Creamless Choco Mousse

This is an old 1980ish recipe from Gabriel Gate, a French born Australian chef. I found it online, tried it and it works.

CHOCOLATE MOUSSE W/O CREAM
Ingredients
200g semi-sweet chocolate (best that you can afford)
6 eggs, separated
1 teasp instant/espresso coffee
1 4 teasp rum (or use Grand Marnier if available)
1 teasp white sugar
Pinch salt

Directions
Break chocolate into pieces and melt in a bowl with 4teasp water. Slowly whisk until smooth. Remove from heat.
To melted chocolate, add 4 egg yolks, coffee, rum and whisk until smooth.
Add salt to 6 egg whites and beat with an electic mixer until fairly firm, add sugar and beat until stiff peaks form.
Gently incorporate a quarter of the egg whites into the chocolate preparation *then* carefully fold in the rest.
Gently spoon the mixture into small souffle/mousse pots and leave to set in the fridge for at least 6 hours.