AND OBSERVATIONS ON LAC. 49 



5. Nilric acid applied to Jac emits nitrous gas at firft, and NJtrIc ac ' ld b y 

 caufes the lac to fwell much at the fame time that it converts it tJ[ ^ e dinolves^t. 

 into a deep opake yellow briuie fubftance, which by a fufficiency 



of nitric acid, and continuance of the digeftion for 48 hours, 



is diffolved. The folution however is turbid, and when poured The folution is 



into a large quantity of diftiiled water, depofits fome yellow-^ 1 ^ ^"^ 



ifh flocculi, which, being collected, are found to be a fort of a wax. 



wax. 



The filtrated liquor is of a bright golden yellow ; and, when The filtered 



faturated by ammonia, changes to orange colour, but does not folution contains 

 • I, . ., , c ,. ,. ., a yellow matter. 



yield any precipitate, nor any traces or oxalic or malic acid. 



This yellow nitric folution is converted, by evaporation, into Its properties, 

 a deep yellow fubftance, which burns like refin, but is foluble &c ' 

 in boiling water. 



The alkalis and lime, being added to this aqueous folution, 

 do not produce any precipitate, but the yellow colour is very 

 confiderably deepened; and, by evaporation, an orange-coloured 

 fubftance is obtained, which is ftill eafily foluble in water, and 

 confifts of the deep yellow fubftance above-mentioned, com- 

 bined with the alkali or lime. 



6. Muriatic acid dilfolves the colouring matter and gluten 6; Muriatic acid 

 of lac ; but its a£tion on thefe is feeble, unlefs the refin has been co ] ounnE; matter 

 previoufly feparated. and gluten. 



7. Acetous acid, in its ejfefts, much refembles muriatic 7- Acetous acid. 

 acid. 



8. Stick lac, feed lac, and (bell lac, are partially diflblved by 8. Acetic acid 



acetic acid ; and, if this be heated, a confiderable portion is a & s u P on the 



r whole except the 



taken up. wax . 



The diflblved part confifis of the colouring extracl, of refin, 

 and of gluten ; the wax being the only ingredient which is in- 

 foluble in this menftruum; but a portion of the former fubftances, 

 being enveloped by the wax, are protected from the a&ion of 

 the acetic acid. 



The acetic folution of lac becomes turbid when cold, and 

 depofits part of the refin; a portion however remains in folu- 

 tion, and may be precipitated by water ; after which, the liquor 

 retains fome gluten and colouring extract, which may be pre- 

 cipitated by faturating the acid with an alkali, and by fubfequent 

 boiling. 



For the reafons above ftated, it would be difficult to efTe£t a 

 complete folution of lac by means of acetic acid ; but this may 



Vol. X. — January, 180.5. E nevertheless 



