COLLECTION OF SAMPLES. 13 



to obtain the best results. The supply should be uniform and con- 

 tinuous. When using iron kettles or pans this can hardly be accom- 

 plished, as they are either filled with sap and the fire built under them 

 or are filled and swung down onto the fire by block and tackle or by 

 the arm and the contents allowed to concentrate. With other forms 

 of iron pans or of patent evaporators there is a continuous stream, 

 which is siphoned over into other parts of the boiling system. The 

 best results with iron kettles or iron pans are obtained by concen- 

 trating the charge, drawing off the sirup, and then recharging. Care 

 should be exercised, as with all forms of evaporators, to keep the 

 fire from touching parts of the surface not covered with the boiling 

 sirup, which will scorch or blacken the sirup. Scorching is the cause 

 of much of the dark-colored sirup noticed in the iron-kettle method 

 of evaporation, as well as the fact that a great many makers add to 

 the boiling pot all day and finish the sirup at night. 



The effects of cleansing and also of lack of cleansing on the color 

 and flavor of sirup are described under the appropriate caption 

 (p. 54). 



COLLECTION OF SAMPLES. 



Many chemists have made analyses of pure maple sirups and have 

 determined their constituents. Prominent among these are Jones, 

 of the Vermont Agricultural Experiment Station, Hortvet, Winton, 

 and others, while McGill has published analyses of the Canadian 

 sirups. These results are based on samples obtained from one or 

 more restricted localities. It might be said in this connection that 

 it is only within the last ten years that any successful attempt has 

 been made to differentiate between pure maple sirup and that mixed 

 with other sugar sirups. 



In order to obtain as complete a knowledge as possible of the pure 

 maple sirups produced in the United States an investigation was begun 

 during the maple season of 1909. Having succeeded in obtaining 

 numerous representative samples of maple sirup from all of the 

 important maple-producing sections of the United States, it was 

 thought well to include also those sirups made in the Dominion of 

 Canada just north of our boundary line. As the sirup season is 

 very short and the field to be covered was large, it was found advis- 

 able to have the official inspectors of the Bureau collect a portion of 

 the samples. Letters of instruction were sent out clearly defining 

 the kind of samples wanted, the field to be covered, and the informa- 

 tion to be obtained, including the manufacturing data, etc. The 

 following assignments were made, and the valuable service rendered 

 by the inspectors in the collection of samples and data is acknowl- 

 edged: Indiana and western Ohio, W. H. Jenkins; Michigan, O. R. 

 Sudler; eastern Ohio and West Virginia, William T. Ford; western 

 New York ; W. C. Miller; Pennsylvania, C. A. Meserve; central and 



