INSECT POWDER. 



41 



Grieb (107) gives the ether-soluble matter of a number of insect 

 powders. Nine samples obtained at different times from the same 

 source gave ether-soluble matter from 7.3 to 12.4 per cent, while 5 

 samples from another source gave 7.0 to 12.0 per cent. Grieb makes 

 a preliminary test with 1 gram of powder, shaking it with 10 cc. of 

 ether in a test tube, and if, after settling, the ether is of a marked 

 green color ("indicating the presence of ground stalks"), the assay 

 is not proceeded with and the sample is rejected. 



Jean (147), in his analysis of a number of samples of Pyre thrum 

 powder, determined moisture, ash, ''acidity," alcohol-ether extract, 

 resinous substances, substances soluble in water, and the iodin 

 absorbed by the water solution after rendering it alkaline by bicar- 

 bonate of soda (Table 18). In order to compare these results, Jean 

 prepared a powder from genuine Pyrethrum flowers, called the "type" 

 sample. 



Table IS. — Chemical analysis of Pyrethrum potvder (Jean).^ 





Determination on dry basis. 



Sample. 



Ash. 



Acidity 

 as 



Alcohol- 

 ether 

 extract. 



Resinous 



sub- 

 stances. 



Soluble 

 in 



water. 



Iodin ab- 

 sorbed. 



Moisture. 



Type 



Per cent. 

 8.90 

 7.47 

 10.04 

 8.70 

 9.02 



Per cent. 

 1.00 



.99 

 1.09 



.64 

 1.03 



Per cent. 

 24.03 

 24.94 

 30.47 

 21.91 

 24.40 



Per cent. 

 9.30 

 8.01 



13.76 

 9.41 



11.14 



Per cent. 

 14.73 

 16.93 

 16.70 

 12.50 

 12.26 



Per cent. 

 3.86 

 7.65 

 5.22 

 3.15 

 5.8 



Per cent. 



ak. :.. 



11.5 



B 



9.9 



C 



8.0 



D 



12.5 







1 Jean does not give his methods of analysis. 



2 Contained potassium chromate and sawdust. 



Sato (236) states that mature flowers of the CTirysanihemum 

 cinerarisefolium should be used in preparing insect powder. The 

 most desirable moisture content is 7 to 8 per cent; the ash is 6 to 7 

 per cent, and always shows the reaction for manganese. The greater 

 the content of ether-soluble matter, the greater the value of the 

 powder. If the ether extract is green, leaves and stalks have been 

 mixed with the flowers. The amount of ether extract should not be 

 less than 6 per cent, and the ratio of ether extract to ash should be 

 greater than 1. H. W. and S. C. Gadd (90) give methods for 

 detecting turmeric and chrome alum in insect powder. For the 

 determination of ether-soluble material they use Durrant's method. 

 According to them the ash of a genuine powder should bo of a light 

 gray color and should not amount to over one-sixteenth of the 

 original. 



Vogt (286) in 1906 wrote that he invariably found a rich yellow 

 percolate to be characteristic of the finest insect powders. He ob- 

 tained 7.72 per cent of ether extract in a sample of insect powder 

 ground by himself from closed flowers, and stated that samples of 



