These have an interesting history which we learned just recently (Jerry, correct me if I get this wrong).
This is a KU-18. This is the most common size/color. It also comes in Cornflower, Amber and Green. These also come in 5" and 7 1/2" which are rare. These were made by the Norwich Glass Co. Many of them were used (Conveniently) by the Norwich Chemical Co, but were used by others as well.
Prices differ greatly between sizes and color. This issue is worth about $100 (as would the Cornflower). The Amber would be $200, Green - $2500 (very rare color, I've never seen one). All issues larger (5" & 7 1/2") range from $800 to $12000 as they are very rare. (These are historical highs for undamaged examples)
We have 3 of the 3 1/2" on our website and a 7 1/2" we picked up recently you can see here:
https://www.antique-bottles.net/forum/Tales-from-the-Columbia%2C-SC%25-show!/m-385495/tm.htm
We also picked up the very rare KU-18B Crystal Coffin. It looks very similar to the Norwich, but has some key differences which are hard to see in the image. The shoulders where it starts to taper back towards the neck ( The widest part of the bottle) has a more defined corner where the Norwich is more rounded. Crystal is embossed on the bottom. It's a bit shorter at 3 1/8" tall with a narrower body ( Though it does come in a 4" size as well ).
There are several other nice coffin shaped bottles out there. KU-4, KU-8, KU-22 and KU-36 (all can be found on our website)
You have a nice bottle there, a very popular addition.
If you want too see all of the sizes of the amber and cobalt NORWICH COFFINS that exist scroll down in the" POISONS" thread to the date 1/17/12 listed as the "MONEY SHOT" and you will see two small show cases showing all three sizes of the amber and cobalt NORWICH poison bottles plus a clear 3 1/2 example. There are several other pictures showing a large number of other rare poison bottles in large display cases.