SECURITIES AND EXCHANGE COMMISSION
                             Washington, D. C. 20549
                                  SCHEDULE l3D
                    Under the Securities Exchange Act of 1934
                                (Amendment No. 7)

                                   OCTEL CORP.
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                                (Name of Issuer)

                     Common Stock, par value $0.01 per share
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                         (Title of Class of Securities)

                                    675727101
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                                 (CUSIP Number)
                                                      with a copy to:
                                                      Peter S. Friedman, Esq.
         Jeffrey S. Halis                             Lowenstein Sandler PC
         10 East 50th Street                          65 Livingston Avenue
         New York, New York 10022                     Roseland, New Jersey 07068
         (212) 588-9697                               (973) 597-2570
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                 (Name, Address and Telephone Number of Persons
                Authorized to Receive Notices and Communications)

                                December 22, 1999
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             (Date of Event which Requires Filing of this Statement)

If the filing person has previously  filed a statement on Schedule l3G to report
the  acquisition  which is the subject of this  Schedule 13D, and is filing this
schedule because of Section 240.13d-1(e),  240.13d-1(f) or  240.13d-1(g),  check
the following box. [ ]

Note:  Schedules  filed in paper format shall include a signed original and five
copies of the schedule, including all exhibits. See Rule 13d-7 for other parties
to whom copies are to be sent.

*The  remainder of this cover page shall be filled out for a reporting  person's
initial filing on this form with respect to the subject class of securities, and
for  any  subsequent   amendment   containing   information  which  would  alter
disclosures provided in a prior cover page.

The information required on the remainder of this cover page shall not be deemed
to be "filed" for the purpose of Section 18 of the  Securities  Exchange  Act of
1934 ("Act") or otherwise  subject to the liabilities of that section of the Act
but  shall be  subject  to all other  provisions  of the Act  (however,  see the
Notes).



________________________________________________________________________________ 1) Names of Reporting Persons/I.R.S. Identification Nos. of Above Persons (entities only): Jeffrey S. Halis ________________________________________________________________________________ 2) Check the Appropriate Box if a Member of a Group (See Instructions): (a) Not (b) Applicable ________________________________________________________________________________ 3) SEC Use Only ________________________________________________________________________________ 4) Source of Funds (See Instructions): WC ________________________________________________________________________________ 5) Check if Disclosure of Legal Proceedings is Required Pursuant to Items 2(d) or 2(e): Not Applicable ________________________________________________________________________________ 6) Citizenship or Place of Organization: United States ________________________________________________________________________________ Number of 7) Sole Voting Power: 832,260* ------------------------------------ Shares Beneficially 8) Shared Voting Power: Owned by Each Reporting 9) Sole Dispositive Power: 832,260* Person With ------------------------------------- 10) Shared Dispositive Power: -------------------------------------- ________________________________________________________________________________ 11) Aggregate Amount Beneficially Owned by Each Reporting Person: 832,260* ________________________________________________________________________________ 12) Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions): Not Applicable ________________________________________________________________________________ 13) Percent of Class Represented by Amount in Row (11): 6.1%* ________________________________________________________________________________ 14) Type of Reporting Person (See Instructions): IA ________________________________________________________________________________ * 411,300 shares (3.0%) of Octel Corp. common stock, par value $0.01 per share (the "Common Stock"), are owned by Tyndall Partners, L.P., a Delaware limited partnership ("Tyndall"). 392,500 shares (2.9%) of the Common Stock are owned by Tyndall Institutional Partners, L.P., a Delaware limited partnership ("Tyndall Institutional"). 28,460 shares (0.2%) of the Common Stock are owned by Madison Avenue Partners, L.P., a Delaware limited partnership ("Madison"). 0 shares (0%) of the Common Stock are owned by Halo International, Ltd., a company organized under the laws of the Cayman Islands ("Halo International"). Pursuant to the Agreement of Limited Partnership of each of Tyndall, Tyndall Institutional and Madison, and the Investment Management Agreement of Halo International, Jeffrey S. Halis possesses sole power to vote and direct the disposition of all the shares of Common Stock owned by each of Tyndall, Tyndall Institutional, Madison, and Halo International, respectively. Jeffrey S. Halis' interest in the Common Stock as set forth herein is limited to the extent of his pecuniary interest, if any, in Tyndall, Tyndall Institutional, Madison and Halo International, respectively. See Item 5 below for further information.

