This paper is a study of textbooks in chemical technology in Sweden during the industrialisation in the 19th century. In this period, teaching in technological education in general became more and more founded on science. However, there existed very few textbooks in chemical technology, and it is argued that the reason was that the essentials of the knowledge used for developing chemical industry were of a tacit and local character. Such knowledge could only with difficulty be transferred through textbooks with scientific ambitions. Thus the textbooks written or translated by scientists were not as widely used as the ones written or translated by chemical engineers. The usefulness of the latter group can be explained by the fact that they had been adapted to local circumstances, and expressed generalisations, not as scientific laws, but as rules of thumb. Finally, a model for the diffusion of knowledge is suggested, by which the role of textbooks in chemical technology better can be understood.Studies on the development of higher technical education have been abundant but the role played by textbooks in such an education has often been neglected. Textbooks are often considered to be the last step in the spread of science and knowledge, and once an idea, a theory or a technicality can be found in a textbook it is the final proof that the idea, the theory or the technicality has been commonly accepted and reached the status of a canon. 1 In this paper I intend to show that the picture is more complicated by discussing the special case of textbooks aimed for chemical engineers. 2 My discussion centres on two questions, first the diffusion of knowledge, second the relation between science and technology. Since education is diffusion of knowledge, I will end this paper by suggesting a tentative model for how technical knowledge was diffused, and how the role of textbooks in chemical technology can be understood in relation to this model.The discussion is limited to the 19th century for two reasons. First, it was the time of the industrial revolution, with which followed a need for new forms of engineering knowledge. Second, teaching in technology during the 19th century changed from having consisted of transfer of ''simple'' handicraft knowledge, to a teaching based on science, especially in higher technical education. 3 This has mostly been considered as a progressive step in the education of engineers, but once again, the picture is more complex.
