June, 1912.] 



499 



Dye Stuffs. 



work, comes a statement which shows 

 that with all the advance of chemical 

 knowledge during that period of time, 

 original contention as to the chemical 

 process in the Indigo vat was absolutely 

 correct, and holds the field. 



It has been necessary for me to write 

 these details in order to show planters 

 that in the matter of Indigo my opinion 

 may, after all, be worth attention in 

 view of what is to follow. I have 

 no axe of my own to grind, nor do I 

 own one rupee worth of Indigo property, 

 but, just as my original investigations 

 were begun from a scientific interest in 

 indigo manufacture, so now I am in- 

 fluenced solely by a desire to do what I 

 can to avert the ruin which seems to 

 threaten the industry. There must be 

 living many Iudigo planters in Behar 

 and Champarun, who remember me 

 personally, and will realise that I should 

 not write this letter, did I not feel that 

 I have, in virtue of my special study of 

 the subject, advice to offer which is 

 worth following. It would, I feel, be 

 ungrateful indeed, in view of all the 

 generous hospitality and good-fellow- 

 ship which I enjoyed during the years I 

 spent among them at Segoulie, from so 

 many of the planters, were I to abstain 

 from telling them and their successors 

 what is, in my opinion, a sine qua non 

 if the Indigo industry is to be saved. It is 

 " up to them " to follow my advice or 

 not. At least I will do what I feel to be 

 due to them. 



The position then is. The Indigo in- 

 dustry is seriously threatened by the 

 advent of "synthetic." I purposely 

 omit the word Indigo after " synthetic " 

 because that product is from the dyers » 

 point of view not "Indigo." By this I 

 mean, that whereas natural ''Indigo" 

 contains numerous chemical bodies, all 

 of which are important from the point 

 of view of dyeing power, "synthetic" 

 contains only one of them, viz., " Indigo- 

 tin," which is of any value to the dyer. 

 Planters have been misled by having it 

 drummed into their ears that the value 

 of "Indigo" is to be meaeured by the 

 percentage of Indigotin" it contains, 



Now I have no hesitation in saying 

 that this statement is false, The 

 value of any dyestuff is to be gauged 

 simply and solely by its dyeing power. 

 I shall return to this point later. 

 The natural " Indigo " is acknowledged 

 be the most impor tant dyestuff known, 

 owing to its great fastness, a quality in 

 which it is unsurpassed by any other blue 

 dyestuff." This is a quotation from the 

 highest authority on dyestuffs at the 

 present day. Now to what does natural 

 Indigo owe this pre-eminence ? Is it solely 

 to Indigotin ? Emphatically, No. It is 

 to the other chemical bodies which it 

 contains in company with its Indigotin, 

 bodies be it observed, which are not and 

 cannot be contained in any synthetic 

 imitation of Indigo, which has no more 

 right (if indeed as much right) to be 

 called " Indigo" than Margarine has to be 

 called "Butter." Consequently, any 

 tests of commercial " Indigo " based upon 

 the percentage of Indigotin contained in 

 a given sample, even iflhey are reliable 

 are absolutely without value in arriving 

 at an estimate of the worth of that 

 sample as a dyestuff. Listen to the 

 words of the leading authority on dyeing. 

 Dr. I Merritt Mathews, in his Labora- 

 tory Manual of Dyeing and lextile 

 Chemistry (New York, 1909) says, "In 

 the testing of a dyestuff sample for its 

 money-value it is, of course, necessary 

 to test it in comparison with another 

 sample of the same (or a strictly similar) 

 dyestuff of a known or established 

 money-value." 



These words go to the root of the 

 matter, and, obviously true as they are, 

 I beg planters to weigh them carefully 

 and consider their bearing upon the 

 question of Indigo values. At present 

 Indigo samples are, I understand, esti- 

 mated solely on the basis of percentage 

 of Indigotin, and even this is estimated 

 by methods which are admittedly un- 

 reliable. This results in many '' marks " 

 of high dyeing value being relegated to 

 inferior positions, and consequently 

 selling at far less than their actual money- 

 value. Let me urge upon the planting 

 community to act upon the unbiassed 



