Figure 4.

The conversion of apatite to phosphite by spark discharge in a model atmosphere containing initially 60% CO₂ and 40% N₂, but with increasing additions of H₂ and CO (the abscissa shows the sum of the contents of H₂ and CO, which were present in equal concentrations). Data points (solid squares) are averages of three to five replicate analyses and the vertical lines show the average deviation of the mean of each set of measurements (De Graaf & Schwartz 2000; reproduced with kind permission of Springer Science and Business Media).