"But helium will not burn!" returned the captain smartly. "That was beyond your powers." A mocking, sardonic laugh came from the robber chief as the Englishman uttered these words. "Would you like to see it burn?" he almost hissed. The captain faltered in his reply; he was not quite so decisive as he had been. Evidently there was some sense of humour, if not much, about this irreconcilable German. "Here, Carl!" cried the bandit. "Detach one of those nineteen ballonettes from the airship." "Yes, sir," replied the subordinate, stepping up to the king and saluting smartly. "Take it away to leeward there, and show this dull Englishman how he may learn chemistry and science even from inhabitants of the Hamadian Desert. Here, take this, you will need it," and the chief handed to his assistant a small cylindrical tube with which to carry out his orders. Turning next to the Englishman, he observed, "Know, you dullard, that a small admixture of a secret gas, which is known only to three living men, will make your renowned helium flare like hydrogen. You shall see it in a short space of time." "Recall your man, I will take your word for it, Sultan!" exclaimed the captain, who now felt that it must be so, for he was already bewildered by the strange things which he had witnessed that day, and he had no desire to see this experiment carried out. "You believe me, then," returned the air-king, who seemed particularly to relish this interview with the Englishman, especially with this group of celebrities within earshot, for they had listened eagerly to every word which he had spoken. And the German knew that though his days might be numbered, as indeed he felt they were, yet his fame would be greatly enhanced by the episodes of this day, for vanity was not the least among his failings. Once more he glanced at his watch; for the allotted space of time had nearly run. "How now, Englishman!" he exclaimed in a harsher tone. "The bill of lading, where is it?" The chief purser, receiving the captain’s nod, at once advanced towards the regal horseman, handed him a bundle of papers and said: "Here, sir, is the document you desire." *CHAPTER XII* *THE MAHARAJAH’S CHOICE* A dramatic episode followed the examination of the airship’s bill of lading by the _pseudo_ monarch and his so-called chancellor of the exchequer, Carl, who aided his master in the task. "Item one. What does that consist of?" asked the brigand. "Mails. His Britannic Majesty’s mails," replied the chancellor. "Where from?" "From India for Egypt and London," replied Carl, maintaining a grave and solemn deportment. "H’m! They may pass when the usual tribute is paid," remarked the bandit in serious tones, as though he had delivered himself of some weighty pronouncement.