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Copper castings for electrical purposes
April, I918. l
CURRENT TOPICS.
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effort of visualizing the project from the plans in considering the merits of a given arrangement of the component elements of the project. In the planning of country estates the work of the model maker is of paramount importance. Plans mean next to nothing to the average man, and, though wash-drawings convey a more understandable impression of the subject, the advantages and faults of an undertaking are much more prominently shown in a model from which the relationships of each detail may be at once seized. In the planning of large buildings the model has very definite application. Such buildings as the Woolworth skyscraper had been reproduced in miniature long before the structure raised itself above the crowded sidewalk of Broadway. Model skyscrapers have enabled many a prospective owner to appreciate what he was ordering.
Copper Castings for Electrical Purposes. G. F. COMSTOCK. (Proceedings of the American Electrochemical Society~ October 4, i 9 1 7 . ) - - B e f o r e the work of Matthiesson in 186o the resistance of the usual grades of copper, even i n t h e form of wire, was only about 5° per cent. of the standard which we have to-day. This work by Matthiesson emphasized the importance of eliminating all possible traces of impurities from coppei" to be used for conducting electricity. For instance, he found the conductivity of copper with 1.6 per cent. zinc to be only about 79 per cent. that of pure copper, both being in the form of wire. With 1. 3 per cent. tin it was decreased to about 5° per cent., with o.I per cent. aluminum to 76.5 per cent., and with 0. 5 per cent. iron to 36 per cent., while only o.13 per cent. phosphorus decreased the conductivity to 7 ° per cent,, and even traces of arsenic to 60 per cent. In order to obtain copper wires of high conductivity it is necessary only to start with extremely pure copper bars. Two difficulties are encountered when this is attempted. First, sound castings are almost an impossibility, and, second, the pure metal in the cast condition is too soft and weak to give the best satisfaction in most electrical uses. The difficulty of obtaining soun.d castings of pure copper is caused by its rapid absorption of oxygen and other gases when it is melted. The gases not only dissolve in the molten metal, but copper oxide is also formed which is held in solution until the metal freezes. The second difficulty of softness and weakness cannot be overcome except by adding some other metal to the copper, thus making it no longer pure, or by giving the casting some mechanical treatment, such as forging, after which it is, properly speaking, no longer a casting. Zinc is the element most often used for the purpose of deoxidation, thereby producing sound castings fairly easily with the minimum reduction in conductivity. Such castings deoxidized by zinc had a considerably lower conductiyity than copper wire, in many cases only about 4o to 5o lger cent. Phosphorus and silicon have both been used VoL: 185, No. 11o8 42. a
582
CURRENT TOPICS.
[J. F. i.
in place of zinc, and, while very small quantities of either are normally sufficient, their use is attended by the disadvantage that an excess of either of these elements does more harm to the conductivity than an equal excess of zinc. The use of silicon has for several years been under investigation with promising results ; 75 to 85 per cent. conductivity has been obtained for castings deoxidized with silicon.
Two Million More Horsepower from the Niagara River. R.G. SKERRETT. (Scientific American, vol. 117, No. 26, p. 489, December 29, I 9 I T . ) - - A c c o r d i n g to the estimates of government experts, it is physically possible to develop at Niagara Falls a maximum of 6,5oo, cx~o horsepower, but because of international agreement the legal maximum cannot exceed 790,0o0. As a matter of fact, because of various hampering circumstances, the total energy actually available for commercial service probably does not exceed 550,0oo horsepower. The difference between fact and potentiality is the price paid for scenic beauty. The public generally, time and time again, has registered its vigorous protest against any impairment of this natural wonder. Engineers, therefore, have striven to find acceptable solutions of this economic problem, and among the latest is what is known as the Thomson-Porter Cataract project. Additional hydro-electric energy has become an acute national necessity, and Dr. T. Kennard Thomson, the engineering sponsor of the plan, is satisfied that the scheme in question will make it possible to obtain the desired power without in any wise detracting from the charm of Niagara Falls. Briefly, the fundamental feature of the project is a massive dam rising from the rocky bed of the Niagara River and blocking the gorge from bank to bank at a point a little more than 4 ~ miles below the famous Cataract and something like 2 ~ miles south of Lewiston, N. Y., and Queenston, Ontario. By means of this dam the water level would be raised high enough above the present surface of the river to provide an effective head of 9 ° feet. The local result would be to lower the visible rise of the flanking cliffs by something like one-third, ~but the new level would merge exactly with the existing water surface, at the Falls, and would therefore in no wise change the scenic conditions there. The existing Rapids would, necessarily, be submerged, but the scheme contemplates substitute rapids below the dam that would be equally tumultuous and probably more spectacular. The hydro-electric installation, that would be made practicable by the building of the proposed dam, would develop quite 2,000,000 horsepower, and one-half of this would be for the United States and the other half for the Dominion of Canada. Assuming a horsepower to call on an average for the consumption of IO tons of coal a year, the energy so obtained would be equivalent to the conserving of 20,000,0o0 tons of fuel annually. According to Doctor Thomson's figures, it would cost .substantially $IOO,OOO,Oo0 and take three years to rear the dam and to build and equip the associate hydro-electric plants for the development of 2,000,000 horsepower.
