SIMPLE BODIES. 



vvliichfupport combuRioii. Some of the latter appear to aft 

 the part of both. This is evidently the cafe with fulphur, 

 which gives light and heat to a certain extent in ita com- 

 bination with fome of the metals, and alfo when it com- 

 bines with oxygen, with which, as an inflammable body, 

 it forms an acid. In the oppofite characters, hke chlorine 

 and jodine, it forms an acid with hydroRea, which is now 

 termed the hydrofulphuric acid. Gay Luflac goes farther, 

 and fuppofcs that phofphorus, carbon, and azote, have a 

 fimilar double property. Carbon he fuppofes to be the 

 acidifying principle of fome of the vegetable acids, and that 

 azote afts a fimilar part in the pruffic acid. 

 Simple Combultible Bodies. 



The bodies of the firft ciafs, with the exception of fulphuf, 

 phofphorus, azote, hydrogen, and carbon, are known to 

 be metals ; and there is (Irong reafon to believe that hydro- 

 gen is a metal in the elallic form. It is very remarkable, 

 that thofe bodies, the metallic nature of which is doubtful, 

 appear to pollefs the property of combining more llrongly 

 With inflammable bodies, than the metals with each other in 

 forming alloys. Indeed, the combinations of moft of the 

 metals w'ith thofe that are not metallic, are generally con- 

 fpicuous, and always definite. 



The firft of the feeond clafs of bodies, viz. oxygen, has 

 long been confidered a fimple body. The feeond has been 

 lately, by the French chemilts and by fir Humphrey Davy, 

 confidered in the fame light. It was till lately confidered 

 as a compound of muriatic acid and oxygen, from which 

 it was called oxymuriatic acid. Its name is now changed 

 to chlorine, from its green colour. Jodine is another fub- 

 ilance of the fame clafs, exhibiting ttriking properties with 

 inflammable bodies. Its name has been derived from the 

 violet colour of its vapour. It was dilcovered in kelp, a 

 fubftance which confilts of foda combined with certain 

 impurities. The jodine is extrafted from it by the follow- 

 ing procefs. Infufe the kelp in hot water till all the fo- 

 luble part is taken up ; then evaporate the folution till 

 the carbonate of foda cryftalUzes on cooling. In this way, 

 by repeating the evaporation and coohng, feparate as 

 much as poffible of this fait ; then continue the evapora- 

 tion to drynefs. This refiduum is now to be introduced 

 into a glafs retort, or a long-necked matrafs, and a quantity 

 of fulphuric acid poured upon it. This is then applied to, 

 at firlt, a gentle heat. When the temperature reaches 

 about 300°, a purple or violet-coloured vapour appears 

 in the neck of the retort, which condenfes into (hining 

 opaque cryftals of the appearance of plumbago. Thefe 

 cryftals are pure jodine. Jodine, in the folid form, is of 

 a greyifli-black colour, its vapour being of a beautiful violet. 

 Its cryftals have a ihining fcaly appearance, like mica. Their 

 form is that of rhomboidal plates, and fometimes of elongated 

 oftohedrons. It is foft and friable, fo as to rub to powder 

 between the fingers. It ftains the fl<in of a deep brown 

 colour, but not permanently. It has the fmell of chlorine 

 or oxymuriatic gas. Its tafte is acrid, although it requires 

 feven thoufand parts of water for its folution. It deftroys 

 vegetable colours, like chlorine, but with lefs energy. 



Itsfpecific charafteris 4948 at the common temperature, 

 water being i. It fufes at 225° of Fahrenheit, and affumes 

 theelattic form at 374° or 356° ; but it will come over in 

 diftillation with the vapour of water. It is a non-conduftor 

 of eledlricity. 



Jodine, like oxygen and chlorine, has the property of 

 fupporting combuftion with combuftible bodies. With 

 fome of thefe it forms compounds analogous to oxyds, and 

 with hydrogen it forms an acid refembling the muriatic acid, 

 the compound formed by hydrogen with chlorine. In thefe 

 inftances, jodine and chlorine have not only the property of 

 fupporters of combuftion, but of forming acids witli an in- 

 flammable bafe. They, however, in their turns, aft the part 

 of combuftible bodies, by forming acids with oxygen. It 

 appears alfo, from the views of Gay Luflac, that fulphur has 

 alfo this double property, for by combining with hydrogen 

 it forms the well-known compound called fulphuretted hy- 

 drogen, which pofl'efles the properties of an acid, and is ren- 

 dered fo by afting the part of oxygen with the inflammable 

 bafe. On the contrary, it forms fulphuric acid with oxygen 

 by itfelf, afting the part of an inflammable bafe. 



It alfo appears to this philofopher, that azote, carbon' 

 and phofphorus, may have the power of producing acidity 



by 



