1864.] Prof. A. H. Church on certain Ethylphosphqtes. 525 



an, 



1 



fe }■ POj+Aq 

 inadmissible, and the expression 



correct, since we can replace not half only of its iron, but one-fourth also 

 by aluminium — a replacement manifestly impossible with the simpler ex- 

 pression. I am submitting this matter to further scrutiny by an investi- 

 gation of the mineral phosphates containing not only aluminium and iron, 

 but also calcium &c. 



The higher atomic weights of iron still remain to be considered in con- 

 nexion with these complex salts. If the atom of ferricum be triatomic and 

 therefore =56, then the normal ferric ethylphosphate already described is 

 readily represented thus, 



(C.H,)3l 

 ¥e"' l3PO, + 3Aq, 

 ¥e"' I 



a compound which equally well admits the expression 



where Ffe=112. But with the mixed ferric-aluminic ethylphosphates 

 the case is altered. The compound (Cg £[5)3 AI2 3POj^+3Aq allows 

 us indeed to assume the triatomicity of ferricum and aluminium, 



(C.H,)3l 

 ¥e"' l3PO, + 3Aq, 

 Al'" J 



though excluding the supposed hexatomic value of these metals ; while the 

 other salt described, (C^ 115)3, ^^3' 3PO^ + 3Aq, does not allow their 

 triatomicity even ; we return in fact to the oldest view, where Fe=28, and 

 is sesquiatomic. 



Ferroso-ferric Ethylphosphate. — By acting upon a warm saturated so- 

 lution of basic ethylphosphate with a solution of mixed ferrous and ferric 

 sulphates, filtering rapidly, and adding to the filtrate strong alcohol till a 

 precipitate begins to separate, a solution is obtained which, after filtration 

 and standing, soon deposits a greenish-white precipitate, slightly crystalline. 

 This salt is constant in composition when prepared under rather widely 

 varied conditions ; but if in its preparation the ferric salt preponderate, the 

 normal ferric ethylphosphate will be first precipitated. Perhaps a better 

 way of preparing the new compound than that above given consists in 

 warming a strong solution of ethylphosphoric acid with ferrous hydrate, 

 filtering and adding strong alcohol. The precipitate produced by either 

 method is to be washed with weak alcohol, and dried as rapidly as possible 

 in vacuo over sulphuric acid. It contains iron in both conditions, and 



