TWENTY-FOURTH ANNUAL FRUIT-GROWERS' CONVENTION. 91 



green. They are sold mostly by paint-dealers, and were probably 

 manufactured for use as a cheaper form of green pigment than is Paris 

 green. 



Adulterated Paris Green. — This class of Paris green is often sold by 

 unscrupulous dealers — sometimes by honest dealers who have been 

 supplied by unscrupulous jobbers — and indicates always an intention 

 of fraud on the part of some one. It consists of Paris green in part, 

 generally upward of fifty per cent, and to this is added some other 

 substance for the purpose of increasing the weight. Any white powder, 

 such as gypsum, will do, and even flour has been used. The intensity 

 of the green color in good Paris green allows considerable addition of 

 white material, though, in some cases, green or blue pigments are added 

 to prevent detection. Most of these forms of cheapening Paris green 

 are at once recognized by either the "ammonia" or the "glass" test, 

 and especially are they at once detected under the microscope. 



Low-Grade Paris Green. — The third type of unsatisfactory Paris green, 

 and the one most difficult to recognize, is a " low-grade Paris green"; by 

 which term it is intended to designate those manufactured in such a 

 way as to contain a low per cent of arsenious oxid in combination. A 

 strictly pure Paris green can be produced, according to our observa- 

 tions, with not over forty per cent of arsenious oxid, but such a sample 

 is simply low-grade. To use such in spraying would require nearly 

 one half more material to produce effective spraying than would be 

 necessary with a sample containing the normal fifty-eight per cent of 

 arsenious oxid. For this class of green it appears that the only test 

 now available is the chemical determination of the quantity of arsenic 

 present. 



The production of low-grade Paris green is almost as expensive, or 

 perhaps quite as expensive, so far as the ingredients used are concerned, 

 as is the production of the high-grade article. 



It therefore appears that the low-grade greens are produced not with 

 any intention of defrauding the public, but rather because of the ease 

 of manufacture. The laws, especially of New York, where the greatest 

 amount of Paris green is manufactured, require the total arsenious oxid 

 to be above fifty per cent, and this has required the addition, either 

 during or after manufacture, of sufficient arsenious oxid in the free 

 state to come within the requirements of the law. As a result of this 

 the greater part of the low-grade Paris green on the market contains as 

 an adulterant a considerable proportion of the free acid. The deter- 

 minations that have been heretofore made have only taken into 

 consideration the total arsenic per cent, and so all these samples of 

 low-grade, "doctored" Paris green have been passed as pure. 



