CHEMICAL SCIENCE. 243 



trace of starch, in order to avoid any secondary reaction. On examining 

 the amoniaco-cupric solution which had reacted on the cells, it was found to 

 contain the traces of nitrogenous bodies, and all the cellulose which formed 

 the primary membrane of the cells and fibrous tissue. The proportion of 

 cellulose which has been dissolved may be readily determined by saturating 

 the liquor with a weak acid, and washing the precipitate with a dilute solu- 

 tion of potash. The green insoluble matter, which has preserved exactly 

 the form of the original cells, consists of the pectic substance modified by 

 the action of the reagent. Analysis proves that it is formed of pectate of 

 copper; it is decolorized by the action of acids, and leaves a residue of pectic 

 acid which may be entirely dissolved by the alkalies, only imponderable 

 traces of mineral matter remaining in the liquid. Thus, then, the new re- 

 agent dissolves the cellulose and the nitrogenous bodies, and it transforms 

 the pectose into pectate of copper, without, however, at all affecting the 

 shape or form which it had in the cell ; the acids decompose the pectate of 

 copper, leaving the pectic acid insoluble. Potash dissolves the pectic acid, 

 precipitating the traces of lime salts. These facts leave no doubt of the 

 important part which the pectie compounds play in vegetable organization. 

 In certain cells these bodies are more abundant than the cellulose itself; 

 they incrust the cells, and augment the thickness of their walls. 



This new reagent does not attack all cellular membranes. Thus, the pith 

 of certain trees, and the spongy tissues of champignons, resist its action. It 

 may therefore be inferred, seeing that this body instantly dissolves the cellu- 

 lose of roots and fruits, but exerts no action upon the cells which form the 

 pith of trees, that several species of cellulose may exist, differing in their 

 chemical properties. 



In the course of his experiments, M. Fremy obtained from the cells of 

 fruits a new and interesting body, which he terms cellulic acid. It is readily 

 obtained by submitting the pulp of fruits or roots, from which all soluble 

 matter has been removed by washing, to the action of lime. Cellulate of 

 lime is produced, which remains dissolved in the water, and is precipitated 

 by alcohol. This salt, decomposed by oxalic acid, gives the pure cellulic 

 acid. This body is soluble in water. Its acidity is comparable to that of 

 malic acid. It forms soluble compounds with all the bases, and reduces 

 with great facility the salts of gold and silver. This acid is not derived from 

 cellulose or from pectine, because these bodies, properly purified, do not 

 yield it. M. Fremy is still engaged in the investigation of this body. It ap- 

 pears, however, to be of some importance, in a practical point of view. In 

 one process, for preparing sugar from beetroot, the pulp is submitted to the 

 action of lime before being pressed. The vegetable membrane is thus mod- 

 lied, it loses its elasticity, and is more easily expressed, the pectic compound 

 being changed into pectate of lime. A juice is then obtained, which is very 

 easily worked, but it retains an alkaline reaction, which carbonic acid does 

 not remove, and retains in solution a notable proportion of lime salt, which 

 prevents the crystallizing of the sugar, and gives it a disagreeable odor. 

 This body proves to be cellulate of lime. From the foregoing experiments, 

 M. Fremy concludes that the cell walls of fruits or roots are formed of differ- 

 ent membranes, which microscopic observation cannot distinguish, the ex- 

 ternal membranes being formed essentially of cellulose, and the internal of 

 pectic substances. This latter substance is associated in the cell to a new 

 principle, which, under several influences, produces an energetic acid, which 

 he terms cellulic acid. 



