Sec. 36.

The preceding section shall not be construed to extend to a letter of attorney, or other instrument containing a power to convey lands as agent or attorney for the owner of such lands; but every such letter or instrument, and every executory contract for the sale or purchase of lands, when acknowledged or proved in the manner prescribed in this chapter, may be recorded in the registry of deeds of any county in which the lands to which such power or contract relates, may be situated; and when so acknowledged or proved, and the record thereof when recorded, or a transcript of such record duly certified, may be read in evidence in the same manner, and with the like effect, as a conveyance recorded in such county.