US 2939070

I'll check for any litigation or docket activity on this patent number before summarizing.

US 2,939,070 — Summary

Sourcing note: The analysis below is drawn from the authoritative full text you supplied (Google Patents, https://patents.google.com/patent/US2939070/en). My searches of public web sources and docket/court document aggregators returned no litigation, no PTAB/Court of Appeals for the Federal Circuit activity, and no 2026 CAFC docket entry involving this patent number. I could not directly query USPTO PatentCenter or the CAFC docket system; no authoritative record of such proceedings was found in the sources I could reach.

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Bibliographic data (from the patent document)

Prior art cited in the file (4 U.S. patents):

• US 1,592,979 — Keeler, July 20, 1926
• US 2,525,754 — Albrecht, Oct. 17, 1950 ("Conductivity cell")
• US 2,611,007 — Cade et al., Sept. 16, 1952 ("Temperature-compensating conductivity cell")
• US 2,709,781 — Douty et al., May 31, 1955 ("Instrument for determining the electrical conductance of liquids")

Later documents citing it (6): US 3,166,485; US 3,195,551; US 3,355,665; US 3,834,232; US 4,020,677; US 5,223,114.

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Abstract

Uncertainty flag: The patent as published in 1960 carries no separately labeled formal abstract, and the authoritative text you supplied has no "Abstract" field. The customary abstract-of-the-disclosure is the opening paragraph of the specification, which functions as the summary:

The invention relates to conductivity cells and the electrodes thereof used for measuring the electrical conductivity of fluids, where quantitative indications of electrolyte concentration may be had. Each electrode is an elongated cylinder of tough plastic (e.g., Teflon or Kel‑F) with a longitudinal bore carrying a tightly fitting metallic conductor that extends out the terminal end; the immersed end has a recess or chamber (optionally wider than the bore) with a conducting disc connected to the conductor. A sleeve-like compression fitting, a double-conically-tapered gland sleeve, and a beveled gland nut mount each electrode in a liquid-tight wall of a tank. The chamber isolates a narrow, high-resistance column of the test liquid so that leakage past the gland or bore cannot partially short-circuit the electrodes, making measured resistance depend almost exclusively on the solution and largely independent of electrode position.

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Background and stated purpose

Conventional high-temperature (250–400 °F), elevated-pressure (>50 p.s.i.g.) conductivity cells had small sealing areas and gaskets that leaked, causing partial short-circuiting of the electrodes and erroneous resistance readings. The patent addresses this with electrodes that are effectively "leak free," and whose chamber geometry yields a high cell constant (stated range: 1 to 10 reciprocal centimeters), improving accuracy with A.C. Wheatstone-bridge instrumentation. A stated illustrative result: with a cell constant of 1, the two electrodes may be displaced as much as 6 inches from each other without changing the net cell constant by more than 1 percent.

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Independent claims — plain-language overview

Claim 1 — Electrode assembly (generic structure).
An electrode for a conductivity cell: an elongated insulator with a bore; a conductor fitting tightly against and in close contact with the bore wall, ending inside the insulator short of one end; near that end, a recess or opening in the wall (from the outer surface) forming a chamber; a conducting element inside the chamber wired to the conductor; and a pressure-tight fitting for mounting the unit on/within a liquid-tight vessel. Key limitation: the conductor is effectively completely internal to the insulator and is the sole conductor emerging from the other end.

Claim 7 — Electrode assembly with specific mounting hardware.
Adds structural detail to the claim‑1 concept: cylindrical insulator with an axial bore; an end chamber wider than the bore; a conducting disc at the chamber bottom connected to a tightly fitting metallic conductor; plus the mounting stack — a sleeve-like compression fitting threaded at both ends, a packing/gland sleeve with conical tapers at both ends, and a gland nut threaded to the fitting whose interior is beveled at the base of the threading to compress the gland and form a liquid seal. (The gland's widest diameter is smaller than the nut's inside diameter.)

Claim 8 — Conductivity cell (two assemblies).
A cell comprising two entirely separate, similarly constructed, physically spaced-apart electrode assemblies (each as in claim 1). The resistance between them, when immersed and separated by fluid, is substantially independent of their relative positions and depends almost exclusively on the fluid's characteristics. The spacing of the assemblies on the container is set by where their mounting means are placed.

Claim 9 — Electrode assembly with a side-wall entry hole (Fig. 4-type variant).
An insulator with a bore and a hole through its side wall near to but removed from one end, allowing fluid to enter; a tightly fitting conductor in the bore that passes through that hole and ends within the insulator; insulation remains above and between that end and the nearest conductor end; plus a pressure-tight mounting fitting. The conductor again constitutes an electrode effectively completely internal to the insulator, and is the sole conductor emerging from the other end.

Claim 10 — Conductivity cell (full mounting structure).
Two separate, spaced-apart assemblies in a liquid-tight container; resistance substantially independent of relative positions and of the container walls. Each assembly adds: chamber wider than the bore but narrower than the insulator's thickness; disc at the chamber bottom; tightly fitting conductor; compression fitting threaded at both ends, one end threadedly engaging the container wall; double-tapered gland sleeve; beveled gland nut forming a liquid seal. The spacing between the fittings on the container determines the electrode spacing.

Claim 11 — Conductivity cell (broadest mounting formulation).
Two separate, similarly constructed, spaced-apart electrodes in a fluid-tight container, resistance substantially independent of relative electrode and wall positions. Each electrode: elongated insulator with axial bore; metallic conductor fitting tightly in the bore and extending outward from only one end; the other end has a recess/chamber whose width is less than the insulator's thickness; one end of the conductor is electrically coupled to the chamber interior and terminates within the insulator at a distance removed from that end (so the conductor is effectively completely internal). Adds mounting means individual to each electrode surrounding a portion of the insulator, mounting it fluid-tight with the chamber inside the container and the conductor's extending portion outside, the mounting spacing determining electrode spacing.

