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Telemetering aids operation of district steam distribution system
816
CURRENT TOPICS.
[J. F. I.
chloride. The refrigeration unit constitutes a compact group comprising a compressor, condenser and evaporator. R. H.'O. Death Light for Insects. (Business Week, Oct. 5, I935.)--Prof. W. B. HERMS and his assistant, J. K. ELLSWORTHof the University of California, experimenting in their laboratory with the effect of colored light on insects, found that each type of pest has a "favorite color." Continued experiments indicated the color preferences of each kind of flying insect and the exact intensity which attracts it most effectively. The grape leafhopper for instance, nightmare of California's vineyardists, prefers pale blue. So does the artichoke plume moth. A device was worked out putting the discoveries to actual use in the fields. It consists of a wire cage 8 in. in diameter, the alternate wires being connected to the terminals of a transformer which supplies enough voltage to electrocute the insects. A luminescent tube is used as a lure and is suspended along the axis of the cage so that the insect will come in contact with the wires as it flies toward the light. R. H. O. Cotton-Fabric Reinforced Roads. W . K . BECKHAM AND W. H. MILLS. (Engineering News Record, Vol. 115 No. I4.)--For the purpose of developing additional use for the product that occupies so important a place in the agricultural and manufacturing activities of the state, the South Carolina highway department in 1926 began studies on cotton fabric as a reinforcement for bituminous surface treatment. To date this practice and use has reached a stage of high development. Eight practical experiments were made on roads using several kinds of fabric. Conclusions recommend for future work a fabric with warp ends from 12 to 17 per inch and fill ends from 12 to I7 per inch, weighing about 4.25 oz. per sq. yd. Based on results obtained on experiments conducted prior to 1935, it appears that cotton fabric used as a reinforcement in bituminous surface treatment reduces cracking, raveling and failures. When the fabric is properly embedded in bituminous material, it is well preserved. In one instance, fabric which has been down for nine years is still in good condition. The experimental sections constructed this year should give very valuable additional information, as a number of different methods of construction have been included. R. H. O. Telemetering Aids Operation of District Steam Distribution System.--T. E. PURCELL describes in Heating, Piping and Air
Dec., 2935.]
CURRENT TOPICS.
8I 7
Conditioning, Vol. 7, No. IO, a modern installation which is a decided asset for good service provided by the Allegheny County Steam Heating Co., Pittsburgh. The district heating system consists of two modern plants having a combined capacity of about 1,2oo,ooo lb. per hr. of steam and a smaller plant held in reserve. The distribution area comprises about one square mile and serves 242 customers. A distinctive feature is the return of about 80 per cent of the condensate through pipe lines paralleling the main steam lines. In the telemetering installation an oscillating element operated at a uniform speed by a synchronous motor at the transmitter makes and breaks an electric telemetering circuit at time intervals proportional to the displacements to be transmitted. These displacements are actuated by either pressure, rate of flow, etc. The intermittent electric current thus transmitted operates a pair of electric clutches in the receiving instrument which also revolve at uniform speeds but in opposite directions by means of a local synchronous motor. The motion of these clutches through a limited arc is transmitted to the recording and indicating elements of the meter. Variations in strength of the transmitting electric current do not affect the accuracy of metering, since its only function is one of timing, and this is done by making use of relatively low voltage telephone circuits. Fourteen long distance recorders are installed in order that all steam pressures be maintained reasonably constant. A particularly important instrument used in addition is the multi-point recorder which gives a continuous record of the contamination of the returning condensate. R. H . O . Removal from Solution of Minute Amounts of Gold and S i l v e r . , \¥M. E. CALDWELL, Oregon State Agricultural College, speaking
before the San Francisco American Chemical Society Convention described a method whereby as little as I part of gold in 4 billion and 'I part silver in 40 million can be successfully removed from the solution. Such quantitative recovery is accomplished by permitting to fall through the solution, a mercury-mercurous chloride residue, which residue is produced by reduction of mercuric chloride by powdered magnesium and acid. Assay of the residue permits the quantitative determination of gold and silver with an accuracy equivalent to the more general cupellation procedure. The removal of gold and silver from seawater is quite possible with such a method but not practical from the standpoint of present costs. C.
