838 



STARCH-PEODTJCINa PLANTS. 



other matters will be best determiued by practical men in England ; 

 but having had occasion many times to prepare specimens for 

 trying the tenacity, the opportunity was always taken of arranging 

 the specimen of jellies in the order of their clearness, or, to speak 

 more accurately, of their transkicenc;, . In this respect also they 

 exhibit considerable differences, varying, when prepared according 

 to the formula described under the head of tenacity, from very 

 translucent approaching to opaque. The order is shown in the 

 annexed list, which begins with the clearest, ; . ^ 



Table jSTa. IV. — SnornxG the order of clearness or transltjcency of 



UNIFORMLY PREPARED STARCH JELLIES. 



INames of specimens. 

 Tannia, C, C.L. 

 Sweet potato, C, C.L. 

 Common yam, C. C.L. 

 Tons les mois, Grenada, CmL 

 Barbados arrowroot, ComL 

 Tons les mois, C, C.L. 

 Barbados yam, C , C.L. 

 Guinea yam, C, C.L. 

 Wheat starch, Coml. 

 Maize, C, C.L. 



Order. Names of specimens. Order 



1. St. Vincent Arrowroot, Commercial 12. 



2. Arrowroot, C, C.L. 13. 



3. Sweet cassava, C, C.L. 14. 



4. Bitter cassava, C, C.L. 15. 



5. Bermuda arrowroot, Coml. 16. 



6. Arrowroot, C, C.L. 17. 



7. Irish potato, C.L. 18. 



8. Potato stai'ch, Coml. 19. 

 6. Buck yam, C, C.L. 20. 



10. Arrowroot, C. 21. 



11. Plantain, C, C.L. 



On comparing this list with the former one, and taking a gene- 

 ral view of the subject, it wnll be seen that the jellies that are 

 most tenacious are generally the least translucent, and that the 

 order of the two lists is more nearly the converse than occurs in 

 regard to any other properties. 



Fer eentage of starch yielded hy different plants. — On this point 

 no two writers do or can agree. The quantity of starch, even in 

 the same plants, the potato for instance, varies with the season, 

 the soil, climate, age, ripeness, length of time the roots have been 

 out of the ground, &c. 



In the following table I have given the result of a series of 

 trials made in the Colonial Laboratory, Deinerara. The roots were 

 all fresh dug, and, with two exceptions, noticed in the remarks, 

 w^ere fair average specimens. The process was the common one. 

 The grater or rasping machine was of copper, to avoid injuring 

 the color of some of the starches, which an iron grater is liable 

 to do : — 



Table No. V. — Per centagb of starch yielded by different plants. 



No. Names of plants. Per eentage of starch. 



1. Sweet cassava 26'92 



2. Bitter cassava 24*84 



3- Another sample * 20'26 



4. A third 16-02 



5. Common yam 24-47 



6. Arrowroot (roots scarcely ripe) 21-43 



7. Another sample 17 "28 



8. Barbados yam 18-75 



9. Tannia 17 05 



10. Another sample 15-35 



11. Guinea yam 17'03 



