Professor Goodman had got his whispered message—that he knew. But had he been in time? In addition, so far as he could tell, he had, up to the present, successfully bluffed Peterson and everyone else in the house as to his mental condition. But could he keep it up? And, anyway, trussed up as he now was, and as common sense told him he would continue to be until he was taken on board the yacht, what good would it do even if he could? It might save his life for the time being, but it wouldn’t help his ultimate hopes of getting away. Nor the Professor’s. Once they were on board he had to admit to himself that their chance of coming out alive was small. Anything can happen on a boat where the whole crew are unscrupulous. And even if the possibility arose of his getting away by going overboard and swimming, it was out of the question for the Professor. The chances were that the old man couldn’t swim a stroke, and Drummond, powerful though he was in the water, was not such a fool as to imagine that he could support a non-swimmer for possibly several hours. Besides, it was not a matter of great difficulty to lower a boat, and an oar is a nasty thing to be hit on the head with, when swimming. No, the only hope seemed to be that Professor Goodman should hold out, and that by some fluke he should get away. Or send a message. But whom to?—and how? He didn’t even know where he was.
And at that very moment the principal part of that forlorn hope was being dashed to the ground in the next room. Once again the benevolent Mr. Robinson was chiselling out the clinker from the metal retort, while the Professor watched him wearily from his chair. There was no mistake this time; Drummond’s warning had come too late. And with a cry of triumph Mr. Robinson felt his chisel hit something hard: the diamond was there. He dug on feverishly, and the next minute a big uncut diamond—dirty still with the fragments of clinker adhering to it—lay in his hand. He gazed at it triumphantly, and for a moment or two felt almost unable to speak. Success at last: assured and beyond doubt. In his notebook was the process; there was no need for further delay.
And then he realised that Professor Goodman was saying something.
“I have shown you as I promised.” His voice seemed very weary. “That is the method of making the ordinary white diamond. Tomorrow, after I have rested for a while, I will show you how to make one that is rose-pink.”
Mr. Robinson hesitated.
“Is there much difference in the system?” he remarked thoughtfully.
The Professor’s voice shook a little—but then it was hardly to be wondered at. He had had a trying evening.
“It will mean obtaining a somewhat rare strontium salt,” he answered. “Also it has to be added to the other salts in minute doses from time to time to ensure perfect mixing. The heat also has to be regulated a little differently.”
His eyes searched the other’s face anxiously. Delay him—at all costs. Drummond’s urgent words still rang in his ears, and this seemed the only chance of doing so. The main secret he had already given away; there was nothing he could do or say to alter that. Only with Drummond’s warning had he realised finally that he had been fooled; that in all probability the promise of rejoining his wife had been a lie from beginning to end. And the realisation had roused every atom of fight he had in him.
He was a shrewd old man for all his absentmindedness, and during the hour he had sat there while the furnace cooled his mind had been busy. How Drummond had got there he didn’t know, but in Drummond lay his only hope. And if Drummond said delay, he would do his best to carry out instructions. Moreover, Drummond had said something else too, and he was a chemist.
“Where can you obtain this strontium salt?” asked Mr. Robinson at length.
“From any big chemist in London,” replied the other.
Mr. Robinson fingered the diamond in his hand. It would mean additional delay, but did that matter very much? Now that he was in possession of the secret he had half decided to get away early in the morning. The yacht was ready; he could step on board when he liked. But there were undoubted advantages in being able to make rose-pink diamonds as well as the ordinary brand, and it struck him that, after all, he might just as well adhere to his original plan. Drummond was safe; there was nothing to fear from the old fool in the chair. So why not?
“Give me the name of the salt and it shall be sent for tomorrow,” he remarked.
“If you’re sending,” said the Professor mildly, “you might get some other salts too. By my process I can make them blue, green, black, or yellow, as well as red. Each requires a separate salt, though the process is basically the same.”
Once again Mr. Robinson frowned thoughtfully, and once again he decided—why not? Blue diamonds were immensely valuable, and he might as well have the process complete.
“Make a list of everything you want,” he snapped, “and I will get the whole lot tomorrow. And now, after you’ve done that, go to bed.”
He watched the old man go shambling along the passage to his room; then, slipping the diamond into his pocket, he went in to have a look at Drummond. He was apparently asleep, and for a while Mr. Robinson stood beside him with a look of malignant satisfaction on his face. That his revenge on the man lying bound and helpless on the
