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Upkeep of shop-lighting systems
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CURRENT TOPICS. Siloxide, a Valuable Substitute for Quartz Glass. F. THOMAS.
(Chem. Zeit., xxxvi, 25.)--Siloxide is the name given to products prepared by fusing silica with small proportions of refractory acidic oxides, such as zirconia or titania, for the purpose of obtaining materials more resistant to the action of metallic oxides, especially alkalies, than quartz glass, and being less liable to devitrification on heating. Specimens of Z. siloxide or zirconium glass and T. siloxide or titanium glass were examined, and, although these did not exhibit the beautiful silky lustre of quartz glass (" vitreosil "), they possess distinct advantages over the latter with respect to strength, thermal properties (resistance to devitrification), and resistance to the action of alkalies. The zirconium glass with the most strength contained I per cent. of zirconia, while that which had the best thermal properties contained 0.5 per cent. The titanimu glasses (containing o.I to 2 per cent. of titanium) have a somewhat lower resistance to compression than quartz glass, but resist transverse fracture better than the latter and are superior even to zirconium glass as regards their thermal properties. Colloidal Gold and Platinum. N. PAPPADA. (Zeit. Chem. Ind. Kolloide, ix, 27o.)--Colloidal gold and platinum solutions, especially the latter, are much more stable than other electro-negative sols. such as Prussian blue, copper ferrocyanide, etc. The sols prepared by Bredig's method of cathodic disintegration are much more stable than those prepared by chemical reduction methods. T h e activity of electrolytes in causing coagulation of gold and platinum hydrosols follows in general the same order as with other electro-negative sols. Colloidal gold and platinum act as reducing agents, but are much less active than colloidal silver. When colloidal gold is treated with potassium cyanide or hydrocyanic acid, the dark violet color changes to yellow, and the colloidal character is destroyed, for even tri-valent cations such as AI'" or Te'" now fail to produce flocculation. Colloidal gold acts energetically with chlorine, forming gold chloride. With iodine the reaction proceeds much more slowly. Colloidal platinum acts similarly. Upkeep of Shop-Lighting Systems. C . E . CLEWELL. (Amer. Mach., xxxvi, 13, 5oI.)---This paper on shop lighting is of considerable interest, and indicates the economy of keeping Sights clean and efficient. In brief, attention is drawn to some of the items involved in the maintenance of shop-lighting systems at high continuous efficiency. From the stand:point of economy alone, the expense is justified. When to economy are added the comfort and assistance that a well-regulated system gives to employees, ttie matter becomes yet more important. The outlay for lighting upkeep is more than compensated by the better illumination, more contented employees, and a more cheerful shop.
CURRENT TOPICS. Siloxide, a Valuable Substitute for Quartz Glass. F. THOMAS.
(Chem. Zeit., xxxvi, 25.)--Siloxide is the name given to products prepared by fusing silica with small proportions of refractory acidic oxides, such as zirconia or titania, for the purpose of obtaining materials more resistant to the action of metallic oxides, especially alkalies, than quartz glass, and being less liable to devitrification on heating. Specimens of Z. siloxide or zirconium glass and T. siloxide or titanium glass were examined, and, although these did not exhibit the beautiful silky lustre of quartz glass (" vitreosil "), they possess distinct advantages over the latter with respect to strength, thermal properties (resistance to devitrification), and resistance to the action of alkalies. The zirconium glass with the most strength contained I per cent. of zirconia, while that which had the best thermal properties contained 0.5 per cent. The titanimu glasses (containing o.I to 2 per cent. of titanium) have a somewhat lower resistance to compression than quartz glass, but resist transverse fracture better than the latter and are superior even to zirconium glass as regards their thermal properties. Colloidal Gold and Platinum. N. PAPPADA. (Zeit. Chem. Ind. Kolloide, ix, 27o.)--Colloidal gold and platinum solutions, especially the latter, are much more stable than other electro-negative sols. such as Prussian blue, copper ferrocyanide, etc. The sols prepared by Bredig's method of cathodic disintegration are much more stable than those prepared by chemical reduction methods. T h e activity of electrolytes in causing coagulation of gold and platinum hydrosols follows in general the same order as with other electro-negative sols. Colloidal gold and platinum act as reducing agents, but are much less active than colloidal silver. When colloidal gold is treated with potassium cyanide or hydrocyanic acid, the dark violet color changes to yellow, and the colloidal character is destroyed, for even tri-valent cations such as AI'" or Te'" now fail to produce flocculation. Colloidal gold acts energetically with chlorine, forming gold chloride. With iodine the reaction proceeds much more slowly. Colloidal platinum acts similarly. Upkeep of Shop-Lighting Systems. C . E . CLEWELL. (Amer. Mach., xxxvi, 13, 5oI.)---This paper on shop lighting is of considerable interest, and indicates the economy of keeping Sights clean and efficient. In brief, attention is drawn to some of the items involved in the maintenance of shop-lighting systems at high continuous efficiency. From the stand:point of economy alone, the expense is justified. When to economy are added the comfort and assistance that a well-regulated system gives to employees, ttie matter becomes yet more important. The outlay for lighting upkeep is more than compensated by the better illumination, more contented employees, and a more cheerful shop.