Principles and practice of agricultural analysis. Volume 2 (of 3), Fertilizers

by Harvey Washington Wiley

Figure. 2.

Plate Grinder for Minerals.

8. Mixed Fertilizers.—In fertilizing materials in bulk, the first requisite is that they shall be thoroughly mixed so that a given volume of the material may represent, practically, definite quantities of the materials sampled. The finer the material is, in the original state, and the more thoroughly it has been mixed, the better the sample will be. If the sample be already in sacks it will be sufficient to take portions by means of the ordinary trier, such as is used for sampling sugar and other substances. This consists of a long metal implement 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 should be taken from various parts of the sack and these samples well mixed together and a subsample of the amount necessary to be taken to the laboratory can then be obtained.

9. Method of the French Experiment Stations.—In the method employed by the French Experiment Stations it is directed that in no case should stones or other foreign particles be removed from the fertilizer sampled, but they should enter into the sample taken in, as nearly as possible, the same proportions as they exist in the whole mass.

In the case of stones or other solid masses which are to be sampled, as many samples as possible should be taken from all parts of the heap and these should be reduced to a coarse powder, thoroughly mixed together and sampled.

In case the material is in the form of a paste, if it is homogeneous, it will be sufficient to mix it well and take the sample directly; but in case there is a tendency for the pasty mass to separate into two parts, of which the one is a liquid and the other, more of a solid consistence, it may be well to take samples from each in case they can not be thoroughly incorporated by stirring.

10. Method of the French Association of Sugar Chemists.—The method adopted by the French sugar chemists directs that the sample should be taken from the fertilizer in bulk or from a portion used for industrial purposes.[4] The sample for analysis is to be taken from the above sample after it has been sent to the laboratory. The method of taking should be varied according to the condition of the substances to be analyzed.

The large sample selected from the goods delivered to commerce having been delivered at the laboratory, the analytical sample is taken as follows:

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 contains 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 sample is to be properly prepared in order that a portion may be taken representing exactly the mean composition of the whole.