2 AGRICULTURAL ANALYSIS 



or which may once have been part of vegetable and animal organ- 

 isms. 



For a full description of the extent and origin of these deposits 

 the reader is referred to works on economic geology. A brief 

 description of them is given further on in connection with the 

 fertilizing materials which they furnish. These deposits are the 

 chief sources of the commercial fertilizers of a mineral nature 

 which are offered to the farmers of to-day and to which the agri- 

 cultural analyst is called upon to devote much of his time and 

 labor. The methods of determining the chemical composition and 

 agricultural value of these deposits, as practiced by the leading 

 chemists of this country and Europe, will be fully set forth in the 

 following pages. 



3. Waste Matters as Fertilizing Materials. In addition to the 

 natural products just mentioned, the analyst will be called on also 

 to deal with a great variety of waste materials which, in the last 

 few years, have been saved from the debris of factories, abattoirs 

 and other sources and prepared for use on the farm. Among 

 these waste matters may be mentioned bones, horns, hoofs, hair, 

 tankage, dried blood, fish scrap, oil cakes, ashes, sewage and sew- 

 age precipitates, offal of all kinds, leather scraps, and organic 

 debris in general. 



It is important, before beginning an analysis, and especially be- 

 fore passing a final judgment on the data obtained, to know the 

 origin of the substances to be determined. As has already been 

 pointed out in the first volume, the process which would be ac- 

 curate with a substance of a mineral origin might lead to error 

 if applied to the same element in organic combination. This is 

 particularly true of phosphorus and potash. A simple micro- 

 scopic examination will usually enable the analyst to determine 

 the nature of the sample. In this manner, in the case of a phos- 

 phate, it would at once be determined whether it is derived from 

 bone, mineral, or basic slag. The odor, color and general con- 

 sistence will also aid in the determination. 



4. Valuation of Fertilizing Ingredients. Perhaps there are no 

 more numerous and perplexing questions propounded to the 

 analyst than those which relate to the value of fertilizing materials. 



