454 M. Stolzel on Artificial Ultramarine. 



telluride of potassium, a reddisli-ycllow oilj^ body is obtained. 

 The mode of its formation leads to the supposition that it is tel- 

 luramyle, C^'^ H" Te, but the analyses gave a result which agrees 

 more closely with the composition of tellurbutyle, C^ H^ Te. It 

 is evidently an impure substance. It seems to act as a radical, 

 and forms compounds with chlorine, iodine, bromine, and nitric 

 acid, of which the latter alone is crystallizable. The oxide, ob- 

 tained by digesting the chlorine compound with oxide of silver 

 and water, is soluble in water, and is so strong an alkali that it 

 liberates ammonia from chloride of ammonium. 



By acting on selenide of potassium with sulphomethylate of 

 baryta, selenmethyle, C'^ H^ S^, is formed. It is a reddish-yellow, 

 very mobile liquid, of an extremely unpleasant odour. It is 

 heavier than, and insoluble in water. It has more similarity in 

 its i-eactions with sulphide of aethyle than with selensethyle. 

 When acted on by nitric acid at a gentle heat, methyloselenious 

 acid, HO + C^ H^O, 2SeO^, is produced. This acid crystallizes 

 in groups of colourless prisms, and forms well-defined crystalline 

 salts with ammonia, baryta, and silver, in which the water of the 

 acid is substituted by one equivalent of the base. Heated with 

 hydrochloric acid, chloromethyloselenious acid is formed. This 

 has the formula HO + C^ H^ CI, 2Se02. It is readily obtained 

 in crystals. Similar compounds with bromine and iodine were 

 produced. 



M. Stolzel analysed several specimens of green and of blue 

 ultramarine, and tried the action of various chemical reagents on 

 them. The methods used in the analysis are also described. 

 The results he arrived at may be given in his own summary of 

 them. 



Blue ultramarine exhibited, under exclusion of the air, various 

 degrees of resistance to fire ; at a higher tempex'ature it lost its 

 colour, a mass being left behind which developed sulphurous 

 acid on the addition of hydrochloric acid : blue ultramarine, pre- 

 pared by igniting green, remained unchanged, and liberated sul- 

 phuretted hydrogen on the addition of hydrochloric acid. Air, 

 oxygen, chlorate of potash, saltpetre, sulphurous acid, and hy- 

 di'ogen decompose the colour of both ultramarines at a high 

 temperature, solid potash at a moderate heat, and strong acids 

 and chlorine in the cold. 



When hydrogen is passed over blue ultramarine heated, sul- 

 phuretted hydrogen is evolved ; this is not the case with green 

 ultramarine. Both leave, after this treatment, a grayish mass, 

 which in the oxidizing flame of the blowpipe becomes first green 

 and then blue. 



Solid potash and soda, and still more perceptibly potassium 



