Hence the volume-resistivity of pure annealed copper at 0° C. is 1.594 microhms per c.c., or 1594 C.G.S. units, and that of pure hard-drawn copper at 0° C. is 1.626 microhms per c.c., or 1626 C.G.S. units. Since Matthiessen's researches, the most careful scientific investigation on the conductivity of copper is that of T. C. Fitzpatrick, carried out in 1890. (_Brit. Assoc. Report_, 1890, Appendix 3, p. 120.) Fitzpatrick confirmed Matthiessen's chief result, and obtained values for the resistivity of hard-drawn copper which, when corrected for temperature variation, are in entire agreement with those of Matthiessen at the same temperature. The volume resistivity of alloys is, generally speaking, much higher than that of pure metals. Table V. shows the volume resistivity at 0° C. of a number of well-known alloys, with their chemical composition. TABLE V.--_Volume-Resistivity of Alloys of known Composition at 0° C. in C.G.S. Units per Centimetre-cube. Mean Temperature Coefficients taken at 15° C._ (Fleming and Dewar.) +-----------------------+-----------+-----------+-------------------+ | |Resistivity|Temperature|Composition in per | | Alloys. |at 0° C. |Coefficient| cents. | | | |at 15° C. | | +-----------------------+-----------+-----------+-------------------+ |Platinum-silver | 31,582 | .000243 |Pt 33%, Ag 66% | |Platinum-iridium | 30,896 | .000822 |Pt 80%, Ir 20% | |Platinum-rhodium | 21,142 | .00143 |Pt 90%, Rd 10% | |Gold-silver | 6,280 | .00124 |Au 90%, Ag 10% | |Manganese-steel | 67,148 | .00127 |Mn 12%, Fe 78% | |Nickel-steel | 29,452 | .00201 |Ni 4.35%, remaining| | | | | percentage | | | | | chiefly iron, but| | | | | uncertain | |German silver | 29,982 | .000273 |Cu5Zn3Ni2 | |Platinoid[9] | 41,731 | .00031 | | |Manganin | 46,678 | .0000 |Cu 84%, Mn 12%, | | | | |Ni 4% | |Aluminium-silver | 4,641 | .00238 |Al 94%, Ag 6% | |Aluminium-copper | 2,904 | .00381 |Al 94%, Cu 6% | |Copper-aluminium | 8,847 | .000897 |Cu 97%, Al 3% | |Copper-nickel-aluminium| 14,912 | .000643 |Cu 87%, Ni 6.5%, | | | | | Al 6.5% | |Titanium-aluminium | 3,887 | .00290 | | +-----------------------+-----------+-----------+-------------------+