1825.] Frof. Renwick on Torrelite. 219 



muriatic solution and washings (4), having been ixfixed, liquid 

 amaionia was added in excess, which threw down a red preci- 

 pitate; the supernatant clear liquor was poured ofF; the residue 

 thrown on a filter and washed, and the liquor with the washings 

 set by for further experiment. See (12). 



(6.) The precipitate (5) was redissolved in a small quantity of 

 muriatic acid, and the solution concentrated ; tartrate* of potash 

 was added until effervescence ceased, when crystals of tartaric 

 ^cid were thrown in, by which a copious white precipitate was 

 produced. ^ 



(7.) This precipitate (6) was decomposed by heat, which, 

 being pushed too hastily, a portion of charcoal was left ; lest 

 any carbonate of potash should be present, in consequence of a 

 portion of the precipitate (6) being the difficultly soluble bitar- 

 trate of potash, the mass was washed with very weak vinegar. 

 To separate the carbon, the mass was again acted upon by a 

 small quantity of muriatic acid, and the solution filtered. 



(8.) The new muriatic solution was decomposed by ammonia, 

 which threw down a red precipitate^ that, when washed and 

 dried, weighed 6*16 grains, 



(9.) Lest the acetic acid (7) had carried oiF any part of the 

 mineral, it was tested with ammonia, but no precipitate ensued, 

 (10.) Into the liquor remaining after precipitation by tartrate 

 of potash and tartaric acid (6), ferrocyanate of potash was 

 dropped ; a milky appearance first took place, and finally a 

 copious precipitate of a pale blue colour. This precipitate, 

 when dried, weighed 28*9 grains ; which, supposing it to be a 

 ferrocyanate of the protoxide of iron, and its equivalent number 

 99, gives on reduction lO'O grains protoxide of iron. 



(11.) To the liquor yet remaining (10), carbonate of ammonia 

 was added ; a white powder was thrown down, weighing 1*84 

 grains. 



(12.) The ammoniacal liquor and washings after the first pre- 

 cipitation (5) were boiled for an hour, but no precipitate ensued; 

 being then acted upon by carbonate of soda, a greyish precipi- 

 tate fell, weighing when dried 20*92, and manifesting the pre- 

 sence of r2'04 grains caustic lime. 



C. 



(1.) Another portion of the powdered mineral was exposed 

 for an hour to a red heat in a platina crucible ; its weight was 

 reduced from 50 to 48 25 grains. 



(2.) It was then treated as before (B. 3) with nitro-muriatic 

 acid, the insoluble portion fused with caustic potash, &-c. as in 

 (B. 4), and the whole of the liquors united, as in (B. 5). The 

 mixture was then concentrated to separate the excess of acid, 

 and again diluted with water. Crystals of sulphate of soda 



• Query Carbonate ?— C. 



