Tang Dynasty: Slacking off in the Imperial Kitchen, exposed by Si Zi

Chapter 214 The Correct Method of Making Ice with Saltpeter

A faint sound came from the wooden barrel.

It wasn't the sound of water boiling; quite the opposite.

Saltpeter dissolves in water, absorbing heat rapidly.

A layer of water vapor quickly condensed on the outside of the wooden barrel!

Little Sizi jumped down from the stone steps, went to the edge of the wooden tub, and peered inside while holding onto the rim with both hands.

A thin layer of ice is forming on the surface of the well water in the copper basin.

"ah!!"

The little girl's mouth opened into a circle.

"Bingbing! Guoguo has conjured up some ice cream!"

She reached out to touch it.

The moment my fingertips touched the ice shards, I bounced up.

"So cold! So cold! So cold!"

She tucked her hand away, but couldn't resist touching it again and flicking it once more.

After going back and forth three or four times, my fingers were frozen red.

Su Mu slapped her hand away.

"Don't touch it, it's not done yet."

The ice in the copper basin grew thicker and thicker.

The ice layer spreads from the edges towards the center, changing from transparent to translucent, and finally solidifies into a single piece.

Su Mu stirred the copper basin with a wooden stick.

The ice was churned up, the ice shards tumbled in the water, and new ice fragments quickly clung to the walls of the copper basin.

After repeating this three times, he took the copper basin out of the wooden bucket.

The basin was full of crushed ice.

Crystal clear, it refracts tiny fragments of light under the sunlight.

Su Mu changed the water and put it in again.

Continue freezing.

He poured the first bowl of crushed ice into a large earthenware pot.

He picked up the watermelon and chopped it in half with a cleaver.

click!

The melon split in two, its red flesh dazzlingly bright in the sunlight, juice dripping down the cut.

The Su Mu scooped out the seeds, put them in gauze, and wrung them out.

The watermelon juice gushed into the bowl, its color a thick, rich crimson.

Dice the melon.

The pieces, each about the size of a fingernail, were neatly arranged on a plate.

Scoop the yogurt out of the jar, stir it, and let it drip slowly from the back of the spoon.

Su Mu took four rough porcelain bowls.

First, lay a layer of crushed ice in each bowl, then drizzle watermelon juice, add a few diced melon pieces, and finally pour a spoonful of yogurt over it.

Red, white, and yellow, piled up layer upon layer on top of the crushed ice.

Cool air wafted out from the rim of the bowl, forming a visible white mist.

Little Sizi was lying on the edge of the table, her nose less than two inches from the rim of the bowl, her face covered in a cloud of cool white mist.

She shuddered.

His eyes were wide open, and drool hung from his chin.

"Pot—pot pot—"

Su Mu handed her a wooden spoon.

"Eat slowly, don't bite into the ice."

Little Sizi picked up the bowl, scooped up a spoonful, and put it in his mouth.

Crushed ice, watermelon juice, and yogurt explode on your tongue at the same time.

The ice is real ice.

A chill ran down my spine!

The sweetness of watermelon juice, coated with icy shards, glides down the throat, while the richness of yogurt finishes the way, melting the excessive chill into a soft, comforting sensation.

Xiao Sizi hunched her shoulders.

His neck was tucked into his collar, and his legs were stretched straight.

But the spoon didn't stop.

The second spoonful, the third spoonful.

When she ate the fourth spoonful, the little girl's teeth started chattering.

"Bingbing! Brother, your tooth is going to fall out!"

But the spoon kept reaching into the bowl.

Su Mu reached out and pressed down on her bowl.

"Take a break before you eat."

"No duck!"

The little ox protected the bowl and hid to the side, afraid that it would be snatched away.

Her cheeks were white from the cold, but the tip of her nose was red, and her mouth was smeared with watermelon juice and yogurt, making for a gaudy face.

Su Mu couldn't be bothered with her anymore.

Just then, footsteps came from the courtyard gate.

More than one person.

Li Shimin walked ahead, waving a bamboo fan in his hand; the handle of the fan was blackened by sweat.

Li Lizhi and Wang Dequan followed behind.

Li Shimin stopped in his tracks as soon as he stepped into the courtyard.

He sniffed.

