It is a common law principle that an extension of time for consideration to a principal releases the surety. And where a firm is continued on the retirement of one partner with assumption of debts and mere notice of the arrangement to creditors, the retiring partner stands somewhat in the relation of a surety to those who continue the business so far as old firm debts are concerned. The creditors may or may not join the retiring partner or partners in suit on the debt. Nevertheless, it has been held that an extension of time given by the creditors to the continuing partner does not release the retiring partners. That is, the continuing partner is still the agent of the retiring partner as to settlement of firm debts, but an agent who has entered into an engagement to be personally responsible for them in the first instance.25