Before electron tube rectifiers or silicon rectifiers - chemical rectifiers was a way to go.
Top figure is glass jar (3 inch X 3.5 inch) with 1/2 inch X 4 inch piece of clean tin can on left of jar. Right side of jar is 4 inch piece of #8 aluminum wire.
In jar, pour throughly mixed 8 ounces Borax - (the 20 mule team laundry room stuff - or, Sodium Borate , another name )- and 8 ounces of water.
Bottom electrical circuit is to form semiconductor film on aluminum - doorbell chime transformer to tin strip (one part of diode) through electrolyitic Borax mixture and out aluminum wire ( second part of diode) to automotive # 57 bulb ( 14 volts at 3 amps). Run circuit about 15 minutes and note bubbling action around aluminum wire.
To check diode performance: do not disturb electrodes but take ohm meter readings both ways to verify results. Larger aluminum electrode or sheet strip will increase current carrying capacity.
