That's what I've always wished for.' At the word 'WISH' the children knew that the Psammead would attend to THAT bit of magic.

It did, and the floor was littered with a spreading heap of gold and precious stones.
'Any other little trick ?' asked Cyril loftily.

'Shall we become invisible?
Vanish ?' 'Yes, if you like,' said the soldier; 'but not through the door, you don't.' He closed it carefully and set his broad Egyptian back against it.
'No! no!' cried a voice high up among the tops of the tall wooden pillars that stood against the wall.

There was a sound of someone moving above.
The soldier was as much surprised as anybody.
'That's magic, if you like,' he said.
And then Jane held up the Amulet, uttering the word of Power.

At the sound of it and at the sight of the Amulet growing into the great arch the soldier fell flat on his face among the jewels with a cry of awe and terror.
The children went through the arch with a quickness born of long practice.