Cobalt

Cobalt, Cobaltum (chem. symbol Co), a lustrous metal of white color with reddish tint, belonging to Group VIII and the 4th row of Mendeleev's periodic system. In its typical compounds, cobalt is divalent and trivalent, forming two series of salts: suboxides and oxides. Its atomic weight is 58.97, specific gravity is 8.9, melting point is 1,490°. Cobalt salts containing crystallization water are pink in color, while in anhydrous state they are blue. In nature, cobalt is found mainly in combination with arsenic (speiss cobalt) and with arsenic and sulfur (cobalt glance). Cobalt is extremely similar to nickel both in chemical properties and in its effect on the animal organism. Cobalt salts, introduced per os, are poorly absorbed by the intestine. In acute poisoning, when cobalt is introduced into an animal's blood, vomiting, increased respiration and heart activity, convulsions occur, followed by paralysis and cessation of respiration, while the heart continues to contract for some time. In subacute and chronic poisoning in animals, the first symptom is vomiting, then diarrhea with mucus secretion, continuing intermittently until death; stomatitis, loss of appetite, emaciation, tremor, choreiform movements are observed; death occurs after convulsions with paralysis, and sometimes during convulsions. According to Stuart, vomiting depends on the central action of cobalt, as it occurs rapidly with parenteral administration but is absent with larger doses administered per os. Excreted mainly through the intestine, cobalt causes enteritis and may also cause a sharp drop in blood pressure due to paralysis of intestinal capillaries. The effect of cobalt on the kidneys, through which it is also partially excreted, may result in nephritis, although some authors did not find changes in the kidneys in animals poisoned with cobalt (Stuart). The cobalt compounds excreted in the urine give it a color ranging from brown to ink-black depending on the dose that caused the poisoning. To detect cobalt in urine, the ash residue of pre-alkalized urine is boiled with aqua regia, precipitated with ammonia solution and filtered; if cobalt is present, the filtrate has a brownish or reddish color; after evaporating the filtrate and mixing the residue with dilute HCl, the solution turns pink, and with strong HCl it turns blue. A sensitive reaction for cobalt was proposed by Vogel: to the test solution add an excess of strong ammonium thiocyanate solution and a little mixture of ether with amyl alcohol (or ethyl acetate); after shaking and standing, a blue color of the alcohol-ether layer is obtained. In humans, cobalt can cause chronic poisoning (see below). For therapeutic purposes, the use of cobalt nitrate salt as an antidote in cyanide poisoning was proposed, based on the formation of an insoluble cyanide compound; however, such action of this salt in the living organism is questioned by some researchers (Cushny). Cobalt oxide was tried to be used as a powder as an astringent and antiseptic, but in general at present cobalt compounds have no therapeutic application.

M. Likhachev. In industry, cobalt compounds are used in the processes of coloring glass, porcelain, faience, wallpaper, paper, in the production and use of certain oil and watercolor paints, in the production of certain valuable grades of steel and particularly strong metal alloys. In the extraction of cobalt (by roasting ores), there is a danger of poisoning with hydrogen sulfide, arsenic, CO. The so-called 'Schneeberg miners' disease' or 'Schneeberg cancer' has become widely known in the literature. This disease, known for a long time, is manifested in the fact that workers engaged in the extraction of nickel and cobalt ores (in the Schneeberg district, in Saxony) develop neoplasms (most often sarcoma) of the lungs. Hesse and Hartung (1878-79) consider arsenic, which is always present in these ores and enters the respiratory tract with dust, as the cause of this disease. Arnstein (1912-13), based on questionnaire data, determined that 44% of these workers die from lung neoplasms. More recent research has revealed a lesser prevalence of this disease; among 143 miners, only 8 cases of lung neoplasms were found. The course of the disease is extremely unfavorable - fatal outcome occurs after 6-18 months. Workers with long professional experience of 10-20 or more years fall ill. What is the true cause of the development of these neoplasms - the effect of arsenic or cobalt or the radioactive action of dust - has not yet been precisely determined. Cobalt and its compounds can also have an effect on the skin. Margain describes various lesions he observed in workers with cobalt; these lesions very much resemble those caused by arsenic (hyperkeratoses, ulcers, etc.). According to the German law of May 25, 1925, 'Schneeberg miners' disease' is included in the list of occupational diseases subject to compensation along with accidents.