the last time, previous to the fatal moment, that Dr. Llewes used that hydrogen cylinder?'
'I-I don't know. He worked alone. Very secretly It was part of his way of making sure he had sole credit.'
'Yes, I know. We've been making our own inquiries. So the platinum black might have been put on the cylinder a week before for all we know.'
Gorham whispered disconsolately, Then what do we do?'
Davenport said, The only point of attack, it seems to me, is the platinum black on the oxygen cylinder.
It's an irrational point and the explanation may hold the solution. But I'm no chemist and you are, so if the answer is anywhere it's inside you. Could it have been a mistake-could the murderer have confused the oxygen with the hydrogen?'
Gorham shook his head at once. 'No. You know about the colors. A green tank is oxygen; a red tank is hydrogen.'
'What if he were color blind?' asked Davenport.
This time Gorham took more time. Finally he said, 'No. Color-blind people don't generally go in for chemistry. Detection of color in chemical reactions is too important. And if anybody in this organization were color blind, he'd have enough trouble with one thing or another so that the rest of us would know about it.'
Davenport nodded. He fingered the scar on his cheek absently, 'All right. If the oxygen cylinder wasn't smeared by ignorance or accident, could it have been done on purpose? Deliberately?'
'I don't understand you.'
'Perhaps the murderer had a logical plan in mind when he smeared the oxygen cylinder, then changed his mind. Are there any conditions where platinum black would be dangerous in the presence of oxygen?
Any conditions at all? You're the chemist, Dr. Gorham.'
There was a puzzled frown on the chemist's face. He shook his head. 'No, none. There can't be. Unless-'
'Unless?'
'Well, this is ridiculous, but if you stuck the oxygen jet into a container of hydrogen gas, platinum black on the gas cylinder could be dangerous. Naturally you'd need a big container to make a satisfactory explosion.'
'Suppose,' said Davenport, 'our murderer had counted on filling the room with hydrogen and then having the oxygen tank turned on.'
Gorham said, with a half-smile, 'But why bother with the hydrogen atmosphere when-' The half-smile vanished completely while a complete pallor took its place. He cried, 'Farley! Edmund Farley!'
'What's that?'
'Farley just returned from six months on Titan,' said Gorham in gathering excitement. Titan has a hydrogen-methane atmosphere. He is the only man here to have had experience in such an atmosphere, and it all makes sense now. On Titan a jet of oxygen will combine with the surrounding hydrogen if heated, or treated with platinum black. A jet of hydrogen won't. The situation is exactly the reverse of what it is here on Earth. It must have been Farley. When he entered Llewes' lab to arrange an explosion, he put the platinum black on the oxygen, out of recent habit. By the time he recalled that the situation was the other way round on Earth, the damage was done.'
Davenport nodded in grim satisfaction. That does it, I think.' His hand reached out to an intercom and he said to the unseen recipient at the other end, 'Send out a man to pick up Dr. Edmund Farley at Central Organic.'
A Loint of Paw
There was no question that Montie Stein had, through clever fraud, stolen better than $100,000. There was also no question that he was apprehended one day after the statute of limitations had expired.
It was his manner of avoiding arrest during that interval that brought on the epoch-making case of the
State of New Yorkvs. Montgomery Harlow Stein, with all its consequences introduced law to the fourth dimension.
For you see after having committed the fraud and possessed himself of the hundred grand plus, Stein had calmly entered a time machine, of which he was in illegal possession, and set the controls for seven years and one day in the future.
Stein's lawyer put it simply. Hiding in time was not fundamentally different from hiding in space. If the forces of law had not uncovered Stein in the seven-year interval that was their hard luck.
The District Attorney pointed out that the statute of limitations was not intended to be a game between the law and the criminal. It was a merciful measure designed to protect a culprit from indefinitely prolonged fear of arrest. For certain crimes, a denned period of apprehension of apprehension-so to speak-was considered punishment enough. But Stein, the D.A. insisted, had not experienced any period