■"ROM READING, PENNSYLVANIA. 347 



edges transparent, like hyacinth, and of deeper colour than the other crystals. The clea- 

 vage of the mineral was indistinct and fracture very uneven, but apparently in planes 

 perpendicular to the vertical axis. Hardness, between quartz and topaz. <>r 7 — S of 

 Molls' scale. Its powder was brownish yellow, very lii_ r lit. 0*965 grammes weighed in 

 distilled water of temperature 26° C, - 7o."> corresponding to a density of 1*595. Before 

 the blowpipe alone in the forceps, and on coal, infusible, deepens in colour. The crystals 

 heated to redness in a closed tube give off water, and are unchanged in colour. Dues not 

 tinge the blowpipe flame. With borax and salt of phosphorus, gives the reaction of iron. 

 No reaction for manganese on platinum foil with carbonate of Boda and nitre, but yields 

 an opaque reddish white mass. Is not attacked by acid-. A portion of the mineral finely 

 powdered by washing over, tested for potassa and soda after attacking by concentrated 

 hydrofluoric acid, gave negative results. An examination by the moist way, detected 

 silica, zirconia, iron. The iron present tinged the zirconia green when precipitated bj am- 

 monia and bydrosulphuret of ammonium. In a preliminary experiment 0*8985 grammes 

 of the finely powdered mineral exposed to a white heat in a platinum crucible, lost 0*005 

 which corresponds to a per-centa^e of ()•.">.">'*> water. It will be perceived that in its beha- 

 viour, this mineral corresponds, with one exception, to zircon, or anhydrous Bilicate of 

 zirconia. Its water would assimilate it to malakon 2 (Zr s 3 Si0 3 )+HO, but it contain- less 

 water. Malakon has a lower hardness and sp.gr. than zircon, but by ignition its densit} 

 is raised to that of zircon. It is supposed by some mineralogists, that malakon is zircon 

 slightly altered by the absorption of water, and by Damour, that water constitutes the 

 difference between them, with which malakon is chemically combined. An analysis of 

 the present mineral is, therefore, interesting, as perhaps throwing light upon the nature 

 of these two species. 



The analysis of zircon presents well known difficulties in the separation of its silica and 

 zirconia. According to Schcerer, when water i< added to the result ol ln-in_ r the mineral 

 with carbonate of soda, a gritty powder remains, which is a combination of soda and 

 zirconia, and which by treatment with concentrated hydrochloric acid becomes gelatinous. 

 Gibbs ha-, however, shown, that besides the above mentioned constituents, this compound 

 contain- 24*76 silica, and, that if, after attacking by hydrochloric acid to decomposi it. 

 the solution be evaporated to dryness for determining the silica in the usual manner, this 

 silica will be found to contain 30*15 per cent of zirconia. In an analysis where the silica 

 was determined in the usual manner, I found it contained, beside a small quantitj ol tin onia, 

 other impurities. In tins analysis one gramme of the elutriated mineral (dri< d at a -team 

 heat] was ignited in a platinum crucible, ami the water obtained l>\ I"--- I our tim< - the 

 weight of the mineral of carbonate of soda, with the addition according to lb nm I" 

 suggestion of one-eighth nitre, were mingled with the residue in the crucible and exposed 

 to a white heat. The result was found to be well melted, ami was treated bj watei 

 and hydrochloric acid. If sufficient water be present, the acid acts in the cold upon tin 

 granular Bilicate of zirconia Boda, percept ibl j to the eye, leaving white flal dica 



without the least grittiness. The hydrochloric solution was evaporated with the water- 

 bath to complete dryness, and the residue treated with hydrochloric acid iter, 



