ON TIx\*, 47 



Sin minor fall into each, and three very different shades will Facts and ob- 



ons on 

 its com- 



immediately be perceived, which perfectly confirms all that I nervations on 



kave h<?re affirmed. pounds. 



JNIosaic gold, then, decomposes the water in presence of 

 »ulpiiuret of potash, as has been just shown; but it also 

 decomposes it in the midst of hydro-sulphuret of potash, one 

 of the most disoxidating compositions known. Heat mosaic 

 gold in hydro-sulphuret, and it will be dissolved : add to the 

 solution an acid, the precipitate will *^be yellow, and exhibit 

 all the properties of hydro-sulphuret of tin major: that is to 

 ■say, sulphurated hydrogen, alone or combined, cin never 

 t'eprive 'tin. of its tendency to decompose v.ater, in order to 

 arrive at the maximum of oxidation. 



Muriate' af the Maximum and Tin. 

 \i hydrogen, assisted hj the affinities which sulphur adds 

 to those which it possesses, cannot lower the oxidation of tin, 

 it will be conceived that hydrogen alone is still less hkely to 

 erfoct it; and, irideed, if thin plates of tin be heated in a 

 solution of tin at the maximum (such as the diluted fuming 

 muriate, or residuum of muriatic ether, an old sulphate, &c.) 

 the oxide at a maximum separates in white flakes, which be- 

 come vitreous in drying, and, m a word, possess all the pro- 

 pt'^rtics of wliich we already have said so much. This is a 

 moan of restoring the integrity of solutions which have been 

 dianged by the atmosphere. During this solution, a decora- 

 position of water, and disengagement of hydrogen take 

 place. This hydrogen, which tmdcr similar circumstances 

 would lower the oxidation of iron, has not the same power 

 over that of tin ; zinc itself precipitates the oxide of tin, and 

 the hydrogen, procured In such great abundance, has no 

 greater effect upon this oxide. 



All these Experiments prove, that the oxide of tin in passing 

 from a minimum to a maximum decreases in solubility, and 

 follows the same law as iron, manganese, cobalt, iand many 

 other metals; they also show why it is that acids have so 

 little action upon the native oxides of this metal, and that 

 pc^tash, on the contrary, has so great an aptitude to dissolve 

 them, as has been remarked by Morveaux, viz. that native 



oxide 



