244 METALLIC OXIDES. 



Indirect me- In my essays on determinate proportions, I have often ascer- 



Utod ot dr- tained the composition of an oxide, which was difficult to ana- 



ducing the . r ' 



components Jjse with exactness, by analysing the sulphuret of the same 



of an oxide, metal, aad calculating the composition of the oxide from this 



analysis. I endeavoured to do this in the present case. 



Sulphuret of 3, Sulphuretum stibii. I mixed 100 parts of pulverized an- 

 anhmony was .. . , 1 ..'.-. 1 



made by heat- Oniony with 500 parts of very pure cinnabar, and I exposed 



in? antimony the mixture to heat in a retort. When the cinnabar appeared 



' to be entirely decomposed, and the excess driven out of the 



bulb of the retort, I left the sulphuret of antimony in fusion 



for several minutes at a cherry red heat, and then took the 



retort from the fire. The sulphuret of antimony weighed 



137'3grs. In the upper part of the retort I found a small 



quantity of a reddish substance sublimed. I supposed it to 



be cinnabar not completely expelled, and heated the sulphuret 



Cause of in- again in the retort till it boiled. The red substance was in- 



accur cy. cre ased, and I at last discovered that it was crocus of antimony 



produced by the access of air. As the sulphuret of antimony 



is slightly volatile in a very elevated temperature, the result of 



Inference that this experiment likewise is not very exact ; but it may, how- 



18 6 parts oxi- ever, be inferred, that the quantity of oxigen in the oxidium 



antimony stibiosum cannot be less than 18*6 for one hundred parts of 



form this metal. 



4 X \Vhitcox- 4. White oxide of antimony*., (a) Two parts of pulverized 

 ide.Crt)Antim. antimony oxided (in a phial carefully weighed) by pure nitric 

 ac^and^Umit- ac ' I( *' and { ^ e ox,( * ed mass strongly ignited in the phial, pro- 

 ed. duced in different experiments 125*8, 126:13, and 127-8 parts 



of white oxide. 

 (b.) Antim. b. 100 parts of pulverized antimony first dissolved in nitro- 



dissolved in muriatic acid, and then precipitated and well washed with 

 nitro-mur. ' «>.»'#. . , . , r 



acid, and pre- water, produced a quantity or oxide of antimony, which, after 



cipitated by stron g ignition, weighed 12656 parts. The acid liquor, after 



nited. dilution, contained no more oxide, and did not become turbid 



Deduction, by saturation with an alkali. The experiments appear, there- 



100 antim. and f ore ^ f p r0 ve, that this oxide does not contain less than 258 



gen which is nor more than 27*8 of oxigen to 100 parts of metal. We see, 



neirUf if times therefore, that this oxide must contain ]£ times as much oxi- 

 the oxigen in 

 the §fcmi ox- 

 ide. * I shal! hereafter explain why I do not here use the words oxidum 

 xtihicum. — B. 



gen 



