William Cullen, lecturer in chemistry at Glasgow and Edinburgh Universities, spent many years formulating his own theory of heat and combustion, the most developed version of which appears in a little-known set of lecture notes of 1765. Cullen's theory is of particular interest to historians of chemistry as an example of his ideal of ‘philosophical chemistry’, an autonomous branch of natural philosophy distinct from the mechanical philosophy, with its own general laws and explanations of phenomena justified by observation. The theory (...) assimilated Joseph Black's recent discovery of fixed air as well as Cullen's investigations of the generation of heat in chemical operations. It was formulated just one year before British chemists' sudden identification of new ‘airs’ was dramatically to change the field of phlogiston theory. The theory differs in important ways from any version yet discussed. It successfully brought both heat and elective attraction within its explanatory domain. It set out a causal hierarchy which reversed the usual pattern evinced in earlier sets of lecture notes, subordinating the mechanical to the chemical in the form of Cullen's theory of elective attraction. The paper argues that Cullen was attempting to bring the study of heat as well as combustion within the bounds of his ‘philosophical chemistry’ by means of his single unifying theory. (shrink)

The effect of gamma irradiation on the dislocation relaxation peak, i.e. the Bordoni peak, of high purity polycrystalline gold has been studied at frequency of 10MHz. It was found that the effect of gamma radiation is more significant in specimen irradiation at room temperature (1A) than that irradiated at liquid nitrogen temperature. The variation of the peak height, and temperature of the dislocation relaxation peak as a function of gamma doses are explained in terms of the Kink-Pair formation model.

It has often been claimed that Priestley was a skilful experimenter who lacked the capacities to analyze his own experiments and bring them to a theoretical closure. In attempts to revise this view some scholars have alluded to Priestley’s ‘synoptic’ powers while others stressed the contextual role of British Enlightenment in understanding his chemical research. A careful analysis of his pneumatic reports, privileging the dynamics of his experimental practice, uncovers significant yet neglected aspects of Priestley’s science. By focusing on his (...) early experimental conduct and writing on nitrous air, I demonstrate how his methodological and rhetorical devices, far from being consequences of compulsive writing or theoretical naïveté, were deeply entwined with his chemical research. I employ the notion of ‘style of experimental reasoning’ —derived from A. C. Crombie and I. Hacking—to shed light on the intersection at which Priestley’s unique method, literary style, and epistemology converged to generate scientific knowledge. Establishing Priestley’s SER advances a finer understanding of the interactive character of his pneumatic experimentalism, peculiar dimensions of which have evaded both traditional as well as revisionist scholarship, thus infusing the longstanding historiographic debate over his scientific merits.Keywords: Joseph Priestley; Eighteenth-century chemistry; Pneumatic research; Style of reasoning; Epistemology. (shrink)

The stability of phlogiston in eighteenth-century French chemistry depended not on its role as a comprehensive theory, but on its operational (instrumental), theoretical, and philosophical (speculative) identities that were forged in different contexts, yet were interwoven to designate a single substance. It was as 'real' as any other chemical substance to the degree that it was obtained through material operations, occupied a place in the theoretical edifice of the affinity table, and was endowed with a corpuscular ontology. Lavoisier labeled it (...) as an 'imaginary' substance because it offered a unique resistance to his vision of the new chemistry based on 'metric' measurements and algebraic representations. (shrink)

The ArgumentEtienn-François Geoffroy' Table des Rapports is generally regarded as a landmark in the evolution of chemistry during the eighteenth century. Issues have arisen among historians concerning the significance and originality of the Table that require fuller attention to the immediate context of chemical research in the Academie des sciences during the two decades that preceded its appearance. The present paper argues that, despite the transition from communal to individual research projects that marked the reorganization of the Academy in 1699, (...) chemists continued to pursue shared problems within a communal ethos. The interactions between Wilhelm Homberg, Etienne-François Geoffroy, and Louis Lemery were particularly prominent. The paper traces one example of this interaction, involving the sulfur principle and its influence on one entry in Geoffroy's Table. Further such studies are needed to elucidate the relation between the concepts of chemical composition and reactions implied in Geoffroy's table and the concepts embodied in the previous work of Geoffroy and his associates in the Academy. (shrink)

Summary Contrary to common belief, Lavoisier's greatest phlogistic rival was not Joseph Priestley but Richard Kirwan, a fact that was firmly recognized by both the Lavoisians as well as Priestley himself. During the 1780s, which saw the unprecedented rise of the chemistry of air(s), Kirwan's ‘ingenious modifications…into the theory of phlogiston’, in Mme. Lavoisier's words, became the most dominant alternative to the revisionist pneumatic interpretations of the French. A genealogical contextualization of Kirwan's phlogistic contributions, the circumstances of their emergence and (...) the nature of their evolution and impact, reveals the intricate process of transformation that pneumatic phlogistic thought and practice have undergone during the final years of phlogiston's existence. Originally introduced as an adverse reaction to Scheele's phlogistic reasoning, Kirwan's work evolved as a sophisticated integration between notions of aerial permutations and Adair Crawford's innovative formulation of the phlogistic role of heat, with its origins in the Scottish pneumatic tradition of Black and Irvine. Examining Kirwan's views against the background of metaphysical conflicts over the constitution of pneumatic entities and the role of phlogiston in pneumatic processes traces their origins and advances to a complex interplay between innovation and renovation, proclamation and reclamation, thus depicting the dynamics of (dis-)continuity in the broader phlogistic sphere from which Kirwan's ‘modifications’ have stemmed and which they came to forcefully represent. (shrink)