CURRENT TOPICS.
[J. F. I.
chloride. The refrigeration unit constitutes a compact group comprising a compressor, condenser and evaporator. R. H.'O. Death Light for Insects. (Business Week, Oct. 5, I935.)--Prof. W. B. HERMS and his assistant, J. K. ELLSWORTHof the University of California, experimenting in their laboratory with the effect of colored light on insects, found that each type of pest has a "favorite color." Continued experiments indicated the color preferences of each kind of flying insect and the exact intensity which attracts it most effectively. The grape leafhopper for instance, nightmare of California's vineyardists, prefers pale blue. So does the artichoke plume moth. A device was worked out putting the discoveries to actual use in the fields. It consists of a wire cage 8 in. in diameter, the alternate wires being connected to the terminals of a transformer which supplies enough voltage to electrocute the insects. A luminescent tube is used as a lure and is suspended along the axis of the cage so that the insect will come in contact with the wires as it flies toward the light. R. H. O. Cotton-Fabric Reinforced Roads. W . K . BECKHAM AND W. H. MILLS. (Engineering News Record, Vol. 115 No. I4.)--For the purpose of developing additional use for the product that occupies so important a place in the agricultural and manufacturing activities of the state, the South Carolina highway department in 1926 began studies on cotton fabric as a reinforcement for bituminous surface treatment. To date this practice and use has reached a stage of high development. Eight practical experiments were made on roads using several kinds of fabric. Conclusions recommend for future work a fabric with warp ends from 12 to 17 per inch and fill ends from 12 to I7 per inch, weighing about 4.25 oz. per sq. yd. Based on results obtained on experiments conducted prior to 1935, it appears that cotton fabric used as a reinforcement in bituminous surface treatment reduces cracking, raveling and failures. When the fabric is properly embedded in bituminous material, it is well preserved. In one instance, fabric which has been down for nine years is still in good condition. The experimental sections constructed this year should give very valuable additional information, as a number of different methods of construction have been included. R. H. O. Telemetering Aids Operation of District Steam Distribution System.--T. E. PURCELL describes in Heating, Piping and Air
Dec., 2935.]
CURRENT TOPICS.
8I 7
Conditioning, Vol. 7, No. IO, a modern installation which is a decided asset for good service provided by the Allegheny County Steam Heating Co., Pittsburgh. The district heating system consists of two modern plants having a combined capacity of about 1,2oo,ooo lb. per hr. of steam and a smaller plant held in reserve. The distribution area comprises about one square mile and serves 242 customers. A distinctive feature is the return of about 80 per cent of the condensate through pipe lines paralleling the main steam lines. In the telemetering installation an oscillating element operated at a uniform speed by a synchronous motor at the transmitter makes and breaks an electric telemetering circuit at time intervals proportional to the displacements to be transmitted. These displacements are actuated by either pressure, rate of flow, etc. The intermittent electric current thus transmitted operates a pair of electric clutches in the receiving instrument which also revolve at uniform speeds but in opposite directions by means of a local synchronous motor. The motion of these clutches through a limited arc is transmitted to the recording and indicating elements of the meter. Variations in strength of the transmitting electric current do not affect the accuracy of metering, since its only function is one of timing, and this is done by making use of relatively low voltage telephone circuits. Fourteen long distance recorders are installed in order that all steam pressures be maintained reasonably constant. A particularly important instrument used in addition is the multi-point recorder which gives a continuous record of the contamination of the returning condensate. R. H . O . Removal from Solution of Minute Amounts of Gold and S i l v e r . , \¥M. E. CALDWELL, Oregon State Agricultural College, speaking
before the San Francisco American Chemical Society Convention described a method whereby as little as I part of gold in 4 billion and 'I part silver in 40 million can be successfully removed from the solution. Such quantitative recovery is accomplished by permitting to fall through the solution, a mercury-mercurous chloride residue, which residue is produced by reduction of mercuric chloride by powdered magnesium and acid. Assay of the residue permits the quantitative determination of gold and silver with an accuracy equivalent to the more general cupellation procedure. The removal of gold and silver from seawater is quite possible with such a method but not practical from the standpoint of present costs. C.