Sweet potato 19.57 C., C.L.**
3. Buck yam 19.43 C., C.L.
4. Barbados yam 19.40 C., C.L.
5. Arrowroot 18.81 Bermuda, commercial
6. Irish potato 17.28 Tubers from Belfast, C.L.
7. Guinea yam 17.14 C., C.L.
8. Tous les mois 16.74 Grenada, commercial
9. Arrowroot 16.43 Barbados, ditto
10. Common yam 16.36 C., C.L.
11. Plantain 16.23 C., C.L.
12. Arrowroot 15.65 C., C.L.
13. Arrowroot 14.84 C., Plantation Enmore
14. Tous les mois 14.64 C., C.L.
15. Tannia 14.60 C., C.L.
16. Sweet cassava 14.30 C., C.L.
17. Maize 14.22 C., C.L.
18. Arrowroot 13.36 C., C.L.
19. Bitter cassava 11.88 C., C.L.
20. Wheat starch 11.16 Commercial, of English manufacture

[** The initial C. throughout these tables indicates that the plant
was grown in the colony; C.L., that the starch was prepared in the
colonial laboratory.]

That the extremes in this table should occur in the case of the
starches of commerce, was, perhaps, to be expected; nevertheless the
difference between the starch of the sweet potato and that of the
bitter cassava is nearly as great, and both these specimens were
prepared in the laboratory, by the same process, and subject to the
same temperature and exposure.

_Characters of the jellies formed by various
starches._--_Tenacity_.--I have met with no very precise results on
this subject, except the well-known fact that it takes a much larger
quantity of some starches, the arrowroot for instance, to form a jelly
of equal tenacity with that formed by others, such as the _Tous les
mois_; and hence in the West Indies the latter is universally
preferred to the cassava starches.

After trying various plans, the method which I found best fitted for
comparing the tenacity of different starch jellies, was the
following:--Of each of the kinds of starch, 24 grains were weighed out
and mixed with 400 grains of distilled water, in a porcelain capsule
of suitable size. The mixture was then heated and boiled briskly for
three minutes, with constant stirring, and was immediately poured into
a conical test-glass,[45] whi