"These first rooms are small studios for student painters," Detective Tildon explained, referring to his notes as he trotted along beside Sigrid's tall figure.
"Harley Harris uses one of them. There're three here and four more scattered around campus. The photography lab's in an annex of the library, and somebody said something about a ceramics workshop over at the gym. In what used to be the basketball team's dressing room?"
He looked at his notes doubtfully; his previous academic experience had been limited to night courses at John Jay College of Criminal Justice. But Sigrid nodded, remembering a college roommate who'd complained about taking a drawing class in the basement of the biology building. It had reeked of formaldehyde, and so did her roommate after every session of that class. Art departments seemed to follow a pattern. Redheaded stepchildren, all.
"As soon as Yanitelli tested for fingerprints and got all the chemical samples he wanted here, we went across to the library annex and checked out the photography lab," said Tillie. "There were only a couple of boxes marked Poison, and Yanitelli doesn't think any of them fit the bill. He says that developing chemicals used to come separately and a few were pretty strong-I forget their names. Anyhow,t he only developers and fixatives that we found were prepared compounds. Yanitelli took samples, but he said it'd take a lot of stuff to kill, diluted like that-more than you could dissolve in one cup of coffee anyhow."
(What Yanitelli, who had little respect for the academic mind, had actually said was: "It'd take a damned absentminded egghead not to notice there was a hell of a lot more powder than coffee in a cup that little." But Tillie saw no point in repeating that opinion to Lieutenant Harald. It was still not definitely established that she had a sense of humor.)
They moved along the deserted hallway.
"This next is a lecture room for art historians," said Tillie.
Sigrid paused to read a schedule tacked to the door. Professors Saxer, Simpson and Ross were listed as using the room this semester; in fact, it was where Andrea Ross had been due to lecture at eleven that morning.
"And here, right across the hall," Tillie said meaningfully, "is the printmaking workshop."
The door was unlocked, and they stepped into a big boxy studio that smelled of ink and a vaguely metallic acrid odor. The opposite wall was all tall windows facing north, and the space beneath was lined with open shelves that held an assortment of copper, zinc and aluminum plates, lithography stones and drying prints. Makeshift clotheslines strung across a corner had more prints clipped to them. There were mismatched worktables and stools, and a large hand-operated, antiquated-looking press stood in the center of the room. To Sigrid's untrained eyes it looked like something Ben Franklin might have been right at home with. No wonder Vance complained. A smaller iron-press was bolted to one end of a heavy workbench, and a second workbench held two electric hot plates.
Tillie had collared a student earlier for a crash course in the mechanics of printmaking and was eager to share his new knowledge.
"As I understand it, you start with one of those flat zinc or copper plates. If you're going to engrave it, you just gouge out your picture with a steel needle-it's called a burin-and then put ink on it and runi t through the printing press. But for an etching, you heat some varnish on the hot plate, coat your plate, and when it cools, you draw your picture by scratching away the varnish. Etching's supposed to be easier than engraving because varnish is softer to get through than the metal. Then you stick it in an acid bath back there."
Along the rear wall were three deep stone sinks connected by stained and pitted counters, which held large shallow plastic trays.
"You mix the chemicals in those trays, stick your plate in, and the acid will eat out the lines you drew without touching the part that still has varnish on it. When you've got the line as deep as you want, you rinse it off, heat the plate again until the varnish is melted, and you can wipe every bit of it off. Then you ink the plate and print it just like you did with the engraving."
"Very concise," said Sigrid and the detective beamed. "Is that the chemical closet over there?"
"Right, ma'am. You can go in. Yanitelli checked for prints and took a sample of everything he thought Quinn could have been poisoned with."
The chemical closet was actually a small supply room lined with shelves that held neat stacks of paper sorted by size and thickness, and cartons and tins of powdered varnish, talc and inks of various colors. Sigrid's eye was drawn to a collection of containers ominously decorated by skulls and crossbones.
"I made a complete inventory," said Detective Tildon, thumping his clipboard.
"And which do you favor?"
"I guess any of them would do it," Tillie said judiciously. "The nitric acid or the sulfuric; but my money's on the end one, the potassium dichromate. That lid was put back crooked, and Yanitelli wasn't the one who spilled some on the shelf. That was already there. And another thing: it was the only one that didn't have any fingerprints at all. That's always significant to me. Remember that cup we found polished clean in that model's kitchen cabinet?"
"No," smiled Sigrid. "That was just before I came, but I remember Captain McKinnon telling me about it. That cup changed a tentative suicide verdict to murder, didn't it?"
"Well, it just stood to reason," said Tillie modestly. "Just like now. One squeaky-clean jar on a shelf full of dusty ones? Uh-uh. Anyhow, the kid I was talking to said their normal procedure was to take all the jars over to the mixing trays and measure the stuff out there, so nothing should have been spilled in here, right?"
The suspect jar seemed to hold orange salt. Underneath the label Potassium Dichromate was the ubiquitous skull-and-crossbones. Some sophomoric wit had inked a red Marcel Duchamp mustache on the skeletal head and closed one eye socket in a raffish wink.
"I'd like to speak to Professor Vance again," Sigrid said thoughtfully. "See if he's still around, would you, Tillie?"
While she waited for his return, Sigrid walked down the hall to examine the last two classrooms on that floor. They were duplicates of the print workshop in size and north lighting, but the first reeked of turpentine and oil paints and held an undergrowth of various sized easels. Canvases in different stages of completion showed a nude girl poised on a stool, one leg outstretched. The neophyte artists were evidently troubled by that leg, for several showed signs of paint build-up there. Charcoal sketches of other nudes, both male and female, were thumbtacked to the molding all around the studio, and the card on the door confirmed that this was indeed Professor Leyden's life class.
The last studio-Prof. Oscar Nauman, Color and Basic Design, read the card on the door-was different again. Despite the bursts of color blocks and circles tacked to the molding, there was a feeling of order, calm and discipline that had been lacking in the first two studios. Drawing tables stood in neat rows, their precision marred only by their tops being tilted at different angles. Twenty-three of the tables were completely bare; the twenty-fourth was littered with a drift of two-inch paper squares in every conceivable shade of red.
A young girl whose hands and face carried smudges of the same red looked up as Sigrid entered the room and gave her an electric smile. "I did it!" she said, dazed triumph in her voice. "I really did it!"
"Did what?"
"Went from dark red to light pink in nine equal steps. See?"
On the table in front of the girl was a white sheet of paper on which were aligned nine of the little squares of red tones. The gradations shaded from almost black to light pink and reminded Sigrid of a paint store's sample card.