Prior to January 1, 1936, the rate of duty on imports of vinyl resins was 6 cents per pound and 30 percent ad valorem under paragraph 2, and 4 cents per pound and 30 percent ad valorem under paragraph 11 of the Tariff Act of 1930. Under the terms of the trade agreement with Canada, the duty under both paragraphs was reduced to 3 cents per pound and 15 percent ad valorem. This rate was generalized to the other countries from which we have received imports, with the exception of Germany. Exports from the United States. Exports of vinyl resins are not separately shown in official statistics. 11. OTHER SYNTHETIC RESINS The synthetic resins already discussed are those in substantial commercial production but, by no means, the only ones known or produced. Several thousand new ones have been reported and the search continues in laboratories throughout the world. A successful new product must be one made from inexpensive raw materials or must possess some property or advantage that will permit its sale at a price level above that of other resins. No attempt is here made to list the host of less important resins. Certain ones of unusual interest or possessing unique properties are described below. These include resins obtained from adipic acid, aniline, citric acid, diphenyl, furfural, lignin, sugar, and sulphonamide. Adipic acid resins. The resins from adipic acid are classed as alkyd resins. Those obtained by the condensation of adipic acid and glycerin are soft and rubbery and are used to some extent in surface coatings and in photographic films. In these the resin is formed in three stages as in other alkyd types: A soluble liquid, a viscous rubbery product, and a form insoluble in the usual solvents. Commercial domestic production of these resins was reported for the first time in 1935 and the output has increased each year since then. Aniline resins. Resins obtained by condensing aniline and formaldehyde have been developed in recent years. Much of the research on this type of resin was done in Switzerland by the Ciba Co., which holds a number of patents on it. The Swiss product, called Cibanite, has excellent electrical and mechanical properties. At least one domestic manufacturer is licensed under the Swiss-owned patents. Citric acid resins. Considerable interest has recently been manifest in synthetic resins derived from citric acid. The sharp decline in the price of citric acid, as a result of large scale synthesis from sugar has placed it within the realm of possibility as a raw material for synthetic resins. The citric acid resins, classed as alkyd resins, are obtained by condensing citric acid and glycerin. Commercial production is said to have started in Europe, but there is no known domestic production as yet. Diphenyl resins. A series of products known as Aroclors and made by chlorinating diphenyl are available in commercial quantities.