Tim – try following this link it should take you to a downloadable pdf and I think the info you're after is on page 25. It looks as though the fluid could be available from folk who stock spares for old (1930s) Fords, I've seen references to suppliers in the USA but I don't know whether you'd be able to get it over here though.

It's used in a U-tube manometer to measure the pressure at the bottom of the petrol tank so needs to have the correct SG. The instrument was called a Hobson Telegauge. A google search for Hobson Telegauge fluid comes up with a number of suppliers. No idea what it consists of though. I did have some some years back from my car restoring days but can't find it now.

Russell

Seems to be a lot of information online if your search "Hobson K-S petrol telegage".

It seems the original fluid is tetrabromoethane.

Neil

Pure compounds of this type are easily identifiable.

Methylene Iodide like to solidify just below RT and it smells very similar to bromoform which smells similar to chloroform but its boiling point and density is much higher.

Mercury iodide is very difficult soluble solid – it won't be there and barium Iodide is solid but will form very heavy liquid once dissolved in water. This solution mix with water but bromoform, methylene iodide or tetrabromoethane does not do so. Mercury or barium iodide do not have smell unless partially decomposed – then there might be faint iodine smell

Forget tungsten, thorium or uranium compounds (mainly halides) – they are not there. Very reactive, corrosive and are reacting with water violently.

If not miscible with water measure boiling point (boil it in conical flask with termometer above liquid level), check if it solidify in fridge and in freezer (may take few days, shake flask vigorously once cold to speed process up), describe smell and will give you idea.

Hydrohalocarbons (tetrabromoethane, bromoform or methylene iodide) are not flammable and they are miscible with petrol, acetone or ethanol.

Of course it might be mixture of few compounds.

Tertabromomethane (carbon tetrabromide, not to be confused with tetrabromoethane) is solid.

Regarding safety of halocarbons – politically correct assesment is "very dangerous, cancerogenic ozone depletors blah blah blah…" but practically only slightly harmful compounds. Was working with all of them in the lab, breathed vapours because fumecupboard was working poorly, poured over my hands on number of occassions, nothing happened. My former boss is over 80, was doing it whole life – nothing happened.

Mercuric iodide or barium iodide are in practice moderately toxic – very difficult to absorb toxic quantity not deliberately. Poliitically correct peoples are calling them to be very or extremely toxic, but then powderized dried roots of A. napeallus (monkshood) common in English gardens would be *extermely extremely toxic*, so it is best not to abuse meaning of words.

I would pay a bit of respect to tungsten, thorium or uranium halides due to their great chemical reactivity (would dissolve or rather decompose skin or eye tissue nicely).

Edited few times for clarity

Martin

Edited By Martin Dowing on 11/10/2017 18:41:23

Edited By Martin Dowing on 11/10/2017 19:03:01

Edited By Martin Dowing on 11/10/2017 19:05:56