Magnesium Arsenates

Description

A number of United States patents cover processes for the manufacture of magnesium arsenates for use as insecticides. The magnesium arsenates tested as insecticides consisted generally of the dibasic magnesium arsenate, MgHAsO4, the tribasic magnesium arsenate, Mg3(AsO4)2, or the pyro-arsenate, Mg2As2O7, with varying amounts of water of crystallization and excess magnesium oxide or hydroxide. These magnesium arsenates have been tested against a large number of insects affecting fruits and vegetables and at one time were recommended for the control of the Mexican Bean Beetle but their use has declined due to the toxicity of As.
Various magnesium arsenates are available commercially but it is the dibasic and tribasic salts that are used in industry because of their relative stability.