-------------------+---------+---------+--------- Imported from— | 1935 | 1936 | 1937[1] -------------------+---------+---------+--------- | Quantity (pounds) +---------+---------+--------- Germany |7,869,120|6,095,040|5,297,600 Netherlands | | | Canada | 320,320| | All other countries| | | +---------+---------+--------- Total |8,189,440|6,095,040|5,297,600 +---------+---------+--------- | Value +---------+---------+--------- Germany | $366,371| $272,679| $266,166 Netherlands | | | Canada | 13,056| | All other countries| | | +---------+---------+--------- Total | 379,427| 272,679| 266,166 +---------+---------+--------- | Unit value +---------+---------+--------- Germany | $0.047| $0.045| $0.050 Netherlands | | | Canada | .041| | All other countries| | | +---------+---------+--------- Average | .046| .045| .050 +---------+---------+--------- [1] Preliminary. Source: Foreign Commerce and Navigation of the United States. Imports of urea enter the United States free of duty under paragraph 1793 of the Tariff Act of 1930. In spite of that fact a substantial production in the United States has been achieved. This is due, at least to a considerable extent, to the production of crude urea in ammonia solution, which is used in ammoniating superphosphates for fertilizer use. It is shipped by tank car but would be difficult to transport by ship. The volume market for this form of the product has aided in the production of crystal urea for both resin and fertilizer use. THIOUREA Thiourea (thiocarbamide) is a white crystalline solid, melting at 180° C. It is made commercially by treating a solution of calcium cyanamide with sulphur and ammonium sulphide or with hydrogen sulphide and ammonia. The principal uses of thiourea are in making intermediates and pharmaceuticals, as a photographic developer, as an insecticide, and in medicine. Because of the water resistance it imparts it was for some time widely used in urea resins. During the past few years, however, its use in resins has declined sharply owing to its deleterious action on ordinary molds and its slow rate of cure. In molding compounds, thiourea requires about 10 minutes curing time as compared with 3 minutes or less for urea resins and tar-acid resins. Since ways have been found to fabricate water-resistant urea resins without using thiourea, the consumption of thiourea in this use has declined.