STAECH-PEODrCI^^a PLANTS. 



387 



further addition of weights is made, and the weight of the disc, 

 framework, and cup being known, we have an estimate of the 

 tenacity of the jelly. This process is but approximative, and 

 some practice is necessary before the operator succeeds in getting 

 imiform resiJts from the same series of specimens. 



The following stateirent shows the results on such specimens 

 as I could procure. The disc was exactly 7-lOihs of an inch in 

 diameter. 



Table Xo, III. — Tenacity of starch in jellies. 



Ko. 



1. 



2. 



3. 



4. 



5. 



6. 



7. 



8. 



9. 

 10. 

 11. 

 12. 

 13. 

 14. 

 15. 

 16. 

 17. 

 18. 

 19. 

 20. 

 21. 



Names of specimens. 

 Tons les mois, C, C. L. 

 Tous les mois, Grenada, Commercial . 

 Maize, C, C. L. . 

 Barbados yam, C, C. L. 

 Irish potato, from Belfast, C. L. 

 Tannia, C, C. L, . 

 Bermuda arrowroot, finest Commercial 

 Common yam, C, C.L. 

 Guinea yam, C, C. L, 

 Plantain, C, C.L. 

 Potato starch, Commercial 

 Arrowroot, C, C. L. 

 Sweet potato, C, C. L. 

 Arrowroot, C, C. L. . 

 Arrowroot, C. 



Arrowroot, St. Vincent's, Commercial 

 Barbados arrowroot. Commercial 

 Wheat starch, Commercial 

 Back yam, C, C. L. 

 Bitter cassava, C, C. L. 

 Sweet cassava, C, C. L. 



Weight in grains required 

 to break the jelly. 

 2,446 * 

 1,742 

 955 

 895 

 756 

 630 

 627 

 657 

 571 

 467 

 467 

 393 

 368 

 340 

 301 

 289 

 273 

 183 

 151 

 150 

 78 



From this list it is obvious that, in respect of tenacity, there 

 is a very great difference between the jellies prepared from the 

 different starches — greater, indeed, than exists in regard to any 

 other character. At first I thought it probable that the tenacity 

 of the jelly would bear some relation to the size of the globules, 

 and it is true that we find the Grenada Tous les mois, the largest 

 globule, next the top, and the cassava among the smallest, at the 

 bottom of the scale. But, on the other hand, we have the Buck yam 

 starch, a large sized globule, very high ; together with many other 

 exceptions. 



As an article of diet, the most tenacious varieties of starch are 

 preferred, on account of the economy of employing an article of 

 which a less quantity will suffice ; and the same is true when ap- 

 plied to starching linen, provided the jelly be not deficient in 

 clearness. 



Clearness of jellies. — When starch jelly is used for the purpose 

 of starching or glazing l^nen, or cotton goods, those varieties that 

 are most transparent are understood to be preferred, provided, at 

 the same time, they possess the requisite tenacity. This and 



* In this instance the -weight stated detached the jellj from the sides of the glass, but the 

 skin of the jellj was not torn as in the other cases. 



Z 



