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with much ardour to the study of chemistry, to which his 
attention had been directed by the purchase at an old book- 
stall of a copy of “ Parkinson’s Pocket Chemistry.” He 
then began to experiment on colours for calico printing, and 
at the end of 1817 had succeeded in applying some totally 
new colours to calico. Amongst these was the orange sul- 
phuret of antimony, a colour so much brighter than the one 
up to that time dyed with annotto as to immediately attract 
the notice of the calico printers in the neighbourhood. His 
success led to his appointment as chemist in Mr. Fort’s 
works, at Oakenshaw. In 1825 he was admitted a partner 
in the concern, and continued in this capacity till 1848, 
when the firm, having been very successful, gave up the 
business, Mr. Mercer retiring with a handsome fortune. He 
thenceforward devoted himself to theoretical chemistry, and 
was during later years in correspondence with many of the 
first chemists of the day. 
It would be difficult to name all Mr. Mercer’s inventions 
in connection with calico printing. It may suffice to mention 
those with which his name is chiefly associated. The long 
popular style of manganese brown, with white discharge 
and wood-colour illuminations, was his invention, and hun- 
dreds of thousands of pieces in this style must have been 
printed. He contributed largely to the chemistry of indigo 
dyeing, and invented an ingenious process for discharging 
indigo blue by means of alkali and red prussiate of potash. 
He was the original maker of dry stannate of soda, now so 
largely used by calico printers, Mr. Steiner having previously 
introduced the liquid stannate of potash, a much more 
costly article. He was the first to apply arseniates as a 
substitute for cow’s dung in madder dyeing, phosphates 
having previously been employed for the same purpose. 
The chlorinating of woollen fabrics and mixed fabrics of 
wool and cotton, whereby a property of seizing and retaining 
colours with greater facility is given to wool, was, as all 
