9 
species. Owing to the difficulty of obtaining it in a fit 
state for investigation the few analyses hitherto published 
by Berthier. Dufrenoy, Jacquelin and others have taught 
us but little concerning its real nature. The following 
analysis made on a comparatively pure specimen may throw 
additional light on the constitution of this compound. The 
sample analysed was discovered unclassified in the mineral- 
ogical cabinet at Heidelberg, and was stated by Professor 
Blum, who was disposed to regard it as Pinguite, to have 
been found in the neighbourhood of Heppenheim in the 
Bergstrasse. 
1*4155 grm. of the substance was heated with fuming 
hydrochloric acid until the mineral appeared to be com- 
pletely decomposed ; the solution was evaporated to com- 
plete dryness, and the separation of the silica effected in 
the usual manner. 
Silica obtained 0*5680 grm. 
The weighed silica was then dissolved in caustic potash 
and proved to be entirely free from sand or quartz. 
To the filtrate from the silica were added a few drops of 
nitric acid, the solution boiled and the iron precipitated by 
ammonia. 
Ferric oxide 0*5757 grm. 
The weighed precipitate was next dissolved in strong 
hydrochloric acid, water added and the solution filtered 
from a minute quantity of silica which had escaped separa- 
tion by the previous evaporation. 
Silica (not completely separated) 0*0030 grm. 
Caustic soda was then added in slight excess to the 
filtrate, and the ferric oxide again precipitated, washed, 
ignited, and weighed. The re-precipitated ferric oxide 
weighed 0*5740 grm. Hence the substance was free from 
any appreciable quantity of alumina. 
To the ammoniacal filtrate a few drops of ammonium 
oxalate were added, and the precipitate ignited and deter- 
mined as caustic lime, 
