ir 
A. Platinum vessel. 
B. Iron casing. 
C. Fireclay crucibles. 
D. Tube to nitrogen 
gas-holders. 
E. Platinum tube for 
expelling va- 
pours. 
Between A and B 
calcined mag- 
nesium. 
Between B and C 
sand. 
This illustration belongs to paper by Dr Alexander Scott, p. 410. 
