APPARATUS FOR PBUSSIAN BLUE. QQ^ 



rim that appears in the figure. Before the cover is put on, the 

 edge of the tub and the lower face of the rim are to be coated 

 with potter's clay well diluted, which will render the juncture 

 perfect. 



c is a copper tubulure, through which the stem of the beater 

 h is to be passed, before the cover is put on the tub, 



h elevation of the beater. Toward the upper end of the 

 stem is seen a piece of skin fastened to it. When the beater 

 is placed in the tub, and the stem passes out through tlje cover, 

 the lower part of the skin is fastened to the rim of the tubu- 

 lure, and thus the communication with the air is prevented, 

 without prejudice to the movement of the beater. The skin 

 used should be soaked in oil^ that it may not be injured by the 

 liquids put into the tub. 



g plan of the foot of the beater. 



d funnel through which the different solutions are poured 

 into the tub. 



/ a wooden plug used to stop the neck of the funnel 



i a cock, or spigot and faucet, by which the Prussian blue is 

 drawn off from the tub, after the solutions have been well 

 mixed in it. 



n a small tub, sunk into the ground, into which the result 

 of the mixture runs. As the liquid Prussian blue runs into 

 this, it is dipped out with a ladle into a bucket, to be carried to 

 the casks, in which it is to be washed with a large quantity of 

 water, 



e a curved tube fixed to the dome. 



fa tube of the game diameter fixed in the ground. The 

 dotted lines, terminating at m, point out the situation of this 

 tube, which is placed parallel with the surface of the ground, 

 and terminates in the ash-pit, near the grate of the furnace 

 where the prussiate of potash is prepared. When the cover is 

 put down on the tub, the tube e should enter into the tube f, 

 and the juncture is to be luted with a little potter's clay. 



Fig, 2 represents the apparatus put together, and ready for Mode of uiinj 

 use. When ihe solutions are prepared, the door of the ash-pit, ''• 

 in which the tube terminates, is to be shut close ; the plug / is 

 to be taken out of the funnel, and the solution of alum and 

 sulphate of iron poured in, A workman mounts a little stool, 

 takes hold of the stem of the beater /i, and begins to agitato the 



liquor 



