Gas: the greatest terror of the Great War.

The Great War began just over a century ago and this monumental event changed the world forever. 1915 saw the emergence of gas warfare-the first weapon of mass terror. It is relevant to anaesthetists to reflect on these gases for a number of reasons. Firstly and most importantly we should acknowledge and be aware of the suffering and sacrifice of those soldiers who were injured or killed so that we could enjoy the freedoms we have today. Secondly, it is interesting to consider the overlap between poison gases and anaesthetic gases and vapors, for example that phosgene can be formed by the interaction of chloroform and sunlight. Thirdly the shadow of gas warfare is very long and covers us still. The very agents used in the Great War are still causing death and injury through deployment in conflict areas such as Iraq and Syria. Industrial accidents, train derailments and dumped or buried gas shells are other sources of poison gas hazards. In this age of terrorism, anaesthetists, as front-line resuscitation specialists, may be directly involved in the management of gas casualties or become victims ourselves.

[Van Helmont and gas]. / Van Helmont en het gas.

Johan Baptista van Helmont (1579-1644) was born in Brussels, around the time the Southern Netherlands ceased their resistance against the Spanish rule. He studied a variety of disciplines in Louvain and made a 'grand tour' in Europe, but remained dissatisfied with traditional knowledge, which he regarded as empty phrases and sophistry. His spouse being wealthy, he devoted himself to studying nature anew, unencumbered by prejudice, as Paracelsus (1493-1541) had done before him. Yet in his attempts to explain living and inanimate matter he could not avoid making basic assumptions. Among these was his view that there were only two elements: water and air. Water might carry elementary seeds from which a variety of substances could develop. When a substance was consumed by fire, an ethereal essence would remain, which he called 'Gas' (a term perhaps derived from Paracelsian 'chaos', perhaps from 'Geist'). Today 'gas' is defined as the volatile state of a given substance, but in Van Helmont's view it was mainly a metaphysical characteristic. Most of Van Helmont's work was published only after his death, through a verdict of the Spanish Inquisition.

Johann Wilhelm Hittorf and the material culture of nineteenth-century gas discharge research.

In the second half of the nineteenth century, gas discharge research was transformed from a playful and fragmented field into a new branch of physical science and technology. From the 1850s onwards, several technical innovations-powerful high-voltage supplies, the enhancement of glass-blowing skills, or the introduction of mercury air-pumps- allowed for a major extension of experimental practices and expansion of the phenomenological field. Gas discharge tubes served as containers in which resources from various disciplinary contexts could be brought together; along with the experimental apparatus built around them the tubes developed into increasingly complex interfaces mediating between the human senses and the micro-world. The focus of the following paper will be on the physicist and chemist Johann Wilhelm Hittorf (1824-1914), his educational background and his attempts to understand gaseous conduction as a process of interaction between electrical energy and matter. Hittorf started a long-term project in gas discharge research in the early 1860s. In his research he tried to combine a morphological exploration of gas discharge phenomena-aiming at the experimental production of a coherent phenomenological manifold--with the definition and precise measurements of physical properties.

The advantage and disadvantage of peripheral ignorance: the gas adsorption controversy.

In the early history of surface chemistry, in the 1920s, the nature of gas adsorption was a pivotal subject. A theory created by Michael Polanyi in the peripheral Hungary contradicted the received view originating from the American Irving Langmuir. When working out his theory, Polanyi had not even heard of Langmuir's rival description. However, Polanyi emigrated from Hungary to Germany, the centre of his field, and tried to defend his adsorption theory in the circle of the leading experts, including Einstein and Fritz Haber. This controversy seemed vital to his survival as a scientist and as an immigrant. The aim of this article is to recapitulate this controversy, with its sad undercurrents, the role of local science, methods of argumentation, and the work of a central scientific community.

Válvula de Boussignac y CPAP frente a diferentes situaciones de temperatura y humedad ambiental / Boussignac CPAP Valve against different situations of temperature and environmental humididty

Introducción. La válvula de Boussigna permite entregar un nivel de presión positiva continua en vía aérea (CPAP) a los enfermos, con la única necesidad de una fuente de gas de alto flujo. Estudiamos si las variaciones en la humedad y temperatura podrían afectar al dispositivo de CPAP. Material y Método. Estudio experimental, realizado en condiciones de laboratorio. Medimos la CPAP conseguida mediante una válvula de Boussignac de Vygon® ante distintas condiciones de humedad y temperatura ambiental. Se utilizaron, además de la citada válvula, una fuente de O2 medicinal con un caudalímetro, un serpentín de cobre para calentar/enfriar el gas, un humidificador Respiflo de Kendall®, y una cubeta de aislamiento térmico. Las mediciones de CPAP se hicieron con un manómetro digital, y las de temperatura y humedad con un termo-higrómetro (previamente calibrados). Tras realizar varias mediciones para un mismo flujo, ante distintas condiciones de humedad y temperatura, se compararon los resultados obtenidos mediante la prueba de la "t" de Student (comparaciones dos a dos) y ANOVA. Se demandó un intervalo de confianza mínimo de 95%. Resultados. Para los diferentes flujos analizados (15, 20 y 25 litros/minuto) se comprueba cómo ante distintas condiciones de temperatura (en rangos de 4-6 ºC, 24-26 ºC y 40-42 ºC) y humedad (2%, 15-20%, 35-40% y 80-85%) se obtienen diferencias estadísticamente significativas en los niveles de CPAP entregados. Conclusión. La temperatura y la humedad a la que se utilicen el oxígeno y el dispositivo de CPAP de Boussignac influyen en los niveles de presión obtenidos, pudiendo llegar a diferencias de presión cercanas al 20% en algunas circunstancias, para un mismo flujo (AU)

