2(5 PrOi-ifi ftr BUachiiig Raw Si/l, 



fliewn that the maviiie acul is preferable to any other. The proportions admit of much 

 latitude, though he prefers tlie ilofe hereinbefore defcribcd. 



Spirit of wine which lias been mixed with nitrous acid, cannot be ufcd in bleaching, 

 even thougli afterwards reililicd upon an alkali, bccauCe it Hill retains a portion of nitrous 

 pas. 



Pure fpirit of wine withc'ut acid extracts a fine yellow colour from filk, which does not 

 fcparate for years, even thou;;h expofed to the fun's light. Yellow filk cxpofed to the fua 

 lofes its colour in a fiiort time. The acidul.ited fpirit which has been ufcd in the infufion 

 of filk, is changed by cxpofurc to the fun, but not in fuch a manner as to be rendered fit 

 for ufe a fecond time. 



In order to obtain a beautiful white oolour, it is cCfential that the filk fliould be immerfed 

 in a large quantity of the fluid, efpecially at the firll infufion. Without this management 

 it would become neceflary to make three infufions in the acidulated fpirit. When the firft 

 infufion is well managed, the filk will have loft all its yellow colour, and become confi- 

 derably white, at the fame time that the liquor will have begun to change colour a little. 

 As long as it continues of a fine green, it is certain that it has not exhaufted its whole action 

 upon the filk. 



The duration of this -firft infufion may be longer or fliorter, without inconvenience, ac- 

 cording to the temperature. When the temperature is at 20 degrees of Reaumur, which 

 anfwers to 77 of Fahrenheit, the firft infufion is often made in ten or twelve hours. In 

 fmall experiments the heat of the atmofphere may be fupplied by the water-bath ; in which 

 cafe, all the infufions arc eafily made in the courfe of a day. 



When the firft infufion is finiftied and the liquor drawn off, the filk appears greenifh : the 

 fubfequent wafliings in fpirit of wine clear it of the liquor it retained. This fprinkling 

 fliould be made with the watering-pot, otherwife the quantity poured will be greater, and 

 the management more wafteful. 



The cocons may be bleached in this way, but the inconveniences are too great to render 

 this procefs defirable. 



Pieces of gauze and entire garments of filk have been fuccefsfully bleached in this way. 



The fineft natural white filks are rendered infinitely whiter by this procefs. Spirit of 

 ■wine alone has the property of depriving yellow filk of its colour, which it brings to the 

 ftate of the naturally white filk. In this ftate the filk is difpofed to acquire a greater de- 

 gree of brightnefs by a Gngle infufion in the acidulated' fpirit. This procefs has its ad- 

 vantages over the other, to which it is alfo inferior in certain refpccls ; concerning neither 

 of which the author has entered into any detail. 



The colouring matter was found to be a refin perfeiSlly animalized, affording by diftilla- 

 tion the fame produ£ts as other animal matters, and the concrete volatile alkali. 



Silk whitened by fcouring may be dried freely in the air without afte£ling its luftre. 

 This h not the cafe with the filk bleached in the gum : if it be left at liberty to dry in the 

 air, it rcfemblcs white flax without any luftre. The beauty of this filk confilts in its fliining 

 brilli.\ncy ; to fccure which, it muft be dried in a ftate of tcnfion. Mr. Baume has contrived 

 a fimplc machine for this purpofe. It confifts of a ftrong fquarc frame of wood ftanding 

 upright upon feet; the upper horizontal bar is fix feet long, and has fu iron pins driven 

 ' through 



