It is well-known that the ring
Qn of n × n matrices over a lattice-ordered ring Q may be lattice-ordered by
prescribing that a matrix is positive exactly when each of its entries is positive. We
conjecture in case Q is the field of rational numbers that this is essentially the only
lattice-order of the matrix ring in which the multiplicative identity 1 is positive and
settle the conjecture in case n = 2. There are however other lattice-orders
of Q2 in which 1 is not positive. A complete description of this family is
obtained.