ARSENIC FOR DESTROYING COTTON WORMS. 147 



use of them by planters. The letter of the law too often negatives the 

 spirit of the law, and it seems that the Patent Office has been forced to 

 issue the patents above alluded to on the ground and decision that any 

 change in the compounds of a mixture makes of it, in law, a new sab- 

 stance. 



ARSENIC. 



While commercial arsenic, salts of arsenic, and their various com- 

 pounds are much cheaper than Paris green, yet this advantage is 

 more than counterbalanced by the injurious property they possess, in 

 a more or less marked degree, of scalding the leaves and causing the 

 squares and young bolls to shed. Moreover, on account of their white 

 color, there is more danger of injury to man and animals in their use 

 than in that of colored preparations, which are less likely to be mis- 

 taken for harmless substances. Great care and precaution are, there- 

 fore, necessary in applying these arsenic poisons. When applied in 

 just the right proportions to kill the worms without injuring the cotton 

 they are valuable substitutes for the more expensive Paris green, but 

 unfortunately these proportions vary with each particular combination, 

 the condition of the plants, temperature, and weather, and time of ap- 

 plication, so that they can be satisfactorily ascertained only by abso- 

 lute experiment. 



It is for this reason that the Paris green mixtures have held their 

 own against the cheaper compounds, and most planters, even where 

 these last are used, find it desirable to still mix a certain proportion of 

 the green with them. 



The cheapness of the arsenic, combined with the fact that under very 

 favorable circumstances it is not uncommonly applied with success, will 

 give to it a conspicuous place among the remedies for the Cotton Worm, 

 so long as mineral poisons are not superseded by others. The high 

 price asked for some of the patented compounds is entirely unwarranted, 

 as their value in every case depends on the arsenic. 



Commercial ai-senic, costing from 7 to 10 cents per pound, is applied 

 in powder form at the ratio of J pound to from 18 to 25 of any of the 

 ingredients used with Pa,ris green. Used in water, these arsenic com- 

 pounds give less satisfaction because of the dangers to the plant already 

 alluded to, which are then increased. Counting 40 gallons of liquid for 

 one acre of cotton, the arsenic used should not exceed 1 pound to 200 

 gallons of water ; and this mixture must be very evenly distributed, as 

 even a slight overdose will scorch the leaves. It is an interesting fact 

 that already in 1871 a patent was obtained for the use of arsenic against 

 the Cotton Vv'orm by Mr. Thomas W. Mitchell, of Eichmond, Tex. fKo. 

 110774, January 3, 1871 j reissue Ko. 5935, June 30, 1874: 92 grains of 

 opaque arsenic, or 293 grains of transparent arsenic to one pint of 

 water). 



Arseniate of soda, — This has the advantage of being perfectly sol- 