CURRENT TOPICS.
58I
effort of visualizing the project from the plans in considering the merits of a given arrangement of the component elements of the project. In the planning of country estates the work of the model maker is of paramount importance. Plans mean next to nothing to the average man, and, though wash-drawings convey a more understandable impression of the subject, the advantages and faults of an undertaking are much more prominently shown in a model from which the relationships of each detail may be at once seized. In the planning of large buildings the model has very definite application. Such buildings as the Woolworth skyscraper had been reproduced in miniature long before the structure raised itself above the crowded sidewalk of Broadway. Model skyscrapers have enabled many a prospective owner to appreciate what he was ordering.
Copper Castings for Electrical Purposes. G. F. COMSTOCK. (Proceedings of the American Electrochemical Society~ October 4, i 9 1 7 . ) - - B e f o r e the work of Matthiesson in 186o the resistance of the usual grades of copper, even i n t h e form of wire, was only about 5° per cent. of the standard which we have to-day. This work by Matthiesson emphasized the importance of eliminating all possible traces of impurities from coppei" to be used for conducting electricity. For instance, he found the conductivity of copper with 1.6 per cent. zinc to be only about 79 per cent. that of pure copper, both being in the form of wire. With 1. 3 per cent. tin it was decreased to about 5° per cent., with o.I per cent. aluminum to 76.5 per cent., and with 0. 5 per cent. iron to 36 per cent., while only o.13 per cent. phosphorus decreased the conductivity to 7 ° per cent,, and even traces of arsenic to 60 per cent. In order to obtain copper wires of high conductivity it is necessary only to start with extremely pure copper bars. Two difficulties are encountered when this is attempted. First, sound castings are almost an impossibility, and, second, the pure metal in the cast condition is too soft and weak to give the best satisfaction in most electrical uses. The difficulty of obtaining soun.d castings of pure copper is caused by its rapid absorption of oxygen and other gases when it is melted. The gases not only dissolve in the molten metal, but copper oxide is also formed which is held in solution until the metal freezes. The second difficulty of softness and weakness cannot be overcome except by adding some other metal to the copper, thus making it no longer pure, or by giving the casting some mechanical treatment, such as forging, after which it is, properly speaking, no longer a casting. Zinc is the element most often used for the purpose of deoxidation, thereby producing sound castings fairly easily with the minimum reduction in conductivity. Such castings deoxidized by zinc had a considerably lower conductiyity than copper wire, in many cases only about 4o to 5o lger cent. Phosphorus and silicon have both been used VoL: 185, No. 11o8 42. a
582
CURRENT TOPICS.
[J. F. i.
in place of zinc, and, while very small quantities of either are normally sufficient, their use is attended by the disadvantage that an excess of either of these elements does more harm to the conductivity than an equal excess of zinc. The use of silicon has for several years been under investigation with promising results ; 75 to 85 per cent. conductivity has been obtained for castings deoxidized with silicon.
Two Million More Horsepower from the Niagara River. R.G. SKERRETT. (Scientific American, vol. 117, No. 26, p. 489, December 29, I 9 I T . ) - - A c c o r d i n g to the estimates of government experts, it is physically possible to develop at Niagara Falls a maximum of 6,5oo, cx~o horsepower, but because of international agreement the legal maximum cannot exceed 790,0o0. As a matter of fact, because of various hampering circumstances, the total energy actually available for commercial service probably does not exceed 550,0oo horsepower. The difference between fact and potentiality is the price paid for scenic beauty. The public generally, time and time again, has registered its vigorous protest against any impairment of this natural wonder. Engineers, therefore, have striven to find acceptable solutions of this economic problem, and among the latest is what is known as the Thomson-Porter Cataract project. Additional hydro-electric energy has become an acute national necessity, and Dr. T. Kennard Thomson, the engineering sponsor of the plan, is satisfied that the scheme in question will make it possible to obtain the desired power without in any wise detracting from the charm of Niagara Falls. Briefly, the fundamental feature of the project is a massive dam rising from the rocky bed of the Niagara River and blocking the gorge from bank to bank at a point a little more than 4 ~ miles below the famous Cataract and something like 2 ~ miles south of Lewiston, N. Y., and Queenston, Ontario. By means of this dam the water level would be raised high enough above the present surface of the river to provide an effective head of 9 ° feet. The local result would be to lower the visible rise of the flanking cliffs by something like one-third, ~but the new level would merge exactly with the existing water surface, at the Falls, and would therefore in no wise change the scenic conditions there. The existing Rapids would, necessarily, be submerged, but the scheme contemplates substitute rapids below the dam that would be equally tumultuous and probably more spectacular. The hydro-electric installation, that would be made practicable by the building of the proposed dam, would develop quite 2,000,000 horsepower, and one-half of this would be for the United States and the other half for the Dominion of Canada. Assuming a horsepower to call on an average for the consumption of IO tons of coal a year, the energy so obtained would be equivalent to the conserving of 20,000,0o0 tons of fuel annually. According to Doctor Thomson's figures, it would cost .substantially $IOO,OOO,Oo0 and take three years to rear the dam and to build and equip the associate hydro-electric plants for the development of 2,000,000 horsepower.