This section is from the book "Bepler's Handy Manual of Knowledge And Useful Infomation", by David Bepler. Also available from Amazon: Bepler's Handy Manual of Knowledge and Useful Information.
Gold leaf is the 254-248th part of an inch in thickness, which is common work of the gold-beater. Sheets have been beaten the 367,-500th part of an inch in thickness. One ounce of gold can be beaten out so as to cover 160 square feet of surface.