[ 360 ] 



LVI. Chemical Researches on Starch, and the different amyla- 

 ceous Substances of Commerce. By M. J. B. Caventou. 



[Concluded from p. 293.] 



Reflections on the true and original nature of Sago and of 



Tapioca. 



|0 sago and tapioca, in the state in which they have been 

 submitted to our examination, exist in the plants which 

 produce them ?, or in other terms, Do not these vegetable pro- 

 ducts, after having been extracted from their respective plants, 

 undergo from the natives some manipulations insignificant in 

 appearance, yet nevertheless capable of modifying their che- 

 mical nature ? If we rely on the reports made by naturalists 

 on the subject of the extraction of these two amylaceous sub- 

 stances, recollecting also what precedes, we shall not, I hope, 

 encounter great difficulties in resolving the question. In fact, 

 sago is white when it is extracted from the medullary part of 

 the palm which contains it ; it suffices to crush it and to di- 

 lute it in water, then to pass through a sieve the kind of amy- 

 laceous milk which results from it, and to let the liquid settle ; 

 the sago is precipitated under the form of a white powder, 

 and very fine, which is easily collected to be dried. It is nearly 

 the same with tapioca ; but according to the simple detail of 

 this manipulation, is it not evident that these two bodies are 

 insoluble in cold water, and that they do not act in this liquid, 

 as we have remarked in regard to the same principles as thev 

 exist in commerce ? 



But if we follow up to their completion the methods of* 

 extraction and preparation of these substances, we find that 

 tapioca while yet damp is slightly heated in wide basins, in 

 order to dry it and make it fit for granulation ; that sago is 

 submitted to a similar operation, and that the natives carry 

 the desiccation of this latter even to the first degree of torre- 

 faction, in order to give it the reddish tinge which characte- 

 rizes it. Is then any thing more needed to modify the che- 

 mical nature of these amylaceous feculas ? 



Nevertheless it appears that the state of these substances in 

 commerce is not always regular, which, indeed, need not be 

 wondered at, in consequence of the irregularity of the modes 

 of desiccation to which they are submitted in the country : we 

 may easily conceive that the solubility may become complete 

 or partial, accordingly as the temperature employed in the 

 desiccation has been more or less raised, prolonged, and ap- 

 plied with less or more uniformity to the mass of these sub- 

 stances. 



Thus 



