114- Prof. Del Rio's Analysis of two new Mineral Substances. 



diately sublimed, and a sub-oxide of zinc remains at the bot- 

 tom of the retort. That the metallic gray powder attached 

 to the upper part of the retort is selenium, is proved by the 

 red colour of the light transmitted through it, and by the high 

 metallic lustre of the surface in contact with the glass. The 

 residuum is shown to be sub-oxide of zinc by its solubility in 

 acids, and by its being redissolved by an excess of potass, 

 soda or ammonia, after having been precipitated by the alkali 

 from an acid solution : also by its phosphorescence when fused 

 by the blowpipe, by the white smoke which it emits and which 

 attaches itself to the charcoal, and by the enamel which it forms 

 with borax and microcosmic salt. 



In order to determine the proportions of the component 

 parts of the gray substance, I first treated it with concentrated 

 sulphuric acid, which dissolved the mercury and some of the 

 zinc ; I then applied nitric acid, which dissolved the remain- 

 der of the zinc, and I finally employed nitro-muriatic acid to 

 oxidate the selenium. By these operations 1*5 grain of sul- 

 phur, without any red tinge, and which I therefore suppose to 

 be pure, was separated ; and after the nitro-muriatic acid had 

 been distilled offj selenic acid was sublimed : this was partly in 

 acicular crystals, and partly in a dense white mass half fused 

 and semi-transparent. There remained at the bottom of the 

 retort the sulphate of lime formed by the sulphuric acid used 

 in the first process, and the lime of the calcareous spar acci- 

 dentally mixed with the mineral. 



I think that it may be deduced from the foregoing experi- 

 ments and others, that the gray mineral is composed of 



Selenium 49 



Zinc 24 



Mercury 19 



Sulphur V5 



93-5 

 which, with the addition of six grains of lime obtained, will 

 amount to 99*5. But the lime merely accompanies the ore, 

 and does not enter into its composition. 



The gray mineral is therefore a bi-seleniuret of zinc united 

 to a protosulphuret of mercury, the latter giving, in my opi- 

 nion, the dark or gray colour to the mineral. 



The red mineral will also be a bi-seleniuret of zinc, but the 

 mercury will be in the state of a bi-sulphuret or cinnabar, 

 which will give the red colour to the mineral. 



These two minerals are therefore in my view, and accord- 

 ing to Berzelius, two distinct genera, because they are ex- 

 pressed by two distinct formulae, as is the case with orpiment 



and 



