The Treasure of the Incas by G. A. Henty

Historical novel. The Preface begins: The mysterious loss of a large portion of the treasure of the Incas has never been completely cleared up. By torturing the natives to whom the secret had been entrusted, the Spaniards made two or three discoveries, but there can be little doubt that these finds were only a small proportion of the total amount of the missing hoards, although for years after their occupation of the country the Spaniards spared no pains and hesitated at no cruelty to bring to light the hidden wealth. The story of the boat which put to sea laden with treasure is historical, and it was generally supposed that she was lost in a storm that took place soon after she sailed. It was also morally certain that the Peruvians who left the country when the Spaniards became masters carried off with them a very large amount of treasure into that part of South America lying east of Peru. According to Wikipedia: George Alfred Henty (8 December 1832 - 16 November 1902), referred to as G. A. Henty, was a prolific English novelist, special correspondent, and Imperialist born in Trumpington, Cambridgeshire, England. He is best known for his historical adventure stories that were popular in the late 19th century. His works include Out on the Pampas (1871), The Young Buglers (1880), With Clive in India (1884) and Wulf the Saxon (1895).