Determining wire size, insulation and ampacity used to be one of the test problems in the practical section of the NYC Electrician's exam. You have to measure the diameter of one strand with a micrometer, calculate the cross-sectional area and multiply it by the total number of strands in order to get the overall cross-sectional area of the conductor. You then have to determine the type of insulation. The old NYC code book is a bit different from our current NEC code book but you'll find the information in Chapter 9, Table 4 for wire size, then go to the ampacity tables.;)
BTW, this information is just for your reference, I'd rip the old stuff out too. The guy at the scrap yard only cares how much it weighs.
Andy
