of the fixed Alkalis. \ 5 



phate of potash. When heated upon a plate of platina, fumes 

 exhale from it, arid it does not burn till it attains the tempe- 

 rature of the rapid combustion of the basis of potash. 



When the basis of potash is brought in contact with sul- 

 phur in fusion, in tubes rilled with the vapour of naphtha, 

 thev combine rapidly with the evolution ol heat and light, 

 and a gray substance, in appearance like artificial sulphuret 

 of iron', is formed, which if kept in fusion, rapidly dissolves 

 the glass, and becomes. bright brown. When this experi- 

 ment is made in a glass tube hermetically sealed, no gas is 

 liberated if the tube is opened under mercury ; but when it is 

 made in a tube connected with a mercurial apparatus, a small 

 quantity of sulphuretted hydrogen is evolved, so (hat the 

 phenomena are similar to those produced by the union of 

 sulphur with the metals in which sulphuretted hydrogen is 

 likewise disengaged, except that the ignition is stronger*,, 

 When the union is effected in the atmosphere, a great in- 

 flammation takes place, and sulphuret of potash is formed. 

 The sulphuretted basis likewise gradually becomes oxyge- 

 nated by exposure to the air, and is finally converted into 

 sulphate. 



The new substance produces some extraordinary and beau- 

 tiful results with mercury. When one part of it is added to 

 eight or ten parts of mercury in volume at 60° Fahrenheit, 

 they instantly unite and form a substance exactly like mer- 

 cury in colour, but which seems to have less coherence, for 

 small portions of it appear as flattened spheres. When a 



* The existence of hydrogen in sulphur, is rendered very probable by the 

 ingenious researches of M. Berthollet Jun. Annales de Cliimie, Fevrier 1807, 

 page 143. The fact is almost demonstrated by an experiment which I saw 

 made by W. Chyfield, esq., at Bristol, in 1799. -Copper filings and pow- 

 dered sulphur, in weight in the proportion of three to one, rendered very 

 dry, were heated together in a retort, connected with a mercurial pneumatic 

 apparatus. At the moment of combination a quantity of clastic fluid was li- 

 berated amounting to nine or ten times the volume of the materials employed, 

 and which consisted of sulphuretted hydrogen mixed with sulphureous acid. 

 The first-mentioned product, there is every reason to believe, must be re- 

 ferred to, the sulphur, the last probably to the copper, which it is easy to 

 conceive may have become slightly and superficially oxidated during the pro- 

 cesses of filing and drying by heat. 



globule 



