Attempts are being made to attack the locust of the Philippines and the far west and the boll weevil of the cotton states of the South. So far these tests have not proven more successful than other methods, but inasmuch as the number of gases available for trial are so great and the value of success of so much importance, this research should be continued on a large scale to definitely determine whether poisonous gas can be used to eradicate these pests—especially the boll weevil. As an interesting application of war materials to peaceful uses, we may consider the case of cellulose-acetate, known during the war as “aeroplane dope,” the material used to coat the linen covering aeroplane wings. With a little further manipulation, this cellulose-acetate, or aeroplane dope, becomes artificial silk—a silk that today is generally equal to the best natural silk—and which promises in the future to become a standard product better in every way than that from the silk worm. [Illustration: FIG. 121.] These few examples of the peacetime value of gas are worthy of thought from another standpoint. Being so valuable, their use in peace will not be stopped. If they are thus manufactured and used in peace, they will always be available for use in war, and as the experience of the World War proved, they certainly will be so used even should anybody be foolish enough to try to abolish their use. As for this latter idea, the world might as well recognize at once that half-way measures in war simply invite disaster. This chapter would not be complete without a brief statement of the necessity of a thoroughly developed chemical industry in the United States as a vital national necessity if the United States is to have real preparedness for a future struggle. As will be indicated a little later, no one branch of the chemical industry can be allowed to go out of existence without endangering some part of the scheme of preparedness. Let us consider first the coal tar industry. Coal tar is a by-product of coke ovens or the manufacture of artificial gas from coal. The coal tar industry is of the utmost importance because in the coal tars are the bases of nearly all of the modern dyes, a large percentage of the modern medicines, most of the modern high explosives, a large proportion of poisonous gases, modern perfumes, and photographic materials. A consideration of these titles alone shows how vital the coal tar industry is. The coal tar as it comes to us as a by-product is distilled, giving off at different temperatures a series of compounds called crudes. Ten of these are of very great importance. The first five are benzene, toluene, naphthalene, anthracene and phenol (carbolic acid). The second group comprises xylene, methylanthracene, cresol, carbazol and phenanthrene.