44 



extended, and they attracted a good deal of attention, and 

 led to a further utilisation of Tusser silk, then a drug in 

 the market, except for dress silks for women and girls in 

 the undyed and pleasing shade natural to it, which is fawn 

 colour. 



The development up to that time had been that this 

 silk could be dyed into any middle or dark shade of drab, 

 slate, brown, green, violet, or dark red, whilst to pale 

 shades of blues, pinks, cerise, scarlet, and others the dark 

 natural ground colour of the silk interposed an insuperable 

 barrier, as sulphur, or any then known bleaching agent, 

 could not reduce the silk to a winter state. 



The desideratum of pale shades led our quick French 

 neighbours to study the composition of the brown-colouring 

 matter, and to find a solvent for it. The credit of this 

 achievement must be awarded to the late M. Tessie' du 

 Motay, who was led to try permanganate of potash, which 

 was at that time attracting much attention on account of 

 its great oxidising power on organic matter. He found 

 the browny colorant yielded to this agent. Unfortunately, 

 the oxidising action being too violent, the fibre of the silk 

 as well as its coloration was affected, and by the time 

 it became white enough for dyeing into pale colours the 

 silk was rendered useless. However, a secret had been 

 discovered ; and it was this, that oxygen, under certain 

 combining conditions, united with the colouring matter, 

 which then became separated from the silk. 



The object now was to apply the oxygen under gentler 

 conditions. This M. Tessie^ du Motay again succeeded in 

 doing, and in a very ingenious way. He brought into 

 contact with the silk an insoluble body ; this, on contact, 

 should yield up an atom of oxygen, in the nascent form, 

 which should gently unite with the fawn-coloured matter 

 of the silk without attacking the fibre. This, although a 

 rough method, solved the difficulty, and the silk can now 

 be bleached so as to have a sufficiently pale ground to 

 admit of its being dyed into any pale colour except 

 white. 



The substance he found to comply with the required 

 condition is binoxide of barium. Unfortunately, the process 

 is expensive. It costs almost 2s. per lb. to use and apply 

 it. This, in addition to the cost of dyeing, prevents its 

 being used as extensively as it would be if it were as cheap 

 as the mode of bleaching ordinary silk, which is by 

 sulphurous acid; but there is a probability of the principle 

 being shortly applied by other methods which will be at 



