The method of treatment above described suffices to render coils of manganin constant for at least a year (in 1892 the tests had only been made for this time) within a few thousands per cent.
After annealing as for manganin it can be made into serviceable standards which do not change more than a few thousandths per cent.
Other experiments in which themanganin wire was immersed in paraffin oil did not exhibit this effect, though stronger currents were passed.
Like German silver, manganin changes in resistance on winding, and coils made of it require to be artificially aged by heating to 150° for five hours before final adjustment.
On the whole, manganin appears to be the best material for coil boxes and "secondary" resistance standards.
Nichrome wire has a resistance 60 times that of copper; and manganin wire has a resistance 65 times that of copper, of the same gauge.
At present the best results have been obtained by using enameled manganin wire.
Two leads from the terminals of the manganin coil connect with the voltmeter outside the chamber, and hence the drop in potential can be measured very accurately and as frequently as is desired.
To vary the current passing through the manganin heating coils in the air-spaces next the zinc wall, a series of resistances is installed connected directly with the rheostat R{2} in fig.
A standard of resistance for use in a laboratory now generally consists of a wire of manganin or platinum-silver carefully insulated and enclosed in a brass case.
Hence within a certain range of temperature on either side of this critical value the resistivity of manganin is hardly affected at all by temperature.
It appears, however, that in order that manganin may remain constant in resistivity when used in the manufacture of a resistance coil, it is necessary that the alloy should be aged by heating it to a temperature of 140 deg.
Manganin has about twenty-five times the resistance of copper, and increases in resistance about 0.
Weston, and used in his instruments, are manganin and nickelin.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "manganin" in a variety of sentences. We hope that you will now be able to make sentences using this word.
