“That’s a pretty paperweight. Is that a real flower in it?” Blithely ignoring his instructions, she reached for the green glass.
“I said don’t…” He paused, seeing the line between her brows. “What’s the matter?”
“The paperweight. It won’t move.” She frowned, tugging at the object. “Maybe if I…”
She twisted, and an audible click came from the direction of the bookcase.
“Crikey,” she breathed.
Harry was already striding to the bookcase. Placing his hands on its side, he pushed, and this time it moved easily. It slid along the wall, revealing an entryway into gaping darkness.
Tessa was by his side in a heartbeat, lamp in hand.
He took it from her. “Stay behind me.”
She gave an avid nod.
He led the way, and, as the circle of light fell, the hairs on his nape rose. The small chamber was a replica of his laboratory at Cambridge. The lamp’s flame gleamed off glass vessels, burners, and metal implements, each step he took bringing him closer to the past. As a numbing chill spread through him, his mind turned as clear as ice.
“Is this where the rotter is making the hellfire?” Tessa whispered.
“I doubt it. Even De Witt wouldn’t be so foolish as to risk blowing up his own house. At most, he’s conducting preliminary experiments here.” Harry stopped at a table lined with stoppered flasks. As a precaution, he handed Tessa the lamp. “Keep the flame at a distance.”
Eyes huge, she took a step back. He lifted the first flask. It was filled with a clear, colorless liquid. He uncorked it and wafted the scent toward his nose. He knew the acrid, suffocating scent: the smell of destruction and failure.
“What is it?” she asked.
“Nitric acid.”
She peered at it warily. “Is it explosive?”
“Not on its own.” When she looked relieved, he said, “It is highly corrosive, however, and, more to the point, an agent that can cause other flammable substances to combust. It plays a similar role to that of saltpeter in gunpowder.”
She chewed on her lip. “So if the nitric acid were combined with a flammable substance, it could make the hellfire?”
He nodded, setting down the flask and picking up another. This one was also filled with a clear liquid, one with an oily viscosity. He knew what it was; he confirmed it anyway.
Tessa wrinkled her nose at the released odor, like that of rotted eggs. “Is that oil of vitriol?”
He gave a tight nod. “Also known as sulphuric acid. It acts as a catalyst, enhances the effect of the nitric acid. All you need is a source of fuel…” He pulled open a drawer. “And here it is.”
She stared at the folded linens. “Towelsare the principle ingredient of hellfire?”
“Soaked in a solution of nitric and sulphuric acids, the cotton becomes highly combustible. All you would need is a spark and—boom.”
And he would know, he thought grimly. One fateful night back at Cambridge, he’d been heating a mixture of the two acids when the flask shattered. He’d grabbed the nearest cloth, a cotton apron, using it to wipe up the mess. He’d hung the apron up to dry by the fire, and a minute later,whoosh. Before his startled eyes, it had gone up in flames.
His accidental discovery had opened a new door of experimentation. That door had been shut when De Witt stole his invention and discredited him. Disgraced him so that he was no longer welcome in the scientific community.
“Didn’t you say the compound was unstable? If so, how is De Witt producing and storing it?”
A good question. One that Harry still didn’t have the answer to.
“He’s making the hellfire somewhere,” he said darkly, “and I have to find that factory, see it with my own eyes. As of now, we have no proof of anything. De Witt could claim he’s just running a few experiments—”
He cut short as a shrill, bird-like call sounded in the distance. Ambrose’s warning signal.
“Damn it, they’re back.”
