Browning — Free Nitric Acid and Aqua Begia, etc. 399 



the writer by Mr. J. G. Hiestand of Manitou, Colo. It is over 

 one centimeter in diameter and is implanted on a gangue of 

 quartz and feldspar. Associated with it are crystals of hema- 

 tite and astrophyllite. The xenotime is very fresh and pure, 

 has a brown color and in thin splinters is pale pink. The form 

 of the crystal is the unit pyramid with its middle edges slightly 

 modified by the prism and a steeper pyramid, probably 331, 

 but the faces of the latter were too dull to measure on the 

 reflecting goniometer. The faces of the unit pyramid were 

 bright and the following measurement was made, 111 ,\ 111 = 

 55° 32', agreeing very well with the measurements of G. vom 

 Kath* and C. Klein,f 55° 30'. The prismatic cleavage was 

 very well shown by cracks running through the crystal. 



Without destroying the specimen a little over - 2 gram was 

 removed for a quantitative analysis, the results of which are 

 as follows : 



Specific gravity 5*106 Ratio. 



P 2 B 32-11 -r- 142 = -226 1-00 



(Yt, Er) 2 3 67-78 -4- 284 = -238 1-05 



Ignition -18 



100-07 



The only metals that were found were those of the yttrium 

 and erbium group and the joint molecular weight of the 

 oxides was found to be 284, equivalent to a joint atomic 

 weight of 118. A solution of the oxides tested with the spec- 

 troscope showed the absorption bands of erbium and the 

 atomic weight indicates that yttrium is also present. The 

 ratio of P 2 B : (Yt, Er) 2 3 is almost 1 : 1 showing that the min- 

 eral is a normal phosphate. 



The author desires to express his thanks to Mr. J. G. Hies- 

 tand for giving him this interesting crystal which is now in 

 the United States National Museum. 



Aet. XLYIII. — The Influence of Free Nitric Acid and Aqua 

 Regia on the Precipitation of Barium as Sulphate / by 

 Philip E. Browning. 



[Contributions from the Kent Chemical Laboratory of Yale College — XXIL] 



The fact demonstrated by Dr. F. W. Mar;}: in an interest- 

 ing series of experiments, that free hydrochloric acid even in 

 large quantities does not interfere with the complete precipita- 

 tion of barium as sulphate when sulphuric acid is present in 



* Pogg. Ann., 1864, B. 123, p. 187. \ Jarb. Minn., 1879, p. 536. 



% This Journal, xl, 283. 



