Dr. Schunck on Colouring Matters. 211 



On analysing alizarine prepared by sublimation from pure cry- 

 stals, I obtained the following numbers : — 



I. 0*3970 grm. gave 1 0115 carbonic acid and 0'1340 water. 

 II. 0*4110 grm. gave 1*0510 carbonic acid and 0'1375 water. 

 In 100 parts — 



I. II. 



Carbon 69*48 69*73 



Hydrogen 3*75 3*71 



Oxygen 26*77 26*56 



100*00 100*00 



It will be seen from this that sublimed alizarine does not differ 

 materially in composition from alizarine which has been freed from 

 its water of crystallization. 



Of the compounds of alizarine with bases I prepared the lime, 

 baryta and lead compounds. The two former were prepared by 

 dissolving alizarine in ammonia, and precipitating with chloride of 

 calcium and chloride of barium, the latter by dissolving alizarine in 

 alcohol and precipitating with an alcoholic solution of sugar of lead. 

 The latter forms a purple precipitate, which, after standing for some 

 hours, becomes of a dull red. 



The lead compound gave on analysis the following numbers : — 

 T. 0*4800 grm. gave 0*2095 oxide of lead and 0*0245 metallic 

 lead, equivalent to 0*2359 oxide of lead. 



0*5125 grm. burnt with chromate of lead gave 0*7050 carbonic 

 acid and 0*0780 water. 



II. 0*5865 grm. of a different preparation gave 0*3970 sulphate 

 of lead, equivalent to 0*2920 oxide of lead. 



0*6915 grm. gave 0*9370 carbonic acid and 0*1005 water. 

 Hence was deduced the following composition :- 



Calculated 

 Numbers. 



Found. 



I. II. 



14 eqs. Carbon 84 37*57 37*51 36*95 



4 „ Hydrogen .. 4 1*78 1*67 1*61 



3 „ Oxygen 24 10*75 11*70 11*65 



1 „ Oxideof lead 111-7 49*90 49*12 40*79 



223*7 100*00 100*00 100*00 



The lime compound gave the following results : — 

 I. 0*4685 grm. gave 0*2065 sulphate of lime, equivalent to 

 0*0857 lime. 



II. 0*4750 grm. gave 0*2125 sulphate of lime, equivalent to 

 0*0882 lime. 



Assuming that the formula for this compound is C^ H4 03 + CaO 

 + H0, its composition would be as follows : — 



Calculated 



Numbers. j jj 



1 eq. Alizarine 112 74*91 



1 „ Water 9 6*03 



1 „ Lime 28*5 19*06 18*30 18*58 



149*5 100*00 

 P2 



Found. 



