Assessing the quality of pipe borne water using Magnetic Susceptibility Measurements
Magnetic susceptibility measurements and chemical analysis were performed on samples of water taken from the academic and residential areas of the Kwame Nkrumah University of Science and Technology (KNUST) campus, Kumasi. The aim of these measurements was to see if water delivered through metallic pipes was clean. Magnetic susceptibility measurements were performed using the Bartington MS2 magnetic susceptibility meter, with MS2G single frequency sensor and the chemical analysis was performed with the Varian SpectrAA 220FS Atomic Absorption Spectrometer. Results of the measurements showed that the water samples had negative magnetic susceptibility (χ) values of the order of 10 –5 and were thus diamagnetic. The χ values obtained for the samples were between –1.3  10 -6 SI and –1.23  10 -5 SI for the Academic Area (sampled colleges) and –3.0  10 -7 SI and –8.7 10 -6 SI for the Residential Area (sampled Halls of residence). Chemical analysis of the samples showed variation in the concentrations of iron and zinc. Regression analysis of their concentrations with their χ values revealed zinc to have a strong inverse relationship with a correlation coefficient of 73%. Although the study showed some level of metallic contamination in the water samples of average concentration of 0.03mg/l, these were well below the concentration of 3mg/l which is of detrimental concern as outlined by the World Health Organization (WHO). This makes drinking water from the study area safe for drinking.
Magnetic Study of Weakly Contaminated Forest Soils
This paper reports on magnetic and magnetomineralogical studies of forest soils from Krkonoše (Giant Mountains) National Park in the Czech Republic. Low-field magnetic susceptibility was measured in 32 soil profiles using a field probe. Thermomagnetic analysis, acquisition of remanent magnetization, alternating-field demagnetization of saturation remanence and frequency-dependent magnetic susceptibility were measured in laboratory samples from individual soil horizons as well as on their magnetic extracts. X-ray diffraction and SEM were used to identify ferrimagnetic fractions. The uppermost layer, which is dominated by magnetically soft magnetite of presumably anthropogenic origin, can be reliably identified in soil profiles over the whole region of concern. Subsoil horizons are characterised by significantly different magnetic properties.
KANT'S SECOND THOUGHTS ON RACE
During the 1780s, as Kant was developing his universalistic moral theory, he published texts in which he defended the superiority of whites over non-whites. Whether commentators see this as evidence of inconsistent universalism or of consistent inegalitarianism, they generally assume that Kant's position on race remained stable during the 1780s and 1790s. Against this standard view, I argue on the basis of his texts that Kant radically changed his mind. I examine his 1780s race theory and his hierarchical conception of the races, and subsequently address the question of the significance of these views, especially in the light of Kant's own ethical theory. I then show that during the 1790s Kant restricts the role of the concept of race, and drops his hierarchical account of the races in favour of a more genuinely egalitarian and cosmopolitan view.