Patent US1897638A successfully refreshed from Google Patents.
US1897638A
Expired / Lapsed
US
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Purifying art
Assignee: SILICA Co OF CALIFORNIA L
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Filing: 1930-03-04
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Granted: 1933-02-14
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Expires: 1950-03-04
Abstract
No abstract record available.
Inventors
- 👤 Irving D Hubbell
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 14:12
CPC Classifications
C; C03; C03C; C03C1/00; C03C1/02; C03C1/022; C04; C04B; C04B33/00; C04B33/02; C04B33/10
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) | 1936-02-14 | 1936-08-15 | 1937-02-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1940-02-14 | 1940-08-15 | 1941-02-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1944-02-14 | 1944-08-15 | 1945-02-14 | $7700.00 | Window Closed / Lapsed |