Introduction. The Boussignac valve makes it possible to provide a continuous positive airway pressure (CPAP) level to the patients, this only requiring a high flow gas source. We have studied if the variations in gas humidity and temperature could affect the CPAP device. Material and method. Experimental study performed under laboratory conditions. We measured the CPAP obtained with a Boussignac valve (Vygon)®, under different humidity and environmental temperature conditions. In addition to the mentioned valve, a source of medicinal O2, a copper coil to modify the gas temperature, Respiflo humidifier (Kendall)® and a bucket of heat insulation were used. CPAP measurements were made with a digital pressure gauge, and temperature and humidity conditions were measured with a previously calibrated thermus-hygrometer. After several measurements were obtained for a same flow, with different humidity and temperature conditions, the results obtained were compared with the Student's t test (two-sided comparison) and ANOVA. A minimum interval of 95% confidence was required. Resuts: For the different flows analyzed (15, 20 and 25 liters/minute), it was verified that different conditions of temperature (in ranks of 4-6 ºC, 24-26 ºC and 40-42 ºC) and humidity (2%, 15-20%, 35-40% and 80-85%) obtained statistically significant differences in the CPAP levels. Conclusions. The temperature and humidity under which oxygen and Boussignac CPAP device are used influence the CPAP pressure levels, and it was possible to reach differences in pressure close to 20% under some circumstances for a same flow (AU)

Let it burn: distinguishing inflammable airs 1766-1790.

The issue of the number of species of inflammable air was debated particularly in the period 1777-1786. The work of Henry Cavendish in 1766 and Alessandro Volta in 1777 in characterising two species of inflammable air set the stage for the work of other chemists, particularly in Paris, as they debated this question, mostly concerning heavy inflammable air. Different ways of generating gases were discovered up to 1783, when the synthesis of water and the proposal of carbon as an element created a framework for the question to be answered. In 1785-1786, Claude-Louis Berthollet reported the composition of heavy inflammable air and volatile alkali, while Philippe Gengembre analysed phosphorated hydrogen and hepatic air. In the end, it was the new chemical nomenclature of 1787 that spread their results widely.

"Inhale it and see?" The collaboration between Thomas Beddoes and James Watt in pneumatic medicine.

The collaboration of Thomas Beddoes and James Watt in the development of pneumatic medicine--the treatment of disease by the breathing of airs--is well known but little understood. Its protagonists presented the venture as an empirical one, in which the efficacy of different airs was tested independently of theoretical considerations. Historians have generally accepted that claim at face value. We contend, on the contrary, that the divergent theoretical chemical commitments of Watt and Beddoes significantly shaped their different approaches to, and their interpretations and expectations of, the pneumatic project. In particular, Beddoes's broad adherence to Lavoisian chemistry gave him an oxygen-centred approach to pneumatic medicine, while Watt's ongoing belief in phlogistic chemistry inclined him to expect great things of "hydrocarbonate." In addition, we show that a close examination of Watt's experiments and writings in his collaboration with Beddoes reveals a great deal about Watt's chemistry of airs.

Our changing atmosphere: evidence based on long-term infrared solar observations at the Jungfraujoch since 1950.

The Institute of Astrophysics of the University of Liège has been present at the High Altitude Research Station Jungfraujoch, Switzerland, since the late 1940s, to perform spectrometric solar observations under dry and weakly polluted high-mountain conditions. Several solar atlases of photometric quality, extending altogether from the near-ultra-violet to the middle-infrared, were produced between 1956 and 1994, first with grating spectrometers then with Fourier transform instruments. During the early 1970s, scientific concerns emerged about atmospheric composition changes likely to set in as a consequence of the growing usage of nitrogen-containing agricultural fertilisers and the industrial production of chlorine-bearing compounds such as the chlorofluorocarbons and hydro-chlorofluorocarbons. Resulting releases to the atmosphere with ensuing photolysis in the stratosphere and catalytic depletion of the protective ozone layer prompted a worldwide consortium of chemical manufacturing companies to solicit the Liège group to help in clarifying these concerns by undertaking specific observations with its existing Jungfraujoch instrumentation. The following pages evoke the main steps that led from quasi full sun-oriented studies to priority investigations of the Earth's atmosphere, in support of both the Montreal and the Kyoto Protocols.

Aspects of the scientific network and communication of John Hyacinth de Magellan in Britain, Flanders and France.

The subject of gases was on the agenda of many learned scientific gentlemen in the second half of the eighteenth century. This was not only because of the extraordinary account that had been given as to the physical and chemical composition of the third state of matter, but also, and perhaps mainly, because of the extraordinary properties that at least one of these gases seemed to offer for food preservation, the medicinal properties of natural waters and medical applications. These putative practical applications were highly sought after by society at the time, particularly for long-distance sea journeys. This paper focuses on the Portuguese polymath João Jacinto de Magalhães (1722-1790), also known as John Hyacinth de Magellan. It shows some specific aspects of his activities as a disseminator of Priestley's discoveries on pneumatics, mainly in Flanders, Holland and France, and through his large network of scientific correspondents.