“…The cooling curves of calcium amalgams and their microstructures when frozen on glass surfaces are consistent with the existence of three compounds, CaHg,, CaHg5, and CaHg,,, and the second of these may be obtained in relatively large crystals by pouring the amalgams into water. 39 Stock has directed attention to the possibility that workers exposed to the vapour given 08 by mercury a t laboratory temperatures may contract very serious mercury poisoning, unless there is an extremely good system of ventilation. The condition of chronic poisoning thus developed can only be cured by several years' abstention from all work involving the use of mercury.…”