182 OWEN'S DESCRIPTION OF TWO NEW MINERALS AND A NEW EARTH. 



soap stone analyzed by Klaproth, contain 3 to 4 per cent, more silica; 4 to 5 per 

 cent, more magnesia ; 4 to 5 more alumina, and about the same quantity of water 

 and oxide of iron. 



The specimens of saponite from Brusksveden, analyzed by Svanberg, contain 8 

 to 9 percent, more silica ; 22 per cent, more alumina, and 10 per cent, less magnesia 

 and 8 per cent, less water. 



From the green earth often disseminated in the Italian amygdaloids it differs 

 essentially. Most of these contain a large per centage of oxide of iron and very little 

 magnesia — 2 to 6 per cent. only. Several of the analysis of Serpentine and Mar- 

 molite indicate nearly the same amount of silica as in this mineral, but in them the 

 magnesia is doubled. 



Some specimens yielded a fraction of one per cent, of copper, but this is an accidental 

 impurity, like the adhering carbonate ; the acid solution of the pure mineral gives 

 with sulphuretted hydrogen a slight milkiness only from a small quantity of pre- 

 cipitated sulphur, caused by the reduction of the small quantity of peroxide of iron 

 present. The green color of the mineral may probably be attributed to the presence 

 of this peculiar earth which produces green salts. 



In consequence of the difficulty in separating the traces of magnesia, without 

 dissolving part of the earth itself, I have not been able to ascertain the exact per 

 centage of the earth in the mineral, nor yet determine its combining proportion. 



From the quantity of chlorine evolved during the solution of the mineral and the 

 earth in hydrochloric acid, it appears that this earth must exist in at least two degrees 

 of oxidation : the chlorine being disengaged, just as in the case of the solution of the 

 higher oxides of manganese* when treated with hydrochloric acid. 



If the small per centage of alumina and oxide of iron present be regarded as acci- 

 dental, it is probable that the constitution of the mineral is : 



Two equivalents of bi-silicate of magnesia and one equivalent of the peroxide of 

 the earth, with two equivalents of water; or, 



2 Mg SP+NE, Si+2H, 



Although most of the water is expelled by a heat below redness, still I think 

 it must be regarded as almost all combined ; since the quantity obtained is very 

 uniform, and is within a fraction of a percent, of two equivalents. 



From the above I conclude that the earth contained in the mineral, which is nearly 

 insoluble in sal ammoniac, insoluble in caustic potash, and producing the above 

 reaction with reagents, and green and yellow salts, must either be a new earth or 

 else a modification of some known earth not previously noticed. 



The name Thalium is proposed for the base of this earth. Thalia for the earth 

 itself, and Thalite for the mineral from which it is extracted. 



* The mere trace of manganese present in the mineral will not account for the quantity of chlorine evolved. 



