Read the excerpt from a newspaper article about world war i. the gaseous vapor which the germans used against the french divisions near ypres last thursday, contrary to the rules of the hague convention, introduces a new element into warfare. the attack of last thursday evening was preceded by the rising of a cloud of vapor, greenish gray and iridescent. that vapor settled to the ground like a swamp mist and drifted toward the french trenches on a brisk wind. what does the article reveal about the use of chemical weapons?