Here are the two sizes of bottle for 7.7cm. The purpose of the bottle was to cool the heat of the explosion, so that the agent was not completely destroyed. The Germans fired more than 13,000,000 blue cross projectiles during the war, making it by far the most use CW of the war. The idea was that the small molecule would act as a mask breaker, the sneezing/vomiting effect of the agent then forcing the soldiers to remove their masks, then lethal gases would follow. In truth, it was rarely effective or noticed at all. the Allies considered it worthless, but Germany persisted. It is still the most commonly recoverd old chemical weapon in France and Belgium today.