134 THE MONTHLY BULLETIN. 



slight taste. This harmless appearance greatly adds to the danger of 

 accidental poisoning. 



Danger to Live Stock: Forage plants, when sprayed with arsen- 

 icals, seem to be especially attractive to live stock. Cattle, horses and 

 even poultry have been poisoned by eating Johnson grass which had 

 been sprayed with an arsenical weed killer. Areas which are to be 

 treated with a poisonous herbicide should, therefore, be carefully fenced 

 to avoid the possible loss of valuable live stock. 



Arsenic Carried by Smoke: When a rank growth of vegetation 

 has been destroyed with a heavy arsenical application, considerable 

 caution must be used if it is desired to burn the brush. The arsenic 

 would be very readily volatilized in this manner and would be carried 

 in the smoke. Persons should, therefore, be extremely cautious about 

 inhaling the smoke, for it is thought that a poisonous dose of arsenic 

 could be easily inhaled in this way. 



Poisonous to Crops: The action of sodium arsenite is more severe 

 on broad-leafed plants than on grasses, although a violent poison to 

 practically all plants. In using it for the destruction of weeds, it is, 

 therefore, usually necessary to avoid getting it on trees and cultivated 

 crops. 



Effect on the Soil: The Experiment Station is observing the 

 effect of arsenic and other chemicals upon the soil. It has been found 

 elsewhere that arsenic is accumulated in the top layer of the soil and is 

 not easily washed out by rains, so that it should be rather sparingly 

 used on this account. 



Notwithstanding its poisonous nature, however, it may be proven 

 that arsenic will be a valuable aid to the farmers of the State in the 

 control of some of the most troublesome weeds, if used with discretion. 



UNQUALIFIED ENDORSEMENT OF ARSENIC NOT GIVEN. 



The writer has received many requests for a formula for the prepara- 

 tion of soluble arsenic for use in weed control. He has usually 

 hesitated to give a formula, thinking that by so doing an endorsement 

 of the general use of arsenic as a weed killer might be implied. The 

 experiments have now been conducted for a sufficient length of time, 

 however, to justify the recommendation of formulas for the benefit of 

 those who wish to conduct independent experiments on weed control. 



The uncompleted state of the experiments now in progress does not 

 warrant recommendations for their use except in an experimental way, 

 and in the preparation of a spray to prevent the maturing of seeds as 

 indicated in statement " 6 " at the close of the article. The writer does 

 not assume any responsibility for their use other than noted above. 



SOURCE OF ARSENIC. 



The raw material used for the preparation of all compounds of 

 arsenic is the white arsenic of commerce, chemically known as arsenic 

 trioxide. This substance is recovered as a by-product from the smoke 

 of some of the smelters of the western states. According to the United 

 States Geological Survey, some three thousand tons are annually 

 produced in this country and a much larger amount is imported under 

 normal conditions. 



