460 Mr. Mawlinson’s Colour Mill. 
As to the quantity ground at onee on this mill, it must 
be regulated by the state of fineness to which it is re- 
quired to be ground. If it is wanted to be very fine, a 
smaller quantity must be put on the roller at a time; and 
as to time requisite for grinding a given quantity of co- 
lour, this will also depend on the state of fineness to 
which it is ground. I have observed that my colour- 
grinder has ground the quantity of colour which used to 
serve him per day, with this machine, in three hours, and, 
as he said, with ease. The colour also was much more 
to my satisfaction than in the former way, and attended 
with less waste. 
I have mentioned the pulverizing the colours in a co- 
vered mortar, which would prevent waste, and prevent 
the dust and finest parts of noxious colours from being in- 
jurious to the grinder. In some manufactories, where 
large quantities of colours, prepared from lead, copper, 
and arsenic, are used, this precaution is particularly ne- 
cessary. I do not mean to say that my machine is in- 
tended to supersede the paint-mill now in use for coarse 
common colours. It is intended for no such purpose; 
but to supersede the use of the very awkward and un- 
mechanical marble slab now in use, and on which all the 
colours for china manufactories, coach -painters, japan- 
ners, and colour-manufacturers for artists, &c. are now 
ground. 
Several of the colour-manufacturers have expressed to 
me their great want of such a machine ; and that I had no 
desire of troubling the public with a machine that would , 
not answer, is evident, from my having used it several 
years before I presumed to recommend it to their atten- 
tion. Being therefore now completely convinced of its 
utility, and hoping that it might relieve a number of my 
fellow -creatures from a dangerous employment, I have 
ventured to commit it to the protection of tbe Society of 
