and on the Sulphurcts of Lime, 163 



is so enlarged with azote as to render the measuring of it not 

 so accurate. 



Third Method,^ hy Quadrisulphuret of Lime, 



Quadrisulphuret of lime is an excellent test for oxygen, and 

 may be applied to common air or to other mixtures of which 

 oxygen is a part, up to the purest oxygen. As this and other 

 similar compounds seem to me destined to act an important 

 part in chemical operations, it may not be improper here to 

 give some account of their origin and their constitution, as 

 far as actual experiments have demonstrated. 



The alkalies and the alkaline earths that are soluble in 

 water have been long known to combine with sulphur, both 

 in the dry and humid way. In the last century they went by 

 the name of hepar stdpkurisy or liver of sulphur, from their 

 colour. 



Scheele was the first to use the quadrisulphuret of lime to 

 abstract oxygen from atmospheric air. Lavoisier also made 

 use of the same article ; but it was to De Marti of Spain we 

 owe the most successful attempt with the quadrisulphuret of 

 lime to abstract the oxygen from atmospheric air. His me- 

 moir, printed in 1795, and reprinted in the Journal de Phy^ 

 sique^ vol. lii. 1801, may still be read with interest*. All the 

 heparSf when dissolved in water, have usually gone by the 

 harsh name of hydroguretted sulphurets in our English works 

 of chemistry since the commencement of the present century. 



In 1798 BerthoUet published an essay on the nature and 

 combinations of sulphuretted hydrogen, with reference to the 

 part it acts in the sulphurets. Proust afterwards controverted 

 some of Berth oUet's opinions in the 59th volume of the JbwrwaZ 

 de Physique i 1804?. Gay-Lussac, in the 78th volume of the 

 Annates de Chimie, 1811, gives some important results on the 

 mutual action of metallic oxides and alkaline hydrosulphurets ; 

 he finds amongst other results that no sidphates are formed, 

 that water is formed, that sulphites or sulphuretted sulphites, 

 and often metallic sulphurets are formed ; and that conse- 

 quently it is not possible to obtain the simple metallic bases 

 of hydrosulphurets by means of hydrosulphurets of their 

 oxides ; and that when a sulphuret is dissolved in water, no 

 sulphate is ever formed, as is commonly imagined, but sul- 

 phites and sulphuretted sulphites. Some proofs are after- 

 wards given-j-. Vauquelin, in the 6th volume of the An7iales 

 de Chimie et de Physique^ 1817, presents us with a laboured 



[* A translation of De Marti's Memoir appeared in Phil. Mag., first 

 series, vol. ix. p. 250. — Edit.] 

 t See also vol, Ixxxv. p. 11)9. 



X2 



