The change in thermal conductivity and viscosity of a gas placed in a strong magnetic field was first noted by Senftleben. The explanation of this effect by Zernike could not account for different behavior by different gases. In Beenakker's recent rigorous treatment all physical insight is lost. A two-parameter toroidal molecule formed of two merging atoms is developed. An equation is derived relating atomic diameter and molecular length to the sillhouette area, which is taken to represent the collision cross- section. Internuclear distance is obtained from spectroscopic data from the literature. Molecular "thickness" is determined by noting experimental thermal conductivity and then comparing toroid area with the rigid sphere area necessary to produce that thermal conductivity. When this model precesses in a magnetic field, the swept-out volume is taken to be a new molecule, whose sillhouette is similarly determined. Appropriate averages of the two areas are found, and the change in thermal conductivity is calculated by mean free path methods. The results differ from experiment by half an order of magnitude. A discussion of the usefulness and limitations of the model is given.