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Anticorrosive alloy
206
CURRENT TOPICS.
Change of Structure of Aluminum. H. LE CHATELIER (Comptes rend., clii, 65o.)--Some aluminum articles underwent spontaneous disintegration, and on examination showed that in each case a cellular structure had developed, and that the disintegration was evidently due to the opening of the joints between the cells. Laboratory experiments indicated that the presence of small quantities of calcium were probably the cause of the development of this cellular structure. Anticorrosive Alloy, G. JACQUIER,Johannesburg. Eng. Pat., 20601 of I9Io.--This anticorrosive alloy has the composition aluminum 92 per cent., bismuth 2, copper 5 and silicon I per cent. ; or of aluminum 91 per cent., bismuth 2, copper 5 and magnesium 2 per cent. The metals except the aluminum are melted together, and then the molten aluminum added. Coffee Glazes Containing Arsenic. F . E . NOTTBOHM AND E. KocH. (Z. Unters. Nahr. Genussm., xxi, 288.)--Shellac is one of substances used for glazing coffee beans, and attention is drawn to the fact that shellac is sometimes colored by arsenic trisulphide. Samples of shellacs were found to contain from 0.0785 to o.12 per cent. of arsenic, while samples of colophony were free from arsenic. Coffee beans glazed with arsenical shellac were found to be strongly contaminated with arsenic. Two New Compounds of Stannous Chloride and Ammonia.
A. J. SOFIANOPOULOS. (Coln~tes rend., clii, 865.)--Persoz found that stannous chloride, heated with dry ammonia gas, gave a compound with the formula SnC12NHv The author finds that this compound is produced in the cold, even below o ° C. A compound with the formula SnClv2NH 3 is formed by passing dry, cooled ammonia gas over a shallow layer of well dried stannous chloride in a large glass tube, cooled by a mixture of ice and salt. Ammonia is passed until the contents of the tube are of a uniform light yellow color. This product should be kept in a colored bottle, shaded from light. A third compound, 3SnClv2NH~, is formed by the action of gaseous ammonia on stannous chloride at a temperature between I2o ° C. and 3oo ° C. It is a reddish-brown crystalline mass, powerfully do.uble-refractive, and is apparently the most stable of the ammonia and stannous chloride compounds. Colored Etching of Steels. F. ROBIN AND P, GARTNER. (ne~/.7. MJt., viii, 224.)---The polished specimens are etched in a saturated solution of picric acid for thirty seconds, and it is claimed that on rinsing them in water and then allowing them to dry without wiping, a variety of colors are produced, by which the various constituents, such as austenite and martenslte, may be distinguished. The original article is illustrated with microphotographs.
CURRENT TOPICS.
Change of Structure of Aluminum. H. LE CHATELIER (Comptes rend., clii, 65o.)--Some aluminum articles underwent spontaneous disintegration, and on examination showed that in each case a cellular structure had developed, and that the disintegration was evidently due to the opening of the joints between the cells. Laboratory experiments indicated that the presence of small quantities of calcium were probably the cause of the development of this cellular structure. Anticorrosive Alloy, G. JACQUIER,Johannesburg. Eng. Pat., 20601 of I9Io.--This anticorrosive alloy has the composition aluminum 92 per cent., bismuth 2, copper 5 and silicon I per cent. ; or of aluminum 91 per cent., bismuth 2, copper 5 and magnesium 2 per cent. The metals except the aluminum are melted together, and then the molten aluminum added. Coffee Glazes Containing Arsenic. F . E . NOTTBOHM AND E. KocH. (Z. Unters. Nahr. Genussm., xxi, 288.)--Shellac is one of substances used for glazing coffee beans, and attention is drawn to the fact that shellac is sometimes colored by arsenic trisulphide. Samples of shellacs were found to contain from 0.0785 to o.12 per cent. of arsenic, while samples of colophony were free from arsenic. Coffee beans glazed with arsenical shellac were found to be strongly contaminated with arsenic. Two New Compounds of Stannous Chloride and Ammonia.
A. J. SOFIANOPOULOS. (Coln~tes rend., clii, 865.)--Persoz found that stannous chloride, heated with dry ammonia gas, gave a compound with the formula SnC12NHv The author finds that this compound is produced in the cold, even below o ° C. A compound with the formula SnClv2NH 3 is formed by passing dry, cooled ammonia gas over a shallow layer of well dried stannous chloride in a large glass tube, cooled by a mixture of ice and salt. Ammonia is passed until the contents of the tube are of a uniform light yellow color. This product should be kept in a colored bottle, shaded from light. A third compound, 3SnClv2NH~, is formed by the action of gaseous ammonia on stannous chloride at a temperature between I2o ° C. and 3oo ° C. It is a reddish-brown crystalline mass, powerfully do.uble-refractive, and is apparently the most stable of the ammonia and stannous chloride compounds. Colored Etching of Steels. F. ROBIN AND P, GARTNER. (ne~/.7. MJt., viii, 224.)---The polished specimens are etched in a saturated solution of picric acid for thirty seconds, and it is claimed that on rinsing them in water and then allowing them to dry without wiping, a variety of colors are produced, by which the various constituents, such as austenite and martenslte, may be distinguished. The original article is illustrated with microphotographs.