14 AGRICULTURAL ANALYSIS 



the sample is apt to be nonrepresentative. The finer the materials 

 in the original state and the more thoroughly they have been 

 mixed the better the sample will be. If the materials be in bags 

 it will b*e sufficient to take portions from every tenth bag or from 

 three or four of the bags if there be less than ten, by means of an 

 ordinary trier which is thrust through the bag and filled with the 

 material therein contained. This consists of a long metal im- 

 plement such as would be formed by a longitudinal section of a 

 tube. The end is pointed and suited for penetrating into the 

 sack and the materials contained therein. On withdrawing it, 

 the semi-circular concavity is found filled with the material 

 sampled. Samples in this way are removed from various parts 

 of the bag and these samples well mixed together and a sub- 

 sample of the amount necessary for the laboratory is then ob- 

 tained. Quite a great deal more of the sample should be secured 

 than is necessary for the analysis and this quantity may be 

 called the "Industrial Sample." When the industrial sample, 

 more or less voluminous, reaches the laboratory, the chemist is to 

 begin by taking a note of the marks, labels and descriptions found 

 thereon, and of the nature and state of the package which con- 

 tains it and the date of its arrival. All this information should 

 be entered upon the laboratory book and afterwards transcribed 

 on the paper containing the results of the analysis, as well as the 

 name of the person sending it. This having been done, the sam- 

 ple is to be properly prepared in order that a portion may be 

 taken representing the mean composition of the whole. 



If it is in a state of fine powder, such as ground phosphates 

 and certain other fertilizers, it is sufficient to pass it two or three 

 times through a sieve with meshes one millimeter in diameter, 

 taking care to break up the material each time in order to mix 

 it and to pulverize the fragments which the sieve retains. The 

 whole is afterwards spread in a thin layer upon a large sheet 

 of paper and a portion is taken here and there upon the point of 

 a knife until about twenty grams are removed, and from this 

 the portion subjected to analysis is afterwards taken. 



If the sample comes in fragments, more or less voluminous, 

 such as phosphatic rocks or coarsely pulverized guanos contain- 



