The modus operandi with the wet method is as follows:--The barytes, in the requisite fine state of subdivision, is very thoroughly stirred up with water in a capacious vessel fitted with an agitator, the water being in sufficient quantity to make quite a fluid mass. In convenient proximity to the barytes tank, and elevated above it, provide three other tanks of lesser capacity furnished with means of discharging their contents into the barytes tank. In one of these smaller tanks dissolve the green copperas in cold water; in another, the sugar of lead; and in the third the bichromate and prussiate of potash together. When all the salts are thoroughly dissolved, and while the barytes is kept in constant agitation, admit first of all the copperas solution, then the lead acetate solution, and finally the combined bichromate and prussiate solution, never allowing the stirring to slacken till after the last drop of these solutions has been introduced. When the commingling of all the ingredients is judged to be complete, the green pigment formed is allowed to subside, and the clear supernatant fluid is siphoned off. The pigment is washed several times by admitting clean water, agitating and settling, and finally is removed, drained on a filter, and slowly and carefully dried. Many ways of arranging the apparatus will suggest themselves, the chief point to keep in mind being to economise labour as much as possible. The dry method of mixing is simplicity itself in comparison with the above, and merely entails putting the component materials--barytes, chrome-yellow and Prussian blue--through an edge-runner mill simultaneously, in the proportions adapted for producing the shade required. In giving formulæ for compounding these Brunswick greens, it must be understood that they are not absolute, as every manufacturer adopts his own particular proportions for a certain shade, but they form a sufficiently approximate basis from which to work. They are all computed for 100 lb. of barytes forming the body of the new pigment:-- _Pale_: Wet--1 lb. each copperas and prussiate, 12 lb. lead acetate, 3¾ lb. bichromate. Dry--80 lb. chrome yellow, 1¼ lb. Prussian blue. _Medium_: Wet--1½ lb. each copperas and prussiate, 12½ lb. lead acetate, 4 lb. bichromate. Dry--30 lb. chrome yellow, 2¼ lb. Prussian blue. _Deep_: Wet--2 lb. each copperas and prussiate, 13 lb. lead acetate, 4¼ lb. bichromate. Dry--30 lb. chrome yellow, 4½ lb. Prussian blue. _Extra deep_: Wet--3½ lb. each, copperas and prussiate, 14½ lb. lead acetate, 4½ lb. bichromate. Dry--30 lb. chrome yellow, 7 lb. Prussian blue.