Dr. Genth’s Contributions to Mineralogy. 85 
vitreous apophyllite has the same composition, thus indicating 
imorphism, or whether it is a pseudomorph in the form of 
apophyllite, caused by a commencing decomposition of the latter. 
Some of the differences in previous analyses may be attributed 
to a want of care in separating the opaque from the vitreous 
portion, 
The material for Mr. Reakirt’s analyses came from a large crys- 
tal, which was perfectly vitreous and not in the least decomposed. 
he form of the crystal was the square octahedron with the 
second prism. 
The powdered mineral was dried over sulphuric acid. 
I. 1-:167{ grs. mixed and covered with freshly ignited oxyd of 
lead lost by ignition 0-1945 grs. of water. 
I. 3-8700 grs. were fused with carbonate of soda, the fused 
mass was digested with water and filtered from the residue. 
This was dissolved in hydrochloric acid, the silicic acid separated 
by evaporation to dryness. e dry mass was moistened with 
hydrochloric acid and the silicic acid (a) filtered. The filtrate 
{rom the watery solution containing also a considerable portion 
of silicic acid, was precipitated by carbonate of ammonia and the 
Silicie acid (6) filtered and weighed with the other portion: a@ 
and b weighed 2-0321 gers. 
From the filtrate of silicic acid (6) a mixture of fluorid of cal- 
cium and carbonate of lime was precipitated by chlorid of calcium. 
Both were filtered, and after being ignited, treated with acetic 
acid, the excess of acetic acid evaporated in a water-bath and the 
insoluble fluorid of calcium separated from the acetate of lime by 
boiling water. It gave 01438 grs. 
Lime was precipitated from the filtrate of silicic acid (a) by 
oxalate of ammonia and ammonia, which precipitate gave 1:7234 
gts. carbonate of lime. 
III. 1-4570 ers. were fused with carbonate of soda and the 
fluorid of calcium determined as in II. It gave 0:0491 ers. 
IV. 1-9708 grs. were dissolved in hydrochloric acid and eva 
rated to dryness; the dry mass was moistened with hydrochloric 
acid and filtered. The silicic acid, thus obtained with addition 
of a small quantity from the silicofluorid, weighed 1-0384 grs. _ 
The filtrate from the silicic acid was precipitated by ammonia 
and the small quantity of silicofluorid of calcium fused with car- 
bonate of soda. ‘The silicic acid was determined as in Il (5), and 
added to that separated by hydrochloric acid. The lime was 
also added to the other portion of it. The filtrate from the silico- 
fluorid was precipitated by oxalate of ammonia. It gave 08484 
grs. carbonate of lime. d 
The filtrate was evaporated to dryness and the ammoniacal 
salts driven off by heat. The residue was acidulated ir little 
hydrochloric acid to convert the carbonate of potash which on 
