^Yep. We can't tell you anything from 'liquid morphine'. If it's pharmaceutical it should have mg/ml on the bottle. If someone just gave you a blank bottle and said it was liquid morphine it could vary from 0mg/ml to who knows
It's usually either 1mg/ml, 2mg/ml or 10mg/ml. Probably the latter if it's intended for IV use.
Like Quere said, if you got a blank bottle on the street it could be *anything* including water or acid.