The mask-makers were confronted at an early period with the problem of finding a charcoal of sufficient density to absorb the toxic fumes, the wood-charcoal which was used in most of the French and British masks being very far from satisfactory. After considerable experimentation it was discovered that a charcoal having sufficient absorptivity could be produced from the shell of the cocoanut, whereupon officers were despatched to the Hawaiian Islands and the British West Indies to arrange for large shipments of cocoanut-shells to the United States. The supply thus obtained proved entirely inadequate, however, whereupon the Chemical Warfare Service issued an appeal to the American public to save the shells of Brazil nuts, hickory-nuts, and walnuts, the pits of peaches, prunes, apricots, and cherries, and the seeds of dates, the collection of the pits and shells being undertaken by the Red Cross, the Boy Scouts, and kindred organizations. Placards and receptacles were put in public places throughout the country and almost immediately fruit-pits began to pour in by the ton, every family making it a point of honor to save its pits “for the boys fighting overseas,” as they proudly put it. There were numberless cases of old ladies who sent in by mail a few peach-pits which they had conscientiously saved and which they had cleaned as carefully as though they were jewels. As it required 7 pounds of pits and shells to make the charcoal for a single mask, 3,500 tons were used in the million masks which we sent overseas. [Illustration: 1,500 TONS OF PEACH-PITS USED FOR THE MANUFACTURE OF CHARCOAL FOR USE IN GAS MASKS. The result of the appeal of the Gas Defense Division for nutshells and fruit-pits.] [Illustration: TESTING RESPIRATORS OUTSIDE THE GAS CHAMBER.] [Illustration: TESTING GAS MASKS INSIDE THE GAS CHAMBER.]