Hi M, good to see you again !
As you say not FH specifically but this forum has seen many such queries in the past and I hope more to follow. Now I'm NO chemist and struggle to know the differences, it's all "creosote" to me !, but for your ease of searching either online or in books the factory is most often known as the Wood Distillation Works. It was situated at Cannop Crossroads between Coleford and Speech House. More precisely if driving from Coleford along the B4226, it was on the righthand side immediately after/on the junction with the B4234 Lydbrook-Parkend road, so diagonally opposite the Pigmy Pinetum nursery (hope it's still there ?) .

I know you have many local history books; if you have it the best reference by far with many pages of historical text and photos of the Works is the book "Severn & Wye Railway Vol 2, Forest of Dean" by Ian Pope etc, Wild Swan publications. Hopefully this link will take you to it in the Glos Libraries website, several copies are currently available at the local branches. My amateur summary below, which is not copied directly from the book, collects together just a few points from this highly recommended book. As with all links, it's best opened via a new tab or window.
https://gloucestershire.spydus.co.uk/cgi-bin/spydus.exe/FULL/WPAC/BIBENQ/15205668/661590,7

I cannot find any photos online whatsoever, however the Works can be clearly seen on the Old Maps website, a great site but occasionally awkward to use, enter "Cannop" into the search box.
http://www.old-maps.co.uk/maps.html
The best old map to select in this instance is the "1922 pre WW2 1:2500", this shows the layout and associated railway lines very clearly, the later "1960" map is also good. The Works was near the old Speech House Road railway Station, this was a few yards up the hill towards what was Speech House Hill Colliery on the left (since 1969 the Beechenhurst picnic area) and then the Speech House uptop.
If you're new to the Old Maps site may I suggest you read this prior post to help ensure your best viewing, it can be a tricky site to access at first.
https://forum.forest-of-dean.net/index.php?id=38858

(2021 UPDATE - the Old Maps site appears to be u/s - try this much newer & better site instead. The works is at centre/right of this 1940s map.
https://maps.nls.uk/view/102346001

Thanks M for this query, on first reading the book a few months ago I hadn't fully realised the Works' importance for WW1 as you say. The War is an interest of mine and I didn't know the acetone was important in the making of Cordite, the explosive charge used to propel all those millions of artillery shells.
http://en.wikipedia.org/wiki/Cordite

The Wood Distillation Works at Cannop was first built abt 1913 for and run by the Office of Woods, intended to use the large quantities of waste wood generated during the felling of the oaks and other hardwoods. It was deliberately sited for the easy road and rail links. It first produced charcoal, acetate of lime, wood spirit and wood tar. However it was also realised that War was looming and such products would be increasingly necessary for the War Effort, so Government backing was also forthcoming. Ironically the main plant within the works was supplied & installed by the Meyer company of Hamburg. Acetone production was also planned, for Cordite production, but WW1 started before the necessary retorts could be installed in 1915, when the Works was bought by the Ministry of Munitions of War.
By the time it was "closed down, for the time being" in May 1919 the Works was referred to as "HM Factory, Dean Forest". The works were eventually sold and with some new equipment continued to produce albeit within a severely depressed market. After only producing charcoal thro the 1960s, the site eventually closed in June 1972, long afer it's railway links had been severed in 1963.

Re the adjacent Speech House Road Station, or more accurately a Halt with Signal Box, these links & photos may be of interest:
http://en.wikipedia.org/wiki/Speech_House_Road_railway_station
http://www.pastscape.org.uk/maps.aspx?a=0&hob_id=501033&mv=s
http://forestpictures.co.uk/page31.htm
http://www.archive-images.co.uk/index.search.php?sid=16445&img=8
http://www.forestprints.co.uk/speech_house_road_station_v2.htm
Re this last photo, it's hard to imagine this quiet country track is now the main B4226 road from Coleford upto the Speech House, with the Station Signal Box on the right and the main railway line crossing the road, now a cycle path complete with crossing "gates" if I recall correctly(?). The open ground seen between the Station and the camera was next to the sweeping curves of the railway sidings into the Distillation Works. These curves can still be seen as the edge of the treeline on the modern satellite image from the Pastscape site linked above - if you zoom into this photo you can clearly see an area of different (smaller?) trees which were presumably planted to cover the Works site once cleared, it looks a good place for a summer stroll, perhaps this week.

Hope this helps, if you don't have the book and still have any more-specific questions please ask and I'll try to help.
atb Jeff.

ps following our last "chat" I sent you an email re local bus books etc, I do hope you received it ok ?.

If interested this image gives a detailed railway map of the Forest showing the Severn & Wye Railway in red, Speech House Road Station at the centre, and also the competing Great Western Railway.
The S&W bisected the Forest linking the main line at Lydney via Parkend to Lydbrook, Drybrook & Cinderford, en-route serving the major Cannop Colliery etc.
Altho it seems a small image on first loading, clicking on the image will significantly enlarge it.
http://upload.wikimedia.org/wikipedia/commons/1/1a/Bilson%2C_Cinderford%2C_Coleford%2C_...

Campbell

This should help

http://www.forum.forest-of-dean.net/index.php?mode=entry&id=8292

you did not mention if this was related to your family or a more general question, perhaps related to a book you are writing (?) ...in which case I might consider this a breach of acceptable use http://www.forest-of-dean.net/?Help_FAQ_General_FAQ#faq13

regards
S

--
Ἀριστοτέλης A Gloster Boy in the Forest of Dean ><((((*>