M. TECHNOLOGY. 491 



same manner as ungummed silk. In dyeing brown, place 

 the silk, before ungumming it, in a tin composition of 32 

 Baurae, rinse it, on removal from this, three times, ungum 

 it, and dye in a fresh bath of alum, indigo carmine, fustic, and 

 logwood, according to the shade desired. 24 (7, XXXIII. , 

 1875,260. 



BEAUTIFUL BLACK FOR STRAW HATS, ETC. 



The following process, which is said to afford a beautiful 

 and durable black on straw hats, can be readily applied, 

 if desired, with but little trouble or loss of time by cloth 

 dyers : The hats are first placed for several hours in a mod- 

 erately strong soda or lye bath, and, after rinsing from it, 

 are steeped overnight in an old sumac or gall bath. On 

 removal from this, they are allowed to drain off well, and 

 placed for two or three hours in a pyrolignate of iron bath. 

 They are then exposed to the air for some time, when they 

 almost blacken, and rinsed, and dyed up lukewarm with log- 

 wood, and drawn through a weak solution of glue, and dried 

 and brushed. 5 (7, XXXIX., 1875, 312. 



DYEING BLACK WITH CERIUM SALTS. 



Professor Bottger calls the attention of the Physical So- 

 ciety of Frankfort to the recent introduction of the bisul- 

 phate of cerium in dyeing, especially to the production with 

 it, in connection with chloride of aniline, of an intense deep 

 black on cotton yarns and fabrics. He found that by dip- 

 ping the yarn several times, alternately, in a solution of chlo- 

 ride of aniline, slightly acidified with hydrochloric acid, and 

 in a solution of bisulphate of cerium, and finally in a solu- 

 tion of bichromate of potash, it acquired a remarkably beau- 

 tiful black color. 5 6', XXXVIL, 1875, 295. 



NEW BLACK FOR WOOL. 



Wool dyed black according to the following recipe, it is 

 said, does not rub off in the least, while the fibres remain 

 loose and open, and it has a desirable reddish cast. Boil the 

 thoroughly washed wool well for an hour and a half in a 

 bath composed, for one hundred pounds of wool, of two and 

 a half pounds ofchromate of potash, two and a half pounds 

 of alum, one half pound of blue vitriol, and two pounds of 



