358 Elements of Mineralogy. 



ftrike fire with fteel 5 its fpecific gravity fo 

 4,569. 



2. In an open fire it is almoft intirely vo- 

 latil and infufible. Microcofmic fait or borax 

 fcarcely affecT: it, but it is adted upon witk 

 much effervefcence by mineral alkali, and 

 with it forms a reddifh mafs, which fmells of 

 fulphur. 



3. It is affeded by no acid, but the ni- 

 trous and arfenical, both require the affiftance 

 of heat 5 the latter is converted into orpi- 

 ment. 



4. Mr. Scbceltliz& found it to confift of an 

 acid of a peculiar nature united to fulphur ; 

 a fmall proportion of iron is commonly found 

 in it ; but this feems merely fortuitous ; 100 

 parts of it contain about 45 of acid, and 55 

 of fulphur. 



5. It is decompofed either by detonation 

 with nitre, or by folution in nitrous acid : 

 this latter method is the readieft : for this 

 purpofe it is to be 5 times diftilled, each time 

 with 4 times its weight of fpirit of nitre ; -a 

 white calx at laft remains, which is the mo- 

 Jybdenous acid. 



6. This acid is foluble in 570 times its 



weight 



