gif:coupling

Are Mary and John living together yet in MHR

from a close analysis of the text, you can tell Mary hasn’t moved in yet. Maybe they haven’t even met! How do you know?

THE CUSHIONS.

Moffat’s views on cushions are well-known. Single men don’t have them. Women bring them when they move in:

So what does John’s flat look like in MHR?

He does have one large cushion, but that looks to me more like a pillow. Less decorative, more sleeping-off-a-hangover on the couch.

Now, from HLV:

Two cushions, different from the above, and decorative.

Mary bought them when she moved in, therefore she hadn’t moved in yet in MHR. QED.

Coupling diazo compounds with copper bronze (ultra fine copper powder). It exactly looks like glitter powder in the flask. 

Even through it was a heterogeneous reaction (the reaction took only place at the surface of the copper) a relatively high percent of the desired product formed. Good point: the side product could be removed easily via distillation, so this was a quite easy method for producing a compound. Copper and other transition metals are often used as catalyst for coupling reactions, the most popular is palladium, it is good for everything.