Why do I do these things Volume XXX

No, the XXX doesn't refer to hyper-indecent content.  Be calm.. It refers rather to Prussian Blue, and my habit of using colours just because they happen to be on hand, or I fancied a change.  I had an old tube of Prussian Blue - indeed, still have; and here lies the trouble.  I saw it, lit upon it, thought "haven't used that for a long time...", and thought I would; on a WIP.  It's an impossible colour!  I know why WHY I haven't used it for a long time - I've now got a wet oil painting, which reeks of Prussian Blue (I'd forgotten that it stinks): trying to calm it down, apply it subtly, mixed with other colours .... it doesn't mix, it dictates!  It overpowers everything, and because I used it with a non-lead white, which would at least have held it in check through not being slick with oil, it is just so wet (as am I, for having used it).  I'm going to let it surface-dry, before glazing it with reds and yellows, to kill that hard, metallic look - though it isn't a metallic paint, it's a dye.  Even Pthalo Blue would be easier to control - Prussian Blue is a beast!   You might want to bear my experience in mind (it's even given me a sore throat..); if you're thinking of using it, well by all means do - I may well do so again, with some better ventilation next time.  But I wish I'd remembered that given half a chance, it starts an invasion of neighbouring countries.  I bet Alan Bickley gets on with it - indeed, I can see uses for it, but not maybe in what I'd intended as a quiet country scene; the oil version - it's less controlling in acrylic and watercolour - but even with a non-professional grade of paint (this is Daler-Rowney's Georgian range - and a tribute to the strength of their colours ) I shall be very much more careful and reserved with it in future.   Can't but wonder how others get on with it - I know it features on rather few artists' palettes. 

Yes, I use it in acrylic.  In oil, the tube I have has an acrid smell which is very unpleasant; whether other brands (this is an old tube, though not antique) have similar characteristics, I don't know. I do use pthalo blue and green (there's also a Prussian green - I've not seen any for quite some time), both of which are very strong but not so aggressive as the Prussian; I think probably using this on a small painting was a mistake - I think I could more easily handle it over a larger area.  It doesn't behave in the same way in acrylic, or look the same - I'm now looking forward to seeing what Alan produces with it.... I think it'd work in a wintry scene, but far be it from me to recommend a use to him.....  I've just looked at the tube, and I think the explanation of the smell has become clear; it's PB 27, pigment "Ferri - Ammonium Ferrocyanide": I doubt that it's as lethal as that sounds, though I won't be brushing my teeth with it, but that ammonia smell is certainly present  - however, "No Health Labelling Required", apparently; perhaps I'm just over-senstive to ammonia.