| 摘要 |
<p>500,760. Removing metallic coatings. NAAMLOOZE VENNOOTSCHAP MAATSCHAPPIJ VOOR ZWAVELZUURBEREIDING VOORHEEN G. T. KETJEN & CO. Dec. 29, 1937, No. 36008. Convention date, Jan. 25. [Class 1 (iii)] Metallic coatings such as tin and zinc are removed from iron articles, sheets, scrap, and the like bv the action of an acid such as hydrochloric acid or of a mixture of acids in the presence of an organic compound containing a sulphur atom and an amino or substituted amino group or a substance which gives rise to such a compound when, added to the acid and which prevents solution of the iron. Varnished or painted surfaces may be treated by the process of the invention. Certain organic nitrogen compounds which are formed during the distillation of coal, such as those contained in commercial anthracene and in the residues obtained in naphthalene production, or the product obtained by mixing coal tar oil or anthracene oil with concentrated sulphuric acid at 300‹ C., may be used as inhibitors. In examples, a substance containing sulphonamide, and thiocarbonilide are employed. The Specification as open to inspection under Sect. 91, includes the use, with the acid, of any substance which delays the solu-. tion of the iron. This subject-matter does not appear in the Specification as accepted.</p> |
