WASHINGTON, March 24,1806. DEAR SIR,--A last effort at friendly settlement with Spain is proposed to be made at Paris, and under the auspices of France. For this purpose, General Armstrong and Mr. Bowdoin (both now at Paris) have been appointed joint commissioners; but such a cloud of dissatisfaction rests on General Armstrong in the minds of many persons, on account of a late occurrence stated in all the public papers, that we have in contemplation to add a third commissioner, in order to give the necessary measure of public confidence to the commission. Of these two gentlemen, one being of Massachusetts and one of New York, it is thought the third should be a southern man; and the rather, as the interests to be negotiated are almost entirely southern and western. This addition is not yet ultimately decided on; but I am inclined to believe it will be adopted. Under this expectation, and my wish that you may be willing to undertake it, I give you the earliest possible intimation of it, that you may be preparing both your mind and your measures for the mission. The departure would be required to be very prompt; though the absence I think will not be long, Bonaparte not being in the practice of procrastination. This particular consideration will, I hope, reconcile the voyage to your affairs and your feelings. The allowance to an extra mission, is salary from the day of leaving home, and expenses to the place of destination, or in lieu of the latter, and to avoid settlements, a competent fixed sum may be given. For the return, a continuance of the salary for three months after fulfilment of the commission. Be so good as to make up your mind as quickly as possible, and to answer me as early as possible. Consider the measure as proposed provisionally only, and not to be communicated to any mortal until we see it proper. Affectionate salutations. TO WILSON C. NICHOLAS. WASHINGTON, April 13, 1806.