20 Mil Réis Caixa de Conversão, Provisional Issue

The Caixa de Conversão was a short-lived monetary stabilization mechanism, established in 1906 under Finance Minister Leopoldo de Bulhões to fix the milréis against gold at a rate of 15 pence — a deliberate reversal of Brazil's prolonged depreciation cycle following the Encilhamento speculation crisis of the early 1890s. The institution issued notes directly convertible into gold certificates, a novelty for Brazilian monetary practice at the time.

Duval and Crosbie worked for the Banque de France's printing arm, and their involvement gave this provisional series a quality of manufacture markedly above what Brazilian issuers had typically commissioned. The Caixa itself was dissolved in 1914 when wartime gold flows made the convertibility peg impossible to maintain.