Note: Anything in Italics is Sherlock and John's thoughts.
Just because it's silent, doesn't mean that someone isn't speaking. To some, silence can be equal to a million words being spoken.
If there is one thing that Sherlock Holmes is notorious for, other than his amazing deductive prowess, it would be his constant unusual experiments which, more often than not, include the use of dangerous chemicals or other hazardous things. Normally, Sherlock has control of the experiment enough that nothing bad ever happens because of them, but there are times where, while it is rare, an experiment will backfire and can cause damage to the flat or have other adverse side effects.
Today, was one of those rare times.
Sherlock had been in the kitchen preforming some sort of experiment; what it was for and why he was doing it, even John didn't know. John didn't ask questions about it - he had learned that he would rather NOT know what Sherlock was experimenting for - And he simply walked