Procefifor Bleaching Raw Silk. 37 



through it at equal dlflanccs, fo as to projctl on each fiJe for the puvpofe of receiving 

 twelve bobbins. The lower horizontal bar is moveable up and down in a mortice by 

 pieans of a fcrew at each end : it is furniflied with fix holes, adapted to rec&ive as many 

 pins to correfpond with thofe above. The Ikains of filk are to be drefltd and arranged 

 upon wooden pins, as they are taken out of the fack from wafl.ing. As foon as there are 

 twelve together, they are to be wrung with a flaff; after which the ikains are to be hung 

 one by one upon as many bobbins put upon the upper pins of the fquare frame. Another 

 bobbin with tails is to be inferted in the lower loop of the ft.iin, and faftened to the cor- 

 refponding piri of the lower bar, by means of a ftrap and hook, which need not be de- 

 fcribed to fuch as are flightly acquainted with mechanical objetls. When the machine is 

 thus fupplied with fkains on both fides, the lower bar of the frame is to be prelTtd down by 

 the fcrews until the filk is moderately ftretched. When it is dry, the fcrews are to be 

 equally flackened, the fkains taken off, and folded with a flight twlft, that they mny.not be- 

 come entangled. 



After this defcription of the whole of his procefs, the author proceeds to make certain 

 general remarks on the white China filk. He obferves, that in-hls procefs the filks acquire 

 the perfett whitenefs without much handling, and confequently that there is little caufe 

 for them to become entangled. Accordingly the lofs in unwinding is found to be no greater 

 than when they are unwound in the yellow ftate : that is to lay, from a dram to a dram 

 and a half in the pound. This faving is of the greateft importance in the price of the filk. 



The filk of Nankin, which he fuppofes to be bleached by fome procefs of the fame na- 

 ture, is probably handled much more. The lofs is neatly twclv^e per cent, when it comes 

 to be opened, and not unfrequently even twenty-five per cent. ;'a lofs whicK cannot in any 

 refpea arife from the package. The ,quality of the Nankin filk differs much in the pack- 

 age ; the external part being always of the beft quality, and that whith is packed withia 

 is^'of fuch an inferior quality as fometimes not to exceed half the value. On examining 

 this filk, it not only exhibited unequivocal marks of alkali, but its imperfedions were alfo 

 of the fame kind as thofe which had occurred to Mr. B:ume during the prcgreffive im- - 

 provement of his own manipulations. The beft China filk was neither improved nor in- 

 jured by the procefs of Baume ; whence he concludes that they are not naturally white, but 

 have undergone a procefs fimilar to his. 



The refult of the whole is, that the yellow filks of Europe may be bleached to equal or 

 greater perfeftion than thofe ofNankin; and that thefe maybe even greatly exceeded by 

 winding the naturally white filk apart from the other, and bleaching it by itfelf. 



The methods of recovering the fpirlt fo as to be ufed again, and of obtaining the marine 

 acid in therequifite ftate of purity, will be defcribed in our next. 



IX. 



On the Hydrometer of Baume. 



As many French chcmifts refer to the pefe-liqueur of Baume, which has never, hetn 

 ufcd in this country, it will be of advantage to defcribe the method by which it is Con- 

 ftrudlcd, and flicw the fpccific gravities indicated by the graduations upon the Rem. In- 



ftead 

 3 