Item 1. Security and Issuer. This statement relates to the common stock, par value $0.01 per share (the "Common Stock"), of Octel Corp., whose principal executive offices are located at Global House, Bailey Lane, Manchester, United Kingdom M90 4AA. Item 5. Interest in Securities of the Issuer. Based upon the Quarterly Report on Form 10-Q of Octel Corp. for the quarter ended September 30, 1999, as of November 3, 1999 there were 13,640,730 shares of Common Stock outstanding. As of December 22, 1999, Tyndall Partners, L.P. ("Tyndall") owned 411,300 shares (3.0%) of the Common Stock; Tyndall Institutional Partners, L.P. ("Tyndall Institutional") owned 392,500 shares (2.9%) of the Common Stock; Madison Avenue Partners, L.P. ("Madison") owned 28,460 shares (0.2%) of the Common Stock; and Halo International, Ltd. ("Halo International") owned 0 shares (0%) of the Common Stock. Jeffrey S. Halis possesses sole power to vote and direct the disposition of all shares of Common Stock owned by each of Tyndall, Tyndall Institutional, Madison and Halo International. Therefore, for the purposes of Regulation Section 240.13d-3, Jeffrey S. Halis is deemed to be the beneficial owner of 832,260 shares (6.1%) of the Common Stock. The following table details the transactions during the past sixty days, each of which was effected in an ordinary brokerage transaction, in the Common Stock by Mr. Halis or any other person or entity controlled by him or any person or entity for which he possesses voting or investment control over the securities thereof: A. Tyndall Partners, L.P. (Purchases) NONE (Sales) Date Quantity Price November 1, 1999 35,823 $12.19 November 10, 1999 7,500 $10.99 November 11, 1999 4,177 $10.63 November 11, 1999 1,823 $10.63 November 12, 1999 18,000 $10.19 November 16, 1999 2,200 $10.26 November 17, 1999 10,000 $9.97

B. Tyndall Institutional Partners, L.P. (Purchases) NONE (Sales) Date Quantity Price November 1, 1999 31,269 $12.19 November 10, 1999 5,269 $10.99 C. Madison Avenue Partners, L.P. (Purchases) NONE (Sales) December 21, 1999 9,800 $10.22 December 22, 1999 5,000 $10.22 D. Halo International, Ltd. (Purchases) NONE (Sales) Date Quantity Price October 26, 1999 5,000 $12.69 November 1, 1999 59,108 $12.19 November 10, 1999 20,500 $10.99 November 16, 1999 2,200 $10.26 November 17, 1999 10,000 $9.97 November 29, 1999 6,800 $9.94 November 30, 1999 22,092 $9.94 December 1, 1999 12,500 $9.94

Signature After reasonable inquiry and to the best of the undersigned's knowledge and belief, the undersigned hereby certifies that the information set forth in this statement is true, complete and correct. January 5, 2000 /s/ Jeffrey S. Halis Jeffrey S. Halis, in his capacity as a member of Jeffrey Management, L.L.C., the general partner of Halo Capital Partners, L.P., the general partner of each of Tyndall Partners, L.P., Tyndall Institutional Partners, L.P., and Madison Avenue Partners, L.P., and as a member of Jemi Management, L.L.C., the investment manager for Halo International, Ltd. Attention: Intentional misstatements or omissions of fact constitute Federal criminal violations (See 18 U.S.C. 1001).