'Enquiries on Plaister of Paris': a material history of early agrochemical knowledge in the United States of America, 1785-1812.

Key figures in the founding years of the United States of America were part of the first American learned agricultural society, known as the Philadelphia Society for Promoting Agriculture (PSPA). Its members were georgic farmers who set out to describe, explore and explain agricultural processes by practical experiences, observations, and theories written in British books. Those theories, however, did not provide any reason for the widespread agricultural practice in Pennsylvania of using plaster as fertilizer, which was German in origin. Although imports were heavily tariffed and later even banned, plaster became, and remained, a top commodity in America. In order to keep agricultural businesses and investments afloat, several members of the PSPA began to scientifically justify the application of plaster fertilization. In so doing, they incorporated chemical theories and methods to both their agricultural practices and investigations. Thus, I argue, they acquired and developed an agrochemical knowledge that was mainly determined by a material history of plaster. Their knowledge was new, unique and more practicable in comparison to the British knowledge in this sector. Eventually, it was through the newly developed knowledge by PSPA members that contributed to the formation of agricultural chemistry as a science in its own respect.

The rise of alternative bread leavening technologies in the nineteenth century.

This article reveals how nineteenth-century chemists and health reformers tried to eradicate the use of yeast in bread, claiming they had devised healthier and more sanitary ways to raise bread. It describes the alternative technological solutions to baking bread, investigating factors that influenced their development and adaptation in the marketplace. A lack of scientific and cultural consensus surrounding yeast, what it was and what it did, fermented during this period. The conflict over yeast helped create a heterogeneous industrialization of the baking industry, changing processes and ingredients and creating new forms of bakery products. By examining the claims of promoters of rival scientific beliefs and technologies, as well as those of users and social commentators, we can see that technology's eventual adaptation and impact on society is not predictable at its outset. Exploring the relationship between differing scientific beliefs, cultural understandings and alternative technologies also shows how science and industry cannot be isolated from their social and cultural context. The examination of the nineteenth-century technological development of commonplace commodities such as bread, baking powder and yeast, also reveals and explores a story that has not been told before in the history of science and technology. Why it has not been told is as enlightening as the story itself, revealing as it does our own privileging of what is important in science and history.

Plaster: our orthopaedic heritage: AAOS exhibit selection.

BACKGROUND: Plaster has been used for centuries as a stiffening agent to treat fractures and other musculoskeletal conditions that require rest, immobilization, or correction of a deformity. Despite modern metallurgy and internal stabilization, plaster casts and splints remain an important means of external stabilization. Casting is a dying art as modern internal and external fixation replace external immobilization. Proper casting technique is paramount. This manuscript outlines the history and chemistry of immobilization materials and techniques as well as the differences among them and the advantages and disadvantages of each. METHODS: Historical references, peer-reviewed journals, textbooks, and primary sources were reviewed to provide data for this review. RESULTS: The history of immobilization reveals a progressive development and refinement of materials that culminated in Mathijsen's plaster bandage in 1851. In 1798, calcium sulfate (plaster of Paris) was introduced. By 1927, crinoline rolls dipped in plaster treated with binding agents facilitated application. Synthetic casting "tapes" (45% polyurethane resin and 55% fiberglass) were introduced in the 1970s. Splinting techniques are ancient, with development spurred by treatment of war wounds. Plaster relies on soft-tissue contact to maintain rigidity. There are well-known advantages, disadvantages, and complications of plaster management. Casting materials all create an exothermic reaction. Burns are associated with water temperatures of >24°C, more than eight layers (ply), and inadequate ventilation. The maximum water temperature must be lower with fiberglass casts. Plaster was the definitive management for most fractures for over 100 years until it was replaced by modern surgical techniques involving internal fixation in the latter part of the twentieth century. CONCLUSIONS: Plaster casts and splints remain an important treatment method for acute and chronic orthopaedic conditions.

[The anatomy of a reduced skull model--visualisation of Leonardo da Vinci's anthropology]. / Die Anatomie eines Miniatur- schädelmodells--Visualisierung der Anthropologie Leonardo da Vincis.

The article focuses on a rare example of a miniature skull of unknown origin. The profoundness of the anatomical details, conjoint with outstanding virtuosity, reminds of Leonardo da Vinci's anatomical skull studies and asks for additional interpretation beside the emblematic "memento mori"-character. Following the miscellaneous topics of his skull studies an anatomical-anthropological interpretation is proposed. For such a project the mergence of anthropology, history of medicine and history of art was mandatory. Concerning some discrepancies within the anatomical realism, the depiction of a pathology is discussed and beyond the visualisation of a historic concept of brain function.

The weathering of natural and artificial stones in the baroque church of S. Pietro in Valle (Fano-Italy).

The church of San Pietro in Valle in Fano is with good reason considered one of the outstanding examples of baroque art in Central Italy. Currently the church is in a serious degradation status. For this reason, and in order to devise a correct conservative restoration project, a scientific study has been carried out, aimed at characterizing mortars used for the application of marble decorations and the different degradation products occurring in the church (i.e. pulverizations, encrustations, salt efflorescences, and condensation water). In the following, results obtained analyzing the different sample typologies by optical microscopy, X-ray diffraction, electron scanning microscopy with energy-dispersion micro-analytical system, ion chromatography, and head-space solid phase microextraction-gas chromatography-mass spectrometry will be reported.

The wall paintings in the Oratorio of San Giovanni Battista in Urbino: a study finalized to a correct conservation project.

The walls of the Oratorio of San Giovanni Battista in Urbino are decorated with outstanding mural paintings dating back to the 15th century. Due to degradation processes that have occurred in the past years, such paintings require a conservative restoration project. In order to evaluate reasons of the decay, some scientific studies have been performed. They consist of macroscopic observations and chemical (EDS), morphological (SEM) and mineralogical (XRD) analyses of samples both from the original preparatory layers under the painted layers and from the restored plasters at the surbase of the wall. In addition, environmental studies have been performed to verify microclimatic conditions of the church in which the mural paintings are located. Finally, a conservative restoration project was proposed.

Calcium sulfate-aided bone regeneration: a case report.

A technique is presented for treating periodontal osseous defects. Medical grade calcium sulfate hemihydrate is used as both a component of a composite graft with demineralized freeze-dried bone allograft (DFDBA) and a barrier over the graft to contain it and to exclude unwanted soft tissue. A case report is presented demonstrating clinical and radiographic success using the technique in the resolution of a severe osseous defect on a maxillary lateral incisor.

Treatment of broken legs before and after the introduction of gypsum.

Gypsum or plaster-of-Paris has given long and efficient service in the management of fractures of the leg, and in spite of the recent introduction of a variety of synthetic materials (Hunt, 1980) it remains the most commonly used splintage material. Plaster-of-Paris bandages can compete successfully with synthetic ones because of their convenience and easy use notwithstanding the superior strength, shorter curing time, water resistance, and radiotranslucence of the synthetics. However, Orthoplast in sheet form is a very satisfactory material for forming the tibial cast brace while synthetic bandages with plastic flexible hinges are advantageous for femoral cast bracing. Nowadays, in fact, plaster-of-Paris has been supplanted to some extent. A review of the methods of fracture splintage that were used before the introduction of gypsum helps to provide a perspective of the merits of this material, whose properties and availability have been taken for granted for more than a hundred years.