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Dependent claims (brief)

• Claim 2 (dep. 1) — plural vent holes in the chamber side wall; and the fitting interior beveled where it contacts the gland sleeve so the other tapered end is compressed when the nut is tightened.
  • Drafting anomaly worth noting: claim 2 references "said gland sleeve" and "said nut," although neither is recited in claim 1. Read literally, this creates an antecedent-basis gap in claim 2. The same subject matter appears properly integrated in independent claim 7.
• Claim 3 (dep. 1) — insulator is polytetrafluoroethylene (Teflon).
• Claim 4 (dep. 1) — an air vent through the insulator wall communicating with the chamber.
• Claim 5 (dep. 4) — chamber located intermediate the ends, entering only part way into the wall, appreciably narrower than the insulator thickness.
• Claim 6 (dep. 4) — chamber located intermediate the ends and passing completely through the insulator.

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Sources and cautions

• Authoritative source (provided): https://patents.google.com/patent/US2939070/en
• No USPTO litigation record, no CAFC appeal, and no 2026 docket entry for this patent number were located in the sources I could search. Absence of a hit is not proof that none exists — I could not query PatentCenter or the CAFC docket directly.
• Do not conflate this number. My searches surfaced unrelated documents sharing the string "2939070": EP 2939070 A1 (light source device/projector), FR 2939070 A1 / CA2939070 (container forming; downhole sealing element), JP patent 2939070 (in-vehicle television apparatus), DE 2939070 (coke oven door priority), and a Florida LLC's FEI number. None of these is US patent 2,939,070.
• The statutorily expired term cited (May 31, 1977) reflects the pre‑1995 17‑year term; the patent is long expired and in the public domain.

I'll search for litigation involving US patent 2939070 across patent litigation sources.

Let me search more targeted litigation databases.

Let me try a few more targeted litigation databases.

Summary Finding

I found no evidence of any litigation involving U.S. Patent No. 2,939,070. No district court, Federal Circuit, ITC, or PTAB proceeding asserting or challenging this patent surfaced in my searches, and no plaintiff/defendant/jurisdiction/case-number records exist in the sources I could reach.

Because you instructed me not to return results for similar numbers, I want to be explicit about what I did and did not find.

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Confirmation of the Patent I Searched

To ensure I was searching the correct document:

Source: https://patents.google.com/patent/US2939070/en

I focused on this exact patent. The "cited by" entries above are later patents that cited it as prior art — citation is not litigation and I have not treated it as such.

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Sources Searched and What They Returned

1. General open-web searches for "2939070" combined with litigation/lawsuit/defendant/infringement terms — returned only (a) the Google Patents page for US2939070, and (b) unrelated documents bearing the same numeric string in other jurisdictions or contexts:

   • FR 2939070 A1 (Sidel/container forming) — a French publication, unrelated to the US patent.
   • EP 2939070 A1 (Ricoh, light source device) — unrelated.
   • DE 2939070 (Koppers, coke oven door) — unrelated.
   • JP patent 2939070 (in-vehicle television device) — unrelated.
   • A bankruptcy/registration notice "Pranešimo Nr. 2939070" (Lithuania) and a Florida LLC annual report FEI "99-2939070" — unrelated corporate filings.

   These are false positives on the numeral only and are not records of litigation of US 2,939,070.

2. CourtListener / RECAP-oriented searches — returned no case involving this patent. The only CourtListener hits for "2939070" were a financial-disclosure investment line item and unrelated opinions.

3. Unified Patents portal, Docket Alarm, and Justia-oriented searches — I attempted to reach these litigation trackers, but my session hit its tool-call limit before I could retrieve results from them specifically. I cannot claim to have completed a verified pull from those sites, and I won't invent entries.

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Why "No Litigation Found" Is the Expected Result Here (and the Limits of That Conclusion)

• Expiration long ago. The patent's anticipated expiration was May 31, 1977 (per the Google Patents legal-status record). Enforcement litigation must occur during the patent term; any suit would therefore predate ~1977.
• Database coverage gap. Modern litigation databases (PACER, Unified Patents, Docket Alarm) generally cover federal cases from the late 1980s–1990s forward. A 1958–1977 lawsuit, if one existed, would typically survive only in National Archives holdings, old Federal Reporter/F.2d volumes, or USPTO assignment records — not in today's online docket trackers.
• Therefore, my "no litigation found" is a statement about what is discoverable in the sources I reached, not a categorical assertion that no suit was ever filed and later went unreported or is archived offline.

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Bottom Line

• Plaintiff(s): None identified.
• Defendant(s): None identified.
• Jurisdiction: None identified.
• Case number: None identified.
• Filing date: None identified.
• Outcome/current status: Not applicable — no U.S. litigation involving US 2,939,070 was found.

No known litigation involving US Patent 2,939,070 was located. If you need a negative-result search certified against a specific commercial docket database (e.g., Docket Navigator, Lex Machina, or the Unified Patents caselist), I'd need to run that database directly; my searches here were open-web and were cut short before I could confirm against those paywalled trackers. I'd also flag that a truly exhaustive answer for a 1960 patent would require a National Archives / F.2d print search, which I have not performed.

Proceedings overview

Zero AIA trial proceedings on file. The USPTO Open Data Portal structured block returns no IPR, PGR, or CBM proceedings for US 2,939,070, and independent web searches (Google Patents litigation/PTAB tabs, PTAB docket aggregators, CourtListener) surfaced none either — the only "PTAB-adjacent" hits were unrelated matters involving other patents and other Rosenthals. There is therefore no breakdown to give across active / invalidated / sustained / settled / institution-denied: the count is 0, and the defensible posture for a defendant is not "hardened patent" or "canceled claims" but something more fundamental — this patent expired on 1977-05-31 and has been unenforceable for nearly five decades; any demand letter citing it is a red flag about the sender, not about your product.

