By a remarkable coincidence the same basic process was developed in Germany, by Alfred Wohl, in the laboratories of the Interessen Gemeinschaft Industrie A. G. (German I. G.), at almost the same time that Gibbs and Conover made their discovery. In 1920 Wohl applied for a United States patent covering this process, claiming invention in the summer of 1916. There was some doubt whether his discovery had been made 2 months earlier or 3 days later than that of Gibbs and Conover, but in July 1934 the United States Court of Customs and Patent Appeals rendered a decision in favor of the German inventor, allowing Wohl’s claim filed with the German patent office on June 28, 1916. Therefore, Wohl’s claim covering the air oxidization process was upheld and he was granted United States Patent No. 1,971,888, issued August 28, 1934 and assigned to the German I. G. Several domestic firms began commercial production of phthalic anhydride about 1918 under the patent of Gibbs and Conover and have since operated the process continuously. Such manufacturers are presumably protected from possible patent litigation and the payment of royalties under the Wohl patent by section 3 of the so-called Nolan Act of 1921, which states: “No patent granted or validated ... shall affect the right of any citizen of the United States or his successor in business to continue the manufacture, use, or sale commenced before the passage of this Act, nor shall the continued manufacture, use, or sale by such citizen ... constitute an infringement.” United States production. Table 47 shows the production and sales of phthalic anhydride from 1917 through 1937. TABLE 47.—_Phthalic anhydride: United States production and sales, 1917-37_