  Microcrystals of orthorhombic nickel (II) oxalate dihydrate were synthesized
through a precipitation reaction of aqueous solutions of nickel chloride and
oxalic acid. Magnetic susceptibility exhibits a sharp peak at 3.3 K and a
broadrounded maximum near 43 K. We associated the lower maximum with a
metamagnetic transition that occurs when the magnetic field is about \geq 3.5
T. The maximum at 43 K is the typical of 1D antiferromagnets, whereas weak
ferromagnetism behavior was observed in the range of 3.3 to 43 K.
