24G ANNUAL OF SCIENTIFIC DISCOVERY. 



Tliis is, as is seen, an opinion diametrically opposite to that of Runge, 

 who is so strong an advocate of the chemical theory that he considers col- 

 ored cottons as cottonates. In this view, a faint chamois tint, produced by 

 oxide of iron, is called by him per-cottonate of iron; another, bi-cottonate; 

 another still, basic cottonate of iron. 



Mr. Walter Crum declares that the substance of dead cotton has been 







entirely bleached before becoming flattened; it contains, therefore, he says, 

 neither fatty matter, nor any impurity capable of hindering the fixing of 

 the coloring matter. 



But let us return to the suberic matter, whose presence Mitscherlich recog- 

 nized on leaves and about the exterior of plants. It is over thirty years since 

 Payen showed that the epidermis of plants is covered over with a very thin 

 envelope, containing a fatty matter, some nitrogen and silica. Ad. Brong- 

 niart has isolated this pellicle, on which Mitscherlich experimented, by sub- 

 mitting leaves to a prolonged maceration, and has described it under the 

 name of cuticle; and Fremy, who has also just examined it, has recognized 

 in it all the characteristics of a fatty substance which he calls cutine. In 

 fact, in contact with boiling potassa, the cutine saponifies, and the acid which 

 is produced presents, the characters of a fatty acid. This experiment has 

 been repeated with success on the epidermic membranes of leaves, flowers, 

 and fruits. 



It is easy to develop, ad libitum, this epidermic membrane. It is sufficient, 

 in fact, to experiment on superficial sections of living tissues of leaves, 

 branches, tuberaceous roots, and subterranean stems ; at the end of several 

 days the denuded tissues afford characteristic reactions of epidermic mem- 

 branes. 



Transformation of Woody Fibre into Sugar. On the occasion of the above 

 discussion, Pelouze announced the important results which follow. Cel- 

 lulose, precipitated from its solution in the ammoniacal oxide of copper by 

 a feeble acid, is soluble in dilute chlorohydric acid. Ordinary cellulose is 

 soluble in concentrated chlorohydric acid; water forms with this solution a 

 precipitate of dazzling whiteness; at the end of two days the precipitate 

 ceases to form, and all the cellulose has been transformed into sugar afford- 

 ing the charactei-istics of glucose. The transformation of cellulose into glu- 

 cose can be effected by a prolonged ebullition in water containing a small 

 quantity of sulphuric or chlorohydric acid (some hundredths); paper, old 

 linen, sawdust, and any cellulose, more or less pure, can be thus turned into 

 sugar at the end of several hours' boiling. Pelouze thinks that this reaction 

 will become the basis of a new branch of industry one which has often 

 been attempted since Braconnot succeeded, in 1819, in transferring lignine 

 into glucose; he thinks that the transformation would be rendered much 

 more active by operating in a close vessel at an elevated temperature. 

 Lastly, Pelouze announces that, by treating the cellulose with caustic po- 

 tassa in fusion at a temperature between 150 and 19(P C., and dissolving the 

 product in water, a substance can be separated from it by acids which has 

 the composition of cellulose, but differs from it in that it is soluble in the 

 cold in alkalies; it changes into sugar in the presence of chlorohydric acid. 



ON THE PROPERTY OF AMMONIACAL OXIDE OF COPPER DISSOLVING 



CELLULOSE. 



This property was made known some years since, by Schweitzer. Xot only 

 cellulose, but also silk, is soluble in this reagent. The ammoniacal sulphate 



