BULLETIN OF THE BUSSEY INSTITUTION. 179 
The merest glance at the table will be sufficient to show that, beside 
carbonate of lime, the amounts of fertilizing substances in the sea- 
shells proper are extremely small. The shells of the lobster and of 
the crabs, on the other hand, are not only very much richer in phos- 
phoric acid, potash (magnesia), and nitrogen than the sea-shells, but 
they contain enough of these constituents to make them worthy of 
some attention on the part of those farmers who can procure such 
shells with very little labor or expense. 
The ashes (6.05% as the mean of two experiments) left on burning 
the horse-shoe or king-crab contain, beside much carbonate of lime, 43% 
of phosphoric acid and 1.16% of potash. The results of some analyses by 
C. Schmidt,* of shells of the lobster, craw-fish, and squill or mantis-crab, 
may be cited in this connection. It is unfortunate that the data given by 
Schmidt are insufficient to permit a close comparison of his results either 
with my own, as given in the table above, or with those obtained by other 
chemists, that are given in the table on page 190. Schmidt found in 100 
parts of the shell of the 
Lobster, Craw-fish, Squill, 
Astacus marinus.  Astacus fluviatilis. Squilla mantis. 
“Oeste 8 1S 22.94 46.73 62.84 
Lime salts. ... . 77.06 53.27 37.17 
[ Nitrogen in this chitin 1.50 3.024 4.267] 
In 100 parts of the ash obtained on calcining the shells, he found 
Phosphate of limeft. . 12.06 13.17 47.52 
Carbonate of lime . . 87.94 86.83 52.48 
[Phosphoric acid in this 
phosphate of lime . 5.52 6.03 21.77] 
In the concretions, found in the craw-fish, that are known as crab’s 
eyes or crabs’ stone, Dulk { found 15.76% of organic matter, 8.69%, of 
phosphoric acid, 0.220, of magnesia, and 63.16% carbonate of lime. For 
an earlier analysis of these concretions by Merat-Guillot, see ‘‘ Annales de 
Chimie,’’ 34.71. Analyses of two crabs’ stones, dried at 110°C. by Weiske,§ 
indicated 14.44. and 15.08% of organic matter (chitin), 85.56 and 84.920, 
of mineral matters, 55.72 and 55.420, of lime, 10.73 and 11.289, of phos- 
phoric acid, 31.09% and 30.60% of carbonic acid, and traces of magnesia. 
Beside the substances enumerated in my table, magnesia, also, was 
specially determined in three instances; viz., in the shell of the lobster, 
the oyster, and the clam, as follows: The lobster-shell, dried at 105° 
* Annalen der Chemie und Pharmacie, 1845, 54. 303. 
+ Together with some phosphate of magnesia. 
t “Journal fiir praktische Chemie,” 1834, 3. 313. 
§ “Die landwirthschaftlichen Versuchs-Stationen,” 1877, 20. 45. 
* 
