The new discussion focuses on a class of substances called promoters.
These contained a substance called Spread, and, indeed, that was all you could do with it.
Also some substances, called stimulants - coffee is such an example - can cause poor sleep.
The rest is formed from an invisible substance called "dark matter".
One thing that builds up is a substance called bilirubin.
The main difference between other series is the use of a substance called Regel.
Together we've tasted a tiny piece of the sweet substance called hope.
The letter to Collins said there was evidence she used a substance called "the clear."
They protect the body from damage by substances called free radicals.
According to the theory, the body was filled with four different substances, called humours.