Abstract: A process is disclosed for the fermentative production of the ergotropically effective antibiotic nourseothricin, with which, using different carbohydrate sources and suitable inorganic and organic nitrogen sources as well as different mineral salts, with or without addition of stock substances of the respiratory chain or the intracellular amino acid transport, and through influencing the phosphate substance exchange and avoidance of further limitations with regulated acidity conditions, high concentrations of this antibiotic are cultivated in the culture solution. The recovery of the active substance in the culture solution follows either by chromatographic techniques in the form of salts or through addition of a physiologically compatible adsorbent as mycelium-containing nourseothricin-adsorbate, which preferably can be added to the dosaging of mixed feed agents.

Abstract: Weighting material for a drilling fluid, e.g. a drilling mud, is produced by firing iron oxide solids, e.g. iron oxide ores, calcined pyritic ores or iron-oxide-containing products of other metallurgical processes, in a circulating fluidized bed or rotary furnace at a temperature of 1210.degree. C to 1400.degree. C in an oxidizing atmosphere in which the oxygen content is augmented to transform magnetitic components to oxides of lower magnetic susceptibility. The product is then cooled slowly at least until it reaches a temperature of 780.degree. C, also in an oxidizing atmosphere. The weighting materials have extremely low magnetic susceptibility and thus can be used without interfering with inductive monitoring of the position of the drill string.