Dr. Schunck on Rubian and its Products of Decomposition. 225 



without any residue. Even after being precipitated with basic 

 acetate of lead and again separated from the oxide of lead, rubian 

 leaves some ash on being burnt, so that it appears as if the 

 lime which it contains were an essential constituent, or at all 

 events, that it follows it into the lead compound, from which it 

 cannot be removed by means of water or alcohol. 

 The following results were obtained on analysis : — 



I. 0-3880 grm. rubian, which had been purified by means 

 of sulphuric acid, dried at 100° C, gave, when burnt with oxide 

 of copper, 07210 carbonic acid and 0-1745 water. 



II. - 4780 grm. of the same preparation, burnt with oxide 

 of copper, gave 0-8865 carbonic acid and 0-2180 water. 



III. 0-4755 grm. of the same preparation, burnt with oxide 

 of copper, gave - 8835 carbonic acid and - 2180 water. 



0-1690 grm., on being incinerated, left 00130 grm. of 

 ash = 7'69 per cent. 



IV. 0-3910 grm. rubian, purified by means of acetate and 

 basic acetate of lead, burnt with chromate of lead, gave - 7455 

 carbonic acid and 0-1880 water. 



0-4050 grm. of this preparation left 00215 grm. of ash = 5'30 

 per cent. 



V. 0-4235 grm. rubian, purified in the same way as I. and 

 burnt with chromate of lead, gave 0-7890 carbonic acid and 

 0-2020 water. 



0-6400 grm. of this preparation left 0-0465 ash = 7*26 per 

 cent. 



VI. 0-4390 grm. rubian, purified in the same way as IV., 

 burnt with chromate of lead, gave 08370 carbonic acid and 

 0-2120 water. 



0-8400 grm. of this preparation left 0-0440 ash = 5-23 per 

 cent. 



After making the necessary corrections for the ash, these 

 numbers correspond in 100 parts to — 



Rubian contains no nitrogen. On burning it with oxide of 

 copper and collecting the gas over mercury, 1 found the latter to 

 be entirely absorbed by caustic alkali. When burnt with lime 

 and soda, (inly a minute trace of chloride of platinum and am- 

 monium was obtained. The statement contained in my former 

 paper, which was made at a time when I had not obtained 

 rubian in a state of absolute purity, that nitrogen is one of its 

 constituents, must therefore be corrected. 



Phil. May. S. 4. Vol. 3. No. 17. March 1852. Q 



