The LNER Encyclopedia

This one has come up before, seemingly a single wagon built by Charles Roberts in the 1920s and still available if you're lucky in 00 model form.

Gas works shipped out a variety of by-products, including ammonia and tar, which would have needed tanks, but what was this one used for. I'm inclined to suspect ammonia but I really have no idea.

Up until the early 1970s, gas for domestic and industrial heating purposes was derived from bituminous coal in industrial plants called gasworks. After this time, the availability of natural gas from the oilfields in the North Sea made gasworks and their associated technology obsolete. Incidentally the main difference between Town's Gas from gasworks and Natural Gas from the North Sea was that the former was largely composed of carbon monoxide and the latter is methane.

The gasworks used the incomplete combustion of coal to extract the gas and other by-products, leaving a residue of carbon in the form known as coke. The method used which dated back to the early 19th century was to heat the coal in sealed ovens, just enough to drive off the gas and avoid burning the resulting coke which would produce carbon dioxide. Limiting the air supply gave carbon monoxide - the thermally active component.

The by-products fell into four main parts - hydrogen sulphide gas, ammonia gas, benzol, and coal tar. The hydrogen sulphide was removed by passing the gas coming from the ovens over damp ferrous oxide (rust). This captured the sulphur atoms to give ferrous sulphide (iron pyrites). This material was then sold to sulphuric acid manufacturers as a starter raw material.

The ammonia within the gas was scrubbed out by passing it through water. Ammonia is very soluble in water and the resulting solution of ammonium hydroxide was sold as a general chemical.

The benzol was a generic name given to liquids that were condensed after cooling the gas down and consisted of complex mixtures of benzine, toluene, and hetrocyclics such as pyridine and aniline. These were used as solvents in paints, inks, and general chemical intermediates. These had high vale and would be transported from the gasworks in rail tank wagons.

Finally, the cooling process of the gas gave the coal tars. These could range from thick, sticky, black liquids to tars that were virtually solid at room temperatures. These contained a very large range of valuable chemical building blocks suitable for dyestuffs and pharmaceutical manufacture - anthracene and nathalene are two that come to mind. These would be shipped from the gasworks in wooden barrels rather than tank wagons.

However, the more liquid coal tars were used in electric cable installation work. The early underground cables in the 1890 period were bare copper conductors laid into hot coal tar that had be pre-poured into wooden troughs. The coal tar served as an insulant and gave a modicum of mechanical protection to the conductors. By the 1900s, higher operating voltages had improved the technology into the familiar cable where the conductor(s) are wrapped with the insulant in the factory before being laid. Nevertheless coal tar was still used as a protectant in locations where there was a high incidence of sharp stones that could penetrate the cable covering. Up the 1930s tank wagons labelled Cable Compound carried this form of coal tar.

To summarise, rail tank wagons emerging from or owned by the gas company were likely to be carrying benzol and to a much smaller extent, liquid coal tar. I hope this hasn't been too technical for readers, and will go some way to explaining what was in these tank wagons.

Bill Donald
Dublin, Ireland

Excellent info Bill, you certainly get a wide range of knowledge on this site.

Now here's an interesting twist. I looked up "Newcastle & Gateshead Gas Co" in an old RCH Handbook of stations, and it shows under position "Same as Elswick (or Forth) Gas Works".

Perhaps, therefore, there is a connection with the coal-drops mentioned in the Elswick accident thread.

The Newcastle & Gateshead Gas Company had three main production sites that were rail-connected. These were:

Elswick - about 0.25 miles west of Forth Goods station.
Redheugh - adjacent to Dunston Staiths, about 1 mile east of Blaydon.
Willington Quay - immediately to the north of Willington Quay station.

These were the primary sources of Town's Gas for the Tyneside area.

Bill Donald
Dublin, Ireland.

Thanks Bill; but, just to show how confusing research can get, another document I have ("Traffic for and from Collieries, Works, Sidings & Depots connected with the North Eastern Railway", dated 1-9-18) shows 'St. Anthony's Tar Works' with Newcastle & Gateshead Gas Co as the customer, with Walker St. Anthony's as the accounting point. This may be relevant to the tank wagon.
The only other N&G Gas location shown is Redheugh Gas Works, entered at Dunston-on-Tyne, and for this location, under 'special instructions', there is the note 'Dimension of loads must not exceed Width 8 ft; height in centre from rail, 12ft 9in; height at sides from rail 9ft' (my emphasis). A curious profile!!! (and no mention of intermediate heights between side and centre).
Presumably the other two locations were yet to open in 1918.

The gasworks at Elswick date back to the 19th century. Willington Quay gasworks dates from the 1920s.

The tar works at St. Anthony's on the Riverside Branch processed the coal tar sent by the Elswick and Redheugh gasworks. The Industrial Railway Society's excellent though long out-of-print Industrial Locomotives of Northumberland and its companion volume for Co. Durham give more information on these installations. There was also a very small gasworks east of St. Peters which belonged to the NER and produced gas for carriage lighting purposes.

I gave some details of these in my presentation earlier this year on the Riverside Branch to the Newcastle SLS.

Bill Donald
Dublin, Ireland.

Many [if belated] thanks for that. As the tank in question is emblazoned with the St.Anthony's address, its presumably carrying tar, but the next question is whether it would be carrying the tar out on the big railway [so to speak] to the customer, or, as I suspect rather more likely transferring it from the gas works to St.Anthony's for processing