empldyed in the Art of Dyeing. 1 77 



vool which we purified, required 200 quarts of distilled 

 water, at lOO degrees o\' heat (212 F.) divided into 20 suc- 

 cessive operations, each occupying from seven to eight 

 hours. VVhen calcined and properly tried, it afforded nei- 

 ther lime nor muriatic acid. 



One hundred grammes of this v^ool were alumer! with 

 the same care which had been taken with the silk, ft was 

 afterwards washed twenty times, en)p!oying six quarts of 

 disiilled water, heated to an hundred degrees, fur each 

 washing, fmmediately after the alumino^this woo! took 

 a very deep colour, whilst, alter the last \v"ashing, it would 

 not take any more ccjlour in the dyeing bath, "than some 

 ot the same wool which had never been alumed. These 

 experiments convinced us that the substance which had 

 been fixed in the wool by akiming, and had caused it to 

 receive so deep a colour in the firs't dyeing, had now been 

 carried off by the water. The alum t)ath, when evapo- 

 rated, afforded us, in the stale of crystals, two-thirds of 

 the quantity of alum we had originally employed ; very 

 nearly the whole of the remaining third part was obtained 

 from the residue of the bath, in an uncrystallized state, and 

 from the washings of the wool. This experiment was re- 

 peated several times*, and al\vays with the same result; but 

 as this did not appear to us so decisive as the experiment 

 upon siik, on account of the difficulty of separating the 

 animal matter from the last portions- of the alum bath, we 

 alumed some wool in the cold, as we had done with the 

 silk, being persuaded that in this case the bath would not 

 sensibly dissolve this substance. 



We alumed in the cold, some clean wool with all the 

 precaution observed with the silk, and we obtained from 

 the bath and the washings the alum ctnploved in the ope- 

 ration, with a loss only of -^^~ part ; we were therefore 

 assured, that in the aluining of all animal substances, the 

 alum combines entirely with them, without undergoing any 

 decomposition, and that it forms with them c(.'m%inations 

 more or less soluble, which have a great affinity for the co- 

 louring matters. 



Art. 3. — Anahjsi<i of (he Impregnation of Cotton and 

 Thicad li'ilh Alum. 



Having freed some cotton, by the methods already men- 

 tioned, from all foreign matters, we macerated it for two 

 days in a lukewarm solution of a given quantity of alum. 

 Alter this operation the stuff took the dye remarkably 

 well; but being treated with boiling distilled water, il lost 



Vol.39. .No. IG7. .'^iti/c/t 1812. M the 



