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Geology . 
d. The engraver of copper-plate patterns. 
e. The weaver of the cloths for the printing table-* and 
the roller-work. 
f. The knowledge necessary under what circumstances 
to use the adhesive mixtures of the printer ; when to em- 
ploy, gum arabic, gum Senegal, or gum tragacanth ; 
when to employ raw or parched flour ; when to substi- 
tute gypsum, &c. implying considerable chemical know- 
ledge. 
g. The colour man, who mixes the colours and makes 
the mordants, whose business cannot be well or economi- 
cally conducted, without considerable chemical know- 
ledge. It is his business to know how to make each 
mordant proper to fix the colour of each colouring drug ; 
in what proportion the mordant and the drug must be 
used to give the required colour, when the piece comes 
out of the dye-copper. What drugs from various quar- 
ters of the world, yield not only the required colour, but 
at the cheapest rate and of the required tinge. In what 
order and succession the colours are to be printed on the 
cloth. What patterns will bear colours printed on at once 
without dying, and what requires to be dyed after print- 
ing. How many colours can be raised by one and the 
same immersion in the dye copper. What colours and 
patterns require to be printed, dyed, penciled or discharg- 
ed, to produce the work required in the market. All this 
and much more is necessary to be known in the colour 
shop of the printing establishment. 
h. When to this we add the knowledge requisite to 
erect and manage in the best manner, the water works, 
dash wheels, stoves, calenders, presses, &c. of such an 
establishment, there can hardly remain a doubt but much 
knowledge must exist where these establishments arc 
common, more than where they are unknown. But it is 
not the knowledge required or displayed in each particti- 
