[ 38. ] 



change of colour, or vifible • alteration enfue, ht 

 affured fuch liquor is free from lead, or metallick 

 adulteration. 



adly. If the liquor contain the flightefl: impreg- 

 nation of lead, as litharge, or fugar of lead, (the 

 fubftances generally employed for the purpofes of 

 adulteration) on adding the teft a precipitation will 

 cnfue of a dujky brown /ediment. 



3dly. If the fufpe6led liquor be high coloured, 

 it muft be previoufly diluted with treble its quantity 

 of diftilled water, or the change will not be fuf- 

 ficiently perceptible: and care muft be taken to 

 add deliberately from three to fix drops onlyy atten- 

 tively marking the alteration, A larger quantity 

 may re-diflblve the precipitate, and foon render 

 it invifible, 



4thly. As iron and other metals may produce a 

 change of colour and precipitation, if any doubt 

 ihould arife concerning the nature of the precipi- 

 tate, let a quart of the fufpe<5ted liquor be evapo- 

 rated in a large crucible to an extract, and after- 

 wards cal':ined in a red heat. When it is cold 

 the metallick particles may be difcovercd in their 

 proper form in the aflies. — Or the precipitate may 

 be examined without a tedious evaporation, if it 



be 



