210 Dr. Schunck on Rubian and its Products of Decomposition. 



placed on a filter and washed with water. During the washing 

 its bulk diminished and the colour changed to red, probably in 

 consequence of its losing part of its baryta. Analysis showed it 

 to be a basic compound, in which the acid is to the base as 2 : 3. 

 The neutral baryta salt was obtained by adding chloride of 

 barium to a watery solution of rubianate of potash, when a red 

 precipitate fell, which was collected on a filter, washed with 

 water, and dried in vacuo. 



I. 0-6020 grm. of the latter compound, burnt with chromate 

 of lead, gave 1*0800 carbonic acid and 0*2580 water. 



0-5180 grm. gave 0-0925 sulphate of baryta. 



II. 0*4440 grm. gave 0*7870 carbonic acid and 0*1900 water. 

 0*4890 grm. gave 0*0870 sulphate of baryta. 



These numbers lead to the formula C^^ gas Q^^+BaO + HO, 

 as the following comparison of the experimental results with the 

 theoretical composition shows : — 



Eqs. Calculated. I. II. 

 Carbon . . 52 312 49*24 48-92 48*34 

 Hydrogen . 29 29 4*57 4-76 4-75 

 Oxygen . . 27 216 34*11 3460 3524 

 Baryta . . 1 766 12*08 11*72 11*67 

 633*6 100*00 100-00 10000 

 A lead compound was prepared by adding to an alcoholic so- 

 lution of the acid acetic acid and acetate of lead and then a little 

 ammonia, taking care to leave an excess of rubianic acid in solu- 

 tion. The red precipitate was collected on a filter, washed with 

 alcohol and then dried, at first in vacuo, and then for several hours 

 in the water-bath. Its analysis gave the following results: — 

 0-5490 grm. gave 0*6760 carbonic acid and 0*1580 water. 

 0-6600 grm. gave 0-3760 sulphate of lead. 

 These numbers correspond in 100 parts to- 

 Carbon 33*58 



Hydrogen 3*19 



Oxygen 21*32 



Oxide of lead 41*91 



The most probable formula for this compound is 2C^^ H^^ 0*^ 

 4- 7PbO, though the numbers found by experiment agree better 

 with the formula 2C^^E^ 0^-{-7^hO, as will be seen from the 

 following calculation : — 



Eqs. Calculated. Eqs. Calculated. 



Carbon . . 104 624 33*22 104 624 33*55 

 Hydrogen . 56 56 2*98 54 54 2*90 



Oxygen. . 52 416 22*17 50 400 21*51 



Oxide of lead 7 781*9 41*63 7 781*9 42*04 



1877*9 100*00 1859*9 100*00 



