8 AGRICULTURAL ANALYSIS 



gas, pure air may be blown through it. The mechanical method 

 by paddles or other stirrers, however, is to be preferred when 

 it can be practiced. The sampling of water for analytical pur- 

 poses requires special methods which will be given later. 



12. Sampling a Solid. The general principles which should 

 underlie and regulate the sampling of solid materials are 

 more difficult to enunciate. Here we have the greatest variety of 

 conditions. Solid materials may be of such a character that they 

 may be easily mixed ; as, for instance, in the case of a powder or 

 any substance in a finely subdivided state. On the other hand, a 

 material from which a sample is to be taken may be solid, ex- 

 tremely hard and difficult of disintegration, as is the case with a 

 rock or a piece of metal or of wood. The difficulties which ob- 

 tain, therefore, are very great in this class of bodies and require 

 special precautions, great experience and knowledge of the sub- 

 ject and the exercise of patience in order that good results may be 

 secured. Where bodies can be perforated as in the case of wood 

 very good samples may be taken by means of augers which are 

 made to penetrate the wood at different places, and thus a sam- 

 ple secured. If the material is contained in bags or barrels 

 which are easily penetrated, the ordinary trier which is used for 

 sampling is, as a rule, sufficient to give an average sample. In the 

 case of metal, boring may be practiced with a small drill and rea- 

 sonably satisfactory samples secured. 



The local conditions which obtain, the character, size and shape 

 of the body, the facilities at hand for sampling, the purpose for 

 which the analysis is to be made, and the general environment will 

 be sufficient to guide the expert analyst in his work and enable 

 him to get a sample of material which to him is a reasonably sat- 

 isfactory representative. In a little more general way it may be 

 said in regard to liquids which are supposed to have been mixed 

 at one time and which have been barreled or bottled as in the 

 case of wine, vinegar or beer it is always advisable to take a 

 portion of the sample from each package. Solids which are finely 

 divided and evenly mixed according to a uniform standard and 

 which have been taken from a single source, as, for instance, in 

 the case of fertilizers which are contained in bags, should have at 



