JgJ^ MR. IlAWLI>'SON*S COLOUR Mill. 



R^ert:nce to the improved Mill for grinding Indigo, or other 

 dry Colours, 



Defcription of Plate V» Fig. 4. L reprefents a mortar made of marble or 

 the mill for dry j^^j.^^ |^jj,^g ^^^ j^^^j^ jj^ jj^^ common way will anfwer. M, 

 grinding. , -' 



A muller or grinder, nearly in the form of a pear, in the 



^ upper part of which an iron axis is firmly fixed, which axis, 



at the parts N N, turns in grooves or flits, cut in two pieces 

 of oak proje6ling horizontally from a wall, and when the axis 

 is at work, are fecured in the grooves by iron pins, O O. 

 JP, the handle, which forms a part of the axis, and by which 

 the grinder is worked. Q, the wall in which the oak pieces 

 N N are fixed. R, a weight which may occafionally be 

 added, if more power is wanted. 



fi^, 5. (hews the muller or grinder, with its axis feparale 

 from the other macl>inery ; its bottom ftiould be made to fit 

 the mortar. S is a groove cut through the done. 



On grinding indigo, or fuch fubftance, in a dry flate, in 

 this mill, the muller being placed in the morlar, and fecured 

 in the oak pieces by the pins, the indigo to be ground i$ 

 thrown above the muller into the mortar; on turning the 

 handle of the axis, the indigo in lumps falls into the groove 

 jtUrt through the muller, and is from tlience drawn under the 

 action of the muller, and propelled to its outer edge within 

 the mortar, from whence the coarfer particles again fall into 

 ♦the groove of the muller, and are again ground under it ; 

 which operation is continued, till the whole of it is ground 

 jU) an impalpable powder ; the muller is then eafily removed, 

 jaxid th^ colour taken out. 



A wood cover, in two balves, yv'Uk a hole for the axi«, 

 is ufually placed upon the mortar, during the operation, 

 Ao prevent any lofs to the colour, or bad ejflccl to tliq 

 oprCralor. 



J nciv 



