INSECT POWDER. 
59 
This may be determined in the following ways: 
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. By 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 flowers 
and stems and amount of stems present. 
Sample N o. 
Stems. 
Nitrogen, 
N. 
p 2 o 6 . 
Stems calculated 
from— 
Mean. 
Error. 
Nitrogen, 
N. 
P2O5. 
Per cent. 



10 
10 
20 
20 
60 
60 
80 
Per cent. 
1.280 
1.235 
1.250 
1.185 
1.170 
1.140 
1.170 
1.035 
.919 
.947 
Per cent. 
0.530 
.523 
.510 
.459 
.482 
.411 
.447 
.275 
.300 
.206 
Per cent. 
3 
6 
3 
16 
19 
25 
19 
46 
70 
64 
Per cent. 
1 
3 
7 
24 
17 
40 
28 
86 
77 
100 
Per cent. 
2 
5 
5 
20 
18 
33 
24 
66 
74 
82 
Per cent. 
+ 2 
2 
+ 5 
3 
+ 5 
4 
+ 10 
5 
+ 8 
6 
+ 13 
7 
+ 4 
8 
+ 6 
9 
+ 14 
10 
+ 2 
Minimum error 
2 
Maximum error 
14 
Average error . ; 
6.9 
1 
