[MILLER] CHEMICAL LABORATORY RESEARCHES 55 



concentration streams, indicated by movement of suspended particles 

 seen through a microscope, (2) attaching floats to a crystal so as to 

 adjust its weight to that of the displaced liquid, and observing whether 

 it goes up or down; (3) direct weighing of the crystal. The vessels 

 are kept airtight, the stirrers passing through mercury seals. Up to 

 the present, with one exception, only ambiguous results have been 

 obtained. The following is definite but requires confirmation; a 

 solution of sodium chloride was obtained at 28.15° in which in 52 

 hours a cube gained 0.0046 g and an octahedron alongside it lost 

 0.0014 g. 



(Under direction of Professor F. B. Kenrick) 



(9) The Dehydration of Spencerite, a Basic Phosphate of Zinc 

 By J. W. Rebbeck, B.A.Sc. 



Attempts were made to measure the vapour tension of Spencerite, 

 Zn3(P04)3.Zn(OH)2.3H20, at temperatures between 75° and 200°C. 

 Equilibrium if attained was attained very slowly; calcium chloride 

 acts as a catalyser; at 125°C the vapour tension is at least 126 cm. 

 Microscopic examination by Professor T. L. Walker identified two 

 dehydration products, viz: Zn3(P04)2-Zn(OH)2 and Zn3(P04)2.ZnO, 

 the first of which has the composition but not the optical properties of 

 Tarbuttite. The vapour tension quoted above is that of a mixture 

 of Spencerite and the pseudo-Tarbuttite. 



(Under direction of Professor J. B. Ferguson) 



(10) The Equilihriiim between Hydrogen, Steam, and the Oxides of Lron 

 By D. M. FiNDLAY, R. M. Robertson and H. G. Noble 



Experiments in which gases of known composition were passed 

 over iron and its oxides in a silica-glass tube heated electrically to 

 750°C. The composition of the gas in equilibrium with ferrous oxide 

 is approximately that given by Chaudron. The existence of solid 

 solutions between FeO and the magnetic oxide has been established, 

 and the existence of solid solutions for a limited range in the neighbour- 

 hood of pure iron seems probable. There are, however, no solid 

 solutions approaching FeO in composition on the iron side. 



(Under direction of Professor J. B. Ferguson) 



