PROMISSORY NOTE Principal - $750,000 Loan Date - 04-30-1996 Maturity - 10-31-1997 Borrower: CARBONIC RESERVES Lender: Liberty Bank and 10110 Huebner Road Trust Company of San Antonio, TX 78240 Oklahoma City, N.A. Metropolitan Lending Department/Commercial Loans P.O. Box 25848 Oklahoma City, OK 73125 ================================================================= Principal Amount: $750,000.00 Initial Rate: 9.750% Date of Note: April 30, 1996 PROMISE TO PAY. CARBONIC RESERVES ("Borrower") promises to pay to Liberty Bank and Trust Company of Oklahoma City, N.A. ("Lender"), or order, in lawful money of the United States of America, the principal amount of Seven Hundred Fifty Thousand & 00/100 Dollars ($750,000.00) or so much as may be outstanding, together with interest on the unpaid outstanding principal balance of each advance. Interest shall be calculated from the date of each advance until repayment of each advance. PAYMENT. Borrower will pay this loan in one payment of all outstanding principal plus all accrued unpaid interest on October 31, 1997. In addition, Borrower will pay regular monthly payments of accrued unpaid interest beginning May 30, 1996, and all subsequent interest payments are due on the same day of each month after that. Interest on this Note is computed on a 365/360 simple interest basis; that is, by applying the ratio of the annual interest rate over a year of 360 days, multiplied by the outstanding principal balance, multiplied by the actual number of days the principal balance is outstanding. Borrower will pay Lender at Lender's address shown above or at such other place as Lender may designate in writing. Unless otherwise agreed or required by applicable law, payments will be applied first to accrued unpaid interest, then to principal, and any remaining amount to any unpaid collection costs and late charges. VARIABLE INTEREST RATE. The interest rate on this Note is subject to change from time to time based on changes in an index which is the Lender's National Prime Rate (the "Index"). Lender's National Prime Rate is the reference rate of interest designated by Lender from time to time as the "National Prime Rate" for the guidance of loan officers. The Index is set from time to time by Lender in its sole discretion. The Index is not necessarily the lowest reference rate used by Lender in calculating interest due on its loans. Lender will tell Borrower the current index rate upon Borrower's request. Borrower understands that Lender may make loans based on other rates as well. The interest rate change will not occur more often than each day. The Index currently is 8.250% per annum. The interest rate to be applied to the unpaid principal balance of this Note will be at a rate of 1,500 percentage points over the Index, resulting in an initial rate of 9.750% per annum. NOTICE: Under no circumstances will the interest rate on this Note be more than the maximum rate allowed by applicable law. PREPAYMENT. Borrower may pay without penalty all or a portion of the amount owed earlier than it is due. Early payments will not, unless agreed to by Lender in writing, relieve Borrower of Borrower's obligation to continue to make payments of accrued unpaid interest. Rather, they will reduce the principal balance due. DEFAULT. Borrower will be in default if any of the following happens: (a) Borrower fails to make any payment when due. (b) Borrower breaks any promise Borrower has made to Lender, or Borrower fails to comply with or to perform when due any other term, obligation, covenant, or condition contained in this Note or any agreement related to this Note, or in any other agreement or loan Borrower has with Lender. (c) Any representation or statement made or furnished to Lender by Borrower or on Borrower's behalf is false or misleading in any material respect either now or at the time made or furnished. (d) Borrower becomes insolvent, a receiver is appointed for any part of Borrower's property, Borrower makes an assignment for the benefit of creditors, or any proceeding is commenced either by Borrower or against Borrower under any bankruptcy or insolvency laws. (e) Any creditor tries to take any of Borrower's property on or in which Lender has a lien or security interest. This includes a garnishment of any of Borrower's accounts with Lender. (f) Any of the events described in this default section occurs with respect to any guarantor of this Note or any guarantor seeks, claims or otherwise attempts to limit, modify or revoke such guarantor's guarantee of this Note. (g) A material adverse change occurs in Borrower's financial condition, or Lender believes the prospect of payment or performance of the indebtedness is impaired. (h) Lender in good faith deems itself insecure. If any default, other than a default in payment, is curable and if Borrower has not been given a notice of a breach of the same provision of this Note within the preceding twelve (12) months, it may be cured (and no event of default will have occurred) if Borrower, after receiving written notice from Lender demanding cure of such default: (a) cures the default within fifteen (15) days; or (b) if the cure requires more than fifteen (15) days, immediately initiates steps which Lender deems in Lender's sole discretion to be sufficient to cure the default and thereafter continues and contemplates all reasonable and necessary steps sufficient to produce compliance as soon as reasonably practical. LENDER'S RIGHTS. Upon default, Lender may declare the entire unpaid principal balance on this Note and all accrued unpaid interest immediately due, without notice, and then Borrower will pay that amount. Upon default, including failure to pay upon final maturity, Lender, at its option, may also, if permitted under applicable law, increase the variable interest rate on this Note to 6.500 percentage points over the Index. The interest rate will not exceed the maximum rate permitted by applicable law. Lender may hire or pay someone else to help collect this Note if Borrower does not pay. Borrower also