derived from Indigo- blue. 311 



0*3615 grin, gave 0*1915 grm. chloride of platinum and 

 ammonium. 

 These numberslead to the formula C 48 H 29 NO 10 , whichrequires 



Calculation. Experiment. 



C 18 288 70-07 6970 



H 29 2 9 7'o5 7" 2 ° 



N H 3*4° 3'3 2 



O 10 80 19-48 19*78 



411 ioo-oo lOO'OO 



The substance, it will be seen, is formed by the union of 6 

 ats. of alcohol, 4 ats. of formic acid, and 1 at. of indigo-blue, 

 accompanied by the separation of 20 ats. of water, since 



Indigo-blue. Alcohol. Formic acid. 



C 48 ff 29 NO 10 +aoHO=C 16 H g NO 2 -f6(O 4 H 6 O 2 )+4(C 2 H 2 Q 4 ). 



The composition of the substance corresponding to E was 

 also determined, the results being as follows : — 



0*1960 grm. gave 0*4500 grm. carbonic acid and 0*0820 grm. 

 water. 



0*3635 grm. gave 0*3250 grm. chloride of platinum and 

 ammonium. 



These numbers correspond with the formula C 96 H n N0 8 ; 

 but the only formula which can lead to an explanation of the 

 manner in which the substance is formed, though it gives a 

 calculated composition not agreeing quite so well with the 

 experiment, is C 26 H 13 N0 8 , which requires 



Calculation. Experiment. 



C 2G 156 63-15 62-61 



H "i3 J 3 5*^6 4 -6 4 



N 14 5-66 5-61 



8 64 25-93 27-I4 



247 100*00 IOO'OO 



Assuming this to be the correct formula, its 'formation 

 would take place in accordance with the following equation : — 



Indigo-blue. Alcohol. Formic acid. 



2(C 26 H 13 N0 8 )4-ioHO = 2(C ls H 5 N0 2 ) + 3(C 4 H 6 2 )+ 4 (C 2 H 2 OJ. 



It will be seen that the same law regarding the number of 

 atoms of oxygen prevails here as in the case of the bodies before 

 described, this number being either 8 or 10. 



If in this process ordinary alcohol is replaced by methylic 

 alcohol, the same effect is produced, provided acetate of soda 

 is employed ; but a mixture of methylic alcohol, formiate 

 of soda, and caustic soda does not act in the same manner on 

 indigo-blue, which remains unchanged, however long it may 

 be left in contact with the boiling liquid. It appears, there- 

 fore, that one of the two agents, ethylic alcohol or acetic acid, 

 is quite essential. One of the two may be replaced by an 

 homologous body ; but when both are so replaced, the indigo 

 blue remains intact. 



