the Adrianople Red, and other fixed Colours. 3 13 



sinous, and that drving oils boiled with metallic oxides be- 

 conic thick and hard in consequence of their combination 

 with oxygen. It wa^ also for this reason that my skains, 

 covered with a mixture of boiled linseed oil, were exposed 

 during the whole day to the air, extended and insulated on 

 poles ; but I then supposed them to be saturated uith oxygen, 

 and consequenllv incapable of producing th-c least accident. 

 I was so secure in this point that I caused a great deal of 

 iniprcgnattid cotton to be dried at several times in warm 

 apartments; they v/ere not deranged but at the moment 

 when thev were washed in order to be dyed. It may hovv-- 

 cver be possible that the proportion of a thirty-sixth part 

 of boiled linsci-d oil, mixed with an alkaline solution ox alu- 

 minc, may be insulHcient to excite spontaneous inflamma- 

 tion in skains of cotton heaped up after they have been 

 dried. Those, therefore, who are induced, on account of 

 thesimplicitv of the process, to employ a mixture of boiled 

 linseed oil with an alkaline solution of alunsinc, must take 

 the precaution to leave the skains extended and insulated on 

 poles, until thev are to be washed, previous to the operation of 

 dyeing, which, together with the brightening, conjpletelv re- 

 moves the excess of oil, and leaves only the portion satu- 

 oted with ox^•gen ; so that no fears need aflcr\\ards be en- 

 tertained. 



Since the publication of mv memoir, I have convinced 

 Kiysclf that the simplest brightenino' of Adrianople red, bv 

 wJiich the liveliest and most durable shades arc obtained, 

 consists merelv in very long ebullition in bran water in a 

 boiler furnished with a cover, having in the middle a pipe 

 to suffer the vapours to escape, and prevent the burstinfr of 

 the vessel ; care only must be taken to renew the water a'^ 

 often as it becomes red ; that is to sav, two or three times ai 

 the commcucement of the ebullition. Withoat this pre- 

 caution the skains would continuallv resume the fawn-co- 

 loured parts which the bran water removes, and would never 

 acquire a bright colour. 



One may avoid all danger without lessening much the 

 simplicity of my process, whether the skains be lieaped up or 

 not : nothing is necessarv but to applv at two different tlme-^ 

 a stratum of olive oil, very much divided, after thev have 

 been well lixiviated, washed, and dried. For this purpose, 

 a ley is formed of carbonate of potash or soda, which indi- 

 cates one degree, or a degree and a half, of (be areometer 

 for saltpetre. Some drops of olive oil arc then dropped into 

 it, to try whether the result will be a milky mixture, or whe- 

 ther the oil will asceiid in its nalurul state to float over the 

 V4 lev: 



