A versatile mercury vapour generating system suitable for long-term inhalation experiments

A mercury vapour generating system is described that is based on the reduction of HgCl2 by SnCl2 in the input airstream of the inhalation chamber. The solutions of the two chemicals are pumped by peristaltic pumps from reservoirs through a miniature mixing chamber into the upper part of a sloping glass tube (reduction chamber) through which air is sucked into the inhalation assembly. The liquid flows down the slope and through a port into a Quickfit flask. Reservoirs can be filled and the collecting flask emptied without interruption of exposure. The desired vapour concentration is achieved by varying the rate of mercury injection and the rate of airflow. Concentration in the inhalation chamber can be measured by passing air through a mercury vapour monitor or by radioactivity when 203HgCl2 is used and a known volume of air is passed through a hopcalite absorber. Operation instructions and an experimental example with mice are given.