DEXTRINE DIASTASE. 329 



Dextrine. Intimately connected with starch is the substance 

 to which of late years the name dextrine has been applied. 

 Its ultimate constitution is represented by 12 atoms carbon 

 and 10 atoms water, or it is isomeric with starch. Dextrine is 

 derived from starch by heating it to 400 Fahr. ; that is, by 

 converting starch by such a temperature into British gum, a 

 substance long known, which is found to be identical with 

 dextrine. This soluble terrified starch or British gum, known 

 among French manufacturers as lerogomme, is largely em- 

 ployed by calico-printers for mixing with their colours in order 

 to give them the requisite consistence. 



Dextrine is soluble in water and in dilute alcohol : it is in- 

 soluble in anhydrous alcohol ; it is insoluble in ether ; it dis- 

 solves freely in wood-spirit. It differs from starch by not 

 yielding a blue colour with iodine ; it differs from gum in its 

 effect on potash and sulphate of copper, for when mixed with 

 potash it forms a beautiful blue colour with sulphate of copper, 

 suboxide of copper being deposited on boiling the solution, 

 while gum yields no such result. Dextrine ranks among the 

 nutritive vegetable principles. It is contained in malt liquor. 

 It owes its name to the effects of its solution in producing 1 

 right-handed rotation on a ray of polarised light. 



Diastase. The connection which diastase has with starch 

 does not at all depend on its composition. Diastase is, in 

 truth, a nitrogenised body existing in germinating seeds, and 

 is probably albumen or gluten in a particular state of decom- 

 position. Diastase is placed beside starch because the conver- 

 sion of starch into sugar and dextrine during the germin- 

 ation of seeds appears to be due to the presence of diastase. 

 Malt, which is barley allowed to germinate up to a certain 

 point, and then checked in this process by a high temperature, 

 contains no more than the 500th part of its weight of diastase. 

 One part of malt has the power to change into dextrine and 



