and the different amylaceous Substances of Commerce. 289 



Aqueous maceratum of Salep. 



This maceratum, tried by some re-agents, acts in the fol- 

 lowing manner : it precipitates by nitrate of silver and oxalate 

 of ammonia; corrosive sublimate makes in it a slight cloud; 

 common acetate of lead produces no precipitate in it except 

 when the liquor is very concentrated, but the sub-acetate of 

 lead gives a very abundant precipitate. 



This liquor diminished by evaporation, leaves a viscous 

 matter which has a very great analogy with gum : it does not 

 change by iodine, it is precipitated in the form of white flakes 

 by alcohol ; but it presents this small difference, that it does 

 not easily dissolve again in a pretty large dose of aqua-fortis. 



A portion of this matter calcined in a platina crucible, 

 leaves a residue from which cold water separates sea salt, 

 whilst acidulated water totally dissolves some remaining phos- 

 phate of lime. 



The presence of sea salt in salep, if it be not accidental, 

 is rather remarkable ; for in general this salt has only been 

 found in sea-plants, and I do not think that salep is similarly 

 circumstanced with these: as to the phosphate of lime which 

 is dissolved in a liquid not acid, we should have reason to be 

 astonished at it, if there did not exist in this liquid a certain 

 quantity of viscous matter which holds the calcareous salt, and 

 retains it in solution. It is also known that M. Vauquelin, 

 in his analysis of rice, has announced a similar fact, but which 

 presents this difference, that instead of gum, he made his 

 experiments with starch; and even to dissolve a sensible 

 quantity of phosphate of lime, he was obliged to expose the 

 mixture to heat, for cold water did not act on it. Thus it 

 is very certain that phosphate of lime dissolves in water, 

 not only with the assistance of acids, but also by the help of 

 starch, which receives the action of boiling water, and of a gum 

 similar to that existing in salep. It is very probable that we 

 shall hereafter find other vegetable matters that will also 

 partake of this property, which indeed is common to several 

 animal-matters. 



Aqueous Decoction of Salep first treated by cold 'water. 



Salep purified as much as possible by cold water, and then 

 treated with boiling water, leaves in this fluid a small quan- 

 tity of a matter which gives it an opaline appearance. This 

 liquor filtered and tried by iodine, becomes of a beautiful blue, 

 and precipitates at the end of some hours iodide of starch. 



I found nothing else in this decoction, and had reason to be 

 astonished at the little starch which existed in it, because 

 .salep was generally regarded as nearly pure amylaceous fecula. 



Vol. 68. No. 342. Oct. 1826. 2 There 



