THE POTATO ASTD ITS COMMERCIAL PRODUCTS. 99 



Dextrine, in the form of a syrupy liquor, obtained by means of diastase, 

 is employed in Paris in the preparation of some alimentary substances ; 

 as for sweetening and thickening tisanes, or diet-drinks, and for the manu- 

 facture of the pains de luxe, or dextrine bread. Pulverulent dextrine is 

 used as a substitute for gum in calico-printing, and for a variety of other 

 useful purposes — especially for adhesive labels, such as postage and receipt 

 stamps. 



However useful starch may be in stiffening certain articles of apparel, 

 it appears to be much too largely used in the present day by the cotton 

 and silk manufacturers to give body to their fabrics. It is, however, the 

 rage for cheap goods that leads to this abuse. To meet this demand on the 

 part of the public, and yet retain his profits, the manufacturer weaves his 

 cloth with a proportionately less number of threads to the inch than before. 

 To counteract this flimsy effect to the eye and touch, it is customary to run 

 the cloth through a solution of starch, and until wetted the character of 

 the fabric is not apparent ; only when the article is washed, is the other 

 side of the picture presented. Of course, with farina and fecula at 2d. 

 or 3d. per lb., it must be very profitable to sell yards of starch at even a 

 much lower price than the lowest cotton goods could be supplied. The 

 fabric in some cases appears to be used merely as the vehicle for the 

 starch, being woven extremely coarse or wide, and the interstices filled with 

 starch. 



Dextrine is now met with in commerce in three distinct forms — viz., as 

 a pearly powder, as a syrupy solution, and in the form of exotic gum, in 

 greater or less perfection, either broken into small fragments or made into 

 rolls of various sizes. Some intelligent persons were apprehensive that, 

 taking advantage of the resemblance, exotic gum, or gum-arabic, would be 

 adulterated with artificial gum. This, however, is impracticable, as the 

 smell and taste of potato-oil, which is always given out by artificial gum, 

 are sufficient to betray its presence. 



In making solidified potato-gum, the boiling syrup is poured into small 

 flat tin vessels, placed upon a hot-air stove, kept at a temperature of 40 u 

 or 50°. At the end of twenty-four hours, the gum will acquire the con- 

 sistency of jujube paste. It is then cut up into small oblong pieces with a 

 pair of shears ; and these pieces are rolled out upon a polished table, with 

 a wooden roller dusted with pulverised artificial gum, placed upon wooden 

 frames, and left for three or four days to dry. The artificial gum thus pre- 

 pared is easily dissolved, and makes a very clear solution ; over dextrine, 

 in the state of powder, it possesses the advantage of being more readily 

 packed ; and over liquid gum, the advantage of not fermenting. 



To prepare this " gum- substitute," the dry starch meal or farina is 

 heated to a temperature of 250 to 300 degrees, either in a revolving cylinder 

 or in iron troughs placed in a stove for several hours, where it acquires an 

 amber colour, and' becomes soluble in water. This change is entirely a 

 molecular one, as the raw and calcined fecula have the same composition, 



H 2 



