I haven't seen liquid graphite available in Canada except for the liquid graphite pencils that Brian mentioned. I've tried those and they're horrible.
You can buy liquid graphite from
Jerry's Artarama in the USA and perhaps other places. It is an Australian product. I did write to the manufacturer asking about it, but didn't get a response. Great customer service!

From what I've read, you can get very much the same results with a watersoluable graphite pencil or a grey watercolour for that matter. Once wetted, you can't erase, so it has the same permanency properties as any other waterbased material. I have used
Derwent Aquatone pencils and think they would have similar effects.
I've also just used a graphite wash pencil -
The General...and its similar to aquatone pencils, soft dark tones to draw with and watersoluable.