There was a cool, moist air in the air, mixed with the sweetness of watermelon. In May, the Taiji Palace was so hot that even birds wouldn't fly, yet this courtyard was surprisingly cool?

What does it taste like?

Little Sizi ran over carrying a bowl. Her mouth was a little numb from the cold.

"Ah! Bingbing! Your husband made Bingbing duck! So good!"

Li Shimin took three steps at a time and walked to the stone table, then looked down at it.

Three bowls of iced drinks were still on the table, water droplets clinging to the sides of the bowls, and ice crystals reflecting light inside.

His Adam's apple bobbed suddenly.

Then he saw the wooden bucket and copper basin next to the table.

Li Shimin frowned.

"Using saltpeter to make ice?"

Su Mu hummed in agreement and wiped his hands with a cloth.

"Didn't you teach Lizhi this method last year?"

Li Shimin pulled over a stone bench and sat down, then slapped his bamboo fan on the table.

"I ordered the Ministry of Works to follow the method Lizhi brought back. They used saltpeter, soaked it in water, and managed to freeze the ice. But that ice..."

He frowned and thought for a moment, finding it difficult to find the right words.

"It's astringent; if you lick it, it's both bitter and astringent, with a strange taste. The people in the imperial kitchen dared not use it as food."

Su Mu picked up the remaining saltpeter residue from the wooden bucket and shook it.

"What kind of saltpeter are you using?"

"They came from the Ministry of Works' mines, weighing several thousand kilograms each, filling half a warehouse."

Su Mu poured the saltpeter residue onto the table and stirred it between his fingers. The grayish-white granules were mixed with yellowish-brown fragments and some powder of an indescribable color.

"See that? All this yellow and gray stuff is impurities. Glauber's salt, gypsum, silt, a whole jumbled mess."

He picked up a yellow crumb and crushed it between his fingertips.

"When saltpeter dissolves in water, all the impurities dissolve in with it. When it freezes, all the impurities are locked inside the ice. If you put this kind of ice in your mouth, of course it will taste bitter and astringent."

Li Shimin stopped fanning himself with his bamboo fan.

"Then your ice... My saltpeter has been carefully selected."

Su Mu pointed to the yellow particles he had thrown aside on the bamboo tray.

"First, we screen the materials, removing all those with low purity. Then we wash them twice with clean water to filter out any surface dust and soluble impurities. Only then can we use them."

He tapped the rim of the copper basin again.

"Also, ice made from saltpeter should not be eaten directly."

Li Shimin was stunned.

"There's a copper basin between the saltpeter and the ice."

Su Mu patted the copper basin.

"The saltpeter dissolved in the outer layer of water absorbed heat, while the copper basin contained clean well water. The cold air penetrated through the copper walls and froze the water inside, so the water on both sides never came into contact."

He made a separating gesture.

"Your people in the palace wouldn't be pouring saltpeter directly into the drinking water, would they?"

Li Shimin did not respond.

But his expression said it all.

Su Mu sighed.

"No wonder the ice it makes is so bitter and astringent. Ice made from saltpeter is so bad, you'll get a rash just from touching it, let alone eating it. That stuff can be used in medicine, but eating it raw will give you an upset stomach!"

Li Shimin stood up and paced back and forth a couple of times.

"So the key lies in two things: first, the purity of the saltpeter, and second, the saltpeter solution must not come into direct contact with drinking water."

"right."

Li Shimin suddenly turned around.

"Wang Dequan!"

"Your servant is here!"

"Issue an imperial decree to the Ministry of Works: starting immediately, a screening process will be added to the saltpeter mines. I require the purest saltpeter; any saltpeter with many impurities should be stored separately and not mixed!"

"Have the Imperial Workshops forge another batch of copper basins, following Su Mu's specifications, nested in two layers of different sizes. I want ice-making equipment installed in every hall and pavilion of the Taiji Palace and the Daming Palace!"

Wang Dequan ran away in response.

Li Shimin sat back down on the stone bench.

He stared at the three bowls of iced drinks on the table.

Water droplets on the bowl wall trickled down the porcelain surface.

Half of the crushed ice had melted, and watermelon juice seeped into the gaps between the ice crystals, giving the whole bowl of drink a cool, pinkish glow.