﻿Penfield and Harper — Chemical composition, etc. 107 



Art. X. — On the chemical composition of Herder ite and Beryl, 

 with note on the precipitation of aluminum and separation of 

 beryllium and aluminum; by S. L. Penfteld and D. N. 

 Harper. 



1. Composition of Herderite. 



The rare material for carrying on the present investigation 

 of herderite was given to us by Mr. L. Stadtmiiller and Profes- 

 sor George J. Brush. The crystals were carefully picked by 

 hand and freed as far as possible from all foreign matter. 

 They were then crushed and sifted and suspended in the 

 Thoulet solution ; only the material whose specific gravity 

 was greater than 2*95 was used for analysis. By this means 

 there was separated from the hand-picked crystals a little 

 questionable material, which was used in making a sort of 

 preliminary analysis, and we were able to obtain over five 

 grams of very pure material. Before making the separation 

 with the Thoulet solution we carefully took the specific gravity 

 of some of the purest crystals by taking the specific gravity of 

 the solution in which they were suspended without floating or 

 sinking. This we found to be from 3'012 to 3*006, the heaviest 

 being the specific gravity of a very clear transparent crystal, 

 while the more opaque and cracked crystals were a trifle lighter. 

 The mineral is so much heavier than the quartz and feldspar 

 to which the crystals were attached, that we feel very confident 

 of the purity of the material which we analyzed. 



The analysis was made after we had had considerable expe- 

 rience in the determination of beryllium and had made some 

 experiments in determining it in presence of phosphoric acid. 

 The method which we adopted gave good satisfaction, and we 

 give it here somewhat in detail. The mineral was dissolved 

 in nitric acid, the solution concentrated to a small volume, sul- 

 phuric acid was added, and the gypsum crystals after being 

 collected by filtering through a rubber funnel were ignited 

 and weighed as CaS0 4 . The filtrate was concentrated in a 

 platinum dish and gently ignited to drive off all hydrofluoric 

 acid and the excess of sulphuric acid. The residue was dis- 

 solved in hydrochloric acid, a basic acetate precipitation of a 

 part of the beryllium and phosphoric acid was made in the 

 cold with ammonium acetate, and a little calcium precipitated 

 from the acetic acid filtrate by ammonium oxalate, which was 

 ignited and weighed as CaO. The beryllium in the filtrate 

 from calcium oxalate was precipitated as a phosphate by means 

 of ammonia, filtered, and the phosphoric acid in the filtrate 

 precipitated with magnesia mixture. The two precipitates 

 containing the beryllium as phosphate (the basic acetate pre- 



