of some Oxides of Mercury. 157 



= sufficient to the chemist who is desirous of undcrtakino- 

 operations on a large scale, or who wishes to apply che- 

 mistry to the arts which depend on it. Unless one has ac- 

 quired experience in extensive manufactories, and heen ha- 

 bituated to the operations used in large laboratories, it will 

 be unpossihle to succeed, even after many expensive and 

 discouraging attempts. 



M. Paysse has often employed the different methods here 

 spoken ot, and proceeded with all the care of one desirous 

 to succeed; yet he never obtained results so satisfactory as 

 he wished. He, however, adds, that the means proposed 

 by M. Cnaptal are those which were attended with the 

 most constant succese, thouyh it was not complete He 

 varied his processes, emplovincr nitric acid in different 

 proportions, and ot a different density and purity but 

 notwithstanding the quantity of crystallized oxi-ie which 

 he obtained, it was not possible for him to account exactly 

 for the phenomena which occasion so nianv variations in 

 the results of this operation, which is apparently nothino-, 

 and which, tiowever, is not performed without oreat diffi- 

 culty. So much care is required in the application of the 

 heat necessary to be employed, that in two operation^ where 

 every thing is arranged iu the same manner, and where all 

 the circumstances appear to be absolutely similar, his re- 

 suits were almost always different. Sometimes one of the 

 vessels contained a crystallized portion of oxide, while the 

 other part was a red powder of a brick colour; sometimes 

 the whole of the oxide in one of the vessels was converted 

 into a beautiful crystalline precipitate (red oxide of mercury) 

 and that in the next vessel, which had been treated {he 

 same, exhibited only a mass half yellow and red, without 

 any appearance of crystallizalion; 'sometimes both vessels 

 exhibited this oxide converted, in part, into a brilliant ox- 

 ide and the rest of a disagrt^cable red ; and sometimes this 

 oxide exhibited three very distinct colours, bright red red 

 inclining to brown, and orange red. ° ' 



llie second vessel exhibitcd'only an oxide with two r-o- 

 onrs very distinct, orange and brick red without brilliancy 

 « Where (says M. Pay-c) shall we seek for the cause of 

 these anomalies but in the manner of evaporatiixr the solu- 

 tion, and particularly m that of decomposing the metallic 

 nitrate during the whole course of the operation >" We 

 Fhail see, however, that the purity of the nitric acid con- 

 tributes also very strongly to render difficult the conversion 

 of the mercury into crystallized red oxide, and that the 

 muriatic acid, with which the former is constantly mixed ia 



the 



