﻿112 JPenfield and Harper — Precipitation and 



Si0 2 65-81 



A1 2 3 18-83 



BeO 13-71 



H 2 -_. 1-65 



100.00 



We can add also the alkali determinations in the following 

 European beryls. The alkalies were determined by Smith's 

 fusion method and calculated as sodium, although they all 

 contained some lithia. Limoges, France, 0*73 per cent ; 

 Hiihnerkobel near Bodenmais, Bavaria, 1*20 per cent; Habach- 

 thal, Tyrol, 2*26 per cent 



3. On the precipitation and washing of aluminum. 



Before making the above investigations we tried a few ex- 

 periments in the precipitation and handling of aluminum pre- 

 cipitates which may be of interest to some of our readers. A 

 standard solution of aluminum chloride was first made contain- 

 ing -1002 grams A1 2 3 and 1 c.c. pure concentrated HC1 in 

 every 50 c.c. which were used in our experiments. The pre- 

 cipitation of the alumina was in all cases made in a volume of 

 about 300 c.c. by neutralizing the solution with ammonia till the 

 odor of ammonia could be distinctly obtained from the hot 

 solution ; the beaker was then placed upon a lamp stand and 

 the solution brought to boiling, which was not continued more 

 than one minute. The precipitates were in all cases washed 

 without a pump, but suction tubes 7 inches long were attached 

 to the funnels which cause a gentle suction, and if the filter 

 papers are carefully fitted to the funnels very materially hasten 

 the filtration. 



The following facts were observed: that precipitates which 

 were made in solutions containing large quantities of acid, 

 either hydrochloric or nitric, filtered as well or better than 

 those from solutions containing little ammonia salts, but on 

 washing with boiling water the precipitates from solutions con- 

 taining large quantities of ammonia salts became very. sticky, 

 washed slowly, so that it was almost impossible to free them 

 from the last traces of ammonium chloride, and that very per- 

 ceptible quantities of alumina settled out from the filtrates and 

 washings on adding a few drops of ammonia and allowing the 

 beaker to stand in a warm place. Further, that all of the 

 alumina which ran through did so during the washing. The 

 precipitates after they had become slimy and sticky seemed 

 either to be quite soluble in the hot water or else got into such 

 a condition that they readily passed through the pores of the 



