30 SOME INFERIOR WOOD ASHES 



of arsenic trioxide, while 43.3 per cent, of the substance 

 was insoluble in hydrochloric acid. Pure Paris green 

 should be almost wholly soluble in acid and should con- 

 tain from 55 to 60 per cent, of arsenic trioxide. Further 

 examination of the sample showed it to contain 30.6 per cent, 

 of silica and 5 per cent, of oxides of iron and aluminum. 

 From these results it appears that this "Pure Paris Green " 

 was a mixture of about equal parts of Paris green and 

 earthy matter, either clay or infusorial earth. 



Probably the best way by which users of this imoortant 

 insecticide may protect themselves, is to refuse to buy packages 

 which bear no trade-marks of the manufacturers, since the 

 samples reported in the previous bulletin as being pure were 

 all plainly marked with their respective makers' names. 



