74- Intelligence and Miscellaneous Articles. 



a definite proportion, so that, for one equivalent of electricity em- 

 ployed, one equivalent of the electro-negative element, or at least of 

 the compound which acts the part of acid in the combination, is car- 

 ried to the positive pole, and the corresponding quantity of the 

 electro -positive element, or that which serves as base, is carried to 

 the negative pole. 



This law may be expressed as a formula in the following manner: — 



One equivalent of a combination formed by the union of an equi- 

 valent of acid and of a corresponding quantity of base, always re- 

 quires one equivalent of electricity for its electro-chemical decom- 

 position. 



I have given the name equivalent of electricity to the quantity of 

 electricity necessary to decompose one equivalent of water. 



These laws are relative only to the direct effect of the current, and 

 not at all to the secondary effects ; for there are some salts, such as 

 the acetates of lead, which are only decomposed by the reducing ac- 

 tion of the hydrogen arising from the decomposition of the water, 

 and which always give an equivalent of metal to the negative pole. 



If an equivalent of electricity be required to decompose an equi- 

 valent of any combination whatever, it may be admitted that if the 

 two elements, electro-positive and electro-negative, which form the 

 combination, be separated and again combine, they disengage ex- 

 actly one equivalent of electricity. Hence, by referring to the law 

 stated above, the following conclusions, which are very important as 

 regards molecular chemistry, are deduced ; — 



1. When an equivalent of a body, whether simple or compound, 

 combines with one or several equivalents of another body, if the first 

 acts the part of an acid in the combination, the liberation of electri- 

 city which results from their chemical action is such, that an equi- 

 valent of electricity is always produced. 



2. If an equivalent of a body, such as oxygen, has already entered 

 into combination Math another which acts as a base, and if the com- 

 bination again unites with an equivalent of the first body, that is to 

 say, of oxygen, to form a deuto salt, at the time of this second ac- 

 tion another equivalent of electricity is disengaged. 



Thus the quantity of electricity set free depends solely on the body 

 which acts the part of acid in the combination. 



My memoir only treats of inorganic substances, because the or- 

 ganic compounds are generally non-conductors of electricity, and, 

 when they conduct, the secondary effects so conceal the direct effect, 

 that it is very difficult to recognise the definite action of the electricity. 



The principles which I have laid down very well represent all the 

 results obtained with regard to the direct effects, so that there is a 

 constant relation between the chemical theory of equivalents and the 

 decompositions by electricity. Their establishment was of the great- 

 est importance, for they should serve as the point of departure for 

 every electro- chemical theory. — Comptes Rendus, March 4, 1844. 



PROTO- AND PER-ARSENITE AND ARSENIATE OF IRON. 



M. Damour prepared these compounds by precipitating, according 



