Chemical Science. 159 



tannate is readily dissolved by infusion of galls, the portion of 

 titanium which otherwise would be lost, from the influence of these 

 two causes, may be obtained by evaporating to dryness all the solu- 

 tions which have been set aside, heating the residue to redness, dis- 

 solving in water, filtering, washing the insoluble portion, again 

 heating it, to burn off carbonaceous matter, then washing it with 

 weak acid, and it will be the titanium required. If contaminated 

 by iron or manganese, they may be removed by digestion in 

 nitromuriatic acid, and repeating this process twice more on the 

 washings, adding each time infusion of galls, all the titanum 

 may be obtained from the mineral analyzed. 



In consequence of the tendency of titanium to form double salts, 

 I have always separated several grains from the salts obtained in 

 the search after the alkaline principle of this class of minerals ; 

 its presence is known by the spongy state of the chlorides of 

 potassium or sodium, which, when freed from ammonia, and 

 heated to redness, will not enter into fusion, and which require 

 several solutions, evaporations, and calcinations, for its complete 

 separation. 



Such are the minute operations which M. Peschier has found in- 

 dispensably necessary in the analysis of minerals with a base of 

 titanium (the number of which is greater than is supposed), and 

 by the aid of which, the foliated black mica of Siberia gave — 

 Silica, 24; Alumina, 8.5; Magnesia, 5; Peroxide of iron, 30; 

 Manganese, 0.7; Titanium, 21 ; Potash, 5.7; loss by fire, 2.75 ; 

 total 97.65. Talcs, Chlorites, and Steatites, have yielded from 

 19 to 30 per cent, of a substance which, like that from mica, 

 which M. Peschier has called titanium, and the titanum obtained 

 from rutilite, forms a gelatinous transparent yellowish mass by 

 evaporation at a gentle'heat, from its muriatic solution ; furnishes, 

 like it, a very voluminous gelatinous and white precipitate, by 

 the saturation of its acid solution ; which yields a yellowish pre- 

 cipitate by infusion of galls, deepening in colour by a slight 

 supersaturation of the acid, becoming brown, and dissolving by 

 further addition of the re-agent, producing a blood-red solution ; 

 is soluble in pure alkali ; forms double salts with all the acids ; 

 becomes insoluble in acids by a strong heat, and consequently, 

 possesses all the characters of titanium, with this slight difference, 

 that its precipitate by infusion of galls is not quite so abundant 

 or so deep in colour, nor does it always become of a b^o\^^l colour 

 by heat ; these differences are, however, considered as of but little 

 importance, compared with the many positive characters it pos- 

 sesses. — Ann. de C/ume. xxvii. 281. 



20. Wohler on a Compound of Cyanuret and nitrate of Silver.-"^ 

 Concentrated solutions of cyanuret of mercury and nitrate of silver, 

 being mixed together, no precipitate fell, but after a few minutes. 



