3 



observed that arsenites are more soluble in solutions containing 

 sulphate of copper and sulphate of iron than in water alone. 

 Jones 1 used arsenite of soda on herbaceous weeds and found the 

 effect produced by this chemical to be slow but lasting. The 

 formula used called for one pound sal soda and two pounds of 

 water diluted before using so as to make nine gallons. In Aus- 

 tralia the common practice is to buy arsenite of soda already pre- 

 pared and simply dilute in water at the rate of one pound to five 

 to ten gallons of water. This solution has proven effective in the 

 destruction of the prickly-pear, wild blackberry and various her- 

 baceous and semi-shrubby weeds. 



Asenate of soda has in experiments proven even more effect- 

 ive than the arsenite. For example, Stone in the article cited 

 above found that the mixture of arsenate of soda and corrosive 

 sublimate in equal parts caused a very rapid destruction of the 

 foliage and stems of weeds. Likewise, Morgan 2 found that arse- 

 nate of soda alone caused a rapid and destructive burning on 

 foliage upon which this chemical was applied, and Jones in the 

 article referred to above reports arsenate of soda when used at 

 the rate of one pound to eight gallons of water, to be rather 

 quicker and more effective in its action than arsenite of soda. 



Iron sulphate. In various processes involved in the commer- 

 cial handling of iron ores, iron sulphate is obtained as a by- 

 product and costs about one cent per pound in most cities on the 

 mainland. This chemical has been widely tested in Wisconsin, 

 Iowa, Maine, South Dakota, Rhode Island and other states, as 

 well as in foreign countries, and upon a large variety of weeds, 

 but chiefly upon wild mustard. For this purpose it has been 

 found particularly effective and has the further advantage of not 

 destroying cereal grains. For this reason it is commonly sprayed 

 over grain fields infested with wild mustard, and when thus used 

 gives excellent results. Iron sulphate has been used in different 

 strengths, but where the herbage is quite tender a 20 per cent 

 solution is the one commonly recommended to kill weeds and 

 not injure cereals. Iron sulphate is readily soluble in water, 



1 Vt. Sta. Rpt. 1901, p. 248. 



2 Agric. Education, 6 (1903) p. 11. 



