Patent US1821540A successfully refreshed from Google Patents.
US1821540A
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Process for the extraction of helium from other gases containing the same
Assignee: HELIUM Co
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Filing: 1928-09-28
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Granted: 1931-09-01
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Expires: 1948-09-28
Abstract
No abstract record available.
Inventors
- 👤 Bottoms Robert Roger
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 21:32
CPC Classifications
F; F25; F25J; F25J3/00; F25J3/06; F25J3/063; F25J3/0685; F25J3/069; F25J3/0605; F25J3/061; F25J3/0635; F25J3/066; F25J2215/00; F25J2215/30
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) | 1934-08-31 | 1935-03-02 | 1935-09-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1938-08-31 | 1939-03-02 | 1939-09-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1942-08-31 | 1943-03-02 | 1943-09-01 | $7700.00 | Window Closed / Lapsed |