Since this is a re-read for me, and I stand by my original review/rating, this post will serve as my final reading update. As such a few thoughts on the final three entires:
"[...] to ensure no ricin makes it into the castor oil it is heated to more than 80C at it is extracted; this denatures the protein, so inactivating it."
Something for the raw food movement to remember: don't buy cold-pressed castor oil. Sometimes, processed is better.
Oh dear god what a thoroughly hideous way to die. The deciding factor for me, in a book full of thoroughly hideous ways to go, is that you're completely aware of what's going on the entire time it's happening. Like Hemlock, only here there's zero chance of getting the "nice" kind (if a nice kind of hemlock actually does exist - let's nobody find out).
I also had the weird and totally superfluous thought: I wonder if anyone's ever tried spraying a victim down in solarcaine? (Solarcaine is an aerosol form of lidocaine - topical anesthetic.) Because, you know, it's a numbing agent, which would cut off nerve stimulation. Although I can't imagine it would be very comforting to be in the throes of strychnine and hear: "Quick! Get the sunburn spray - this might feel a little cold..."
So, now you know where my mind goes when it's running from descriptions of horrific death. Sunburn spray.
Moving on... Veronal.
I had almost no thoughts about Veronal at all; probably because I was still musing over the sunburn spray ... not because of any deficiencies in Harkup's writing.
As I said at the start; I happily stand by my first assessment of the book at the 4.5 stars I gave it. It's entertaining and accessible without sacrificing intellectual merit.
If you have a reading retention rate for details better than mine, you might find some of the sections she doesn't label as spoilers to be over-revealing. Unlike others, the only one I found that will stick with me over time is the (to me) dead give away in the Veronal chapter for Lord Edgware Dies, although maybe it isn't. The way it's written it seems there's only one scene needed to identify the murderer, given what Harkup shares here. Perhaps the scene is more complicated than she describes though. Luckily, I need only read enough books between now and my next Christie to completely forget, confuse or conflate the details I've read here. Silver linings...