THE TECHNOLOGIST. [Nov. 1, 1864. 



Ib2 ON CHEMISTRY APPLIED TO THE ARTS. 



change, the stearine and oleine being ouly converted into an 

 emulsion. From experiments I have made, I am able to state 

 that the common opinion, that the differences in qnality observed 

 in various wools are owing to their fatty matters, is erroneous, for 

 the pure wool, obtained as above, yielded to the dyer colours as 

 brilliant as those presented by wools in which a part of the fatty matter 

 still remained. Another important fact connected with the composition 

 of wool is the quantity of sulphur it contains, which does not appear to 

 be part of the fibre, as the matter containing it can be removed by a 

 weak alkali, without destroying the fibrous appearance of the wool, 

 although its tenacity is greatly impaired, and its power of taking dye 

 considerably diminished. Another remarkable fact is, that when wool 

 is bleached by sulphurous acid (the only agent known which will effect 

 that purpose), it becomes incapable of taking many colours, especially 

 the new and brilliant coal-tar dyes. The long-disputed question 

 amongst chemists — How sulphurous acid operates so as to bleach wool ? 

 —has lately been solved by Messrs. Leuchs and "Weber, who have 

 proved that sulphurous acid unites with the colouring matter of the wool, 

 forming a colourless compound ; in proof of which it appears that if the 

 wool is placed in boiling water this colourless compound is dissolved, 

 and the wool regains its susceptibility to dyes, though it is slightly dis- 

 coloured. A small amount of alkali added to the boiling water greatly 

 facilitates the removal of this artificial sulphuretted compound. In a paper 

 lately published by Mr. Grothe, he states that 100 parts of wool fix on 

 an average - 67 of sulphur, or T31 of sulphurous acid to bleach it, and 

 practically 100 parts of wool require about five parts sulphur to be 

 burnt to produce the result. I should also add that wool must always 

 be wet before being submitted to the fumes of sulphur, and it is most 

 advantageous to pass it previously through a soap lye or weak alkali. 

 Wool so bleached should always be well washed in cold water, to remove 

 the excess of sulphurous acid, which otherwise, if the wool were subse- 

 quently exposed to moisture, might be converted into sulphuric acid and 

 destroy the fibre of the wool. It may be interesting to ladies to know the 

 process used by a French scourer, named Jolly, to restore Cashmere shawls 

 discoloured by time. It consists in dipping them into a solution of sul- 

 phurous acid, which bleaches the wool but does not affect the fast 

 colours with which the fibres composing the patterns of the shawls are 

 dyed. The shawls then only require to be washed and pressed to be 

 restored to their original beauty. There is no doubt in my mind that a 

 solution of sulphurous acid might be substituted for the gas in bleach- 

 ing wool with advantage and economy, owing to the sulphurous acid 

 being in a more condensed form, and in better condition for effecting 

 the bleaching process. A few years ago, I took advantage of the fact 

 that wool contains sulphur to produce upon it an artificial lustre. 

 The woollen goods were passed through a weak boiling solution of 

 acetate of lead, washed carefully in pure water, and submitted to 



