604 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



forms a blue powder, with a few small crystals, and differs 

 from aniline color in having the same color in solution. It 

 dissolves with but little residue in water. An alkali de- 

 stroys its color, but an acid restores it ; and the strongest 

 acids improve, instead of attacking its tint. Unlike aniline, 

 it is not soluble in ether nor alcohol ; and it resists the action 

 of light better than aniline. Unfortunately, its preparation 

 is as yet extravagantly expensive : a pound would cost about 

 $15,000. The process is a secret, and it is to be hoped will 

 be so improved as to cheapen the product. 5 (7,1873,XXiy., 

 191. 



FASHIONABLE GREEN FOR SILK. 



This new green is produced by aniline iodine-green, with 

 the addition of a little w^ater- glass. The dyeing must be 

 carefully done, and the silk added very gradually, to keep it 

 uniform. Since iodine-green is not uniform in quality, if the 

 shade is wanting in yellow, it may be brought to that of the 

 sample by the addition of picric acid, the article then being 

 passed through a diluted acetic-acid bath.- 26 (7, 18*73, 107. 



- USE OF HYDROSULPHITE OF SODA IN DYEING TVITH INDIGO. 



Messrs. Schutzenberger and Lalande announce a new meth- 

 od of dyeing and printing fabrics by means of indigo, in re- 

 gard to which they remark that, in consequence of its insol- 

 ubility in neutral dissolvents, whether acid or alkaline, the 

 coloring matter of indigo can only be fixed upon the textile 

 fibre after being previously reduced that is, converted into 

 white indigo, soluble in alkalies and alkaline earths. 



They find, however, that the very strongly reducing prop- 

 erties of the hydrosulphite of soda, in its almost instantane- 

 ous action upon indigo, changing it in the cold state to an 

 alkaline liquid or white indigo, suggests the practical use of 

 this salt in the various applications of indigo in dyeing and 

 printing. The memoir, w^hich is contained in the Moniteur 

 Scientifique, gives first the details of the manipulation for 

 dyeing, and then for printing, and is accompanied by speci- 

 mens of the general effect produced. 



The colors obtained, according to these gentlemen, are very 

 beautiful, and possess a very distinctive outline. Tlie new 

 blue which they produce requires no treatment, after print- 



