A^ Scientific Notices^^ Zoology, [DEd. 



face, the precipitation is rapid ; but when it is placed at the 

 surface of the hquor, touching it only by a point, it requires a 

 long time. Two equal quantities of solution of silver were 

 taken : a plate of copper was plunged into one, and a bar of 

 copper made merely to touch the surface of the other ; the first 

 was entirely freed from silver in one hour, the latter not in three 

 months. 



When a zinc rod is put into a solution of acetate, or nitrate 

 of lead, the first large crystals of lead after a time fall off, and 

 are replaced by smaller, which in turn fall, and are succeeded 

 by others, and this alternate production continues a long time. 

 The cause of this effect appears to be in the power which most 

 metallic solutions have, when saturated with base, of dissolving 

 small quantities of other metals : thus the saturated nitrate, 

 muriate, and acetate of zinc slowly dissolve a notable quantity 

 of lead ; the muriates of zinc and tin and the acetate of lead 

 dissolve a little copper, and the nitrate of copper dissolves finely- 

 divided silver. When, therefore, a piece of zinc is placed at 

 the surface of a solution of lead, the latter metal falling to the 

 bottom of the fluid is in part dissolved by the salt of zinc 

 formed ; and the solution of lead thus formed spreading through 

 the liquid, thus places the zinc in constant contact with it, and 

 hence the successive precipitation of the lead which is found to 

 take place. 



If finely-divided silver is put at the bottom of a narrow tube, 

 and about two inches in depth of a solution of copper saturated 

 with oxide be poured upon it, then a copper-wire plunged to the 

 depth of a couple of lines will soon become covered with silver, 

 and in three or four weeks fine crystals of the metal will appear, 

 which will be larger as the tube is narrower. It appears, that in 

 all these circumstances double subsalts are formed ; crystals of 

 subnitrate of copper almost always appears mixed with those of 

 silver. — Ann. des Mines, xii. 197. — (Institution Journal.) 



Mineralogy. 



^ 6. Bitberg Meteoric Iron, 



According to Stromeyer, it contains iron 81-8; nickel 11-9 ; 

 cobalt 1*0; manganese 02; sulphur 5*1 = 100*0. Stromeyer 

 did not examine it for chrome, but intended to do so. — (Edin. 

 New Philos. Journ.) 



Zoology. 



7. On Female Pheasa7its assuming the Male Plumage, 



The Editor of " The Edinburgh New Philosophical Journal," 

 has annexed the following interesting note to a translation of 

 M. Isidore GeofFroy Saint Hilaire's memoir " On Female 

 Pheasants assuming the Male Plumage," published in the 

 present number of that valuable journal. 



