Refraction. No. 8 in **E.191.6 Herschel, Sir John Frederick William, bart.
On a remarkable peculiarity in the law of the ex- traordinary refraction of differently-coloured rays exhibited by certain varieties of apophyllite.
Camb. 1821. (1), 7, (1) pp. 4°. From the Transactions of the Cambridge philos. soc. |*5290a.1.1 J,