward there was once again no bread in the house, and one evening Hansel and Gretel heard the woman say to the father, “The children found their way back once, and I let it be, but again we have only a half loaf of bread in the house.  I know they’re students and are used to starving to death, but this is ridiculous.  Tomorrow you must take them deeper into the woods, so they cannot find their way home. Otherwise there will be no help for us.”  The man was very disheartened, but because he had done it once, he could not say no.  The children were still awake and had overheard the conversation.  Hansel got up and wanted to gather pebbles once again, but when he came to the door, he found that the woman had locked it. Still, he comforted Gretel and said, “Just go to sleep, Gretel.  We’re kind of like—a feedback control loop, they won’t be able to get rid of us.”  Early the next morning they received their little pieces of bread, even less than the last time.  On the way, Hansel crumbled his piece in his pocket, and threw crumbs onto the ground.  The woman took them deeper into the woods than they had ever been in their whole lifetime.  There they were told to sleep by a large fire, and that the parents would come and get them in the evening.  Midday passed, and evening passed, but no one came to get the poor children.  Hansel comforted Gretel and said, “Wait, when the moon comes up I will be able to see the crumbs of bread that I scattered, and we’ll be back home faster than a new thermo homework getting assigned.”  The moon came up, but when Hansel looked for the crumbs, they were gone. The many thousands of birds in the woods had found them and pecked them up.  Hansel said to Gretel, “We will find our way, what goes in to the woods has to come out again—basic material balance Gret, you know this stuff,” but they did not find it.

They walked through the entire night and the next day from morning until evening, but they did not find their way out of the woods. Gretel moaned, and compared this horrible situation to the time an instructor had asked her to explain what fugacity was.  They were terribly hungry, for they had eaten only a few small berries that were growing on the ground.  “What I wouldn’t give for an AICHE luncheon right now!” said Gretel.  On the third day they walked until midday when they came to a little house built entirely from bread with a roof made of cake, and the windows were made of clear sugar.  “Let’s sit down and eat our fill,” said Hansel. “I’ll eat from the roof, and Gretel, you eat from the window. That will be nice and sweet for you, I saw how you lived off the candy machine in EB1.”  Hansel had already eaten a piece from the roof and Gretel had eaten a few round windowpanes, and she had just broken out another one when she heard a gentle voice calling out from inside:

 

Nibble, nibble, little mouse,
Who is nibbling at my house?

 

Hansel and Gretel were so frightened that they dropped what they were holding in their hands, and immediately they saw a little woman, as old as Riddick, creeping out the door.  She shook her head and said, “Oh, you dear children, you look exhausted—are you college students?  Come inside with me, I’ll feed you and you can stay here for free.” After eating, Hansel and Gretel went to bed, thinking it was though they were in heaven. But the old woman was a wicked witch who was lying in wait there for college kids looking for free food.  She had built her house of bread in order to lure them to her, and if she captured one, she would kill him, cook him, and eat him; and for her that was as fun as seeing Dr. Peretti in a dress.  She grabbed Hansel in his sleep and put him in a little stall, and when he awoke, he found himself in a cage, much smaller than a single dorm room.  Then she shook Gretel and cried, “Get up, lazybones! Fetch water and cook something good for your brother. He is locked outside in the stall and is to be fattened up. When he is fat I am going to eat him.”  “Gretel, this witch locked me up, get me out of here!” yelled Hansel.  “Don’t call her a witch Hansel, we’re educated now, she’s an—estranged female practitioner of the occult?” said Gretel.  But despite Gretel’s political correctness, the old woman forced Gretel to do what she said.  Every day the old woman came to Hansel and said, “Hansel, stick out your finger, so I can feel if you are fat enough yet.”  But Hansel always stuck out a little bone, and she wondered why he didn’t get any fatter—the boy must have an extremely high metabolism.

After four weeks, one evening she said to Gretel, “Hurry up and fetch some water. Whether your brother is fat enough now or not, tomorrow I am going to slaughter him and submerge him in water beginning to change from liquid to vapor phase. In the meantime I want to start the dough that we will bake to go with him.”  Gretel did as the old woman said, but made sure not to salt the water, which would lower its boiling point and expedite Hansel’s death.  The next morning Gretel had to get up early (which she still hadn’t gotten used to despite 4 years of 8am classes), make a fire, and hang up the kettle with water. “First we are going to bake—you should know all about heat transfer, so you can help” said the old woman. “I have already made a fire in the oven and kneaded the dough.” She pushed poor Gretel outside to the oven, from which fiery flames were leaping, radiating heat to the cool outside air.  “Climb in,” said the witch, “and see if it is hot enough to put the bread in yet.”  And when Gretel was inside, she intended to close the oven, and bake her, and eat her as well.  But Gretel, who had honed her critical thinking skills by taking all those chemE tests, saw what she had in mind, so she said, “I don’t know how to do that. How can I get inside?” “You failed life today,” said the old woman. “The opening is big enough. See, I myself could get in.” And she crawled up and stuck her head into the oven. Then Gretel, rapidly converting potential energy to kinetic energy, gave her a shove, causing her to fall in. Then she closed the iron door and secured it with a bar, knowing that the witch would soon become the fuel of an exothermic combustion reaction.  The old woman began to howl as frightfully as students writing their first CHE330 lab report. But Gretel ran away, and the godless witch burned up miserably.

Gretel ran straight to Hansel, unlocked his stall, and cried, “Hansel, we’re saved! The estranged female practitioner of the occult is dead thanks to thermodynamics!  Who would think I would ever say that?!”  Because they now had nothing to fear, they went into the old woman’s house. In every corner were chests of ramen noodles, Hot Pockets, engineering paper, mechanical pencils, TI89 calculators, Superpro and Maple software, a fermenter brewing Hansel’s favorite beer, and even a Perry’s handbook!  They filled their pockets, then ran away and found their way back home, completely prepared and excited to go out and find engineering jobs.  The father rejoiced when he saw them once more, for he had not had a happy day since they had been gone, and now he would be a rich man since the children had decided they would pursue careers in chemical engineering after all.  However, the woman had died, and did not get to share in the success of the well educated chemical engineering students from N.C. State.