Two structural reasons no proceedings can exist (and why the absence is not a meaningful signal either way):

1. Expiration. US 2,939,070 issued 1960-05-31 on Application Ser. No. 710,033 filed 1958-01-20, with a pre-URAA 17-year term. Google Patents records "Anticipated expiration" on 1977-05-31 and legal status "Expired – Lifetime." A patent that expired 35 years before the AIA's IPR provisions took effect (2012-09-16) cannot have an AIA trial history.
2. Availability window. IPR/PGR/CBM are creature-of-statute proceedings created by the America Invents Act. There is no pre-AIA PTAB equivalent that would generate a docket entry for this patent. The only pre-2012 Office-side challenges would have been ex parte reexamination or interference, and neither Google Patents nor any search result shows an inter partes reexamination, interference, or reexamination certificate for 2,939,070.

For completeness on provenance: the items under Google Patents' "Citations (4)" and "Cited By (6)" are prior-art references and forward citations, not proceedings. The four references cited during prosecution were US 1,592,979 (Keeler, 1926-07-20), US 2,525,754 (Albrecht, 1950-10-17), US 2,611,007 (Cade et al., 1952-09-16), and US 2,709,781 (Douty et al., 1955-05-31). The six forward citations run from US 3,166,485 (1965) to US 5,223,114 (1993) and belong to unrelated later patents.

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Proceedings

None. There are no proceeding numbers to list, and I will not invent any. No petitioner, no panel, no institution decision, no Final Written Decision, no settlement, and no Federal Circuit appeal exists for this patent.

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Strategic summary

Claim status. All eleven claims (1–11 as issued) are untested by any AIA trial, simply because no trial could ever have been filed. That is not the same as "sustained." The claims were never adjudicated by the PTAB, and the patent is now expired, so the claim-status question is academic: claims 1–11 all lapsed on 1977-05-31 when the patent term ended. Nothing in the record narrows, cancels, or amends any claim.

Estoppel landscape. § 315(e)(2) estoppel is irrelevant here — it attaches only to petitioners in an instituted IPR/PGR, and there are none. For a defendant today, the operative bars are not estoppel but enforceability and limitations: an expired patent cannot be infringed going forward, and 35 U.S.C. § 286 caps back damages at six years before suit (here, any actionable window closed in the 1970s/1980s). Laches and the statute of limitations would independently dispose of any assertion. Practically, there is no prior-art ground to preserve because there is no live claim to invalidate.

Pattern signals. None available. No repeat petitioner, no Patent Owner appeals, no defensive aggregator (Unified Patents, RPX, etc.) involvement — those signals are generated by litigation campaigns, and this patent predates the entire modern assertion economy. As a general matter, the absence of PTAB activity is a weak negative signal about how seriously an old patent is being asserted, but here the absence is fully explained by expiration, so it carries no diagnostic weight about the patent's merit.

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Recommended next steps

• If you received a demand letter citing US 2,939,070: treat it as evidence of bad faith or error. The patent expired 1977-05-31 (Google Patents legal status: "Expired – Lifetime"; anticipated expiration event dated 1977-05-31: https://patents.google.com/patent/US2939070/en). Send a short response noting expiration, the 17-year pre-URAA term measured from the 1960-05-31 grant, and § 286's six-year damages bar, and decline to engage further. Do not spend budget on an invalidity search or a post hoc IPR — there is no PTAB vehicle to file one, and no live claim.
• If you are evaluating the technology (not the patent right): the expired disclosure is free to practice. The full specification and all eleven claims are public at https://patents.google.com/patent/US2939070/en, and any subject matter disclosed but not claimed in 1960 is dedicated to the public.
• If you are confirming the docket yourself: run the patent number through USPTO PTAB E2E (https://ptacts.uspto.gov/ptabweb/) and the USPTO Patent Center for 2,939,070. Both should return a bare prosecution file with no trial or post-issuance proceeding entries — consistent with the ODP block. If a search vendor shows an "IPR2025-01252" or similar hit, verify the patent number on the caption page before relying on it; my searches returned only unrelated patents under that case number.

Caveat on confidence: the conclusion that no PTAB proceeding exists is high-confidence and rests on the canonical ODP structured data plus corroborating searches. I did not find, and do not claim, any non-AIA Office proceeding (interference, reexamination, or ex parte reexam) for this patent either, but my searches were aimed at AIA trials; if you need a clean bill of health on pre-2012 Office proceedings, a manual review of the paper prosecution file at Patent Center would be the confirming step.

I'll research the assignment record and corporate history before assembling the report.

Assignment & Ownership Analysis — US 2,939,070 ("Conductivity Cell")

Scope note / source limitation (read first): I was able to pull the patent's full text and its legal-events ledger via Google Patents, and to verify corporate history via the Science History Institute and contemporaneous press coverage. The USPTO Assignment Center UI at https://assignmentcenter.uspto.gov/ is a JavaScript-driven search that I could not render directly in this session, so I am relying on Google Patents' assignment/legal-events table (which is populated from the same recorded-assignment corpus) plus the patent front-page assignee data. No reel/frame numbers surfaced for this patent. I am not going to invent them.

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Inventors

• Single named inventor. The front-page "assignor to" language establishes an assignment-on-filing (pre-issue) from the inventor to his employer; there is no indication of a separate post-issuance instrument.
• Tenafly and Cedar Grove are both in Essex/Bergen County, NJ — consistent with a local employee-inventor of the assignee company, whose plant was at 89 Commerce Road, Cedar Grove, N.J.
• Name-collision caution: web results surface a different "Robert J. Rosenthal" (born 1956, life-sciences executive, director of InVivo Therapeutics and Bruker Corp.). That person cannot be this inventor — he was born roughly four years before this patent issued — and must not be merged into this chain.
• Unusual-departure pattern: not present / not determinable. There is no evidence in the record of the inventor leaving the assignee within 12 months of filing, nor any data source (no SEC, no startup) that would let me test it. With one inventor and a 1958 filing at a small private instrument maker, there is nothing to flag.

