Charcoal
The fact that charcoal would condense in its pores or adsorb certain gases, holding them firmly, had been known for a long time.[28] In general, it was known that so-called animal charcoal was the best for decolorizing sugar solutions, that wood charcoal was the best for adsorbing gases and that coke had very little adsorbing or decolorizing power. No one knew the reason for these facts and no one could write a specification for charcoal. The ordinary charcoal used in the scientific laboratory was cocoanut charcoal, since Hunter had discovered more than fifty years ago that this was the best charcoal for adsorbing gases.
Raw Materials[29]
The first charcoal designed to offer protection against chlorine and phosgene was made by carbonizing red cedar. Since this had little value against chloropicrin, attention was turned to cocoanut shell as the source of raw material. This charcoal fulfilled the above conditions for a satisfactory absorbent better than any other form tested. It must not be supposed, however, that investigation of carbon stopped with these experiments. In the search for the ideal carbon, practically almost every hard vegetable substance known was tested. Next to cocoanut shells, the fruit pits, several common varieties of nuts abundant in the United States, and several tropical nuts (especially cohune nuts), were found to make the best carbon. Pecan nuts, and all woods ranging in hardness from iron wood down to ordinary pine and fir, were found to be in the second class of efficiency. Among other substances tested were almonds, Arabian acorns, grape seeds, Brazil nut husks, balsa, osage orange, Chinese velvet bean, synthetic carbons (from coal, lamp-black, etc.), cocoa bean shell, coffee grounds, flint corn, corn cobs, cotton seed husks, peanut shells and oil shale. While many of these substances might have been used in an emergency, none of them would produce carbon as efficient, volume for volume, as that of the cocoanut shell and other hard nuts.
Some idea of the scale of charcoal production may be seen from the requirement for cocoanut shells. When we first began to build masks our demands for carboniferous materials ranged from 40 to 50 tons a day of raw material; by the end of the war, we were in need of a supply of 400 tons of cocoanut shells per day. This demand would absorb the entire cocoanut production of tropical America five times over. (The total production of cocoanuts in Central America, the West Indies and the Caribbean Coast of South America amounted to 131,000,000 nuts annually, equal to a supply of 75 tons of shells daily.) It was equal to one-tenth of the total production of the Orient, which amounted to 7,450,200,000 nuts annually. This large demand always made a reserve supply of charcoal material practically impossible. The “Eat More Cocoanut” campaign started by the Gas Defense more than doubled the American consumption of cocoanut in a brief space of time and in October, 1918, with the help of importation of shell, we averaged about 150 tons of shells per day, exclusive of the Orient.
The first heating of cocoanut shells to make charcoal reduces their weight 75 per cent. It was evident, therefore, that we could more economically ship our oriental supply in the form of charcoal produced on the other side of the Pacific Ocean. A charcoal plant was established in the Philippine Islands and agents were sent to all parts of the Oriental countries to purchase enormous supplies of shells. While the work was only gaining momentum when the Armistice was signed, the plant actually shipped 300 tons of cocoanut shell carbon to the United States and had over 1000 tons on hand November 11, 1918.
In the search for other tropical nuts, it was found that the cohune or corozo nut was the best. These nuts are the fruit of the manaca palm tree. They grow in clusters, like bananas or dates, one to four clusters to a tree, each cluster yielding from 60 to 75 pounds of nuts. They grow principally on the west coast of Central America in low, swampy regions from Mexico to Panama but are also found along the Caribbean coast. The chief virtue of the cohune nut from the charcoal point of view was its extreme thickness of shell; this nut is 3 inches or more in length and nearly 2 inches in diameter but the kernel is very small. Four thousand tons per month were being imported at the time of the Armistice. A disadvantage in the use of cohune nuts was that their husks contained a considerable amount of acid which rotted the jute bags and also caused the heaps of nuts to heat in storage.
A third source of tropical material was in the ivory nuts used in considerable quantities in this country by the makers of buttons. There is a waste of 400-500 tons per month of this material, which was used after screening out the dust. This material is rather expensive, because it is normally used in the manufacture of lactic acid.
Another great branch of activity in securing carbon supplies was concerned with the apricot, peach and cherry pits and walnut shells of the Pacific Coast. A nation-wide campaign on the part of the American Red Cross was started on September 13, 1918. Between this time and the Armistice some 4,000 tons of material were collected. Thus the slogan “Help us to give him the best gas mask” made its appeal to every person in the United States.