118 MR. EDWARD SCHUNCK ON SOME 



0*7035 grm. gave 0*8240 grm. chloride of platinum and 

 ammonium. 



0*7910 grm. left 0*0095 grm. of aslL=i*20 per cent. 



After deducting the ash^ these numbers correspond in 

 100 parts to — 



I. II. III. IV. V. Mean. 



C 57*28 57'53 57-32 58-47 58-26 57*77 



H 6"25 6*26 6-32 5-77 5-65 6-05 



^ 9'39 9*59 9*53 ••• •• 7*77 7*43 8*74 



O 27-08 26-62 26-83 27-99 28-66 27*44 



100-00 loo'oo 100-00 loo'oo 100-00 



It will be seen that in this case^ as in that of colouring- 

 matter A^ there is a wider discrepancy in the numbers 

 yielded by analysis than ever takes place with a perfectly 

 pure substance. Nevertheless the composition of colour- 

 ing-matter B, as represented by the mean of the numbers 

 just given^ approaches so closely that of colouring-matter 

 A from East-Indian cotton as to make it probable that^ 

 when pure, the two bodies do not differ in composition 

 from one another *. 



From what has just been stated it may be inferred that, 

 as regards, their chemical properties, these colouring-mat- 

 ters possess very little interest. It is simply the fact of 

 their being the cause of the yellow or brownish tinge 

 natural to raw cotton which gives them any importance, 

 and makes a knowledge of their properties desu'able from 

 a practical point of view. The darker shade of colour seen 

 in the so-called " nankin " cotton is probably due to a great 

 excess of these colouring-matters existing in the fibre. It 

 is certainly not caused by oxide of iron, since the ash of 

 this kind of cotton contains no more iron than that of or- 



* It is quite possible that these colouring-matters may be products of de- 

 composition derived from some other substance existing in the fibre, and 

 that they may consequently vary in composition according to the strength of 

 the solvent used for extraction, tlie time during which it acts, and other cir- 

 cumstances. 



