390 Scientific Intelligence. [May, 



It is then poured upon an oiled slab. To determine whether all 

 the nitrate of copper has been converted into black oxide, a httle 

 of the salt is dissolved in water, and the solution is tested by 

 ammonia. If the liquid, which ought to have been at first trans- 

 parent and colourless, does not acquire the least tint of blue, 

 we may conclude that it contains no copper. If there be still 

 found traces of copper in the salt, we continue the fusion for 

 some seconds longer. The salt by this treatment becomes 

 black from the mixture of peroxide of copper with the nitrate of 

 silver. To separate them, we have only to digest the salt in pure 

 water. The nitrate of silver is dissolved, and constitutes a 

 transparent and colourless solution, while the peroxide of copper 

 remains behind. We have then only to evaporate the solution 

 to obtain the nitrate of silver in the state of crystals. 



V. Gluten of Wheat. 



M. Taddey, an Italian chemist, has lately ascertained tliat the 

 gluten of wheat may be decomposed into two principles, which 

 he has distinguished by the names, gliadine (from y>n«, gluten), 

 and zimome (from ^umIj ferment). They are obtained in a sepa- 

 rate state by kneading the fresh gluten in successive portions of 

 alcohol, as long as that liquid continues to become milky, when 

 diluted with water. The alcohol solutions being set aside gra^ 

 dually deposit a whitish matter consisting of small filaments of 

 gluten, and become perfectly transparent. Being now left to 

 slow evaporation, the gliadine remains behind, of the consistence 

 of honey, and mixed with a little yellow resinous matter, from 

 which it may be freed by digestion in sulphuric ether, in which 

 gliadine is not sensibly soluble. The portion of the gluten not 

 dissolved by the alcohol is the zimome. 



VI. Properties of Gliadine. 



When dry, it has a straw-yellow colour, slightly transparent, 

 and in thin plates, brittle, having a slight smell, similar to that of 

 honeycomb, and, when slightly heated, giving out an odour 

 similar to that of boiled apples. In the mouth, it becomes adhe- 

 sive, and has a sweetish and balsamic taste. It is pretty soluble 

 in boiling alcohol, which loses its transparence in proportion as 

 it cools, and then retains only a small quantity in solution. It 

 forms a kind of varnish in those bodies to which it is applied. 

 It softens, but does not dissolve in cold distilled water. At a 

 boiling heat it is converted into froth, and the liquid remains 

 slightly milky. It is specifically heavier than water. 



The alcoholic solution of gliadine becomes milky, when mixed 

 with water, and is precipitated in white flocks by the alkaline 

 carbonates. It is scarcely affected by the mineral and vegetable 

 acids. Dry ghadine dissolves in caustic alkalies and in acids. 

 It swells upon red-hot coals, and then contracts in the manner 

 of animal substances. It burns with a pretty lively flame, and 



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