US2140668A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for making zinc sulphide
Assignee: American Zinc Lead and Smelting Co
•
Filing: 1934-09-19
•
Granted: 1938-12-20
•
Expires: 1954-09-19
Abstract
No abstract record available.
Inventors
- 👤 Harlan A Depew
- 👤 William T Maidens
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 23:51
CPC Classifications
C; C01; C01G; C01G9/00; C01G9/08; C09; C09C; C09C1/00; C09C1/04; C09C1/06; C01P; C01P2004/00; C01P2004/10; C01P2006/00; C01P2006/32; C01P2006/33; C01P2006/60
Claims Analysis
Total Claims: 0
No claims parsed yet. Click Sync Now above to re-index claims from Google Patents.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1941-12-19 | 1942-06-20 | 1942-12-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1945-12-19 | 1946-06-20 | 1946-12-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1949-12-19 | 1950-06-20 | 1950-12-20 | $7700.00 | Window Closed / Lapsed |