“Ah-co,” as Tonlos pronounced the Terrestrian name, “we have not been able to make very much of the materials needed for your gas, but before we made any very great amount, we tried it out on an animal, whose blood structure is the same as ours, and found it had the same effect, but that in our case the iodide of potassium is not as effective in awakening the victim as is the sorlus. I do not know whether you have tried that on Terrestrial animals or not. Luckily sorlus is the most plentiful of the halogen groups; we have far more of it than of chlorine, bromine or iodine.”

“Sorlus? I do not know of it—it must be one of the other elements that we do not have on Earth. What are its properties?”

“It, too, is much like iodine, but heavier. It is a black solid melting at 570 degrees; it is a metallic looking element, will conduct electricity somewhat, oxidizes in air to form an acidic oxide, and forms strong oxygen acids. It is far less active than iodine, except toward oxygen. It is very slightly soluble in water. It does not react readily with hydrogen, and the acid where formed is not as strong as HI.”

“I have seen so many new things here, I wonder if it may not be the element that precedes niton. Is it heavier than that?”

“No,” replied Tonlos; “it is just lighter than that element you call niton. I think you have none of it.”

“Then,” said Arcot, “it must be the next member of the halogen series, Morey. I'll bet they have a number of those heavier elements.”

The gas was loaded aboard the Solarite that evening, and when Wade saw the quantity that they had said was “rather disappointingly small” he laughed heartily.

“Small! They don't know what that gas will do! There's enough stuff there to gas this whole city. Why, with that, we can bring down any ship! But tell them to go on making it, for we can use it on the other ships.”

Again that night they spoke with Earth, and Morey, Senior, told them that work was already under way on a hundred small ships. They were using all their own ships already, while the Government got ready to act on the idea of danger. It had been difficult to convince them that someone on Venus was getting ready to send a force to Earth to destroy them; but the weight of their scientific reputation had turned the trick. The ships now under construction would be ready in three weeks. They would be unable to go into space, but they would be very fast, and capable of carrying large tanks of the gas-producing chemicals.

It was near midnight, Venerian time, when they turned in. The following day they planned to start for the Kaxorian construction camp. They had learned from Tonlos that there were but five of the giant planes completed now, but there were fifteen more under construction, to make up the fleet of twenty that was to attack Earth. These fifteen others would be ready in a week—or less. When they were ready, the Solarite would stand small chance. They must capture one of the giants and learn its secrets, and then, if possible, with the weapons and knowledge of two worlds, defeat them. A large order!