190 LOWER PENINSULA. 



and centre post 18 feet high — almost too high to carry off the steam 

 in winter. The length was also calculated for four pans. Three 

 pans only were put on, being each 30 feet long and 16 feet wide on 

 bottom, sides flanging and bolted to the draining boards. 



The pans rest on seven walls, which are so arranged that they make 

 two fire flues in the centre and two return flues on the sides. 



The centre and outside walls run the entire length and width of 

 the pan. All the walls are a foot wide at the top. The two fire 

 flues which are under the middle of the pan on both sides of the 

 centre wall are 2^ feet wide. Height of grate to pan, 3^ feet. 

 The return flues are next to the outside walls, under the sides of 

 the pan, and are 2 feet wide. This gives a heating surface of 

 180 feet in length on both sides of the middle wall. The outside 

 flues run into the chimney, which is placed at one side of the 

 front of the block — the space under the pan being reduced to one 

 foot. 



The advantage of this arrangement of the flues is that, as the brine 

 boils freely over the fire flues, the salt, as it makes, is thrown to the 

 cool side of the pan, and therefore it is not so liable to bake to the 

 bottom of the pan before it is raked out. Another advantage is in 

 the economy of the heating surface, the entire amount being well 

 used up before it gets to the chimney. This is shown in the 

 amount of salt made— Ayres & Co. reporting the making of 140 

 barrels of salt with 13 cords of hemlock wood in a day of 24 hours. 



The brine for pan blocks is settled cold in the outside cisterns, and 

 in most instances is brought to saturation by the inside steam set- 

 tlers. The salt, as it makes in the pan, is drawn out by rakes upon 

 the draining boards, where it remains for a time, when it is shovel- 

 led into barrows and taken to the store bins for further drainage. 



It is very desirable that the draining boards should be so arranged 

 in pan blocks that the workmen should not be compelled to walk 

 over them in the operation of drawing or wheeling off the salt. 



EVAPORATION OF BRINE BY STEAM. 



The evaporation of salt brine by the steam process is now pro- 

 ducing the largest portion of salt made in Michigan. 



In describing the arrangements of a steam salt block and the ac- 

 companying process, we have selected the steam salt block, drill 



