890 Intelligence and Miscellaneous Articles. 



n&mes peciose, and which, by the action of the weakest acids, is con- 

 verted into pectin. Diluted acids produce this effect only at the 

 temperature of ebullition ; and acetic acid, which, as is well known, 

 does not act upon starch, is also without action on pectose. Pectose 

 cannot be confounded with cellulose, for the latter, as was ascer- 

 tained by M. Payen, gives no traces of pectin when treated with 

 acids. M. Fremy's experiments confirm those of M. Payen. 



2nd. The author has found in the greater number of fruits and 

 roots, an amorphous substance, comparable to ferments, and espe- 

 cially to diastase : the gelatinous substances contained in vegetables 

 experience by its action a series of isomeric transformations. This 

 substance M. Fremy calls pectase ; in acting upon the gelatinous sub- 

 stances it gives rise to the different phsenomena which constitute 

 pectic fermentation. 



3rd. The acids which are employed to convert pectose into pectin, 

 may, according to their nature and proportion, form different sub- 

 stances, each of which possesses well-delined distinctive properties. 

 Thus, when the acid is very weak, pectin, properly so called, is ob- 

 tained, which does not render acetate of lead turbid. If the acid be 

 more concentrated, or if the ebullition has been longer continued, 

 the substance formed precipitates the neutral acetate of lead ; this 

 substance the author calls parapectin; and lastly, by employing a 

 powerful acid, a third substance may be formed, which is distin- 

 guished by the name of metapectin ; this is feebly acid to coloured 

 test-papers, and precipitates chloride of barium ; the other com- 

 pounds are neutral. 



4th. If a small quantity of pectase be added to a solution of pec- 

 tin, and the temperature be kept at about 86° F., the pectin is soon 

 observed to change into a gelatinous, consistent substance. This 

 curious transformation, which explains the production of vegetable 

 jellies, may be effected without the contact of the air ; there are 

 formed in this case two acids ; one is new, and termed pectosic acid, 

 and the other is pectic acid. Pectosic acid, which might be con- 

 founded with pectic acid, is immediately distinguishable from it by 

 its perfect solubility in boiling water. In the reaction of pectase 

 on pectin, pectosic acid is first produced, and is afterwards changed 

 into pectic acid by the prolonged action of the pectase. The free 

 alkalies or their carbonates are capable of converting in the cold, 

 pectin at first into pectosates and afterwards into pectates. 



The phsenomena now described are so easy of observation, accord- 

 ing to M. Fremy, and characterize pectin so distinctly, that he finds 

 it difficult to imagine how in later times pectin has been confounded 

 with gums, mucilages, aad especially with pectic acid, which is 

 insoluble in water. 



The author has particularly examined pectic acid, and is of opinion 

 that he has overcome the difficulties attendant upon its analysis, and 

 especially the determination of its equivalent. He has also found 

 that pectic acid, heated to 392° F., loses water and carbonic acid, 

 and a new pyrogenous acid, which he calls pyropectic acid, is pro- 

 duced. 



