368 M. Caventou's Chemical Researches on Starch, 



will suffice, I think, for appretiating whether the new theory 

 which he proposes on the subject of' starch, is as well founded 

 as he wishes us to believe. 



As for me, I am convinced of the contrary, and cannot 

 think, that, in all the circumstances cited by this naturalist, a 

 view by the microscope can take the place of a chemical ob- 

 servation. If this instrument should one day be of known 

 utility in chemistry, this will without doubt be one additional 

 means of investigation, and of which we ought to be glad : but 

 I may be permitted to doubt it until more precise observa- 

 tions, and which agree more with facts, shall have convinced 

 me. 



Besides, it is to be remarked, that in the whole course of 

 his Memoir, M. Raspail does not indicate any means fit to 

 isolate effectually the gum which he says is contained in the 

 integuments that constitute fecula. The most powerful analy- 

 tic means, and by the help of which he establishes the greater 

 part of his deductions, is always to be found in his microscope ; 

 and when the microscopic observation does not agree with the 

 chemical observation, you have seen by what means M. Ras- 

 pail reconciles things. He supposes the existence of a vola- 

 tile substance. You will agree without doubt that such a man- 

 ner of acting and reasoning swerves too much from that now 

 followed in the study of the exact sciences to be admitted. If 

 this were not the case, we should run too much risk of going 

 back again towards the time when flourished phlogiston and 

 acidum pingue, which would, again return, without doubt, 

 under forms and names more appropriate to our epoch. 



Thus, until M. Raspail shall have proved it by chemical 

 experiments more decisive than those on which he rests in his 

 Memoir, I cannot bring myself to believe, 1 st, in the compo- 

 sition of fecula as formed of integuments and gum ; 2dly, in 

 the colouration of this principle by iodine, in the sense that 

 this phenomenon is only a superposition of iodine upon the 

 grain of the fecula, and not a combination ; and, 3dly, that the 

 cause of this colouration is only owing to a volatile prin- 

 ciple. 



Nevertheless I admit with the author the globular configu- 

 ration of the molecules of fecula ; but I believe them homoge- 

 neous, and not of two different natures. 



I am unwilling to terminate this Memoir without offering 

 a just homage to M. Raspail. If I have controverted the 

 view which he takes, I do not the less render justice to the 

 distinguished talents of which he has given proof in his Me- 

 moir. I am persuaded that he is more than capable of com- 

 pletely resolving the question, equallynew and ingenious, which 



he 



