BLACK SAND ON THE BANKS OF THE DON. 25 



The loss wiH not appear excessive, if we consider, that a 

 portion of the arsenic must have been suhlimed, before the 

 presence of that metal was suspected. 



Upon the whole, 1 think we may consider the specimen 

 of iron-sand examined, as composed of <) parts protoxide of 

 iron, and 1 of red oxide of titanium. The presence of ti- 

 tanium in tiiiis ore had been already detected by Lampadius, 

 though, iis I have not seeji his analysis, I cannot say in what 

 proportion. 



The colour of the iserine is iron-black, wltli a shade of T"heiserlned«. 

 , . /. II 1 .11 scribed, 



brown. It consists ot small angular grams, rather larger 



than those of the iron-sand, but very similar to them in 

 their appearance. Their edges are blunt; they are smooth- 

 er, and have a stronger glimmering lustre than those of the 

 iron-sand. Lustre seuiimetallic, inclining to metallic. The 

 fracture could not be distinctly observed, but it seemed to 

 be conchoidal ; at least nothing resembling a foliated 

 fractal e could be perceived. Opake, semihard, brittle, 

 easily reduced to powder; colour of the powder unaltered; 

 Specific gravity 4'49I*; scarcely attracted by the mag- 

 net, 



1. A hundred grains of the powdered ore were mixed Annlysisof it* 

 with six times their weight of carbonate of soda, and ex- 

 posed for two hour* to a red heat, iii a platinum crucible. 



The mass obtaineil, being softened with water, dissolved 

 completely in muriatic acid. When the solution was con- 

 centrated, it assumed the appearance of the yolk of an egg. 

 It was boiled, diluted with water, and set aside for some 

 time. A white matter gradually deposited, which, when Oxide of tita- 

 dried on the steam-bath, weighed 53 grains, and possessed "^""^* 

 the properties of oxide of titanium. 



2. The liquid, thus freed from titanium, was evaporated Silex. 

 to dryness, and the residue redissolved in water, acidulated 

 with muriatic acid. A white powder remained, which, after 

 being heated to redness, weighed 16*8 grains, and possessed 



the properties of silica. 



3. The solution was precipitated Hy amnijonia, and the Aluijiine. 

 brown matter, which had separated, boiled for some time 



* If, as the following analysis would lead us to expect, the specimen 

 examined was a mixture of four parts iserine, and one part quartz and 

 i'elspar, the specific gravity ©f pure iberine should be 4'964. 



in 



