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Improvement in the treatment process of the bristle loaded with tin salts, in order to keep its qualities of resistance, having been the subject of u.s. pat. no. 347.689 of 5, 1904
Improvement in the treatment process of the bristle loaded with tin salts, in order to keep its qualities of resistance, having been the subject of u.s. pat. no. 347.689 of 5, 1904