66 



MAPLE-SAP SIRUP. 



rotation when the invert solution was polarized at 87 C., the results 

 being as follows : 



Polarization of 23 samples of maple sirup, showing rotation at 87 C. 



Only two samples showed plus or dextro rotation, the remainder 

 being negative or levorotatory. To test these observations the ver- 

 niers and scales were set at and a reading made when the tem- 

 perature of the solution had reached 87 C. If the field was of even 

 color, no rotation was indicated and two or three check readings 

 were made. If the field showed a different color, a reading was made 

 in the usual way. 



TANNIN BODIES. 



The ferric chlorid test showed the presence of tannin in 29 of the 

 481 samples. In only one case was the reaction very marked, although 

 in others there was a strong indication of the presence of tannin. In 

 all but four cases the color of the samples was darker than No. 10 of 

 the color scale; the greater number ranging from No. 13 to No. 14. 

 The exceptions are one sample with the color of No. 6 + , two with 

 that of No. 9, and one like No. 7. Tannin is not a normal constitu- 

 ent of maple sirup ; it probably conies into the sap from the washings 

 of the tree and may be taken out with the scum. If a sap containing 

 tannin comes in contact with an iron surface, as in boiling in kettles, 

 it generally yields a dark-colored sirup. 



THE ASH. 



The highest per cent of ash in the United States samples, as collected, 

 was 1.06 and the lowest 0.46, the average being 0.66 per cent. On 

 the 481 samples, including Canada, both this average and the extremes 

 remained unchanged. The 0.46 per cent of ash was determined on 

 sample 6680 from New Hampshire, which in all other particulars 

 seemed to be pure. The water content of this sample was 32.50 per 

 cent and, calculating the ash to the dry basis, the result is 0.68 per cent. 



