The influence of a magnetic field on the motion of iron particles located in a viscous fluid was investigated. A magnetic field gradient was formed by orienting the poles of the magnet to produce a variable gap between the poles. The non-uniform magnetic field caused magnetisable particles to travel in the direction of lower field strength, and hence along the direction of the field gradient. The particles were found to undergo a process of aggregation, which in turn produced larger particles. The particles were also found to align in the direction of the field and hence in a direction perpendicular to the field gradient, and move at a velocity higher than the velocity of a single particle. The aggregates were essentially a series of spheres linked end-to-end, and hence had an aspect ratio similar to a cylinder, given by a length to diameter ratio. The increase in the velocity of the aggregate versus the number of particles in the aggregate was initially linear, but then approached an asymptotic level. Similarly, the velocity of a cylinder increased as the length of the cylinder increased, again with an asymptotic limit. Interestingly, when an ultra thin film of nail polish was applied to the individual particles, normal contact was prevented, resulting in a 10% reduction in the velocity of the aggregate. This work shows the effective magnetisation of the iron particles, is governed by the aspect ratio of the particles, and hence the mass distribution of the particles within the magnetic field.