354 Experiments and Olscrvulions on Lac. 



liut this, is not to be regarded as the total quantity, for A 

 part is obstinately retained by the resin and other ingre- 

 dients, so that it cannot be completely separated ; and 

 moreover, very considerable variations must be expected in 

 diftcrent samples. 



Fine seed lac did not aflbrd more than 2^ or 3 per cent. 

 nf the colouring substance ; and shell lac, when treated in 

 the ^ame manner, (?". e. merely with water) did not yield 

 more than ^ per cnit. 



2. Alcohol dissolves a considerable portion of each of 

 the different kinds of lac ; and, when heat is not employed, 

 the dissolved part is resin, combined with some of the co- 

 louring matter ; but, if the lac is digested with heated alco- 

 hol, then the solution is more or less turbid, in consequence 

 of some of the other ingredients becoming mixed and sus- 

 pended; so that it is afterwards extremely difficult to obtain 

 It in a state of purity and transpairency, either by repose or 

 by filtration. 



The resin may be obtained by immediately subjecting the 

 solution to evaporation or distillation, or by previously 

 pouring it into water with which a small quantity of muri- 

 atic or acetic acid has been mixed ; for thus, when the w hole 

 18 heated, a curdy precipitate of resin is formed, and may be 

 separated by a filter, after which, the liquor may be evapo- 

 rated, in order to obtain any resin or otlier substance, which 

 mav remain in solution after the first operation. 



The solution formed by digesting slick lac in alcohol, 

 without heat, is of a dark brownish-red colour, and th- 

 insolublc part subsides, in the state of a dark coloured 

 magma; this r.'ains the greater part of th« colouring mat- 

 ter, which, as 1 have already observed, is most easily solu- 

 ble in water. 



The proportion of resin thus dissolved, when slick lac is 

 treated w iih alcohol, has, in n)y expeeimcuts, amounted to 

 07 or 68 per cent, but this must depend on the quality of 

 the samples. 



The seed lac which I- exannned was very pvire, and yield- 

 ed to alcohol about SS per cent, of resin: it contained but 

 little of the colouring matter; and the other substances 

 subsided, and formed a cloud at the bottom of the glass 

 vessel. 



Shell lac in small fragments, by simple digestion with 

 alcohol, aflbidcil in the first instance nearly SI per cent. Part 

 of the resin, however, still remained mixed with the resi- 

 duum, and could not be ;cparHtcd but by subsequent opera- 

 tic us : this part amounted to abbut 1<»; so that the total 



quantitj 



