362 M. Caventou's Chemical Researches on Starch, 



maceratum tlian in the decoction ; but, as we have before said, 

 these results may vary according to the circumstances in which 

 the liquors of trial have been made ; and it appears to us very 

 easy to explain the cause. 



Thus, from all these comparisons between the fecula of 

 potatoe, sago, and tapioca, we may then conclude; 1st, that if 

 these two latter substances differ from the first by their solu- 

 bility in cold water, they are not the less of a similar nature, 

 and that the difference of their state in commerce is owing to 

 the mode of extraction and preparation employed, with regard 

 to them, in the countries where they grow. 



2dly, That it is easy to give a similar property to the fecula 

 of potatoes, in like manner as is practised for the manufacture 

 of the poulinta of M. Cadet of Vaux, and very likely for the 

 French tapioca. 



3dly, lastly, That in these operations, one of the most de- 

 cisive properties of the amylaceous fecula is destroyed, what- 

 ever be the vegetable from which it was extracted ; which, in 

 my opinion, should cause it to be identified with the new ve- 

 getable principle designated by the name of amidine by M. de 

 Saussure. 



Before I conclude, I must state that I do not compre- 

 hend under a perfect identity all these feculae extracted from 

 such different vegetables. The last observations of M. 

 Planche on the fecula of the black radish, and the very inter- 

 esting ones of M. Payen relative to the differences these fe- 

 culae present in their specific gravity, would be quite sufficient 

 to destroy such an assertion : — my only object was to prove 

 their great chemical analogy, by the comparative progression 

 of the phaenomena which they present in the same circum- 

 stances, in the same manner as I could cite examples with 

 regard to some other animal and vegetable matters. 



Observations on the new manner in which M. Raspail considers 

 the Fecula of Potatoe. 



If the observations which M. Raspail has just published on 

 the subject of the fecula of potatoes are correct, the chemist 

 will henceforward no longer be permitted to proceed without a 

 microscope. For a long time starch has been regarded as 

 one of the best characterized immediate principles of vegeta- 

 bles ; the most celebrated chemists have never had but one 

 opinion in this respect ; — besides, do not the most authentic 

 and the best verified facts prove it in an evident manner? 

 And, notwithstanding, these chemists would have been de- 

 ceived. Their experiments would have been insufficient to 



i-escue 



