The jug - jar business also was discussed earlier. It would help not only if past information posted here was read, but dogmatic, uninformed statements were avoided.

Before the late 19th c. there was little distinction between jug and jar in definition.

The whisky jar of Ireland and Scotland in the 19th c. is what most people now call a jug- a stoneware container, constricted at the neck, with a single handle on one side.
The Limerick city Museum illustrated one on their website (posted long ago, the site may be changed or dropped so here is the Description):

"Whiskey jar of Thomas Conway, Wine and Spirit Merchant... Limerick. Half gallon. Made at Port Dundas Pottery, Glasgow. Stoneware jar, cream below, pale brown above. Tapered body, bevelled to a flat base, rounded shoulder to tapering and waisted spout at the centre top. Strap handle ...."

http://www.limerickcity.ie/applications/general/museum_details.aspx?RowID=4717

Malcolm, thanks for the summary. I doubt if it will help; some who post here listen solely to their own thoughts.