Chemical Science, 423 



kind on the iodic acid. To render the iodine more apparent, it is 

 better to triturate a little gelatinous starch with the liquid contain- 

 ing the morphia or its salts, and then add a few drops of the solu- 

 tion of iodic acid ; the blue colour of the iodide of starch is im- 

 mediately developed. 



The same test may be applied to opium : a few drops of lau- 

 danum, or an aqueous solution of opium mixed with starch, and 

 added to iodic acid, give the characteristic blue colour. The acid 

 iodates of potassa, as well as the chloro-iodate and sulpho-iodate, 

 act as iodic acid. The neutral iodate does not do so, unless a drop 

 or two of sulphuric acid has been added. 



During this action iodine is evidently set at liberty : the mixture 

 of iodic acid and morphia, when diluted, yields a solution and 

 deposit both of a reddish-brown colour. By exposure to air the 

 iodine flies off, and both become clear yellow. If the liquid be 

 evaporated, it leaves more of the solid yellow matter, but with a 

 crystalline aspect. 



This substance is but slightly soluble in water ; it fuses below a 

 red heat, and, when heated in a tube, is decomposed with a dull 

 explosive action, certain gases escape, iodine is set free, and char- 

 coal is left in the tube. Further experiments appeared to prove 

 that it contained both iodine and iodic acid combined as with a base ; 

 and it appears probable, that by the action of the iodic acid in 

 excess upon morphia, the latter is transformed (probably by the loss 

 of hydrogen) into a new substance, which combines with the 

 iodine and iodic acid, thus forming the new yellow compound, 

 which, being comparatively insoluble, is separated from the solu- 

 tsotti-i-i-Ann. de Chimiey xHii. 211. 



21. On crystallized Acetic Acid. Despretz. — The process by 

 which crystallized or glacial acetic acid is prepared is held secret. 

 After many trials, M. Despretz succeeded by heating an atomic 

 mixture of fused and dried acetate of lead and boiled sulphuric acid 

 (203.4 parts of the first and 61.4 parts of the second). The result 

 was very excellent. The anhydrous acetates ought to give the same 

 result as acetate of lead. — Amiales de Chimie, xliii. 223. 



22. Pollen of Cedar. — MM. Fourcroy and Vauquelin examined 

 the pollen of the date-tree, and found in it malic acid, phosphates of 

 magnesia and lime, a soluble animal substance, and also an inso- 

 luble animal matter, intermediate between gluten and albumen ; they 

 concluded that probably the pollen of all plants was identical and 

 contained azote. M. Macaire Prinseps, having obtained some 

 pollen of the cedars of Beaulien, examined it chemically. It was 

 yellow, pulverulent, without odour or taste, and burnt in the flame 

 of a lamp, bnt with less facility than lycopodium. It contained acid 

 malate of potash, sulphate of potash, phosphate of lime, silica, 

 sugar, gum, yellow resin, and a substance which, by its characters, 

 approximated to starch. Being analyzed as a whole, the polleH 



