Another curious result noticed in some pins on this same line is the softening of the threads so that they can be rubbed off with the fingers.
+------------------------------+-------+--------+--------+-------------+ | |Voltage|Diameter| Height |Length of Pin| | Location of Line. | of | of | of | Covered by | | | Line. |Insula- | Insula-| Insulator. | | | | tor. | tor. | | +------------------------------+-------+--------+--------+-------------+ | | | Inches.| Inches.| Inches. | |Electra to San Francisco | 60,000| 11 | 11-1/4 | 12 | |Colgate to Oakland | 60,000| 11 | 11-1/4 | 8 | |Cañon Ferry to Butte | 50,000| 9 | 12 | 10-1/2 | |Shawinigan Falls to Montreal | 50,000| 10 | 13 | 10-1/4 | |Santa Ana River to Los Angeles| 33,000| 6-3/4 | 4-7/8 | 2-1/2 | |Provo around Utah Lake | 40,000| 7 | 5-3/4 | 4-3/4 | |Spier Falls to Schenectady | 30,000| 8-1/2 | 6-3/4 | 5-1/4 | |Niagara Falls to Buffalo | 22,000| 7-1/2 | 7 | 5 | +------------------------------+-------+--------+--------+-------------+
The softened wood of the threads is not charred, but is said to have a sour taste and to resemble digested wood pulp. While the threads of a wooden pin are destroyed in this way the remainder of the pin may still remain perfect and show no charring.
+------------------------------+----------+----------+-----------+ | |Length of | Distance | Distance | | | Pin |from Outer|from Lowest| | Location of Line. | Between | Petticoat| Petticoat | | | Insula- | to Pin | to Pin | | | tor and | Through | Through | | |Cross-arm.| Air. | Air. | +------------------------------+----------+----------+-----------+ | | Inches. | Inches. | Inches. | |Electra to San Francisco | 0 | 10-1/2 | 3-1/2 | |Colgate to Oakland | 3-1/2 | 10 | 2-1/2 | |Cañon Ferry to Butte | 1-1/2 | 0 | 1-1/2 | |Shawinigan Falls to Montreal | 3-1/4 | 9-1/2 | 1 | |Santa Ana River to Los Angeles| 3-1/2 | 2-3/4 | .. | |Provo around Utah Lake | 3-1/2 | 2-1/2 | .. | |Spier Falls to Schenectady | 4 | 4 | 5/8 | |Niagara Falls to Buffalo | 3 | 4-1/2 | 2 | +------------------------------+----------+----------+-----------+
In explanation of this disintegration of the threads of wooden pins it was stated that a number of these pins, the tops of which were reduced to a white powder, had been taken from the line between Niagara Falls and Buffalo, on which the voltage is 22,000, and that this powder proved on analysis to be a nitrate salt. This salt was thought to be the result of the action of nitric acid on the wood, it being supposed that the acid was formed by a static discharge acting on the oxygen and nitrogen of the air between the threads of the insulator and pin. In support of this view it was stated that an experimental line of galvanized-iron wire at Niagara Falls, which was operated at 75,000 volts continuously during nearly four months, turned black over its entire length of about two miles. This surface disintegration was not due to the normal action of the air, for similar wire at the same place remained bright when not used as an electrical conductor.