142 The Phosphates of America. 



such excess shall therefore be deducted from the total phosphate 

 of lime found in the results of chemical analysis. 



"This chemical analysis shall be made in duplicate, from the 

 same sample, by two chemists, one representing the buyer and the 

 other the seller, and it shall be performed in strict accordance with 

 the method, in all its details, hereunder set forth. If the two 

 analyses only exhibit on their face a maximum difference equalling 

 one per cent, of phosphate of lime, such difference shall be adjusted 

 by taking the mean of the two results ; but in case the difference 

 should exceed this maximum, a third analysis shall be made by 

 another chemist, to be mutually agreed upon by the contracting 

 parties, and the settlement shall then and there take place upon 

 the basis of an average between the results of this third analysis 

 and those of that one of the other two first chemists which wa& 

 nearest to its figures." 



EXAMPLE. 



Chemist No. 1 finds 



Average of Nos. 1 and 3 ........ 77.80 2.92 



To strengthen these preliminary suggestions we will now set 

 forth what we regard as the best and the most practical methods 

 of sampling and analysis. These methods are being constantly 

 employed in our own work, and while we claim no originality for 

 them, they have stood the test of our experience in many fields 

 and on every variety of material with perfect satisfaction. 



SAMPLING. 



As this work is generally undertaken rather by practical working- 

 men than by analytical chemists, it is deemed advisable to point out, 

 in the plainest possible way, the easiest, most effective and accurate 

 method of conducting it. Nor need we dwell upon the importance 

 of this operation and the necessity for its being carefully super- 

 vised by all capable managers, for we have already shown that enor- 

 mous losses have continually been made and must ever surely result 

 from ignoring or disregarding details. 



When the phosphates are sampled upon the mine for the con- 

 trol of the daily work, it is necessary to take them from the piles. 

 The latter are therefore very carefully gone over, and averages are 



