A parish school board may pay all or a part of the expenses of special sessions of schools organized and maintained for the benefit of teachers, and it may pay all or a part of the salaries and expenses of persons employed in the extension service to promote agricultural and other industrial instruction for the benefit of children.
No parish school board shall use any of the parish school funds in purchasing any textbooks, material or supplies as herein authorized, but such purchase shall be made entirely from proceeds derived from the sale of such books, material, and supplies, respectively, as the case may be.