will pay Lender that amount. This includes, subject to any limits under applicable law, Lender's attorneys' fees and Lender's legal expenses whether or not there is a lawsuit, including attorneys' fees and legal expenses for bankruptcy proceedings (including efforts to modify or vacate any automatic stay or injunction), appeals, and any anticipated post-judgment collection services. If not prohibited by applicable law, Borrower also will pay any court costs, in addition to all other sums provided by law. This Note has been delivered to Lender and accepted by Lender in the State of Oklahoma. If there is a lawsuit, Borrower agrees upon Lender's request to submit to the jurisdiction of the courts of Oklahoma County, the State of Oklahoma. Lender and Borrower hereby waive the right to any jury trial in any action, proceeding, or counterclaim brought by either Lender or Borrower against the other. This Note shall be governed by and construed in accordance with the laws of the State of Oklahoma. DISHONORED ITEM FEE. Borrower will pay a fee to Lender of $20.00 if Borrower makes a payment on Borrower's loan and the check or other payment order including any preauthorized charge with which Borrower pays is later dishonored. RIGHT OF SETOFF. Borrower grants to Lender a contractual possessory security interest in, and hereby assigns, conveys, delivers, pledges, and transfers to Lender all Borrower's right, title and interest in and to, Borrower's accounts with Lender (whether checking, savings, or some other account), including without limitation all accounts held jointly with someone else and all accounts Borrower may open in the future, excluding however all IRA, Keogh, and trust accounts. Borrower authorizes Lender, to the extent permitted by applicable law, to charge or setoff all sums owing on this Note against any and all such accounts. LINE OF CREDIT. This Note evidences a revolving line of credit. Advances under this Note, as well as directions for payment from Borrower's accounts, may be requested orally or in writing by Borrower or by an authorized person. Lender may, but need not, require that all oral requests be confirmed in writing. The following party or parties are authorized to request advances under the line of credit until Lender receives from Borrower at Lender's address shown above written notice of revocation of their authority: Clifford H. Collen, Jr., President; Herb Mee, Jr., Vice President; and Randy Thacker, Chief Financial Officer. Borrower agrees to be liable for all sums either: (a) advanced in accordance with the instructions of an authorized person or (b) credited to any of Borrower's accounts with Lender. The unpaid principal balance owing on this Note at any time may be evidenced by endorsements on this Note or by Lender's internal records, including daily computer print-outs. Lender will have no obligation to advance funds under this Note if: (a) Borrower or any guarantor is in default under the terms of this Note or any agreement that Borrower or any guarantor has with Lender, including any agreement made in connection with the signing of this Note; (b) Borrower or any guarantor cease doing business or is insolvent; (c) any guarantor seeks, claims or otherwise attempts to limit, modify or revoke such guarantor's guarantee of this Note or any other loan with Lender; (d) Borrower has applied funds provided pursuant to this Note for purposes other than those authorized by Lender; or (e) Lender in good faith deems itself insecure under this Note or any other agreement between Lender and Borrower. SPECIAL PROVISIONS/REVOLVING LINE OF CREDIT. The total of all the advances made to Borrower during the term of this Note may exceed the principal amount of this Note. Further, there may be times when no amounts are outstanding under this Note, but this shall not impair or in any way affect either the validity or enforceability of this Note or any lien or security interest securing payment of this Note. PAYMENTS. If any stated principal or interest payment date, including the stated maturity date is a Saturday, Sunday or other legal holiday for national banks, the payment due date shall be extended to the next following business day and interest shall continue to accrue during such extension. NON-USE FEE. A non-use fee of .50% will be payable quarterly in arrears as described in the Loan Agreement dated May 19, 1995. LOAN AGREEMENT. This Promissory Note is referred to in that certain Loan Agreement dated May 19, 1995 and the amendment dated April 30, 1996, to which reference is hereby made for additional terms described therein. PRIOR NOTE. The Promissory Note from Carbonic Reserves to Lender dated November 13, 1995 in the amount of $750,000.00. GENERAL PROVISIONS. Lender may delay or forgo enforcing any of its rights or remedies under this Note without losing them. Borrower and any other person who signs, guarantees or endorses this Note, to the extent allowed by law, waive presentment, demand for payment, protest and notice of dishonor. Upon any change in the terms of this Note, and unless otherwise expressly stated in writing, no party who signs this Note, whether as maker, guarantor, accommodation maker or endorser, shall be released from liability. All such parties agree that Lender may renew or extend (repeatedly and for any length of time) this loan, or release any party or guarantor or collateral; or impair, fail to realize upon or perfect Lender's security interest in the collateral; and take any other action deemed necessary by Lender without the consent of or notice to anyone. All such parties also agree that Lender may modify this loan without the consent of or notice to anyone other than the party with whom the modification is made. PRIOR TO SIGNING THIS NOTE, BORROWER READ AND UNDERSTOOD ALL THE PROVISIONS OF THIS NOTE, INCLUDING THE VARIABLE INTEREST RATE PROVISIONS. BORROWER AGREES TO THE TERMS OF THE NOTE AND ACKNOWLEDGES RECEIPT OF A COMPLETED COPY OF THE NOTE. BORROWER: CARBONIC RESERVES By: HERB MEE, JR. Herb Mee, Jr., Vice-President