The curtailment of the supply of cotton to Germany when the war started, because of England's blockade, and later when America entered the conflict, threatened disaster to the "Fatherland." The German chemists began working immediately to supply substitutes for cotton, to be used both in the manufacture of explosives and fabrics. They developed the processes of producing cellulose from wood pulp to take the place of cotton for making guncotton, and certain forms of wood fiber and paper were used in the textile trades. Willow bark was one of the substances utilized to a limited degree in making fabrics. Likewise synthetic--or artificial--camphor to take the place of that secured from nature's own laboratory--the camphor tree--was also produced of necessity, for camphor is an ingredient largely used in making smokeless powder. Before the war most of the camphor was obtained from Japan. Compounds--alloyed steel, iron and aluminum--have also been used in the industrial world to supplant copper. In America we have been educated to regard copper as the ideal metal for conducting electrical power, but in Europe aluminum was used successfully in a large way, even before the war. After the conflict started in all of the countries where there was a scant supply of copper, substitutes were developed by the metallurgists and chemists. POTENCY OF MODERN CHEMISTRY. The acids and salts used in powder making and the creation of explosives were also secured from new places. Nitric acid, which is necessary to the manufacture of guncotton, for many years was made principally with saltpeter and sulphuric acid. Modern chemists, however, made it from nitrogen of the very air we breathe, and in Germany it was made during the war from ammonia and calcium cyanamide, both of which may be obtained from the air. Many such methods of obtaining acids were known and tested before the war, but the processes had not been perfected to such an extent as to make them commercially profitable. However, the increased prices of chemicals, due to the excessive demands of war, and the absolute necessity for producing them inspired the chemists to get the required results, and Germany by the development of these sources of supply found the acids necessary for her own use in war, whether for explosive making or medical purposes. Great quantities of sugar are used in making powder and explosives, too, and when the supply became limited the German chemists began producing in larger quantities the chemical substitute--saccharine. Later even this sweet was denied the population because the chemicals were needed for war uses. So in every line Germany found use for everything which its chemists and chemical laboratories could produce.