It was then his hand froze, and the sick uncertainty of fear surged through him. The flashlight dropped clattering to the floor.

Fool! Incredible and miserable fool! He hadn't been thinking I Under the stress of his emotion and anxiety, he had ended at the wrong cylinder!

He snatched up the flash, put it out, and, his heart thumping alarmingly, listened for any noise. 

In the continuing dead silence, he regained a portion of his self-control, and screwed himself to the realization that what could be done once could be done again. If the wrong cylinder had been tampered with, then the right one would take two minutes more.

Once again, the brush and the black dust came into play. At least, he had not dropped the vial of dust; the deadly, burning dust. This time, the cylinder was the right one.

He finished, wiping the nozzle again, with a badly trembling hand. His flash then played about quickly and rested upon a reagent bottle of toluene. That would do. He unscrewed the plastic cap, splashed some of the toluene on the floor, and left the bottle open.

He then stumbled out of the building as in a dream, made his way to his rooming house and the safety of his own room. As nearly as he could tell, he was unobserved throughout.

He disposed of the facial tissue he had used to wipe the nozzles of the gas cylinders by cramming it into the flash-disposal unit. It vanished into molecular dispersion. So did the artist's brush that followed.

The vial of dust could not be so gotten rid of without adjustments to the disposal unit he did not think it safe to make. He would walk to work, as he often did, and toss it off the Grand Street bridge…

Farley blinked at himself in the mirror the next morning and wondered if he dared go to work. It was an idle thought; he didn't dare not go to work. He must do nothing that would attract attention to him on this day of all days.

With grayish desperation, he worked to reproduce normal acts of nothingness that made up so much of the day. It was a fine, warm morning and he walked to work. It was only a flicking motion of the wrist that was necessary to get rid of the vial. It made a tiny splash in the river, filled with water, and sank.

He sat at his desk, later that morning, staring at his hand computer. Now that it had all been done, would it work? Llewes might ignore the smell of toluene. Why not? The odor was unpleasant, but not disgusting. Organic chemists were used to it.

Then, if Llewes were still hot on the trail of the hydro-genation procedures Farley had brought back from Titan, the gas cylinder would be put into use at once. It would have to be. With a day of holiday behind him, Llewes would be more than usually anxious to get back to work.

Then, as soon as the gauge cock was turned, a bit of gas would spurt out and turn into a sheet of flame.

If there were the proper quantity of toluene in the air, it would turn as quickly into an explosion-- So intent was Farley in his reverie that he accepted the dull boom in the distance as the creation of his own mind, a counter-point to his own thoughts, until footsteps thudded by.

Farley looked up, and out of a dry throat, cried, 'What- what-'

'Dunno,' yelled back the other. 'Something wrong in the atmosphere room. Explosion. Hell of a mess.'

The extinguishers were on and men beat out the flames and snatched the burned and battered Llewes out of the wreckage. He had the barest flicker of life left in him and died before a doctor had time to predict that he would.

On the outskirts of the group that hovered about the scene in grim and grisly curiosity stood Edmund Farley. His pallor and the glisten of perspiration on his face did not, at that moment, mark him as different from the rest. He tottered back to his desk. He could be sick now. No one would remark on it.

But somehow he wasn't. He finished out the day and in the evening the load began to lighten. Accident was accident, wasn't it? There were occupational risks all chemists ran, especially those working with inflammable compounds. No one would question the matter.

And if anyone did, how could they possibly trace anything back to Edmund Farley? He had only to go about his life as though nothing had happened.

Nothing? Good Lord, the credit for Titan would now be his. He would be a great man. The load lightened indeed and that night he slept.

Jim Gorham had faded a bit in twenty-four hours. His yellow hair was stringy and only the light color of his stubble masked the fact that he needed a shave badly.

'We all talked murder,' he said.

H. Seton Davenport of the Terrestrial Bureau of Investigation tapped one finger against the desktop methodically, and so lightly that it could not be heard. He was a stocky man with a firm face and black hair, a thin, prominent nose made for utility rather than beauty, and a star-shaped scar on one cheek.

'Seriously?' he asked.

'No,' said Gorham, shaking his head violently. 'At least, I didn't think it was serious. The schemes were wild: poisoned sandwich spreads and acid on the helicopter, you know. Still, someone must have taken the matter seriously after all… The madman! For what reason?'

Davenport said, 'From what you've said, I judge because the dead man appropriated other peoples' work.'

'So what,' cried Gorham. 'It was the price he charged for what he did. He held the entire team together.

He was its muscles and guts. Llewes was the one who dealt with Congress and got the grants. He.was the one who got permission to set up projects in space and send men to the Moon or wherever. He talked spaceship lines and industrialists into doing millions of dollars of work for us. He organized Central Organic.'

'Have you realized all this overnight?'

'Not really. I've always known this, but what could I do? I've chickened out of space travel, found excuses to avoid it.

I was a vacuum man, who never even visited the Moon. The truth was, I was afraid, and even more afraid to have the others think I was afraid.' He virtually spat self-contempt.

'And now you want to find someone to punish?' said Davenport. 'You want to make up to the dead

Llewes your crime against the live one?'

'No! Leave psychiatry out of this. I tell you it is murder. It's got to be. You didn't know Llewes. The man was a monomaniac on safety. No explosion could possibly have happened anywhere near him unless it were carefully arranged.'

Davenport shrugged. 'What exploded, Dr. Gorham?' It could have been almost anything. He handled organic compounds of all sorts-benzene, ether, pyridine-all of them inflammable.'

'I studied chemistry once, Dr. Gorham, and none of those liquids is explosive at room temperature as I remember. There has to be some sort of heat, a spark, a flame.' There was fire all right.'

'How did that happen?'

'I can't imagine. There were no burners in the place and no matches. Electrical equipment of all sorts was heavily shielded. Even little ordinary things like clamps were specially manufactured out of beryllium copper or other non-sparking alloys. Llewes didn't smoke and would have fired on the spot anyone who approached within a hundred feet of the room with a lighted cigarette.'

'What was the last thing he handled, then?'

'Hard to tell. The place was a shambles.'

'I suppose it has been straightened out by now, though.'

The chemist said with instant eagerness, 'No, it hasn't. I took care of that. I said we had to investigate the cause of the accident to prove it wasn't neglect. You know, to avoid bad publicity. So the room hasn't been touched.'

Davenport nodded. 'All right. Let's take a look at it.'

In the blackened, disheveled room, Davenport said, 'What's the most dangerous piece of equipment in the place?'