US1840644A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Purification of diamino-alpha-alpha'-dihydroxy-anthraquinone disulphonic acid dyestuffs
Assignee: National Aniline and Chemical Co Inc
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Filing: 1926-02-13
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Granted: 1932-01-12
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Expires: 1946-02-13
Abstract
No abstract record available.
Inventors
- 👤 Harold T Stowell
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 06:28
CPC Classifications
C; C09; C09B; C09B1/00; C09B1/50; C09B1/52; C09B1/521
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) | 1935-01-11 | 1935-07-13 | 1936-01-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1939-01-11 | 1939-07-13 | 1940-01-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1943-01-11 | 1943-07-13 | 1944-01-12 | $7700.00 | Window Closed / Lapsed |