Bab 101: Chapter 44 Spring-Wheel Gun and Arrow Flying Spell_2

But what he was holding in his hand was clearly a blank sheet of paper.

Field dipped his hand into a basin of water and explained unhurriedly to his two subordinates, "Some people who shun the light of day use invisible means to write content that can't stand the light of day. This technique is called secret writing. In fact, it's simply using alum water as ink, which turns the paper back to white when it dries. Only by applying water can the writing appear."

He spread the water evenly over the blank sheet, but nothing appeared on the paper.

Major Moritz coughed awkwardly.

Field, however, didn't seem the least bit embarrassed and said with interest, "Oh, they've improved the technique? That's interesting."