226 Dr. Schunck on JRubian and its Products of Decomposition. 



From the above analyses the following composition may be 

 deduced: — 



The compound with oxide of lead, which was the only one that 

 could be employed for the determination of the atomic weight, 

 was prepared by dissolving rubian in alcohol, adding acetate of 

 lead, precipitating with a little ammonia, taking care to leave 

 an access of rubian, and washing with alcohol. If it be prepared 

 by precipitation from a watery solution by means of basic acetate 

 of lead, great difficulties are experienced in the course of filtra- 

 tion; the liquid begins to run through slowly, the precipitate 

 becomes somewhat mucilaginous and adheres to the paper, and 

 sometimes even it seems to be decomposed and no longer gives 

 unchanged rubian, but a dark brown viscid substance. Its ana- 

 lysis gave the following results : — 



I. 0-3670 grm., dried at 100° C. and burnt with chromate of 

 lead, gave - 3520 carbonic acid and 0*0875 water. 



0-3360 grm. gave 0-2390 sulphate of lead. 



II. 0-4440 grm. of another preparation, burnt with chromate 

 of lead, gave 0-4190 carbonic acid and 0-1115 water. 



0-4320 grm. gave 0-3100 sulphate of lead. 



III. 0-4635 grm. of the same preparation as the last gave 

 0-4450 carbonic acid and 0-1050 water. 



0-5405 grm. gave 0-3880 sulphate of lead. 



These numbers lead to the following composition : — 



Eqs. Calculated. I. II. III. 



Carbon ... 56 336 26-25 26-15 2573 2618 



Hydrogen . . 34 34 265 264 287 251 



Oxvgen ... 30 240 1876 18-89 1862 18-51 



Oxide of lead . 6 670 52-34 52-32 52-78 52-80 



1280 100-00 10000 100-00 10000 



Hence it appears that oxide of lead in combining with rubian 

 does not replace any basic water, as is usually the case. 



It may easily be conceived tbat a body so readily decomposed 

 as rubian gives a number of different products of decomposition. 

 It is decomposed by acids, alkalies, chlorine, heat and ferments ; 

 and I shall now proceed to describe the products of decom- 

 position to which these various reagents give rise. 

 [To be continued.] 