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Original assignee

Industrial Instruments, Inc. (89 Commerce Road, Cedar Grove, Essex County, N.J.)

• Business: manufacturer of electrolytic-conductivity instrumentation — Solu Bridges, continuous conductivity indicators/recorders, electrode-type and electrodeless (toroidal) conductivity cells, steam & condensate analyzers, transistor testers. It is described in period literature as being "our business" for electrolytic conductivity, and as a direct competitor/supplier alongside Leeds & Northrup.
• Product embodying the claims: yes — this was a shipping commercial product line. This is the decisive fact for the ownership analysis. The patent's claimed electrode assembly (Claims 1, 3, 4, 7; the cell Claims 8, 10, 11) is the insertion-type conductivity cell the company catalogued (Teflon/Kel-F bodies, graphite/nickel/platinum electrodes, cell constants spanning ultra-pure water to concentrated acid, ratings to 7,000 psi and several hundred °F). The specification's own applications list (black liquor, digester systems, sulfite pulp cooking liquor, detergent and salt solutions at 250–400 °F and 50–5,000 psi) maps directly onto Industrial Instruments' advertised markets. Claims 1 and 7 in particular are the threaded compression-fitting/gland-sleeve tank-mount cell the firm sold.
• Current status: dissolved as an independent entity. Acquired by Beckman Instruments, Inc. in 1965 in a stock-for-assets pooling of interests valued at ~$5.7 million (77,341 Beckman common shares), announced July 8, 1965; the business continued as Beckman Instruments "Cedar Grove Operations," 89 Commerce Road, Cedar Grove, N.J. The Science History Institute / Chemical Heritage Foundation records: "In 1965, Beckman Instruments acquired Industrial Instruments, Inc." Beckman Coulter later passed to Danaher Corporation (2011). Industrial Instruments therefore never sold its patents into a licensing vehicle — it was absorbed into a large operating instrument company.

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Assignment timeline

No post-issuance assignment records were found for US 2,939,070. Concretely:

• Google Patents' legal-events table for US2939070A shows only: 1958-01-20 application filed; 1958-01-20 priority to US710033A; 1960-05-31 application granted; 1960-05-31 publication of US2939070A; 1977-05-31 anticipated expiration; status Expired – Lifetime. There is no "Assignment" event line, which is how Google Patents surfaces recorded reel/frame data.
• The "Current Assignee" field displays Industrial Instruments, Inc., but with Google's standard disclaimer that the assignee list "may be inaccurate" and that it is not the product of a legal analysis. In context this is simply an echo of the front-page assignee, not evidence of a recorded post-issuance transfer.
• I found no reel/frame entry, no correspondent of record, and no conveyance-type record for this patent.

Because there is nothing to enumerate, the timeline section terminates here: the only assignment in this chain is the original inventor-to-employer assignment recited on the face of the patent. The 1965 Beckman acquisition was a corporate stock-for-assets merger of the company; whether the individual patent was carried over by a separate recorded instrument is not evidenced in any record I could retrieve, and I will not assert it was.

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Timeline diagram

timeline
    title Ownership of US 2939070
    1958 : Filed by Robert Rosenthal
         : Assigned to Industrial Instruments Inc
    1960 : Patent issued
    1965 : Industrial Instruments bought by Beckman Instruments
    1977 : Patent expired

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NPE / troll-pattern signals

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Verdict

Insufficient data — and, independently, the asset is unenforceable by anyone because it expired.

Justification: the only ownership event evidenced anywhere in the record is the original inventor-to-employer assignment recited on the face of the patent (Robert Rosenthal → Industrial Instruments, Inc., Cedar Grove, N.J., filed 1958-01-20); Google Patents' legal-events ledger for US2939070A lists no assignment entries and shows anticipated expiration 1977-05-31, status "Expired – Lifetime." The sole subsequent ownership change is the 1965 corporate acquisition of Industrial Instruments by Beckman Instruments, Inc. (NYT, 1965-07-08; Science History Institute Beckman Collection), a going-concern merger between operating companies — with no reel/frame evidence that this patent was separately recorded, and no successor NPE of any kind. Every one of the eight NPE/privateering signals is not present, so no NPE verdict is supportable; the "Insufficient data" label reflects the absence of any recorded post-issuance assignment rather than any ambiguity about the assignee's character.

Verification links:

• USPTO Assignment Center (search by patent number): https://assignmentcenter.uspto.gov/
• USPTO legacy assignment index: https://assignment.uspto.gov/patent/index.html
• Google Patents legal events / assignee panel: https://patents.google.com/patent/US2939070/en

Caveat for the record: I could not open the Assignment Center result page in this session, so the "no records" conclusion rests on Google Patents' mirrored assignment/legal-events data plus the absence of any reel/frame citation in any indexed source. If the Assignment Center returns a hit for this patent, the reel/frame, correspondent, and dates should be pasted in and the signals section re-run — but on the present evidence, this is a 1958 operating-company patent that expired in 1977 and never entered an NPE chain.

I'll verify the patent and its cited prior art against live sources before analyzing.

Prior-Art Analysis — US 2939070 ("Conductivity Cell")

Prepared: April 26, 2026 | Target: US 2939070 A | Source of record for the patent text: https://patents.google.com/patent/US2939070/en (Google Patents mirror of the USPTO record)

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1. Verification of the target patent

I searched for and retrieved the record for US2939070 specifically (not a family member or similar number). Confirmed bibliographic data as they appear in the record:

Literal-reading note (per your strict rule): I am not normalizing identifiers or text. The retrieved claim text contains apparent typographic/OCR defects that I am treating literally rather than correcting — e.g., claim 3 reads "polytetrafluoroethylene" (rendered "polyteradiouroethylene" in one copy), claim 7 reads "the inside diameter of said here" where the antecedent is the bore, claim 7/10 read "eflectively completely internal," and claim 2 as published is grammatically incoherent (see §4). These matter for the § 102 analysis and are flagged rather than silently fixed.

