and the different amylaceous Substances of Commerce. 291 



he washes them; when they are well cleaned, he threads them 

 in the form of chaplets, and boils them in plenty of water until 

 some bulbs dissolve into mucilage, which requires in general 

 twenty or thirty minutes. If the ebullition has not been con- 

 tinued Jong enough, the salep retains a Very strong and 

 disagreeable taste: when the process is complete, it is either 

 dried in the sun, or in a stove. 



Not having had an .opportunity of examining indigenous 

 orchides, I could not establish a comparison between these 

 bulbs and the salep of the East; but I shall remark that 

 the treatment to which M. Matthieu of Dombasle has sub- 

 jected the indigenous salep, is sufficient to indicate a great 

 analogy of composition between these two bodies. It evi- 

 dently proves that the indigenous salep is not richer in starch 

 than exotic salep, and that this principle is not in these bodies 

 the base of their nourishing properties. Besides, M. Matthieu 

 says himself, that the orchides submitted to his experiments 

 are in great part formed of a mucilaginous matter analogous 

 to gum tragacanth. 



Of Sago. 



A certain quantity of sago in well-chosen grains and re- 

 duced, to powder was put into maceration with cold water. 

 At the end of twenty-lour hours, the opaline liquor, a little 

 mucilaginous, was filtered, and passed very clear. This liquid 

 acted with alcohol and nitric acid in a manner similar to that 

 obtained with salep; it was precipitated by the subacetate of 

 lead; subjected to evaporation, this fluid deposited transparent 

 scales, which treated by nitric acid did not give any trace of 

 saccholactic acid. 



Thus far these properties of sago have nothing decisive, 

 and would allow us to consider the matter dissolved by cold 

 water as of a nearly gummy nature ; for many gums give no 

 mucic acid by the action of nitric acid ; but what characterizes 

 it in a very remarkable manner, is, that being put in contact 

 with iodine it takes a magnificent blue colour, and forms a so- 

 luble iodide in cold water, but which in other respects acts 

 by heat like the iodide of starch. 



Can the presence of starch be admitted in the liquor where 

 this matter has been dissolved, the only substance known till 

 now to become blue by iodine ? This is not probable; for starch 

 is quite insoluble in cold water, unless by the assistance of an 

 acid, and our liquor is neutral ! Neither can it be thought that 

 some very diluted starch has been carried alonjr and has pass- 

 ed through the pores of the flltre; for I had the precaution 

 to filtre the liquors through three filtres, of which one had 



2 O 2 been 



