“For fever and headache?” Ivy leaned her elbows on the dining room table in Joan’s home above the chemist’s shop—formerly the Carter home. “That’s an old drug. Do you have it in stock?”
“It’s rarely used, quite toxic. We much prefer aspirin and phenacetin, but if shortages don’t improve, we’ll use it again.” Then Joan sent Ivy a smile. “Yes, I have it.”
“It works?”
“According to this.” Joan lifted Mr. Carter’s book on the role of chemistry in the Great War.
Two weeks ago, Gerrit had run out of secret ink. One week ago, Ivy had worked up the courage to ask Joan for help. Aiding the escapee ring could earn Joan a ticket to prison or a concentration camp, but aiding in espionage would lead to certain death.
Yet Joan had pounced on the opportunity and never asked why on earth Ivy was interested in secret inks. Out of boredom, Joan had been consuming even the dryest of Mr. Carter’s books andhad recently read the tome in her hands, which concerned the wartime use of medications and poison gas, but also included a chapter on secret inks.
“It’s an older book.” Joan shifted her mouth to one side. “That means the information isn’t secret.”
“But if the ink is invisible, the writing might pass unnoticed.” It would protect Charlie and Gerrit.
“Let’s give it a try, shall we?” Joan sprang up from the table and gestured to the sink. “Never mind the dinner dishes. I can’t wash them until the water turns on again tomorrow morning anyway.”
Carrying her medical bag and coat, Ivy followed Joan downstairs to the shop. A dry summer and autumn had led to a serious water shortage on the island, and water from the mains was turned off each day from seven in the evening to seven in the morning.
Joan turned on lamps in the laboratory area in the back of the shop and gathered bottles from shelves.
Ivy set her bag on the counter. “How can I help?”
“Stay out of my way.” But Joan grinned at her.
Ivy laughed and leaned against the counter. Over dinner, she and Joan had told stories from university, finding commonalities, edging toward true friendship. When they met in public, Joan treated her with cool cordiality, as was appropriate given their involvement with the ring.
Joan set weights on one pan of her scale and spooned clear crystals onto a square of paper on the other pan.
Over dinner, Ivy had learned the ring involved dozens of homes around the island and was loosely run by Dr. Noel McKinstry, Jersey’s Medical Officer of Health.
Joan poured the crystals from the pan of the scale into a conical glass flask. “Did you hear about the arrests at West’s Cinema?”
“I did.” Several employees had been arrested in yet another wireless case, and today the cinema owner had been arrested too. “At this rate, Jersey will have more people in prison than out.”
Joan poured water from a jug into a graduated cylinder, thenpoured the water into the conical flask. “Let’s try not to join them.”
“I agree. Yet here we are.” Ivy waved toward the laboratory bench.
“Here we are indeed. Perhaps this is why everyone tells us not to worry our pretty little heads about chemistry. Apparently, it’s a good way to get those heads chopped off, pretty or not.” Joan swirled the flask. “Excellent. The antipyrine dissolves easily. Do you want to test it?”
“Yes.” Ivy reached into her skirt pocket and pulled out a scrap of silk from Gerrit.
Joan handed her a glass stirrer, and Ivy dipped it in the clear solution and wrote her name on the silk. Nothing showed except dampness, and she waved the silk to dry the ink.
“How do you read it?” Ivy asked. “Heat?”
“Inks developed by heat are the most dangerous sort for a spy to use.” Joan slid another book from the shelf. “The earliest secret inks, like lemon juice, were developed by heat, which means heat is the first method tested.”
“I see.” Ivy held the scrap of silk to a lamp and saw no trace of writing. Unless the Germans suspected the presence of an invisible message, they wouldn’t think to search for a developer.
“Ferric chloride is used to develop antipyrine.” Joan flipped pages in the book. “Oh good. Ferric chloride doesn’t require heat to dissolve.”
Very good news, since the gas was already turned off for the day.
Joan weighed brownish-black crystals on the scale.
Gerrit didn’t let Ivy watch him draw his maps. The less she knew, the better, and she already knew too much. But without her involvement, how would he have procured more secret ink?
