INSECT POWDER. 



59 



This may bo determined in the following waj's: 



1. Examination by a microscopist will show whether "open" 

 or " closed " flowers have been used. The presence of a large amount 

 of pollen and the absence of fruit tissues indicate "closed" flowers; 

 and, conversely, the absence of much pollen and the presence of a 

 large amount of fruit tissues indicate "open" flowers. These tissues 

 are very characteristic and can not be mistaken (PI. IV). 



2. Mixtures of flowers and stems are made up on the basis of 

 lowest cost. B}' following the market prices on " closed " and " open " 

 flowers and stems, the analyst can usually tell which has been used 

 in preparing a mixture of flowers and stems. 



3. From the intensity of the green color of the ether extract, 

 after a little experience, the amount of stems present can be told 

 roughly. 



4. The crude fiber determination, taken in connection with the 

 intensity of the green color of the ether extract, general appearance 

 of the powder, and odor, serves as a good indicator as to whether 

 or not the mixture is composed of "open" flowers and stems or 

 "closed" flowers and stems. 



By a combination of all of these tests, but more particularly by 

 microscopical examination, it is possible to tell whether "closed" or 

 "open" flowers have been used in a mixture, and, by the use of the 

 formula, to determine the approximate percentage amount of flowers 

 and stems present. 



In Table 37 are given the nitrogen and phosphorus pentoxid con- 

 tents of 10 known mixtures of open flowers with stems, and the 

 amount of stems calculated from each of these values, using the 

 formulas just given. 



Table 37.^ — Nitrogen and phosphorus pentoxid content of known mixtures of open Jloivers 

 and stems and amount of stems present. 



Sample No. 



Stems. 



Nitrogen, 



N. 



P2O5. 



Stems calculated 

 from — 



Jlean. 



Error. 



Nitrogen, 



N. 



P2O5. 



1 



Per cent. 

 

 

 

 10 

 10 

 20 

 20 

 60 

 60 

 80 



Percent. 

 1.280 

 1.235 

 1.250 

 1.185 

 1.170 

 1.140 

 1.170 

 1. 035 

 .919 

 .947 



Percent. 

 0.530 

 .523 

 .510 

 .459 

 .482 

 .411 

 .447 

 .275 

 .300 

 .206 



I'er cent. 

 3 

 6 

 3 

 16 

 19 

 25 

 19 

 46 

 70 

 64 



Pfrccnt. 

 1 

 3 

 7 



24 

 17 

 40 

 28 

 86 

 77 

 100 



Per cent. 

 2 

 5 

 5 

 20 

 18 

 33 

 24 

 C6 

 74 

 82 



Per cent. 

 + 2 



2 



+ 5 



3 



+ 5 



A 



+ 10 



5. . 



+ s 



+ 13 

 + 4 

 + 6 

 + 14 

 + 2 



6 



7 



8 



9 



10 





Minimuin error 









1 





2 



Maximum error 









14 



Average error 









6.9 









1 





