from rains. All handling of apparatus should be done in as cool a place as possible and out of direct sunlight. In direct hot sunlight the end point is vague, and it is difficult and sometimes impossible to obtain reasonable accuracy. Solutions of iodine and starch carried in the field should be protected from light and heat by covering the bottles with thick toweling, which is kept damp with water.
Frequency of DeterminationsAn operator familiar with the manipulation of the apparatus can make one complete determination in about 3 minutes.It is the best practice to make determinations at 4or 5-minute intervals, using the hourly averages for studying the general trend. Such determinations, made at exactly equal
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