Statutory framework: Because US2939070 was filed 1958-01-20, it is governed by pre-AIA 35 U.S.C. § 102. All four references cited in the file wrapper were granted more than one year before the January 20, 1958 filing date and therefore qualify as prior art. I identify the applicable subsection for each below.

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2. Patent citations in the file of US2939070 (the actual prior art)

The record lists exactly four (4) references under "References Cited in the file of this patent / UNITED STATES PATENTS":

Important disambiguation: The record's "Cited By" table lists six later documents — US3166485A, US3195551A, US3355665A, US3834232A, US4020677A, and US5223114A. These post-date US2939070 and are not prior art to it. They should be excluded from any § 102/§ 103 analysis of this patent. Likewise, the "Similar Documents" list is a classification-based convenience list, not a citation of record.

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3. Reference-by-reference analysis

3.1 US 2,709,781 — Douty et al. (American Chemical Paint Co.), granted 1955-05-31 — the most technically relevant reference

Verification: Full text confirmed, including the printed heading "2,709,781 Patented May 31, 1955," application "June 20, 1952, Serial No. 294,614," inventors "Alfred Douty, Elkins Park, and Walter Graham Smith, Ambler, Pa.," 4 claims. (https://patents.google.com/patent/[US2709781A](/patent/US2709781A)/en; PDF: https://patentimages.storage.googleapis.com/15/3f/58/1a9320686c27cf/US2709781.pdf)

Disclosure: A conductivity cell whose non-conducting body has two chambers of relatively large cross-section, one electrode in each, joined by a passageway of restricted cross-section containing a replaceable bushing-like member. The reference states expressly that the restricted passageway "constitutes the greater portion of the resistance in the path between the electrodes," that "the spacing of the electrodes in the assembly is not critical" because the chamber portions are "a negligible proportion only of the over-all resistance," and that the restricted members are "standardized to produce cells of known cell constant." Electrode assemblies are "readily removable by virtue of being threaded into position."

Claim-by-claim § 102 assessment:

• Claims 8, 10, 11 (and the corresponding "spacing" limitations): Douty teaches the core functional result these claims recite — resistance dependent almost exclusively on the fluid and substantially independent of electrode position/spacing, with a prestandardized restricted geometry fixing the cell constant. However, Douty does not disclose the "two entirely separate ... physically spaced apart electrode assemblies" each with its own wall-mounting fitting — Douty's two electrodes sit in a single shared, rigid cell body joined by an internal passageway. Nor does Douty disclose the insulating cylinder/bore with a conductor in tight contact, wholly internal, emerging as the sole conductor from the opposite end. No complete anticipation; strong § 103 combination candidate.
• Claims 1, 4, 5: Douty's open chambers and removable plug access openings (plugs 7, for access, replacement and cleaning) are structurally distinct from the claimed wall recess/air-vent communicating with a chamber. No anticipation.
• Claim 7: Douty's threaded electrode assemblies do not disclose the thin deformable metal gland with conical tapers at both ends compressed between a beveled fitting end and a beveled gland nut. No anticipation.

Bottom line: Douty is the closest prior art on the functional/result limitations, and the most likely reference to be used in a § 103 rejection, but it does not itself meet any independent claim on an element-for-element basis.

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3.2 US 2,525,754 — Albrecht (Hall Lab Inc.), granted 1950-10-17 — closest on electrode-in-insulator geometry

Verification: Confirmed — "United States Patent 2525754," inventor Kurt Albrecht, application US5166348A, filing date 09/29/1948, publication date 10/17/1950, assignee Hall Lab Inc.; IPC G01N27/07. (https://patents.google.com/patent/[US2525754A](/patent/US2525754A)/en; https://FreePatentsOnline.com/2525754.html)

Disclosure: A conductivity cell for detergent/dairy-wash solutions with two electrodes separated by a dielectric insulator. Electrode 22 "is seated in a recess formed in" the insulator and its exposed face is substantially spherically concave and shrouded by an insulating member so that soil/scale cannot accumulate and so the current path and exposed electrode area remain substantially constant. The reference expressly frames this shroud as protecting operating characteristics against fouling and deposition, and provides a fluid-tight joint via gasket 20 and nut 24, plus a bushing/clamp-bushing wall mounting with gaskets.

Claim-by-claim § 102 assessment:

• Claim 1: Albrecht discloses an insulator having a recess with a conducting element therein, and a fluid-tight, tank-mountable assembly — i.e., elements (a)-part, (d), (e), and (f) in part. But Albrecht's structure is a single housing carrying both electrodes, and it does not disclose an elongated insulator with a bore along its length, a conductor "fitting tightly within and in close contact with the wall of said bore" terminating within the insulator short of one end, or the conductor being "effectively completely internal" and "the sole conductor emerging from the other end." No anticipation of claim 1.
• Claims 4, 5: The shrouded recess is conceptually close to a chamber "for a small portion of the length" of the insulator, and Albrecht's emphasis on a constant current path/electrode area touches the same problem. But no air vent communicating with the chamber is disclosed, and the "cooperating" recess is not a chamber intermediate the ends entering only part way with a width appreciably smaller than the insulator thickness. No anticipation; § 103 relevance only.
• Claims 7, 8, 10, 11: The sealing is a gasket-and-nut arrangement, not the two-ended conical gland sleeve of claim 7/10; and the cell is unitary rather than two separate spaced-apart floor/wall-mounted assemblies. No anticipation.

Bottom line: Albrecht is the best single reference for the recessed, shrouded electrode in an insulator with a fluid-tight tank mount, but it lacks every one of the characterizing "internal conductor in a tight bore" and "separate wall-mounted assemblies" limitations.

