278 PROCEEDINGS OF THE AMERICAN ACADEMY 



which I employed nitrates from a commercial oxalate, added a solution 

 of mercurous nitrate, and then boiled with free mercuric oxide, the color 

 of the oxide changed to a grayish tint. After filtering and washing, 

 the filtrate was found to contain abundance of didymiura (Nd and Ps). 

 The precipitate after washing with boiling water was heated to redness 

 in a platinum crucible, when a clear yellow powder remained. This 

 dissolved in dilute nitric acid to a colorless liquid, which gave no 

 didymium bands with the spectroscope. On adding water to the 

 nitric acid solution a beautiful bright yellow crystalline powder was 

 thrown down. When the oxides were treated with sulphuric acid a 

 white crystalline mass was formed. Hot water gave with this a fine 

 bright yellow crystalline precipitate. I did not obtain these results 

 with any other samples of cerite oxalates. So far as I am aware no 

 known earths exhibit the reactions with nitric and sulphuric acids 

 above described. 



Helations of the Samarskite Oxides to Acid Molyhdates, and to 

 Phospho-tungstates and Phospho -molyhdates. — To determine whether 

 any of the oxides contained in Samarskite were capable of forming 

 complex inorganic acids, the following experiments were made with a 

 bright yellow mixture of oxides prepared by Lawrence Smith's pro- 

 cess with fluohydric acid. The quantity at my disposal was less than 

 five grams, and I am not certain that the cerite oxides had been 

 removed by sodic sulphate. 



1. With 10:5 phospho-molybdate of ammonium. The mixed ox- 

 ides dissolved very easily on boiling with solutions of the phospho- 

 molybdate, giving a fine orange solution. The action of the solution 

 of phospho-molybdate upon the oxides seemed to give instantly a 

 crystalline mass, which on boiling with some excess of the phospho- 

 molybdate dissolved. The solution gave beautiful orange-brown crys- 

 tals, but after twenty-four hours the solution was clear, and had a fine 

 rose-color. This solution gave no absorption bands with the spectro- 

 scope. With ammonic oxalate it gave a white crystalline precipitate 

 with a clear rose-red solution. This on evaporation to dryness in a 

 platinum vessel gave a rose-red mass, which when heated fused to a 

 greenish mass. The white oxalate settled slowly. The orange crys- 

 talline salt dissolved almost completely in boiling water, but some 

 yellow crystalline matter remained. On standing, the solution depos- 

 ited crystals of a yellow salt. 



2. With 14:6 molybdate of ammonium. A solution of 14 : 6 

 molybdate of ammonium (commonly written 7 M0O3 . 3 (MH4)20) also 

 readily dissolved the mixed oxides and gave a deep orange solution. 



