Little Louis just returned from playing by the river. He spent a lovely summer’s day there with his friends. Over the past few days, the sun has shone brightly and Louis frolicked from morning until evening. From time to time he has to help his dad in the leather workshop, but not always! Especially not when the weather is nice. Louis’s dad knows very well that children feel best spending their summer days next to the water or in the woods.
One afternoon, Louis ran back home all sweaty and extra thirsty. His half-full mug of milk, leftover from breakfast, was still on the bench under the old cherry tree. The milk had come fresh from the cow his mum had milked the same morning. Louis hadn’t had time to drink all of it before he went off to play at the start of the day, but now he grabbed it with gusto.
Taking a big gulp, he scowled and instantly spat-it-out. “Ew, it tastes disgusting! How could milk go bad like this in just half-a-day?” Louis ran into the house and found his mother preparing dinner.
“Hey mummy, I’m terribly thirsty, could I have some water please?” As soon as he had downed an entire jugful, he continued: “How is it possible that my milk from breakfast has gone bad already?”
Louis’s mum smiled and explained: “Well, milk goes sour in the heat. If we want it to stay fresh, we have to keep it at a lower temperature. That’s why each day I take the jug of fresh milk to the cellar where it’s cool. Then it will still be good the next day.”
A few days later the weather turned chilly. The boys continued building their dam in the river, regardless.…
