CuSO4 is the chemical symbol for
anhydrous copper sulphate, that is having no water of crystallisation present. It's a very pale green to greyish white powder.
The stuff you by over the counter is usually the bright blue pentahydrate; that is it has five molecules of water attached and is properly denoted as CuSO4.5H2O
Angier intended that the anhydrous form be used unless the word "cryst" is given as a suffix in the formulation.
The basic chemical natures of the two are the same, but using the pentahydrate will put fewer copper ions into the mix than using an equal weight of the anhydrous form. If all you can get is the blue stuff add 1/3 by weight extra, and you'll be close enough.
that was a long, long time ago and knowing Governments they probably renamed it or something.
Angier stated that at the time of writing only 92 elements were known; things have certainly gone with a bang since then!
Eug