discharged of surety's liabilities

The surety is discharged from his liability on 6 circumstances. Among the six, first three are the continuing guarantee. They are as follows :

    By revocation by the surety
    By death of the surety
    By variance i terms and conditions of the original contract
    By release or discharge of the principal debtor
    By composition of the creditor by giving time to the principal debtor and not to sue him
    By any act or omission from the contract
    By loss of security