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SELECT DISTINCT patent.*, YEAR(date) as year FROM patent LEFT JOIN category ON category.patent = patent.patent AND category.type = patent.type WHERE (category.class = '427') AND (category.subclass = '337') ORDER BY date ASC, patent, type

Total of 1 patents found where: Class is '427'; Subclass is '337';

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T / S Patent Date Description Patentee Category Assigned To
 1915
U 1,128,747 February 16, 1915 Method of Manufacturing Porcelain Insulators
Manufacturing process for porcelain insulator firing unglazed, then filling porous porcelain with oxidizable oil and rendering the oil stable with ozone to form a coating to replace expense of firing on a glaze		 BOEHM, Wilhelm
 Manufacturing  

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