86 



Proceedings of the Royal Irish Academy. 



about twenty-four hours. The yield of crude product obtained was usually 

 almost quantitative. All the compounds mentioned acted as direct dyes 

 towards cotton, and the colours obtained were unaffected by washing. The 

 dyeing was effected by dissolving "15 grain of the dye stuff (3 per cent, on the 

 weight of cotton) in a little warm water, and adding it to 100 c.c. of water 

 containing 2 per cent, of sodium chloride and 2 per cent, of sodium carbonate. 

 To the dye-bath was added 5 grams of the thoroughly washed cotton, and the 

 whole was slowly raised t" boiling point, and finally boiled for one hour. 



The colours obtained with the different compounds varied over a wide 

 range, as is shown in the following table: — 



Adji 



Description. 



(oi.ni u in Solution. 



Shade on Cotton. 



Sulphanilic acid. 



• iranee-red powder, 



Deep red, 



Canary yellow. 



Dimethylaniline, 



Dark blue powder. 



Deep red. 



Deep purple. 



N.iphthionic acid, . . 



Dark blue powder. 



Bright red, 



Purple. 



a-Xaphthylamine, . . 



Dark red powder, 



Deep red, 



Navy blue. 



B-Naphthylamine, .. 



Reddish powder, 



Deep red, 



Violet red. 



Salicylic acid, 



Reddish brown powder, . . 



Yellow 



Orange. 



Schiiffer's acid. 



Dark blue powder. 



Deep red 



Light purple. 



"R-aciJ," .. 



Reddish blue powder, . . 



Deep red, 



Violet red. 



"G-acid," .. 



Reddish powder, 



Deep red. 



Pink. 



"H-acid," .. 



Blue powder, 



Deep blue, 



Light blue. 



Pyrocatechin, 



Dark blue powder, 



Dark golden, 



Light brown. 



Resorcin, 



Dark purple powder. 



Light cherry-red, . . 



Maroon. 



Hvdroqurnone, 



Brown powder, .. 



Light amber, 



Buff. 



Pyrogallol, 



Chocolate brown powder. 



Light amber, 



Buff. 



Gallic acid, 



Dark brown powder, 



Light brown, 



Very light brown. 



It will be seen from the above table that the compounds obtained by 

 coupling the tetrazo derivative with hydroquinone, pyrogallol, and gallic acid 

 gave rather poor shades on cotton, whereas most of the other compounds gave 

 good colours. There is a very strikin" difference in the shades produced when 

 a- and /j-naphthylainines are used as adjuncts, the former giving a navy blue 

 and the latter a violet-red colour. On the whole, the amino compounds seem 

 to give bluer colours than the hydroxy compounds. 



Apart from the dyeing properties of these tetrazo derivatives, it is 

 possible that they may prove of importance in the chemotherapy of Spirilla. 



