ON MOLYBD^ENA 169 



in a glass retort to the open fire, till the retort was very 

 near beginning to melt, and really found in the recipient 

 some smell of sulphureous acid. Afterwards I exposed the 

 earth in a crucible, upon which another inverted one was 

 luted to the fire for a quarter of an hour, when, on opening 

 the crucible, the earth was found to be melted, and im- 

 mediately a smoke ascended, which fixed itself to a cold 

 iron plate, that was held over it, in the form of small shining 

 white and yellowish scales. As soon as the covercle was 

 put on, the fumes ceased ; but as soon as the air had access 

 to it, the earth melted, and began again to fume, on which 

 account I could not collect any flowers in the upper crucible. 

 The melted earth was poured upon a plate, when it assumed 

 a light grey colour, with rays emanating from the centre to 

 the circumference. 



Under the blowpipe this earth is soon absorbed by 

 charcoal ; but when placed upon a silver plate it melts, and 

 yields vapours with the same phenomena as molybdsena 

 (Sec. iv.). I was now desirous to know whether this 

 melted earth was still soluble in boiling water, (c) It was 

 therefore pulverised, and a little of it boiled in water, as 

 before (a) ; but it exhibited the same phenomena, and 

 the solution acquired the same taste. This fused earth of 

 molybd^na I made use of for all the following experiments. 

 The flowers which attached themselves to the iron plate 

 showed the same phenomena as this earth. 



SECTION VII. 



The earth of molybdama is of an acid nature. The 

 solution (Sec. vi. (c)) reddens lacmus, coagulates the solution 

 of soap, and precipitates hepar sulphuris. (b) It has likewise 

 some effect upon metals. If it be boiled with filings of all 



