Which preposition to use with negus

of Occurrences 4%

He succoured in turn the Dauphin of France, the King of England, the Templars of Jerusalem, the General of the Parths, the Negus of Abyssinia and the Emperor of Calicut.

at Occurrences 1%

I remember him a quiet good sort of man enough: with a bed-room and kitchen in the area of No. 11, New-square; and his dining-room above, serving also for consultations: and his going, now and then, only to have a game of whist and glass of negus at Serle's;but, now, he is a perfect Monsieur Tonson to all continental travellers.

in Occurrences 1%

At the Datu's we were treated to chocolate and negus in gilt-edged tumblers, with small stale cakes, which had been brought from Manila.

Which preposition to use with  negus