174 



LOWER PENINSULA. 



brine from the upper rock and any fresh water that may come into 

 the well above the offset are shut off. Below the offset, the tube 

 continues in reduced size to the locality of the lower sand rock, at 

 which point the pumping chamber containing the pumping valves 

 is placed. 



In the early history of salt-well boring in Michigan, the pressure 

 of the brine in the well tube forced it within loofeet of the surface. 

 More recently, owing no doubt to the great demand for brine, it 

 does not rise so high. It only requires a small amount of power, 

 after the pumping rods are properly balanced, to lift the brine 

 out of the well into the settling tanks. 



PUMPING BRINE. 



Often, in starting up a new salt well, the brine is weak — that is, 

 shows a small percentage of salt by the salinometer. This arises 

 from the fact that a large quantity of fresh water or weak brine 

 from the upper formations has passed down into the well during 

 the time the well was opened or being tubed. To test this point, 

 and to bring the brine up to the usual strength of salt brines, the 

 pump is put in operation and run for some time. If the brine con- 

 tinues to show an increase of strength on being tested by the sali- 

 nometer, the pumping is continued until the strength of brine re- 

 mains permanent at such a percentage as wells of equal depth in 

 the same locality have shown. 



If, however, the brine does not increase in strength, there are 

 strong probabilities that there is a leakage of fresh water or weak 

 brine into the well at the offset. This should be remedied at 

 once — the more so if the well is a deep one, such as most of those 

 in the Saginaw Valley are ; for in this case the offset in the well is 

 below the so-called gypsum formation, and you are drawing in and 

 mixing with your strong brine a weak brine from these formations 

 which has a higher percentage of gypsum. 



This mixing of the two brines in the well and tubing -causes a 

 precipitation or separation of the gypsum upon the pumping rods 

 and in the pumping chamber. If this is not stopped, it will 

 eventually close up the valves, and prevent them from being drawn 

 out of the chamber. More than one instance has been known where 



