and the different amylaceous Substances of Commerce. 365 



which may be separated from these by dissolving it in a drop 

 of watei*. It is easy to judge from the inconstancy of these 

 results, that it is very difficult to observe well with a micro- 

 scope. 



Without admitting; the existence of the integuments and of 

 the gummy part known here by very uncertain experiments, 

 is it not more simple and more easy to have recourse to the 

 chemical knowledge we possess to explain these phoenomena ? 



It is very well known that starch changes its nature by the 

 direct action of heat or that of hot water ; it is not astonishing 

 then that, under the three circumstances in which M. Raspail 

 microscopically examined this substance, he saw water disen- 

 gaged from it : it must doubtless be this result which effected 

 a change in the molecular form. 



It is notwithstanding according to the result of the three 

 preceding experiments that the author further strengthens 

 himself in his idea of the composition of the grains of fecula. 



M. Raspail submitted some fecula to the action of boiling 

 water, and he saw a part of the preceding phaenomena again 

 produced ; that is to say, torn integuments swim in the liquid, 

 separated from their gummy part which he supposes to be 

 contained there, and which in his opinion had become dis- 

 solved in the water. Thus the empois, instead of being a com- 

 bination of water, of amidine and of starch, would be a solu- 

 tion of gum extracted by the water from a certain number of 

 grains, torn integuments coming from these last, besides 

 some grains of untouched fecula, but diluted with hot water. 

 According to the author, it would be easy to separate the in- 

 teguments of the soluble matter ; it would suffice to dilute the 

 empois with a great deal of cold water, the gum would pass 

 dissolved, and the integuments would remain on the filtre. 



Respecting this experiment, there is a difficulty which 

 stopped M. Raspail a long time, and which I think he has 

 not yet removed : if the gum contained in the grains of fecula 

 does not differ from other known gums, as the author says, it 

 ought not to become blue by iodine; which is what M. Raspail 

 first believed, and having already ascertained the insolubility 

 of the integuments in water,he had in the afore-cited experi- 

 ment, a means of proving the composition of the grains of 

 fecula. In fact, filtration gave him a gummy liquor on the 

 one hand, and on the other integuments on the filtre. The 

 former should not undergo any colouration by iodine, and the 

 latter ought directly to take a beautiful blue colour : but the 

 result did not take place thus; the integuments and the gummy 

 liquor equally became blue, which exceedingly embarrasses 

 M. Raspail ; he repeated and varied this experiment in every 



manner, 



