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Patent US2220929A successfully refreshed from Google Patents.
US2220929A
Expired / Lapsed
US
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Photographic developing solutions containing aromatic hydrazines, their preparation and use
Assignee: DuPont Film Manufacturing Corp
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Filing: 1939-10-16
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Granted: 1940-11-12
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Expires: 1959-10-16
Abstract
No abstract record available.
Inventors
- 👤 Kirby James Emory
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 19:22
CPC Classifications
G; G03; G03C; G03C5/00; G03C5/26; G03C5/29; G03C5/30; G03C5/3014
Claims Analysis
Total Claims: 0
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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) | 1943-11-12 | 1944-05-13 | 1944-11-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1947-11-12 | 1948-05-13 | 1948-11-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1951-11-12 | 1952-05-13 | 1952-11-12 | $7700.00 | Window Closed / Lapsed |