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did not understand the meaning of the hair lines commonly used, and 
were often misled as to the real size of the insect pests. 
Mr. Gillette agreed with Mr. Hopkins, and added that in his opinion 
it was often better to illustrate the work of a pest instead of giving 
figures of the latter. 
Mr. Forbes inquired as to the printing of half-tone blocks on ordinary 
book paper. Messrs. Howard and Garman thought the cost of half- 
tone figures an objection for general use. 
Mr. Smith replied that plates could be made for about $7 apiece. 
Messrs. Howard and Galloway stated that they cost the Agricultural 
Department at Washington from $10 to $20. 
Mr. Gillette wished to know if there was any one in the country who 
could be trusted to make drawings of insects which were sent to him 
for that purpose. Mr. Forbes considered it very difficult in such cases 
to get results satisfactory to the entomologist. 
Mr. Howard did not think the photographs shown by Mr. Smith 
demonstrated that better figures would be produced from them than 
were obtained from woodcuts, or even process drawings. 
The following paper was then read: 
THE ARSENITES AND ARSENICAL MIXTURES AS INSECTICIDES. 
C. P. GILLETTE, Fort Collins, Colo. 
The object in preparing the present paper has been to get together 
ma short article as much as possible of the important knowledge at 
our command concerning the arsenites as insecticides. 
The article does not pretend to be an exhaustive one, and we have 
not been able to examine the extensive literature upon the subject as 
thoroughly as was desired, so it is probable that important matters have 
been overlooked and perhaps erroneous conclusions arrived at. It is 
hoped that such additions and corrections as those present are able to 
offer will be freely made during the discussion that will follow. 
The value to this country of arsenical poisons for the protection of 
crops against insect injuries can hardly be overestimated. Arsenic in 
its various combinations is the great panacea for all the evils inflicted 
upon man by leaf-eating vermin. Through its use the value of our 
annual food supply is increased by many millions of dollars. 
EARLY USE OF THE ARSENITES. 
It is probable that we can never know with certainty who first used 
arsenic in any of its combinations for the destruction of insects, and it 
matters little that we can not. 
A Mr. Bryan Markham, of Michigan, claims to have used Paris green 
for the destruction of the Colorado Potato-beetle as early as 1867, but 
