46 BULLETIN 824, U. S. DEPARTMENT OF AGRICULTURE 
TABLE 32.—WNitrogen in stems. picked from ‘‘closed’”’ flowers (Chrysanthemum 
cinerarizfolium) 
Sample No. peda | Sample No. ert 
Per cent Per cent 
Lis OFA oe oe ral a ee Oe Se Ee ee 160M EAS se sk See ee eee 1.52 
Lig 3h 8 Se ee ae as oe eer ee ee Sa LADS C150 = 1 eee eee L552 
UN ses Seen Soe ee See A eee 1752 ATS 2 ee eee 1. 57 
GT Bt re ee Se Le ee Se ee 12545) $8008 22225. Se See te Oe ee 1. 63 
LF a2) cel ae eee ae Se nS eee eee OY aS 1. & || 
ee ee ee OE ae ee ee 1.77 || IVE = ae 2 ee ee 1,21 
TA i rk late ele pay epg ee Se A ee ae ed 1. 21 |) Maximum = 2 = - 22-22-3222 eee iW 
dtr ee ee te eS a ee 1. 54 JA VETARCQ. =e a es es ee 1. 53 
It was found that a determination of the nitrogen and of the phos- 
phorus, together with a qualitative ether-extract test (to determine 
its color), were sufficient to determine the presence and approximate 
percentage of stems. 
In but few of the published analyses of insect powder, where ether 
extract is given as one of the determinations, is the kind of ether 
specified. In some methods the powder is simply shaken with 
ether and filtered, and an aliquot evaporated. Dietze (70) has 
shown that the results do not agree when ether of specific gravity 
0.720 and 0.735 is used. Ordinary ether contains some alcohol and 
water and extracts from insect-powder material other than the active 
insecticidal constituents. For concordant results, the ether used in 
making the extractions must always be of the same grade. Anhy- 
drous, alcohol-free ether would seem to be the best solvent. 
Pyrethrum flowers usually yield an intensely yellow ether extract, 
whereas the stems give one of a strong green color. The odor of the 
extract from the flowers is also characteristic. In the examination of 
commercial insect powder the presence of a material amount of 
powdered stems can always be detected by the green color of the 
ether extract. Its quantitative estimation is, however, of little value 
in determining the quantity of stems present, and this determination 
was made in only a few cases, the method employed being as follows: 
The 2 grams used in the determination of moisture were transferred 
to an extraction thimble and extracted in a suitable apparatus for 
16 hours with ether that had been freshly distilled over metallic 
sodium. After extraction, the ethereal solution was evaporated to 
dryness on the steam bath and dried to constant weight at the temper- 
ature of boiling water. 
The petroleum-ether extract was determined in a few cases by 
thoroughly extracting 2 grams of the powder in a Soxhlet apparatus 
with commercial petroleum ether (specific gravity, 0.640; boiling 
point, 30° to 65° C.), evaporating the extract on the steam bath, and 
drying for a few minutes in an oven at 100° C. 
The petroleum-ether extract of flowers does not differ enough from 
that of stems to make this determination of value in determining the 
amount of stems present. 
Pentosans were determined in a few of the samples, and it was 
found that the amounts in the different forms of flowers differed but 
little from each other and also but little from that in the stems. 
ee Se 
