IODINE. 



195 



r,.;.--. 



IV I r ! 



(/, : , 



or 



** 



iU 



Hydruxlate of soda may be obtained in fl.it 

 ' boidal prisms < '.ible size. The?c unite to form 



larger GJ ite<l in echelon, anil striated like 



>!iate of soda. They contain a large pro- 

 portion of water of crystallization, and are very deli- 

 quesrent. Heat drives off the water, melts the salt, 

 and then renders it slightly alkaline. It does not sub- 

 lime so easily as hydriodate of potass. At the tempera- 

 ture of 57, 100 parts of this salt are soluble in a little 

 than 57 parts of water. When dried, Gay I.us- 

 sac consider* it as an ioduret of sodium, conformably to 

 the doctrine already mentioned, whirh makes the salt 

 called muriate of soda a chloruret of sodium. Hydri- 

 odate of soda is composed of 



Acid 100. 



Soda 24.728. 



Hydriodate of barytes crystallize* in fine prisms, 

 like those of muriate ofstrontites. These are very gra- 

 dually decomposed by exposure to the air, and iudine is 

 I. They are faintly deliquescent, but have gnat 

 solubility in water. They bear, without change, a very 

 strong beat ; and heat neither melts this salt, nor alter* 

 in state of neutralisation ; but, if oxygen is made to 

 play on its surface when thus heated, vapours of iodine 

 are evolved, and the salt becomes alkaline. A red heat, 

 according to the opinion of the chemist just mention- 

 ed, converts it into an ioduret of barium. Hydriodate 

 of barytes is competed of 



Acid 100. 



Barytes 60.622 



The hydriodates of lime and strontites are very solu- 

 ble. That of lime is alto very deliquescent, ami has a 

 bitter taste, similar to that of the muriate of lime. 



Hydriodate of ammonia may be formed either by 

 combining equal volumes of ammoniac* I and hydriodic 

 gas, or by saturating the liquid acid with ammonia. It 

 possesses nearly the volatility of muriate of ammonia, 

 but it is more soluble and more deliquescent. It cry*. 

 tallizrs in cubes. 



The hydriodate of magnesia, formed by uniting it* 

 coostitaeOU, is deliquescent, and crystallise* with diffi- 

 culty. When heated to redness, the acid abandons the 

 magnesia, in the same way as take* place with the mu- 

 riate of this earth. 



The hydriodate of sine is 

 in water with an excess of 



This salt is extremely deliquescent, 

 ul I liable by evaporation. Heat depriv 

 ter, then melt* it, and sublime* it in fine prisms. If 

 ihi - i- performed in do*e vessel*, the salt is not decom- 

 posed ; bat air. when admitted, disengages iodine, and 

 oxide of sine i* left behind. This hydriodate i* i 

 posed erf- 

 Acid 100 



Oxide of nine 32.352. 



n a solution of hydriodate of soda, or 

 i* mixed with a solution of the salt* of roanganm, 

 nickel, or cobalt, no precipitate i* obtained ; which 

 shews that the hydriodates of these metals are solu- 

 ble. 



i metallic pre- 

 , mercury, silver, 

 copper it whituh-grey, that of 

 ,J>yellow, t"* 1 of protoxide of mercury 

 greenish yellow, that of per.oxide of mercury orange- 

 red, that of silver white, that of bismuth chesnut-brown. 

 These an considered by Gay- I.u.ac, not as consist- 

 ing of hydriodic acid and the oxides, but of iodine and 

 the metal* sad be then-fore calls them metallic i.xluret*. 

 Tbost cfaemiste who adhere to the old opiniuiis, and 



i'.f. 



The hydriodate of soda, however, gives 

 tisotaU* with the salts of copper, lead, mei 

 asm bismuth. That of copper is whiti-h-i 



apply them to the substances now under consideration, Iodine, 

 will not allow that there is any difference correspond- V "Y"" >> ' 

 ini: to these terras, because they consider iodine as a 

 combination of the acid with oxygen. 



All the hydriodates have the property of dissolving lodureted 

 a large quantity of iodine, which imparts to them a Hydrio- 

 deep reilclish-brown colour. It is separated from them dates " 

 by boiling, or exposure to the air in a dry state. This 

 seems to be a simple solution, and not attended with 

 any saturation of properties. 



The oxiodates of the alkalis, as was already mention- Oxiodatw. 

 ed, are formed alon^ with the hydriodates, when iodine 

 and the alkalis are made to act on one another in water. 

 In order to obtnin these salts in a state of absolute pu- 

 rity, it is necessary to boil them repeatedly in small 

 quantities of alcohol of a specific gravity from 8.6 to 9.2, 

 i dissolves the hydriodates, but not the oxiodates. 

 Oxiodate of potass may be obtained in small crystals, Oxiodate rf 

 nearly of a cubic form, which are not altered by expo- P 

 sure to the air, and deflagrate on burning coals like ni- 

 tre. They require 13$ times their weight of water to 

 dissolve them. They require for their decomposition a 

 heat somewhat higher than the hyper-oxymuriatcs. 

 Oxygen is disengaged, and ioduret of potassium (or hy. . 

 driodate of potass.) remains, which forms n neutral solu- 

 tion in water. This decomposition affords the follow- 

 ing proportions of constituents : 



Oxygen 22.59 



Ioduret of potassium 77.41 



100.00 



When we consider the potassium as oxydatcd, vis. 

 in the state of potaas, the portion of the oxygen which 

 belong* to ii The proportions, according t* 



this distribution, therefore, will be 



Potass 22.246 



Iodine 5,s 



Oxygen 18.817 



100.000 



These two last numbers give the proportions of io- 

 dine and oxygen, which form oxyiodic acid, which are 

 as 10. to 31.321. 



Oxiodate of soda crystallise* in small prisms, united 

 in tufts, or in small cubic grains. They deflagrate on 

 hot coals, below a red beat, giving out a very little io- 

 dine. They are nearly of the same solubility in water 

 as the former. When decomposed by beat, they afford. 



Oxygen 24.432 



loduret of soda 75.508 



100.000. 



On potting iodine into a solution of soda, till the Ii- 

 quid begins to be coloured, fine crystals, in six sided 'j* 1 *' * ** 

 prisms, may be obtained by evaporation. These are 

 very alkaline, and deflagrate on burning coal*. They 

 are very sifcble, and contain a large quantity of water 

 of crystallisation. When soda is added to a neutral so- 

 lution of oxiodate of soda, a salt is obtained in smaller 

 crystals, or silky needles united in tufts. They are not 

 altered by the air. Both the oxiodic and the hydriodic 

 acids have a great tendency to form subsalts. 



The oxiodates of potass and soda detonate feebly by 

 percussion when mixed with sulphur. It is not pro- 

 bable that they could be advantageously employed in 

 the manufacture of gunpowder; 100 parts give only 

 2M9 of gas, whereas 100 parts of nitre give 53.62. 

 linadvantage would require to be compensated by 

 a greater rapidity of detonation. 



Oxiodate of ammonia can only be obtained by satu- 



