Vandal, "Napoléon et Alexandre," ch. vii. It is not published in the "Correspondence" or in the "New Letters."
Vandal, "Napoléon et Alexandre," vol. i., ch. iv., and App. II.
In the conversations which Metternich had with Napoleon and Talleyrand on and after January 22nd, 1808, he was convinced that the French Emperor intended to partition Turkey as soon as it suited him to do so, which would be after he had subjected Spain. Napoleon said to him: "When the Russians are at Constantinople you will need France to help you against them."—"Metternich Memoirs," vol. ii., p. 188.
So Soult told Lord Holland ("Foreign Reminiscences," p. 171).