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3.3 US 2,611,007 — Cade et al. (Photoswitch, Marine Division Inc.), granted 1952-09-16

Verification: Confirmed — "Temperature-compensating conductivity cell," inventors Cade, Phillip J. and Shaw, Burton E., application US20915851A, filed 02/02/1951, published 09/16/1952, assignee Photoswitch, Marine Division IN.; IPC G01N27/07. (https://patents.google.com/patent/[US2611007A](/patent/US2611007A)/en; https://FreePatentsOnline.com/[2611007](/patent/2611007).html)

Disclosure: An automatic temperature-compensating conductivity cell (cell tube 30, adapter piece 18, removable metallic outer electrode 6, container electrode 8 enveloped by the outer electrode, a disc-shaped solid resistor within the container electrode soldered to it), in which the two electrodes are insulated from one another by a sealing ring of polytetrafluoroethylene, and in which the adapter piece and container electrode each have an annular tooth that is forced by a spring to bite deeply into the sealing ring to form a liquid seal. Claims 1-7 are directed to this structure and to a coaxial electrode arrangement.

Claim-by-claim § 102 assessment:

• Claim 3 ("said insulator is polytetrafluoroethylene"): This is the most superficially inviting mapping, because Cade expressly recites "a sealing ring of polytetrafluoroethylene." But claim 3 depends from claim 1 and requires the elongated insulator (the body with the bore) to be PTFE — not a seal ring. Cade's PTFE is a resilient insulating ring, and moreover [PTFE did not exist at the time of US 1,592,979 and was not commercialized until the 1940s]. No anticipation of claim 3, though Cade is evidence that PTFE for conductivity-cell sealing was known by 1951 and is § 103-relevant to the material choice.
• Claims 7, 10 (gland/seal limitations): Cade uses an annular-tooth-into-PTFE-ring, spring-loaded seal — a different sealing principle from the claimed thin deformable metal sleeve with conical tapers at both ends compressed by a beveled nut and beveled fitting end. No anticipation.
• Claims 1, 8, 9, 11: Cade's coaxial two-electrode arrangement inside a cell tube is structurally remote from elongated insulated assemblies each inserted through a container wall. No anticipation.

Bottom line: Cade is not an anticipatory reference to any claim of US2939070. Its value is corroborative/§ 103 (PTFE as a cell insulator material; pre-existing sealing practice).

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3.4 US 1,592,979 — Keeler (Leeds & Northrup Co.), granted 1926-07-20 — ⚠ verification gap

What I can state from the record: The file of US2939070 cites "1,592,979 Keeler July 20, 1926," and the Google Patents "Patent Citations" table lists US1592979A with priority date 1920-05-17, publication date 1926-07-20, assignee Leeds & Northrup Co., title "Measuring device." I also confirmed, from parallel searches, that Earl A. Keeler was a Leeds & Northrup inventor of record on contemporaneous instrumentation patents (e.g., US 1,379,266, "Compensation method and apparatus," 1921; US 1,472,125, "Measuring apparatus," 1923) in the G01N27/04 area.

I could not retrieve the specification or claims of US 1,592,979A before exhausting my search budget in this session. I am therefore not going to assert what it discloses. Based only on its title, owner, era, and class, it is most plausibly directed to measurement/compensation circuitry and apparatus for electro-chemical measurement rather than to a wall-mounted, insulated, liquid-sealed conductivity probe of the type claimed.

Claim-by-claim § 102 assessment: Cannot be responsibly performed without the full text. Two observations that are safe: (i) a 1926 grant cannot disclose polytetrafluoroethylene as claimed in claim 3 (the polymer was not discovered until 1938 and not commercialized until the 1940s); (ii) given its age and title, it is unlikely to disclose the "conductor fitting tightly within and in close contact with the wall of said bore," the "effectively completely internal" conductor, or the two-ended conical gland seal. I recommend obtaining US1592979A in full (USPTO PatentCenter / Google Patents PDF) before finalizing any § 102 position on this reference. I am flagging this as an unresolved item rather than guessing.

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4. Aggregate conclusions

4.1 No clean § 102 anticipation by the cited art. On the evidence available, none of US2709781, US2525754, US2611007, or US1592979 (as far as verified) discloses every element of any independent claim of US2939070. Each independent claim (1, 7, 8, 9, 10, 11) requires the combination of:

1. an elongated insulator with a bore along its length, the electrical conductor fitting tightly within and in close contact with the bore wall, terminating within the insulator short of one end, and constituting a conductor that is effectively completely internal and the sole conductor emerging from the other end;
2. an insulator wall recess/open end constituting a chamber with a conducting element therein; and
3. a pressure-tight, individually mounted fitting of the specific gland-sleeve/gland-nut construction.

The cited art splits those threads: Douty supplies the restricted-columns/known-cell-constant/spacing-independence concept (claims 8, 10, 11); Albrecht supplies the insulator-embedded, shrouded electrode in a fluid-tight wall mount (claims 1, 4, 5); Cade supplies PTFE insulation and a spring-loaded liquid seal (claims 3, 7). That is a classic § 103 fact pattern, not a § 102 one.

4.2 Most vulnerable claims.

• Claims 8, 10, 11 — the "resistance independent of relative electrode position" and "spacing determined by the mounting means" limitations are squarely taught in substance by Douty (US2709781), whose specification states the electrode spacing "is not critical" and that the restricted member fixes a known cell constant. These claims are the most exposed to a § 103 attack combining Douty with Albrecht (for the insulated wall-mounted electrode).
• Claim 3 (PTFE insulator) is thin: PTFE was a known cell-insulation/sealing material by 1951 (Cade), making this a routine material-selection limitation.
• Claims 5 and 6 (chamber intermediate the ends; entering part way / passing through) find partial structural support in Douty's cell body with restricted passageway and access plugs, again as § 103 rather than § 102 art.

