1822.) Mr. W. Phillips on the Crystalline Form of Diaspore. 17 
ET Ee , 
1818..| 1819, 
—————— a ee 
Times, |Times. 
b. Rainbows were Seen .........-.eceecceeecseerneceteres sent 1 
Circular round the sun occurred «iets T 9 
Circular round the moon ...........---0+ cee teeerseeeeereeee 5 13 
Northern lights were seen .......-.-+eeee-e cottseet essere ses 6 12 
8. a. The river Neva was frozen on Noy. 15, 1818, and Oct. 27, 1819. 
The ice was broken up on April 17, 1818, and April 9, 1819. 
ArticLe IV. 
On the Crystalline Form of Diaspore. By W. Phillips, FLS. &c. 
(To the Editor of the Annals of Philosophy.) 
In the Annals of Philosophy for the present month there is a 
communication on the subject of that rare mineral diaspore. In 
the cabinet of my friend, 8S. L. Kent, is another specimen consi- 
derably resembling that which is in the possession of G. B. 
Sowerby, but of a more highly crystalline structure. 
The results obtained by subjecting the latter to the blowpipe 
by J. G. Children, Esq. tend to show that it does not difter 
essentially in character from the diaspore of Le Lievre ; and 
having been permitted to examine the specimen in the posses- 
sion of S. L. Kent, which he bought many years ago at a sale 
of foreign minerals, without either a name or locality, I am satis- 
fied that it alsois a true diaspore. 
I succeeded in detaching portions of several fragments of 
crystals, and one very minute and nearly perfect crystal, sufti- 
ciently brilliant for the use of the reflective goniometer. 
This crystal is a doubly oblique prism, of which the form and 
measurements are shown in Pl. XII]. fig. 11. 
IMT.On Ih. touaacter~tetehasde « pete tasvene 65°. 0% 
i Oni Sh eccn ai. donee nae aiateoaraa 2-40 08h530 
| 27d ee Cee ets Bee LOD, 20 
The plane o, though perfectly defined, is not brilliant enough 
for the use of the reflective goniometer, nor are three extremely 
minute planes in connexion with it at the lower solid angle of the 
prism. 
I possess a yery small fragment of Le Lievre’s diaspore, on 
which the plane P of the preceding figure is very bright, and on 
‘which there is a cleavage parallel to the plane M, and hence 1 
have been enabled to procure the measurement by the reflective 
New Series, vou. 1v. c 
