Conversation so far:
What was the first chemical experiment?
From an early age Watt was very interested in chemistry.
When did he start doing chemical experiments?
in March 1788, McGrigor was able to bleach 1500 yards of cloth to his satisfaction.
What was McGrigor's relationship to James Watt?
By 1794 Watt had been chosen by Thomas Beddoes to manufacture apparatus to produce.
What was the name of their company?
CANNOTANSWER.

Question: How long did he work with McGrigor?
Self-contained rewrite: How long did James Watt work with McGrigor?