NATURAL AFFECTION BETWEEN METAL AND LIQUID
A little boy had a silver mug that he prized very highly, as it was the gift of his grandfather. The boy was not born with a silver spoon in his mouth, but, what was much better, he had a mug often filled with what he needed.
One day he dipped it into a glass jar of what seemed to him water, and letting go of it saw it go to the bottom. He went to find his father to fish it out for him. When he came back his heavy solid mug looked as if it were made of the skeleton leaves of the forest when the green chlorophyll has decayed away in the winter and left only the gauzy veins and veinlets through which the leaves were made. Soon even this fretwork was gone, and there was no sign of it to be seen. The liquid had eaten or drank the solid metal up, particle by particle. The liquid was nitric acid.
The poor little boy had often seen salt, and especially sugar, absorbed in water, but never his precious solid silver mug, and the bright tears rolled down his cheeks freely.
But his father thought of two things: First, that the blue tint told him that the jeweler had sold for silver to the grandfather a mug that was part copper; and secondly, that he would put some common salt into the nitric acid--which it liked so much better than silver that it dropped the silver, just as a boy might drop bread when he sought to fill his hands with cake.
So the father recovered the invisible silver and made it into a precious mug again.