Posted by Peter H on October 23, 2007 at 18:15:07 from 86.130.133.85 user Peter_H.
In Reply to: Re: Prospecting - Here's to Copper! posted by Jock on October 23, 2007 at 16:37:53:
In high enough concentrations copper is toxic to animals and humans.
Which is why it should not be used in a laundry! However, I assume that copper sulphate was used for industrial 'whitening'. The 'blue' used for whitening fabrics during ordinary domestic washing was a pigment, a kind of artificial lapis lazuli, assembled from various materials, but not copper compounds. The most famous was 'Reckitts Blue', a Hull firm which took over a 'blue' factory at Backbarrow, at the foot of Windermere (luckily putting this thread slightly back on topic).
Backbarrow Ultramarine Works Co
I have not heard of copper compounds being used by 'washerfolk', but maybe it is or was somewhere. Again, to raise the copper ion content of effluent to a level which would kill tree roots suggests to me an industrial level of usage. (Once again I fear that this thread is getting a bit 'plumbing-ish', or should I say 'cupro-ish'.)