IODIDE OF STARCH. 741 



makes it blue and not purple. When a film of a concentrated 

 solution of these granules is left under the microscope, it is 

 seen to be in a state of agitation so long as the evaporation of 

 the water continues and when the matter comes to be dried, 

 the granules cease to be visible, attaching themselves to each 

 other as if soldered together, and forming a transparent plate 

 in which nothing can be perceived even with a magnifying power 

 of 800 diameters. A solution of the granules, when frozen and 

 afterwards melted, gives the granules in the form of fine fila- 

 ments, which are very short, and have a silky lustre. M. Jac- 

 quelain finds these granules and fecula, both dried between 266 

 and 275, to have the same composition, C 12 H 10 O 10 . But he 

 constantly obtained a small quantity of nitrogen from starch, 

 about J per cent, from his granules and a somewhat larger pro- 

 portion from fecula, which he conceives to be essential to that 

 substance. The power which starch possesses to form these 

 granules, must be considered as an organic property, and proves 

 that it retains contractility, even when dissolved in water.* 

 The original grains of fecula, which consist of concentric 

 layers, are still more highly organised ; starch indeed occupies 

 an important place in organic chemistry, as a link between 

 matters truly organised and those bodies of a less complex 

 constitution, which still belong to the organic kingdom, but 

 approach in their crystallization, volatility or chemical properties 

 to mineral substances properly so called. 



A compound of amidin and oxide of lead was formed by 

 M. Pay en, by dissolving two parts of pure starch in 250 parts 

 of water, with ebullition for twenty minutes and pouring 

 the filtered solution into an excess of the ammoniacal solution 

 of acetate of lead (page 594), collecting and washing the preci- 

 pitate upon a filter, and drying it in vacuo at 356 (180 cent.) 

 He terms it the bibasic amylate of lead, C 12 H 9 O 9 -f-2PbO. 



Starch combines with chlorine, bromine and iodine. The 

 solution of chlorine has little effect upon starch, but when dry, 

 starch is introduced into chlorine gas, the latter is absorbed, a 

 little carbonic acid is evolved, the mass becomes liquid, assumes 

 a brown colour, and is charged with much hydrochloric acid. The 

 bromide of starch is an orange powder, which is formed, ac- 



* Jacquelain, Annales cle Chiinie et dc Physique, tome 73, p. 167. 



