128 Scientific Intelligence. 
tained by connecting the apparatus with an air pump by means of a 
flexible tube having a brass plate at the end sufficiently large to cover 
the opening in the plate d, and by an easy manipulation the interior 
may afterwards be filled with hydrogen, or any other gas. . 
Numerous processes in which this ego csr | be advantageously 
ea will ac themselves to the chem I have found it very 
be found useful in ay both precipitate and filtrate from the dust 
and fumes of a laboratory in many cases even when exclusion of aif 
is hot essential. The apparatus is manufactured by the New England 
Glass Co., and sold by Mr. . Wightman, of Boston, at a price not 
exceeding that of a filtering stand with brass rings. 
Tl. Mrneratoey. 
Chemical Contributions to Mineralogy; by James D. Dana. 
Chlorite Section of Hydrous Silicates—Among Anhydr ous Silir 
cates, there is a group of species (which the writer has called ie An 
dalusite petal in which the oxygen of the bases exceeds that of the 
silica. It in 
1. Staurotide Al iat Andalusite 18i*, Topaz a8 —Trimetric and homaomorphot® 
2, Kyanite 41 Si®, Sillimanite 418i? also 41 Sit, 21 Sis, A) Siz—Triclinie. 
8. Euclase Bit, Sphene (Ti+Ca) Si? =(R02-LRO) sit=xn sit ;—Monoclinic. 
4. Tourmaline (R3, 8, 5) Sit ;—Rhombohedral. 
5. Gehlenite (R3, #) Si? ;—Dimetrie. 
Parallel with this Group, there are Hydrous Silicates, and they cot 
stitute what may be called the Chlorite Section. In a few among them, 
Pg Euphyllite, Hisingerite, and Pyrosclerite us part), there is the ratio 
: 1; but in alt the others, the ratios are eith ,1:gorl: 
"re oxygen ratios of ee gore for the neler peroxyds, silica) 
and water, according to the = recent analyses, together with 
accepted formulas, are as ‘follow 

R i Bi 
Hisingerite (A), - - - 1 2 3 sues 8) 7 bare rer 08 
3 Ce ee Best e 
Whutinhite: <0 2, 400% iS... Bo A i. 6H 
Pyrosclerite (A), - - - 4 2 6 4 2k? Si+ res oll 
” t ‘ DB). = 8 4 it 66 
tiphyiite, <5 ge eg 
iapaeita, Si Ss ee ee Re Si4 sai Si+3H : 
icant Se, ee Re Sit HSi+ Mee 
lessite, - - - - - 9 V4 8 2 
Bitilie 2° REQ AE Es sk? Si+ 8 Sit on 
Aphrosiderite, - - - - 8 3 4 2 ae = 
psd (AS eR, AES BT R* Si + Ar Si+3H 
ne eee te See ee | 
Cronstedite,- - - - - 1 1 1 : 
Bideroschisolite, - - - 0 2 1 1 
ee oe ee ee 2 
s of this species by Meitzendorff the, ratio for B, 4,52 
10 aie Gee ener S : 

