189 



the digestive fluids bpforo its toxic effects can be conveyed throughout the insects' 

 body by Iho cirnulutory Hytiiem, there seems to be no good ground for con- 

 demning an application in which traces of arsenic are already soluble. The chief 

 reason against the use of white arsenic is on account of its injurious eflPect on foUage 

 — it being soluble in water and acid in its character. The arsenic set free in the 

 soap solution is neutralized by the free alkali of the soap, so that where soap solution 

 can be used per se without harm, no injurious results need be appiehended when to 

 it is added the Paris green in the right propoi tion. 



In all the above experiments the soap solution was at the ordinary temperature 

 of the atmosphere when added to the Paris green. If heat had been used undoubtedly 

 a larger portion of arsenic would have gone into solution. 



THE EESULTS OF AN EXPERIMENT TO PROVE THAT APPLES ARE 

 NOT POISONED BY SPRAYING WITH PARIS GREEN FOR 



CODLING MOTH. 



A statement appeared a short time ago in a horticultural paper published in 

 Great Britain to the effect that Canadian apples containedasmallquantity of arsenic 

 and were consequently poisonous. This, it was said, was due to our practice of 

 spraying with Paris green after the petals have diopped, in order to preserve the 

 fiuit from the ravages of the codling moth. This assertion received wide circulation 

 in the British press and was calculated to do a great deal of harm to the Canadian 

 expoi-t apple trade. It is not the first time that a rumour to this effect has been set 

 afloat, either by interested or ignorant people. That the suspicion is entirely with- 

 out a foundation has been asserted by scientists and practical men in Canada and the 

 United States on several occasions. Hitherto, however, no chemical work has been 

 done in Canada to place before our horticulturists and shippers, as well as the British 

 people, scientific proof for refuting the statement. 



Mr. James Fletcher, Dominion Entomologist, therefore procured a sample of 

 apples that undoubtedly had been sprayed, and I submitted them to a careful chemical 

 analysis. The apples examined (Rhode Island Greenings) were kindly furnished by 

 Mr. Wool ver ton, editor of the Canadian Horticulturist, who personally vouches for 

 the fact that they were twice sprayed last June with Paris green of the strenj^ch 

 of lib. of the material to 200 gallons of water. The apples when received were 

 just as they had come from the trees, i.e., had not been rubbed, so that any arsenic 

 left from the spraying would still be on the skin. 



The quantity tested for arsenic was 9 lbs. 7 ozs., measuring about one peck. 

 The process to which they were submitted is one that affords extremely accurate 

 results, and is considered the most delicate of all for the detection of arsenic. It is 

 capable of revealing the presence of one fifty-thousandth part of a grain of arsenic. 

 If 2H.000 bushels of apples contained 2| grains of arsenic (As jOg), the minimum 

 fatal dose for Un adult, the poison could have been detected by this method. 



Though all care was exercised not a trace of arsenic could be detected, thus 

 showing the complete absence of this poison in these apples that had been twice 

 sprayed with Paris green. 



I am of the opinion that further experiments of this nature would only serve 

 to corroborate this negative result and to prove that there are no grounds on which 

 lo base a suspicion that our sprayed apples are poisonous. 



The insoluble character of this poison, precluding its assimilation by the apple 

 if such were possible, the infinitesimal part of Paris green that can remain on the 

 apple, the frequent rains subsequent to the spraying, and the fact that apples are 

 pared before using, all go to substantiate the aigument that there is not the 

 ■"lighteBt danger of poisoning in using sprayed apples. 



