Between 1880 and 1920 the world cane sugar economy was transformed by new methods of production, new forms of labor, and new concentrations of power. My dissertation focuses on an unexplored but crucial element of this transformation: the change from thinking of sugar as a food and agricultural product that could be valued only by experienced judgment, to thinking of it in the chemical terms of its sucrose content. By analyzing factory production records, correspondences, and especially legal and trade disputes in Cuban, British, and American archives, I will show how this shift from sensory to scientific knowledge reshaped the nature of trade, production, and the organization of work in the sugar economy. I will focus on two trading relationships in particular: the flow of sugar and capital between Cuba and the United States, and the flow of people and machines between Cuba and Glasgow. My study of the turn-of-the-century sugar market will draw and expand upon questions and literatures in history and the history of science, especially science in the context of empire. In sugar’s wildly varying natural, technical, and human environments, and across the great distances that separated the U.S., Cuba, and Scotland, instruments, measurements, and people routinely failed to agree, with serious consequences for trade and trust. On a wider scale, I intend to question the way historians write about commodities and about the process by which a natural product becomes a globally tradeable object. The difficulty of making instruments and techniques function equally well in New York, Glasgow, and Havana—which a scientifically-measured commodity required—highlights a problem facing all modern commodity markets: how do dispersed producers, traders, and consumers trust what they are buying and selling, when such trust depends on measurements made on the far side of the planet?