1886.] on Becent Progress in the Coal-tar Industry, 459 



nicety and is very cheap. The blue is formed and the red discharged 

 with such precision that patterns can be produced in which the blue 

 discharge covers a great deal more space than the original red. This 

 new printing process was devised by Mr. H. Koechlin, of Lorrach. 

 The reds used for the purpose are in the case of wool, the usual 

 azo-scarlets, for cotton congo-red. 



Artificial Indigo. — About five years ago the speaker had the 

 honour of bringing before this audience * the remarkable discovery 

 made by Baeyer of the artificial production from coal-tar products of 

 indigo blue. Since that time but little progress has been made in 

 this manufacture, as the cost of the process, unlike the case of alizarin, 

 has as yet proved too serious to enable the artificial to compete suc- 

 cessfully in the market with the natural indigo. 



Through the kindness of a number of eminent colour manu- 

 facturers in this country and on the Continent, the speaker was 

 enabled to illustrate his subject by a most complete series of speci- 

 mens both of the colours themselves and of their application to the 

 dyeing and printing of fabrics of all kinds. His thanks are especially 

 due to his friend, Mr. Ivan Levinstein, of Manchester, for the 

 interesting series of samples of cloth dyed with known quantities of 

 fifty difierent coal-tar colours, each having a different chemical com- 

 position ; also to the same gentleman, and to Messrs. Burt, Boulton, 

 and Haywood, of London, for the interesting and unique series of 

 specimens indicating the absolute quantities of products obtainable 

 from one ton of coal, as well as for much assistance on the part of 

 Mr. Levinstein in the preparation of the experimental illustrations 

 for this discourse. To Dr. Martins of Berlin for a valuable series of 

 colours, especially the well-known Congo red, made by his firm, 

 including samples of wool dyed therewith, he is also much indebted. 

 For the interesting details concerning indophenol and its applica- 

 tions the speaker owes his thanks to Dr. Witt and M. Koechlin. 



Cocd-tar Antipijretic Medicines. — Next in importance to the colour 

 industry comes the still more novel discovery of the synthetical 

 production of antipyretic medicines. 



Up to this time quinine has held undisputed sway as a febrifuge 

 and antiperiodic, but the artificial production of this substance has as 

 yet eluded the grasp of the chemist. Three coal-tar products have, 

 however, been recently prepared which have been found to possess 

 strong febrifuge qualities, which if still in some respects inferior to 

 the natural alkaloids, yet possess most valuable qualities, and are now 

 manufactured in Germany at Hochst and at Ludwigshafen in large 

 quantity. And here it is well to call to mind that the first tar 

 colouring-matter discovered by Perkin (mauve) was obtained in 1856 

 during the prosecution of a research which had for its object the 

 artificial production of quinine. 



' On Indigo and its Artificial Production,' Proc. Koy. Inst., May 27th, 1881, 



