. The Bell System technical journal . rly in the lead sheaths of subterranean currents from trolley systems often cause such corrosion and anelaborate and expensive electrical bonding system is maintained inorder to minimize these troubles. The physical and chemical nature of II CHEMISTRY IN THE TELEPHONE INDUSTRY 619 the soils and the underground waters and atmosphere often play animportant role in determining the kind and extent of corrosion by straycurrent. Other occasional cases of electrochemical corrosion have been en-countered in which stray current, though present, does no
. The Bell System technical journal . rly in the lead sheaths of subterranean currents from trolley systems often cause such corrosion and anelaborate and expensive electrical bonding system is maintained inorder to minimize these troubles. The physical and chemical nature of II CHEMISTRY IN THE TELEPHONE INDUSTRY 619 the soils and the underground waters and atmosphere often play animportant role in determining the kind and extent of corrosion by straycurrent. Other occasional cases of electrochemical corrosion have been en-countered in which stray current, though present, does not arise fromtrolley-line power houses. In one large city it was found that a batterycovering a square mile or more of area had been inadvertently created,such that it affected a large part of the cable system in the center of thecity. The cinder fills underlying the duct runs in this area containedenough carbon to serve as one electrode, while the iron-pipe systemssupplying gas and water to the city furnished the other electrode. The. Fig. 6—Experimental metallurgical shop. moist soil afforded a conducting path for a galvanic current thatwrought a widespread damage to telephone cables in the area. In another and much larger area widespread injury to cables cameabout through the presence of traces of acetic acid in the air in woodenduct systems. The source of this acid was the wood itself, which hap-pened to be of a rather highly acid variety. The natural acidity of thewood was further increased by the somewhat drastic process of heating 620 BELL SYSTEM TECHNICAL JOURNAL which was necessary to secure a fair penetration of the wood with creo-sote. In so far as the creosote penetrated, the acid produced in heatingwas neutralized to a great extent by the nitrogenous bases in the creo-sote. Often, however, the total acid produced far exceeded the neutra-lizing power of the creosote bases contained in the external shell ofcreosoted wood. The sheath of many miles of cables underwent
Size: 1766px × 1415px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1920, booksubjecttechnology, bookyear1
