The surface and bulk properties of five samples of fly ash have been examined by electron spectroscopy for chemical analysis (ESCA), scanning electron microscopy (SEM) and energy dispersive x-ray analysis (EDXA). Samples from a conventional pulverized coal combustor, a conventional stoker-fed combustor, and an experimental fluidized bed combustor (FBC) were examined. ESCA data indicated that all samples contained silicon, aluminum, magnesium, calcium, iron, potassium, carbon, oxygen, and sulfur and all but one contained titanium. Samples from the conventional combustors contained more carbon than samples from the FBC. FBC samples contained large amounts of calcium and magnesium. Valence states of some elements were obtained by a detailed examination of selected ESCA peaks. Sputtering was performed on two samples to obtain a depth profile of the composition. The EDXA data confirmed the presence of silicon, aluminum, magnesium, calcium, iron, potassium, sulfur, and titanium while chlorine was detected in some samples. The EDXA data for individual particles exhibited marked particle to particle compositional variation. SEM studies demonstrated that the morphology of FBC samples was different from that of all of the conventional combustor samples examined.

Study of lung tissue from necropsy of a 58-year-old arc welder with arc welders' pneumoconiosis, confirmed by history, chest radiography, and pathology, demonstrates the versatility and usefulness of new techniques in scanning electron microscopy (SEM). Secondary electron imaging, the most familiar SEM mode, showed heavy cellular infiltrates in alveoli, the interstitium, and within the interstices of loose whorled fibrotic nodules. Backscattered electron imaging, in which contrast is proportional to elemental atomic number, revealed intracellular metal particles not otherwise visible. Microprobe analysis, energy-dispersive x-ray spectrometry, mapped elemeental iron over the particle image and identified traces of silicon in the whorled nodules. Arc welders' pneumoconiosis appears to be more than a benign siderosis resulting from particulate iron deposition. Simultaneous exposure to other components of welding fumes may alter the pathologic picture, inducing a more complicated fibrotic reaction. The more recently developed advanced techniques of SEM are well suited to the study of pneumoconioses and other problems of heterogenous tissue and mixed chemical systems.

The respirable fraction of the exhaust aerosol produced by an experimental 18-in. atmospheric pressure fluidized bed coal combustor was sampled as part of a program to assess the potential inhalation hazard associated with this emerging technology. Aerosol sampling instrumentation and the basis for its choice are described. Respirable fly ash aerosol parameters at four locations in the exhaust cleanup system are reported, as is the penetration of system cleanup devices by the respirable aerosol. Particle morphology was examined by transmission and scanning electron microscopy. Data on the real and aerodynamic particle size were used to calculate

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