4.3 Least vulnerable. Claim 9 (hole through the side wall near but removed from one end, conductor passing through the hole and terminating within the insulator, with insulation above and between that end and the nearest end of the conductor) appears to have no counterpart in any cited reference and is the strongest claim in the set. Claim 7 is also well insulated by its detailed gland-sleeve/gland-nut geometry.

4.4 Drafting defect to note (not a prior-art issue, but it affects enforceability/§ 102 analysis of claim 2). As published, claim 2 recites "a plurality of vent holes in the side wall of said chamber," then abruptly adds limitations about "said gland sleeve," "said nut," and "said fitting" having a beveled interior — none of which have antecedent basis in claim 1. The text appears to be a conflation of claim 2's vent-hole subject matter with the gland-seal language that properly belongs to claim 7. Until that is resolved against the certified printed patent (and any certificate of correction), any § 102 statement about claim 2 must be treated as provisional. Similarly, claim 3's "polyteradiouroethylene"/"polytetrafluoroethylene" spelling variants and claim 7's "said here" (for the bore) should be read literally, and I have not silently corrected them.

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5. Sources consulted

• US2939070A (target, full text and citation tables): https://patents.google.com/patent/US2939070/en and https://patentimages.storage.googleapis.com/2c/5e/f4/bcacc4797fc475/US2939070.pdf
• US2525754A (Albrecht): https://patents.google.com/patent/US2525754A/en ; https://FreePatentsOnline.com/2525754.html
• US2611007A (Cade et al.): https://patents.google.com/patent/US2611007A/en ; https://FreePatentsOnline.com/2611007.html ; https://SumoBrain.com/patents/us/Temperature-compensating-conductivity-cell/2611007.html
• US2709781A (Douty et al.): https://patents.google.com/patent/US2709781A/en ; https://patentimages.storage.googleapis.com/15/3f/58/1a9320686c27cf/US2709781.pdf
• US1592979A (Keeler) — bibliographic data only, via the citation tables of US2939070; full text not yet retrieved.

Caveats stated plainly: (1) US1592979A's disclosure is unverified and its § 102 assessment is expressly withheld. (2) § 102 vs. § 103 characterizations above are my analytical conclusions based on the retrieved text, not statements of what the examiner held. (3) Any conclusion about claim 2 is qualified by the apparent typographic defect in the printed claim.

I'll research the cited prior art references to build a grounded § 103 analysis.

Let me research the remaining two cited references.

Obviousness Analysis — US2939070 ("Conductivity cell"), 35 U.S.C. § 103

Analytical posture. US2939070 (Robert Rosenthal, assignor to Industrial Instruments, Inc.) was filed 1958‑01‑20 and granted 1960‑05‑31, so the pre‑AIA version of § 103 governs, applied through the Graham v. John Deere factors as refined by KSR Int'l v. Teleflex. All four references in the "References Cited in the file of this patent" section were published more than one year before the 1958 filing date and are therefore clean § 102(b) statutory‑bar art usable in a § 103 combination:

Sources: https://patents.google.com/patent/US2939070/en ; https://patents.google.com/patent/US1592979/en ; https://patents.google.com/patent/[US2525754A](/patent/US2525754A)/en ; https://patents.google.com/patent/[US2611007A](/patent/US2611007A)/en ; https://patents.google.com/patent/[US2709781A](/patent/US2709781A)/en

Note: the "Cited By (6)" documents (US3166485, US3195551, US3355665, US3834232, US4020677, US5223114) all post‑date the 1958 filing; absent a § 102(e) date they are not available as § 103 art here. I therefore do not rely on them.

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1. What the claims actually require

Group A — single electrode assembly: claim 1 (generic), claims 2–6 (additions), claim 7 (specific fitting/seal), claim 9 (side‑port variant).
Group B — two‑probe cell: claim 8 (two separate assemblies + position‑independence), claim 10 (claim 8 plus the specific fitting), claim 11 (two electrodes with chambered ends).

Two drafting points I must flag rather than silently correct (per your rule):

• Claim 2 as printed recites "a plurality of vent holes in the side wall of said chamber" and then, in the same claim, "said gland sleeve" and "said nut" — elements that have no antecedent in claim 1. Read literally, claim 2 is defective under § 112(b) (and its stated content simply grafts the gland‑compression feature of claim 7 onto the vent feature). I treat it as a vent‑hole claim with an appended sealing‑fit limitation.
• OCR corruption is present throughout (e.g., "insualtor," "here" for "bore," "eflectively," "diifering," and the cell‑constant range "between 1 and [value] reciprocal centimeters"). I do not reconstruct the missing numbers.

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2. Claim 1 — element chart

Conclusion on claim 1: every element is disclosed, and the only question is whether it was obvious to reassemble them. Albrecht alone supplies the insulator/recess/shrouded‑electrode/mounted‑probe sub‑combination; Keeler supplies the "conductor sealed inside an insulating bore, sole conductor emerging from the container" sub‑combination. Both are in the same field (conductivity/measuring cells; class 324‑30; CPC G01N 27/07), both are directed to protecting the conductor from the liquid, and both use a threaded wall penetration to mount the probe. Under KSR, "a combination of familiar elements according to known methods" yielding no more than predictable results is obvious. Claim 1 is obvious over Albrecht in view of Keeler (and likewise over Albrecht + Douty, since Douty teaches that the chamber, not the electrode spacing, sets the cell constant).

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3. The core functional limitation — "independent of relative positions" (claims 8, 10, 11)

The specification's stated problem and advantage is that partial short‑circuiting through leaked liquid cannot occur because the narrow column in each chamber dominates resistance, so that "the electrical resistance between the two electrodes … is dependent almost exclusively on the characteristics of the solution and independent … of the relative positions of the electrodes." Douty discloses precisely this result as the purpose of his geometry:

• "the spacing of the electrodes in the assembly is not critical because the parts are so constructed and arranged as to constitute that portion of the electrical path falling within the chambers 2, 2′, a negligible proportion only of the over‑all resistance of the electrical path between the electrodes";
• "the passageway through the bushing 5 constitutes the greater portion of the resistance in the path between the electrodes"; and
• the restricted portions are "standardized to produce cells of known cell constant," selected by diameter according to conductivity.

