•'On tie Comhtndtions of the Metals nvith Sulphur, ji r 



rated hidrogen gns. A tranfparent blende which a£ls in this manner with the acids, muft 

 therefore be confidered as the true hidro-fulphurated oxide cff zinc, or fulphuro-hidroge- 

 nated oxide. There may exill oxides of zinc fimply fulphurated, and there wou'd then be 

 two fpecies of ores very different, one foluble in the fulphuric and muriatic acids without 

 cflfervefcence, an'd the other on the contrary affording a greater or lefs quantity of fulphu- 

 rated hidrogen gas. 



Metallic mercury dobs not unite very intimately with fulphur. Mineral ethlops appear 

 rather to be a mixture than a true combination, but when this oxided metal is combined 

 with fulphur, as for example in cinnabar, it adheres fo ftrongly that no fubftance can 

 direftly decompofe it,' and the feparation can never be effefted but byaltering one or 

 other of thefe principles. It is either necefTary to burn the fulphur, or dis- oxide the mer- 

 cury. Cinnabar owes its fine red colour to the great quantity of oxigen which the mercury- 

 contains. 



VI. 



Notice refpeEilng the extenfme Logarithmic and Trigonometrical Tahlesy calculated under the 

 DireElion of Citizen Prony, Member of the National Injlitute-, i^c. and of the Report 

 concerning the fame. By Citizens La Grange, Laplace^ and Delambre, 



w. 



HEN in the year 2 of the Republic, C. Frony was charged to calcufate the new 



tables of fines, tangents, &c. and their logarithms as required for the decimal divifion of 



the quadrant, he was engaged not only to coitipofe tables which fljould leave nothing to be de- 



ftred ivith regard to accuracy, but to make them the mofl extended and mofl Jlriking monument of 



calculation nuhich had ever been executed^ or even imagined, 



Cit. Prony applied to the execution of this grand enterprize fuggefted by Citizen's Carnot, 

 Prieurde la Cote d'Or, Brunet de Montpellier, which required to be finifhed in a fhorf 

 time, the principle of the divifion of labour by means of which the perfection of work- 

 manfhip, with the faving of expence and time, are obtained in the arts. Thi? divifion,. 

 which renders the moft unfkilful hands profitable in manual works, permits the ufeful 

 employ of men of very limited powers in operations, which on the whole are delicate,. 

 but abound with fimple and minute details. It is much to be wiflied, that this expedient 

 might continue to be ufed for the perfedion and extent of great fcientific works, of whicH 

 the plan cannot be underftood but by men of a fuperror order, but of which the execution 

 prodigioufly exceeds their phyfical power. Such for example, are the numerical dcvelope- 

 ment of formulx, which give the perturbation arifing from the mutual attra£lion of different 

 bodies of the planetary fyftem, and the reduQion of the aftronomical obfervatibns proper 

 to determine tlie elements of the orbits of thefe bodies, 



Citizetv 



