l88 Decompojitioji of Earths and Alkalies. 



CHEMICAL NOTICES. 



ProfefTor Lampadius has offered fome fpeculations, accom* 

 panied with experiments, refpe&ing the poffibility of decom- 

 pofing the earths and fixed alkalies. The following obferva- 

 tions deferve attention : 



i . The cawftic ftrontian earth, barytes, and lime, are decom- 

 pofed in the flrongeft white heat, by combining them with 

 carbon; the firft is particularly attracted by coal, and forms 

 azote, water, and carbonic acid, during that procefs. The 

 decompofltion of thofe bodies, alfo, proceeds under the blow- 

 pipe. — 2. Earths potTefs much affinity for oxygen, which is 

 proved by the excellent experiments of HumboTdt, in decom- 

 pofing the pure argillaceous earth by oxygen gas ; and it ap- 

 pears, from the following facts, how great the influence of 

 oxygen is upon the earths. — 3. The fermentatio fojfilis of the 

 porcelain earth, according to fome mineralogitts, is formed 

 by the foffil fermentation of the fieldfpar; but it continues 

 to be in this way decompofed, when it is further expofed to 

 the action of the air, by which means it is alfo prepared for 

 the intended ufe, lofing thus its fandy particles, and becoming 

 foft, and fit for being worked. — 4. The oxidated argillaceous 

 earth is with more difficulty dilTolved in acids than the dc- 

 oxydated. Pure argil, which he happened to keep in com- 

 bination with oxvgen gas and water for fix months, was not 

 perfectly foluble in fulphuric acid. The folution, however, 

 proceeded, as foon as the earth, after being diflblved by cauftic 

 lye in a filver crucible, was precipitated by acetous acid ; by 

 which it feems probable, that the cauftic fixed alkali deprives 

 the argillaceous earth of its oxygen in a red heat. Hence it 

 may be explained why the fapphire is foluble in acids, after 

 being burnt with kali, &c. — 5. It deferves to be attended to, 

 and proved by further experiments, what the late Mr. Gir- 

 tanner has conjectured of the oxidation of earths. — 6. The 

 earths are formed in plants and animals from elements, which 

 thev receive with their nutriment, and through the mediums 

 with which they are furrounded. The interefting experiments 

 of the ingenious Vauquelin on the formation of the calcareous 

 earth in hens, are known to every ehemift. The earths con- 

 tained in plants are the fame, even when they grow in dif- 

 ferent foils, from which, of courfe, they do not originate. — . 

 7. Earths are alfo formed in the atmof'phere, which appears 

 from the late obfervations of ftony maifes having fallen from 

 the atmofphere. H we dare acknowledge hydrogen, oxy- 

 gen, and azote, as the elements of the earths, that pheno- 

 menon will be eafily explained. From thefe remarks we may 



conclude,, 



