Mr. R. Phillips on the passive state of Iron. 509 



Notwithstanding that my arguments thus far have been all 

 d priori, and that no attempt at verification of results, either 

 by arithmetic or common algebra, has at any point been made; 

 so long as my right is not successfully disputed to the assump- 

 tion, that any irreducible multiplet imaginary, in a product of 

 pluquaternions, is equivalent to any of the permutations of itself 

 or differs, at the most, from certain of them only in sign ; so 

 long I shall venture to affirm, and hope to convince the reader, 

 that the much-desired generalization of Euler's four-square 

 theorem, and that of the more ancient two-square theorem, 

 are thus correctly enunciated : 



The product of (n+r) sums each of any (6n — 2) squares, is a 

 sum of 2 2n squares. 



The product qf(n + r) sums each of any (6n + 2) squares is a 

 sum of2 2n+1 squares. 



Croft Rectory, near Warrington, 

 December 19, 1848. 



LXXIV. On the passive state of Iron. 

 By Reuben Phillips, Esq.* 



IN a small platinum crucible *7 inch high I placed 35 grains 

 of chromic acid and 62 grains of water, and having incor- 

 porated the acid and water, the crucible was connected with 

 one end of the wire of a galvanometer and a piece of iron wire 

 with the other end, and then part of the iron was immersed 

 in the acid ; the needle of the galvanometer was thrown about 

 45° from its place of rest, and settled at 0°. Having caused 

 the needle to have a barely perceptible motion about 0°, the 

 circuit was closed and opened through the galvanometric wire 

 at such times as should increase the motion of the needle, sup- 

 posing the iron to act as zinc to platinum; a vibration of 10° 

 was easily obtained. A copper wire rather smaller than the 

 iron wire was now substituted for it ; on its first immersion 

 the current was so strong as to cause the needles of the gal va- 

 nometer to rotate, then a constant current was established 

 which held the needle at 43°. 



The acid was now diluted with about six times its bulk of 

 water, and the crucible nearly filled with this dilute acid, 

 everything else remaining as before. The iron wire caused 

 the needle to move about 30° and then to stand at 0° ; a swino- 

 of the needles could however be obtained by closing and 

 opening the circuit as before, but the current was weaker. 

 The copper wire caused a permanent deflection of 21°. In 

 this and the following experiments the crucible was filled to 

 * Communicated by the Authoi. 



