APPENDIX. 125 
31. Astrea, Wakes Island. 34. Astrea, Feejees. 
32. Astrea, Wakes Island. 35. Astrea, Feejees. 
33. Astrea, Feejees. 36. Shell of Chama. 
‘“« Nine of the above species, of which there was the largest quaniity on hand, were 
selected for a minute determination of each ingredient, while of the others, only the pro- 
portion of carbonate of lime and animal matter to the other ingredients, was determined. 
The following are the nine selected : 
I. Porites favosa (No. 1), Sandwich Islands. 
II. Madrepora palmatum (No. 9), West Indies. 
III. Madrepora spicifera (No. 10), Ceylon. 
IV. Madrepora prolifera (No. 11), Bermudas. 
V. Madrepora plantaginea (No. 12), Ceylon. 
VI. Pocillopora ligulata (No. 22), Sandwich Islands, 
VII. Meandrina phrygia (No. 28), Ceylon. 
VIII. Astrzea orion (No. 29), Ceylon. 
IX. Astrea (No. 30, p. 721, pl. 13, fig. 15). 
‘A few remarks are added upon some of their physical characters, before giving the 
mode and results of analysis. 
“* Hardness.—All the various corals examined were superior in hardness to calcareous 
spar or common marble, and not inferior to Arragonite; while some were as hard as 
Apatite or crystallized phosphate of lime ; or according to the scale used by mineralo- 
gists, the usual hardness will be expressed by 4, though in a few instances as high as 5, 
Using an iron mortar in the earlier trials, the iron pestle was roughened and cut under 
the resistance of the angular masses of coral, to a degree quite remarkable considering 
the nature of the substance operated on, So much iron was communicated to the powder 
from this source, that recourse was had to a mortar of porcelain, and even this was not 
proof against wear, the porcelain pestle being pitted by the repeated blows. The more 
porous species, of course, were crushed with less difficulty ; and this was especially the 
case with the species of Porites. 
“ Specific Gravity.—The specimens were reduced to fine powder before trying the spe- 
cific gravity, as the porous character of the coral would otherwise interfere with obtaining 
correct results. Considerable variation will be observed in the following table. The 
numbers correspond to the catalogue on the preceding page. 
Specimens. Sp. Grav. | Specimens. Sp. Grav. Specimens. Sp. Gray. 
No | © Barr © |} Nov20 2917 No. 31 2-688 
3 | 9.732 99 9-564 33 2-500 
4 | 2-564 23 2-353 34 2.500 
9 2-421 25 | 2-578 Meand. rustica! 2571 
10 2-105 26 2-584 Shell of t BRS 
~ 2-857 
12 2-427 27 2-740 Chama. 
| | 
32 