That is the identical discovery the '070 patent asserts. The only structural difference is that Douty builds one unitary body with two chambers joined by a removable restricted bushing, whereas the '070 claims require "two entirely separate but similarly constructed and physically spaced apart electrode assemblies." Keeler supplies that architecture directly: "two plugs such as illustrated in Figs. 1 and 2 are mounted as illustrated in Fig. 3 and inserted into the liquid the conductivity of which is to be measured, conductors 25 connecting with a Wheatstone bridge."

Conclusion: claim 8 is obvious over Douty in view of Keeler, and claims 10 and 11 are obvious over Douty + Keeler further in view of Albrecht (chambered, shrouded electrode end) and Cade (the threaded fitting/sealing‑ring structure).

Why the combination is motivated (the KSR / Graham factors)

1. Same field, same problem. All four references are conductivity/conductance cells for electrolyte concentration measurement. The '070 background expressly frames the problem as leakage past gaskets at 50–400 °F and >50 p.s.i.g. causing partial short‑circuit and erroneous readings. Douty frames the problem as adapting a cell to "a wide variety of present day industrial needs" and isolating the resistance in a restricted path; Keeler mounts probes through a vessel wall; Cade provides mechanically sealed, threaded, PTFE‑insulated couplings. The references address the same defect the '070 patent claims to cure.
2. Known problem → known remedy, predictable result. Making the chamber's narrow liquid column the dominant resistance element is a standard "cell constant = geometry" technique. Applying Douty's teaching to Keeler's two wall‑mounted plugs produces exactly the claimed functional result, and the '070 specification offers nothing beyond that expected consequence (it even quantifies the tolerance — "as much as 6 inches … without altering the net cell constant … by more than 1 percent" — in the same terms Douty uses).
3. No change in principle of operation. The combination does not require modifying the references' operating principle; it only relocates Douty's restricted path into each of Keeler's probes, which is "the mere arrangement of parts according to known methods."
4. Design incentive / substitution. The patent itself notes the alternative expedients (PTFE vs. Kel‑F, sealed gland) as conventional; Cade already uses a PTFE sealing ring and threaded electrode assemblies, making the material choice of claim 3 and the seal of claim 7 a predictable substitution.
5. No established secondary considerations. I find no evidence in the record of unexpected results, skepticism, or long‑felt‑but‑unmet need that would rebut the prima facie case; the claimed position‑independence is the expected result of Douty's teaching, which weakens any argument that it is a surprising benefit.

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4. Claim‑by‑claim bottom line

Strongest single‑reference positions: Douty is close to anticipating claims 6 and the functional language of claims 8/10/11 (its express statement that electrode spacing is "not critical" and that the restricted passageway "constitutes the greater portion of the resistance" reads on the claimed result). Albrecht is close on claims 1/3 (insulating shroud recess with the electrode seated at its base and mounted to a container).

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5. Where an argument for patentability could still be made (and why it is weak)

• "Bodily incorporation / different architectures." Douty's cell is a single in‑line flow body with a replaceable bushing; Keeler's plugs are sealed with wax/cement and expose bare platinum discs inside a perforated cage. A patentee could argue that joining Douty's resistance‑dominating geometry to Keeler's wall‑mounted plug changes the principle of operation and is not a mere substitution. But the change is predictable in result, and KSR allows combination of references where the improvement is a "predictable variation" using known techniques.
• Albrecht's teaching about cleanliness could be styled a teaching away (Albrecht emphasizes a large spherical cavity and a shroud of ≈½ electrode diameter to "minimize and prevent substantially the accumulation of soil and scale"). A narrow, high‑resistance chamber arguably promotes fouling. This is the most plausible non‑obviousness argument, but it is a preference for one design in a specific detergent‑solution environment, not a disparagement of restricted‑cross‑section cells generally — and Douty shows the art deliberately used restricted passages.
• Claim 7 is the narrowest claim and the one most likely to survive if one insists the specific combination of (a) both‑end‑threaded sleeve fitting, (b) double‑conical tapered gland sleeve, (c) internally threaded gland nut with a beveled base, and (d) the widest‑diameter‑of‑gland < inside‑diameter‑of‑nut relationship is not shown in a single reference. However, coned‑ferrule compression seals of exactly this geometry were notoriously well known in the fluid‑fitting art by 1958; Cade's PTFE ring with annular teeth biting into it, and Albrecht's clamped‑gasket threaded bushings, supply the sealing motivation, so even claim 7 is likely obvious under KSR's "known technique" rationale.

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6. Caveats and confidence

• My reading of US1592979, US2525754, US2611007, and US2709781 relies on the retrieved specification/abstract text and claim excerpts; I did not examine their drawing sheets in detail. The conclusions for claim 1 (Albrecht/Keeler), claim 6 (Douty), and claim 8 (Douty/Keeler) are the best supported. Claims 7 and 9 are the weakest‑grounded and most dependent on how the drawings read.
• I have no information on whether US2939070 was ever litigated, reexamined, or subjected to an IPR, and no evidence of secondary considerations in either direction. I am not asserting that any reference alone anticipates; my conclusions are all § 103 combinations.
• US2939070 expired on 1977‑05‑31 (anticipated expiration) and is shown as "Expired – Lifetime," so this analysis is retrospective/hypothetical in character.
• I have deliberately not "corrected" any patent numbers, dates, or claim text. Where the OCR text is corrupt (claim 2's antecedent basis; the lost cell‑constant numeral; "insualtor"/"here"), I have flagged it rather than reconstructed it.