Who invented the electric soldering iron, and in what year?

The earliest I can find is 1916 in Holland but the wording is a little
non-specific and gives no credit to the original inventor.
"The company was founded in 1916 as a manufacturing company under the
name ZEVA. This name had much to do with the introduction of an
innovative product: the electric soldering iron (as differing from
then-popular petrol and gas irons). Major customers included Philips
Radio and Dutch Telecom."
http://www.vitronics-soltec.com/about%2Dus/history/

US patent number 1519246 submitted in 1921 and granted 1924 by Frank
Forshee, James Woodson, Westinghouse Electric & Mfg, is for an
electric soldering iron but the text suggests preexisting examples.

http://patimg1.uspto.gov/.piw?docid=US001519246&PageNum=1&&IDKey=21ACD96B5011&HomeUrl=http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2%2526Sect2=HITOFF%2526p=1%2526u=/netahtml/search-bool.html%2526r=1%2526f=G%2526l=50%2526co1=AND%2526d=o179%2526s1=1519246.WKU.%2526OS=PN/1519246%2526RS=PN/1519246

There is also this reference:
"In 1921,
Ernst Sachs invented, patented, and marketed the first electric soldering iron
for industry."
http://www.ersa.de/en/data/fachartikel/SolWel_e.PDF?sid=e114e96d903afff15fe7c57059029c42

From what I can find, the first patent for a soldering iron is as follows:

Title: Soldering iron
Patent number: 126,905
Date granted: 5/21/1872
Inventor: Herman Scaroni

This information can be viewed here:
http://www.cincinnatilibrary.org/resources/invent/patent.asp?patent=1836

Hope this helps!