"Yes, the only difference being that nothing is added to the matrix to color or make opaque the finished metal. It is in the preparation of this metal that salt is indispensable. It acts only as a catalyst, being recovered afterward, but neither nation has ever had enough salt to make all the armor they want." "Aren't those monsters--karlono, I think you called them--covered by the same thing? And what are those animals, anyway?" Dorothy asked. "Yes, they are armored with arenak, and it is thought that the beasts grow it, the same as fishes grow scales. The karlono are the most frightful scourge of Osnome. Very little is known of them, though every scientist has theorized upon them since time immemorial. It is very seldom that one is ever killed, as they easily outfly our swiftest battleships, and only fight when they can be victorious. To kill one requires a succession of the heaviest high-explosive shells in the same spot, a joint in the armor; and after the armor is once penetrated, the animal is blown into such small fragments that reconstruction is impossible. From such remains it has been variously described as a bird, a beast, a fish, and a vegetable; sexual, asexual, and hermaphroditic. Its habitat is unknown, it being variously supposed to live high in the air, deep in the ocean, and buried in the swamps. Another theory is that they live upon one of our satellites, which encounters our belt of atmosphere every karkam. Nothing is certainly known about the monsters except their terrible destructiveness and their insatiable appetites. One of them will devour five or six airships at one time, absorbing the crews and devouring the cargo and all of the vessels except the very hardest of the metal parts." "Do they usually go in groups?" asked Crane. "If they do, I should think that a fleet of warships would be necessary for every party." "No, they are almost always found alone. Only very rarely are two found together. This is the first time in history that more than two have ever been seen together. Two battleships can always defeat one karlon, so they are never attacked. With four battleships Nalboon considered his expedition perfectly safe, especially as they are now rare. The navies hunted down and killed what was supposed to be the last one upon Osnome more than a karkam ago, and none have been seen since, until we were attacked...." * * * * * The gong over the door sounded and the Kondalians leaped to their positions back of the Earthly visitors. The Kofedix went to the door. Nalboon brushed him aside and entered, escorted by a full company of heavily-armed soldiery. A scowl of anger was upon his face and he was plainly in an ugly mood. "Stop, Nalboon of Mardonale!" thundered Seaton in the Mardonalian tongue and with the full power of his mighty voice. "Dare you invade my privacy unannounced and without invitation?"