10 REPORT—1843. 
Ellipticity ; at Incidence 
40°, 70°. 
Name of Substance, Remarks and Analysis. 
1, Mica from Hudson’s Strait,|very small] very small “ny ellipticity in 






opake metallic appearance many specimens due to 
By OIBOR MUCK Va syecvnttapysas aes none none films, 
3. Labrador spar, several va- 
NEVES Brataemet esas teraedte. none none 
4, Sulphuret of lead (galaena),) small |considerable|ead 85 in 100,—Thomson, 
to ee abi es eee dea eae Jameson. 
5, Variegated do. No. 350 ...!| small _|considerable/Ividescent,changes with tints. 
Gy Diltharee’ oes... ces. Heree very small] large 
7. Sulphuret of copper......... very small]considerable 
8. Peacock copper ore (twolvery small,|considerable|Copper 69 in 100,—Jameson. 
Specimens) .....+.. are: or none, 
9. Gray copper ore, No. 373 ..] none none 
10. Malachite, No, 238 ......... none none 
11. Brown hematite iron ...... none | very small |Oxide of iron 80 in 100.— 
12, Hexagonaliron glance, No} none | very small | Jameson, 
OY “csepeadenacuseasuntomsne 
13. Micaceous iron glance...,.. none none [ron 70 or 80 in 100.— 
Jameson. 
14. Variegated iron glance from} small or |considerable|Oxide of iron 94 in 100.— 
« Elba, No. 879.......,.... none Jameson. 
15. Sulphate ofiron ..,......... small or |considerable|Oxide of iron 25 in 100.— 
none Jameson. 
16. Tron pyrites (cube), (B.) ...|very small} large [47 iron, 53 sulphur in 100, 
—Jameson. 
17. Arseniferous antimony ...| small large {Antimony with arsenic 61 in 
100.—Jameson. 
18. Ferruginous scheelin, 338.} none none 
19, Laminar titaneous iron .,.|/very small,jor none 
20. Hemitrope crystal of oxide|very small,jor none 
of tin, Was Olinda 
21. Green oxide of uranium .,.| none none 
22. Arsenical cobalt, (B.)......}| small considerable 
Alp Aa LD 2 A small _|considerable}d iron, 95 carbon.—Thomson. 

On the Changes which Bodies undergo in the Dark. By Rosert Hun. 
At the last meeting of the British Association, great interest was excited on the an- 
nouncement of a discovery by Moser, of Kénigsberg. This discovery was, that all 
bodies were capable, in the dark, of impressing their forms upon other bodies brought 
near them. Since that period three papers have been published in the Scientific Me- 
moirs, which fully set forth the views entertained by Moser; and the subject has oc- 
cupied the attention of Professor Draper of New York, of Mr. Prater and others in 
England, and also of Fizeau in France. Both Professors Moser and Draper attribute 
the phznomena, to the radiation, in darkness, of light which has been absorbed, and 
which remains latent in all bodies; while Fizeau seeks to explain them by the exist- 
ence of films of organic matter, which are easily disturbed, and in this view he is fol- 
lowed by Sir David Brewster, by Professor Grove, and to a considerable extent by Mr. 
Prater. For the purpose of testing these hypotheses, Mr. Hunt made the following 
experiment, ‘Three flat bottles, manufactured for Mr. Hunt’s experiments on the in- 
fluence of light on plants, were carefully prepared with three differently coloured fluids ; 
an intense solution of carmine in ammonia, which admitted the permeation of the red 
rays only ; a strong solution of the sulphate of chromium, through which but a por- 

